A surgical instrument for implanting a humeral component

0001The present invention relates generally to orthopaedic implants, instruments, and surgical methods, and more particularly to a stemless humeral component of an orthopaedic shoulder implant, along with its associated surgical instruments and methods.

0002During the lifetime of a patient, it may be necessary to perform a shoulder replacement procedure on the patient as a result of, for example, disease or trauma. In a shoulder replacement procedure, a humeral prosthesis is used to replace the natural head of the patient's humerus. The humeral prosthesis typically includes an elongated stem component that is implanted into the intramedullary canal of the patient's humerus and a generally hemispherically-shaped prosthetic head component that is secured to the stem component. In some shoulder replacement procedures, the natural glenoid surface of the scapula may be resurfaced or otherwise replaced with a glenoid component that provides a bearing surface upon which the prosthetic head component of the humeral prosthesis articulates.

0003<patcit id="pcit0001" dnum="US2009264889A"><text>US 2009/264889</text></patcit> describes a bone cutting assembly that includes a guide pin that may be securely inserted into a bone to define a cutting axis. The bone cutting assembly also includes a housing having a cam surface and features for temporarily fastening the housing to the bone. The bone cutting assembly also includes a burr mounting arm that rotatably and slidably fits onto the guide pin so that the arm can swing around the cutting axis and also translate up and down the guide pin. A user may move the burr mounting arm about the cutting axis so that the arm follows along the cam surface of the housing.

0004The invention is defined in the accompanying claims.

0005According to an aspect of the invention, there is provided a surgical instrument for use during a surgical procedure to implant a stemless humeral component to replace the humeral head of a patient's humerus, comprising: <ul id="ul0001" list-style="none" compact="compact"><li>a drill guide having a guide body comprising: <ul id="ul0002" list-style="none" compact="compact"><li>a planar lower surface;</li><li>an elongated boss secured to, and extending downwardly from, the lower surface; and</li></ul></li><li>a stepped upper surface defining a plurality of discrete planar drill-stop surfaces,</li></ul> in which: <ul id="ul0003" list-style="none" compact="compact"><li>each of the drill-stop surfaces of the stepped upper surface is spaced apart from the lower surface by a distance that is different than at least some of the other drill-stop surfaces; and</li><li>each of the drill-stop surfaces has a number of drill guide holes (730) formed therein, the drill guide holes extending through the guide body and opening into the lower surface.</li></ul>

0006The detailed description particularly refers to the following figures, in which: <ul id="ul0004" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> is a medial perspective view of stemless humeral component.</li><li><figref idref="f0001">FIG. 2</figref> is a lateral perspective view of the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0002">FIG. 3</figref> is a medial elevational view of the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0002">FIG. 3</figref> is a lateral elevational view of the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0003">FIG. 5</figref> is an enlarged cross-sectional view of the stemless humeral component taken along the line 5-5 of <figref idref="f0002">FIG. 3</figref>, as viewed in the direction of the arrows.</li><li><figref idref="f0004">FIG. 6</figref> is a perspective view of an impaction handle that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0004">FIG. 7</figref> is a cross-sectional view of the impaction handle taken along the line 7-7 of</li><li><figref idref="f0004">FIG. 6</figref>, as viewed in the direction of the arrows.</li><li><figref idref="f0005">FIG. 8</figref> is a perspective view of an alignment handle that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0005">FIG. 9</figref> is a cross-sectional view of the alignment handle taken along the line 9-9 of</li><li><figref idref="f0005">FIG. 8</figref>, as viewed in the direction of the arrows.</li><li><figref idref="f0006">FIG. 10</figref> is a medial perspective view of a sizing instrument that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0006">FIG. 11</figref> is a lateral perspective view of the sizing component of <figref idref="f0006">FIG. 10</figref>.</li><li><figref idref="f0006">FIGS. 12 and 13</figref> are perspective views of a trial head component that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0007">FIG. 14</figref> is a perspective view of a surgical punch that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0007">FIG. 15</figref> is an elevational view of a centre drill that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0007">FIG. 16</figref> is an elevational view of a peripheral drill that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0008">FIG. 17</figref> is a perspective view of a head resection guide that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0008">FIGS. 18 and 19</figref> are side elevational views of the head resection guide of <figref idref="f0008">FIG. 17</figref>.</li><li><figref idref="f0009">FIGS. 20 and 21</figref> are perspective views of an implant insertion tool that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0009">FIG. 22</figref> is an end elevational view of the implant insertion tool of <figref idref="f0009">FIGS. 20 and 21</figref> showing the implant insertion tool positioned in its unlocked position.</li><li><figref idref="f0009">FIG. 23</figref> is a view similar to <figref idref="f0009">FIG. 22</figref>, but showing the implant insertion tool positioned in its locked position.</li><li><figref idref="f0010">FIG. 24</figref> is a fragmentary perspective view of a head impaction tool that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref> (note that a portion of the head impaction tool has been cut away for clarity of description).</li><li><figref idref="f0011">FIGS. 25 and 26</figref> are perspective views showing the head resection guide being used to resect the humeral head of a patient's humerus.</li><li><figref idref="f0012">FIG. 27</figref> is a perspective view showing the sizing instrument being installed on the patient's resected humeral head by use of the alignment handle.</li><li><figref idref="f0012">FIG. 28</figref> is a perspective view showing the trial head component installed on the sizing instrument.</li><li><figref idref="f0013">FIGS. 29 and 30</figref> are perspective views showing the surgical punch being used to punch holes in the surgically-prepared surface of the patient's humerus.</li><li><figref idref="f0014">FIGS. 31 and 32</figref> are perspective views showing the surgical drill being used to drill holes in the surgically-prepared surface of the patient's humerus.</li><li><figref idref="f0015">FIGS. 33</figref> and <figref idref="f0016">34</figref> are perspective views showing the implant insertion tool being used to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref> into the surgically-prepared surface of the patient's humerus.</li><li><figref idref="f0016">FIG. 35</figref> is a perspective view showing the head impaction tool being used to install a head component to the implanted stemless humeral component.</li><li><figref idref="f0017">FIG. 36</figref> is a fragmentary cross-sectional view showing the head component installed in the implanted stemless humeral component.</li><li><figref idref="f0018">FIG. 37</figref> is a perspective view of another implant insertion tool that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0019">FIG. 38</figref> is a perspective view of a different implant insertion tool that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0019">FIGS. 39 and 40</figref> are perspective views of yet another implant insertion tool that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0020">FIGS. 41 and 42</figref> are perspective views of another head resection guide that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0021">FIG. 43</figref> is a medial perspective view of another embodiment of a stemless humeral component.</li><li><figref idref="f0021">FIG. 44</figref> is a lateral perspective view of the humeral component of <figref idref="f0021">FIG. 43</figref>.</li><li><figref idref="f0022">FIG. 45</figref> is a medial perspective view of another embodiment of a sizing instrument that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0022">FIG. 46</figref> is a lateral perspective view of the sizing component of <figref idref="f0022">FIG. 45</figref>.</li><li><figref idref="f0023">FIG. 47</figref> is a perspective view of another embodiment of a surgical punch that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0024">FIG. 48</figref> is a perspective view of another implant insertion tool that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0025">FIG. 49</figref> is a perspective view of a drill guide that may be used in a surgical procedure to implant the stemless humeral component of <figref idref="f0001">FIG. 1</figref>.</li><li><figref idref="f0026">FIG. 50</figref> is a top elevation view of the drill guide of <figref idref="f0025">FIG. 49</figref>.</li><li><figref idref="f0026">FIG. 51</figref> is a bottom elevation view of the drill guide of <figref idref="f0025">FIG. 49</figref>.</li><li><figref idref="f0027">FIG. 52</figref> is a perspective view of another embodiment of a sizing instrument that may be used in conjunction with the drill guide of <figref idref="f0025 f0026">FIGS. 49 to 51</figref>.</li></ul>

0007Terms representing anatomical references, such as anterior, posterior, medial, lateral, superior and inferior, may be used throughout this document to refer to both the orthopaedic implants described herein and a patient's natural anatomy. Such terms have well-understood meanings in both the study of anatomy and the field of orthopaedics. Use of such anatomical reference terms in this document is intended to be consistent with their well-understood meanings unless noted otherwise.

0008<figref idref="f0001 f0002 f0003">FIGS. 1 to 5</figref> show a stemless humeral component 10. As described below, the stemless humeral component 10 is used as a substitute for a conventional humeral intramedullary stem component. In such a way, the stemless humeral component 10 functions as a mounting structure for a humeral head component 12 (see <figref idref="f0016">FIGS. 35</figref> and <figref idref="f0017">36</figref>), but does so without removal of bone tissue from the intramedullary canal of the patient's humerus as would be the case with a conventional humeral stem component.

0009The stemless humeral component 10 includes a support flange 14 having a number of legs 16 extending distally away from a bottom surface 18 thereof. In the illustrative embodiment described herein, the support flange 14 is circular in shape. The top surface 20 of the support flange 14 includes an annular-shaped, bevelled surface 22. An annular ring 24 extends around the periphery of the support flange's bevelled surface 22. The annular ring 24 has a number of suture holes 26 formed therein. The suture holes 26 may be used to suture bone wafers or soft tissue to the stemless humeral component 10. For example, the natural attachment of the patient's rotator cuff may be preserved by harvesting a bone wafer around it and then suturing such a bone wafer to the stemless humeral component 10 by use of the suture holes 26.

0010The support flange's annular ring 24 also has a number of revision slots 28 formed therein. As can be seen in <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">4</figref>, one of the revision slots 28 is positioned on the annular ring 24 at a location above, and radially outwardly from, each of the legs 16. In such a way, an osteotome or other cutting instrument may be passed through the revision slots to cut or otherwise break the bony ongrowth to the legs 16 thereby facilitating removal of the stemless humeral component 10 during a revision procedure.

0011The support flange 14 also has a number of viewing windows 30 formed therein. The viewing windows 30 allow the surgeon to visualize the surgically-prepared humeral surface (i.e., the surface created by surgically resecting the humeral head) to ensure the stemless humeral component 10 is fully seated during surgical implantation thereof. It should be appreciated that the viewing windows 30 may also function as additional revision slots through which the surgeon may pass an osteotome or other cutting instrument slots to cut or otherwise break the bony ongrowth to the legs 16 thereby facilitating removal of the stemless humeral component 10 during a revision procedure.

0012As can be seen in <figref idref="f0001">FIGS. 2</figref> and <figref idref="f0003">5</figref>, an elongated sleeve 36 extends distally away from a bottom surface 18 of the support flange 14 in the same general direction as the legs 16. The sleeve 36 includes a tapered distal end 38 that functions as a lead-in to facilitate insertion into a hole drilled or otherwise formed in the patient's surgically-prepared humeral surface (i.e., the surface created by surgically resecting the humeral head). The elongated sleeve 36 has a tapered bore 40 formed therein. A tapered post 42 extends laterally out of the backside surface of the humeral head component 12 (i.e., the side opposite the humeral head component's generally hemispherically-shaped outer bearing surface) and is received into the tapered bore 40 of the stemless humeral component's elongated sleeve 36 (see <figref idref="f0017">FIG. 36</figref>). As will be discussed below in greater detail below, urging the tapered post 42 of the humeral head component 12 into contact with the sidewall defining the tapered bore 40 of the elongated sleeve 36 taper locks the humeral head component 12 to the stemless humeral component 10. As can be seen in <figref idref="f0003">FIG. 5</figref>, the upper end 44 of the tapered bore 40 opens into the top surface 20 of the support flange 14, with the lower, distal end 46 of the tapered bore 40 opening into a threaded bore 48. The threaded bore 48 extends distally away from the distal end 46 of the tapered bore 40 and opens into the distal end 38 of the elongated sleeve 36. As can be seen in <figref idref="f0003">FIG. 5</figref>, a number of threads 50 are formed in the sidewall that defines the threaded bore 48. The threads 50 are sized to match, and hence threadingly receive, the threads of an implant retraction tool (not shown) or, as discussed in more detail below, an implant insertion tool.

0013As can be seen in <figref idref="f0001">FIGS. 2</figref>, <figref idref="f0002">4</figref>, and <figref idref="f0003">5</figref>, each of the legs 16 is cantilevered and, as a result, includes one end secured to the bottom surface 18 of the support flange 14 with the other end of the leg 16 being free (i.e., not secured to the support flange 14, any of the other legs 16, or any other structure of the stemless humeral component 10). As can also be seen in <figref idref="f0001">FIGS. 2</figref>, <figref idref="f0002">4</figref>, and <figref idref="f0003">5</figref>, each of the legs 16 is generally T-shaped when viewed from a bottom elevational view (i.e., a view that is orthogonal to the longitudinal axis of the leg 16) and, as a result, has a T-shaped lateral cross section (i.e., a cross section taken in the plane orthogonal to the longitudinal axis of the leg). In such an arrangement, each of the legs 16 has a bone-engaging plate 52 having a number of serrations 54 formed in a side thereof that faces outwardly from the elongated sleeve 36 (and hence the centre of the support flange 14). As can be seen best in <figref idref="f0003">FIG. 5</figref>, each of the serrations 54 is angled upwardly in a direction toward the support flange 14 (i.e., in a direction away from the distal end 56 of the leg 16). When implanted in bone tissue, such upwardly angled serrations 54 engage the bone tissue in a manner that resists pullout of the stemless humeral component 10. An elongated rib 58 extends along the length of the engaging plate 52 and, as such, forms the "trunk" of the T-shaped leg 16, with the bone-engaging plate 52 forming its "cross bar". Specifically, the rib 58 is secured to the backside of the leg's engaging plate 52 (i.e., the side opposite the serrations 54) and extends inwardly in the direction toward the centre of the support flange 14. The longitudinal axis of the rib 58 is parallel with the longitudinal axis of the engaging plate 52. As can be seen in <figref idref="f0001">FIGS. 2</figref> and <figref idref="f0003">5</figref>, each of the legs 16 includes a bevelled distal end 62 that functions as a lead-in to facilitate insertion of the leg 16 into a hole punched or otherwise formed in the patient's surgically-prepared humeral surface (i.e., the surface created by surgically resecting the humeral head).

0014As can be seen best in <figref idref="f0001">FIGS. 2</figref> and <figref idref="f0002">4</figref>, the bottom surface 18 of the stemless humeral component's support flange 14 has a number of undercuts 70 formed therein. In the illustrative embodiment described herein, the undercuts 70 are positioned radially around the elongated sleeve 36 about 90o from one another. As can be seen in <figref idref="f0001">FIGS. 2</figref> and <figref idref="f0002">4</figref>, the position of the undercuts 70 coincides with the radial position of each of the viewing windows 30. Specifically, the undercuts 70 are formed in the same sidewall 72 that defines the radially inner surface of each of the viewing windows 30 (i.e., the surface defining the viewing windows 30 closest to the centre of the stemless humeral component 10). Each of the undercuts 70 takes the form of a lip 74 that extends radially inwardly into its corresponding viewing window 30. In such an arrangement, as will be discussed below in more detail, the lips 74 of the undercuts 70 are positioned to be engaged by a locking pawl of an implant insertion tool.

0015The stemless humeral component 10 may be constructed with an implant-grade biocompatible metal, although other materials may also be used. Examples of such metals include cobalt, including cobalt alloys such as a cobalt chrome alloy, titanium, including titanium alloys such as a Ti6A14V alloy, and stainless steel. Such a metallic stemless humeral component 10 may also be coated with a surface treatment, such as hydroxyapatite, to enhance biocompatibility. Moreover, the surfaces of the stemless humeral component 10 that engage the natural bone, such as the bottom surface 18 of the support flange 14, the outer surfaces of the elongated sleeve 36, and the legs 16, may be textured to facilitate securing the component to the bone. Such surfaces may also be porous coated to promote bone ingrowth for permanent fixation.

0016The stemless humeral component 10 and the head component 12 may be provided in various different configurations to provide the flexibility necessary to conform to varying anatomies from patient to patient. For example, the stemless humeral component 10 and the head component 12 may be provided in various diameters to match the needs of a given patient. It should be appreciated that the head thickness changes with the diameter of the head.

0017<figref idref="f0004 f0005 f0006 f0007 f0008 f0009 f0010">FIGS. 6 to 24</figref> show a set of surgical instruments that may be used for the surgical preparation of the patient's humerus and the subsequent implantation of the stemless humeral component 10. The first of such instruments is an impaction handle 80 shown in <figref idref="f0004">FIGS. 6 and 7</figref>. As described below, the impaction handle 80 may be secured to a surgical punch or the stemless humeral component 10 to facilitate implantation of the stemless humeral component 10 into the patient's surgically-prepared humeral surface (i.e., the surface created by surgically resecting the humeral head). The impaction handle 80 includes an elongated body 82 having an impact head 84 on one end and an attachment mechanism 86 on its other end. A sleeve 88 is positioned around, and immovably coupled to, the outer surface of the impaction handle's body 82 such as by, for example, over-moulding. The sleeve 88 functions as a grip for allowing the surgeon to hold the impaction handle 80 during a surgical procedure to implant the stemless humeral component 10.

0018The impact head 84 of the impaction handle 80 includes a circular metal plate 90 having an extraction flange 92 extending therefrom. In use, the surgeon holds the impaction handle 80 via the grip 88 and strikes the metal plate 90 with a surgical mallet, sledge, or other impaction tool to drive the surgical punch 240 (see <figref idref="f0007">FIG. 14</figref>) or the stemless humeral component 10 into the patient's surgically-prepared humeral surface.

0019The attachment mechanism 86 of the impaction handle 80 includes a lever 94 pivotally coupled to the impaction handle's body 82. The lever 94 includes a latching arm 96 and an actuation arm 98 extending at an angle from one end of the latching arm 96. A locking pawl 102 is positioned at an opposite end of the latching arm 96 and extends downwardly therefrom. The locking pawl 102 is configured to engage a lip or similar structure formed in one of the surgical instruments described herein (e.g., the surgical punch or the implant insertion tool) to selectively secure such instruments to the impaction handle 80. A connecting pin 104 is formed in the distal end of the impaction handle's body 82. The connecting pin 104 extends outwardly from an annular face 106 and has a cross section that substantially matches the shape of the corresponding opening defined in a number of the surgical instruments described herein (e.g., the surgical punch or the implant insertion tool). As shown in <figref idref="f0004">FIG. 6</figref>, the connecting pin 104 is substantially D-shaped in cross section and, as a result, includes a flat face 108.

0020The latching arm 96 of the lever 94 extends beyond the annular face 106 such that the locking pawl 102 is positioned over the connecting pin 104 and extends toward its flat face 108. This arrangement permits the locking pawl 102 to engage a lip or similar structure formed in a number of the surgical instruments described herein (e.g., the surgical punch or the implant insertion tool) to selectively secure such instruments to the impaction handle 80.

0021As shown in <figref idref="f0004">FIG. 7</figref>, a biassing element, such as spring 110 is coupled to the lever 94. The spring 110 biasses the lever's locking pawl 102 toward the flat face 108 of the connecting pin 104. In doing so, the bias of the spring 110 locks the locking pawl 102, and hence the impaction handle 80, to a number of the surgical instruments described herein (e.g., the surgical punch or the implant insertion tool). When a surgeon or other user presses down on the lever's actuation arm 98, the bias exerted by the spring 110 is overcome, thereby causing the lever 94 to pivot. As the lever 94 is pivoted, the locking pawl 102 is moved in a direction away from the flat face 108 of the connecting pin 104. In such a way, the impaction handle 80 may be released from the surgical instrument to which it is coupled.

0022The metallic components of impaction handle 80 (e.g., the impact handle's body 82) may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used. The grip 88 may be constructed from a polymer such as silicone.

0023Referring now to <figref idref="f0005">FIGS. 8 and 9</figref>, there is shown an alignment handle 120. As will be described below in more detail, the alignment handle 120 may be secured to a sizing instrument or cutting guide during a procedure to implant the stemless humeral component 10 into the patient's surgically-prepared humeral surface (i.e., the surface created by surgically resecting the humeral head). The alignment handle 120 includes an elongated body 122 having an attachment mechanism 126 on its distal end. A sleeve 128 is positioned around, and immovably coupled to, the outer surface of the impaction handle's body 122 such as by, for example, over-moulding. The sleeve 128 functions as a grip for allowing the surgeon to hold the alignment handle 120 during a surgical procedure to implant the stemless humeral component 10.

0024The attachment mechanism 126 of the alignment handle 120 is similar to the attachment mechanism 86 of the impaction handle 80 and, as such, includes a lever 134 pivotally coupled to the impaction handle's body 122. The lever 134 includes a latching arm 136 and an actuation arm 138 extending at an angle from one end of the latching arm 136. A locking pawl 142 is positioned at an opposite end of the latching arm 136 and extends downwardly therefrom. The locking pawl 142 is configured to engage a lip or similar structure formed in the sizing instrument 160 (see <figref idref="f0006">FIG. 10</figref>) to secure the sizing instrument 160 to the alignment handle 120. A keying pin 144 is formed in the distal end of the alignment handle's body 122. The keying pin 144 extends outwardly from an annular face 146 and has a cross section that substantially matches the shape of the corresponding key-hole shape opening 184 defined in the sizing instrument 160 (see <figref idref="f0006">FIG. 10</figref>). As shown in <figref idref="f0005">FIG. 8</figref>, the keying pin 144 is key-shaped in cross section and, as a result, includes a round portion having a rectangular portion secured thereto.

0025The latching arm 136 of the lever 134 extends beyond the annular face 146 such that the locking pawl 142 is positioned over the keying pin 144 and extends toward its upper surface. This arrangement permits the locking pawl 142 to engage a lip or similar structure formed in the sizing instrument 160 (see <figref idref="f0006">FIG. 10</figref>) to secure the sizing instrument 160 to the alignment handle 120.

0026As shown in <figref idref="f0004">FIG. 7</figref>, a biassing element, such as spring 150 is coupled to the lever 134. The spring 150 biasses the lever's locking pawl 142 toward the upper surface of the keying pin 144. In doing so, the bias of the spring 150 locks the locking pawl 142, and hence the alignment handle 120, to the sizing instrument 160. When a surgeon or other user presses down on the lever's actuation arm 138, the bias exerted by the spring 150 is overcome, thereby causing the lever 134 to pivot. As the lever 134 is pivoted, the locking pawl 142 is moved in a direction away from the upper surface of the keying pin 144. In such a way, the alignment handle 120 may be released from the sizing instrument 160.

0027The metallic components of alignment handle 120 (e.g., the alignment handle's body 122) may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used. The grip 128 may be constructed from a polymer such as silicone.

0028<figref idref="f0006">FIGS. 10 and 11</figref> show the sizing instrument 160. As described below, the sizing instrument 160 may be secured to the patient's surgically-prepared humeral surface during a procedure to implant the stemless humeral component 10 to function as both a sizing trial and a punch and drill guide.

0029The sizing instrument 160 includes a generally dome-shaped body 162 having flattened upper surface 164 and a substantially planar lower surface 166. An elongated bore 168 extends through the centre of the sizing instrument 160 from its upper surface 164 to its lower surface 166. As will be described below in greater detail, the elongated bore 168 functions as a drill guide for drilling a hole in the patient's surgically-prepared humeral surface to receive the elongated sleeve 36 of the stemless humeral component 10 (see <figref idref="f0001">FIGS. 2</figref> and <figref idref="f0003">5</figref>).

0030The sizing instrument 160 also includes a number of generally triangular-shaped punch guide holes 170. As can be seen in <figref idref="f0006">FIG. 10</figref>, each of the punch guide holes 170 is located in one of the four quadrants of the sizing instrument's round flange 172. As such, each of the punch guide holes 170 is positioned about 90o from one another. As can be seen in <figref idref="f0001">FIG. 2</figref> and <figref idref="f0002">4</figref>, the position of the punch guide holes 170 coincides with the position of the legs 16 of the stemless humeral component 10. As such, the holes 170 function as a punch guide for punching holes in the patient's surgically-prepared humeral surface to receive the legs 16 of the stemless humeral component 10 (see <figref idref="f0013">FIG. 29</figref>). To that end, the position of the punch guide holes 170 also coincides with the position of each of the tines 252 of the surgical punch 240 (see <figref idref="f0007">FIG. 14</figref>). As such, each of the tines 252 may be aligned with, and advanced through, one of the punch guide holes 170. In such a way, the sizing component 160 guides the surgeon's use of the surgical punch 240 while surgically preparing the patient's humeral surface to receive the legs 16 of the stemless humeral component 10 (see <figref idref="f0013">FIG. 29</figref>).

0031As can be seen in <figref idref="f0006">FIG. 11</figref>, the sizing instrument 160 has a number of spikes 174 extending downwardly from its lower surface 166. Each of the spikes 174 has a pointed distal tip 176. The spikes 174 are pressed or otherwise driven into the bone tissue of the patient's surgically-prepared humeral surface (i.e., the surface created by surgically resecting the humeral head) to secure the sizing instrument 160 in place during its use. A number of pin holes 178 are also formed in the sizing instrument's body 162 near its outer periphery. When a surgeon desires to supplement the attachment functionality of the spikes 174, surgical pins (not shown) may be inserted through the pin holes 178 to pin the sizing instrument 160 to the bone tissue of the patient's surgically-prepared humeral surface (i.e., the surface created by surgically resecting the humeral head).

0032Like the stemless humeral component 10, the sizing instrument's flange 172 also has a number of viewing windows 180 formed therein. The viewing windows 180 allow the surgeon to visualize the surgically-prepared humeral surface (i.e., the surface created by surgically resecting the humeral head) to ensure the sizing instrument 160 is fully seated during its use in the surgical procedure.

0033As can be seen in <figref idref="f0006">FIG. 10</figref>, the sizing instrument 160 has a connector 182 that may be engaged by the attachment mechanism 126 of the alignment handle 120 to secure the sizing instrument 160 to the alignment handle 120. The connector 182 has a key-hole shaped opening 184 formed therein. The key-hole opening 184 is sized and shaped to receive the keying pin 144 formed in the distal end of the alignment handle's body 122. The connector 182 also has a channel 186 formed therein. The connector 182 has an undercut 188 formed along the length of the channel 186. The undercut 188 takes the form of a lip 190 positioned at the top of the channel 186 and extending outwardly into the channel 186. The lip 190 is engaged by the locking pawl 142 of the alignment handle's attachment mechanism 126 (see <figref idref="f0005">FIGS. 8 and 9</figref>) to secure the sizing instrument 160 to the alignment handle 120.

0034As can be seen in <figref idref="f0006">FIG. 10</figref>, the connector 182 is confined within the sizing instrument's dome-shaped profile. As will be described below in greater detail, such an arrangement allows a trial humeral head to be installed on the sizing instrument without interference from the connector 182.

0035Like the other instruments and implants described herein, the sizing instrument 160 may be provided in a number of different sizes. For example, in the illustrative embodiment described herein, the sizing instrument 160 may be embodied in different diameters so as to mimic the various possible diameters of the stemless humeral component 10.

0036The sizing instrument 160 may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used. The polymers may be injection moulded as well.

0037<figref idref="f0006">FIGS. 12 and 13</figref> show a trial head component 210. The trial head component 210 is used for fit assessment during a surgical procedure to implant the stemless humeral component 10 and the humeral head component 12. In essence, the trial head component 210 is used to ensure proper size selection of the ultimate humeral head component 12 (i.e., the humeral head component 12 that is ultimately implanted in the patient's humerus). As discussed below, the trial head component also functions as a drill guide for guiding a drill bit used to drill (or pre-drill) the holes in the patient's surgically-prepared humeral surface to receive the legs 16 of the stemless humeral component 10 (see <figref idref="f0014">FIGS. 31 and 32</figref>).

0038In the example described herein, the trial head component 210 is embodied as a polymer trial instrument. As such, the trial head component 210 may be made of any suitable medical-grade polymeric material. Examples of such polymeric materials include polyethylene such as polyetheretherketone (PEEK) or acetal. In other examples, the trial head component may be formed from metal.

0039As a trial instrument for the humeral head component 12, the trial head component 210 includes a generally hemispherically-shaped body 212. As can be seen in <figref idref="f0006">FIG. 12</figref>, trial head component's body 212 includes a smooth, rounded, outer surface 214 that emanates from an annular rim 216 that defines the great circle of body's generally hemispherical shape. As can be seen in <figref idref="f0006">FIG. 12</figref>, the trial head component's body 212 is hollow. A centre lug 218 extends downwardly from the centre of the body's concave underside surface 220. The centre lug 218 has a number of annular bands 222 formed in its outer surface 224. As will be described in greater detail, the trial head component 210 may be installed on the sizing instrument 160 or the stemless humeral component 10 by inserting the centre lug 218 into the sizing instrument's elongated bore 168 or the stemless humeral component's tapered bore 40. The centre lug's annular bands 222 frictionally engage the stemless humeral component's tapered bore 40 to frictionally secure the centre lug, and hence the trial head component 210 to the stemless humeral component 10.

0040As can be seen in <figref idref="f0006">FIG. 12</figref>, the trial head component's body 212 also has a number of cylindrically-shaped bosses 226 extending downwardly from the centre of the body's concave underside surface 220. Each of the bosses 226 has a cylindrically-shaped metallic sleeve 228 insert moulded or otherwise positioned therein. The sleeves 228 have an elongated bore 230 formed therein, with such bores 230 extending throughout the entire length of the sleeves 228. The bores 230 function as drill guides for guiding a drill bit used to drill (or pre-drill) the holes in the patient's surgically-prepared humeral surface to receive the legs 16 of the stemless humeral component 10 (see <figref idref="f0014">FIGS. 31 and 32</figref>). As such, the position of each of the guide bores 230 coincides with, and is received into, the punch guide holes 170 of the sizing instrument 160 when the trial head component 210 is secured to the sizing instrument 160 (see <figref idref="f0012">FIG. 28</figref>). In particular, when the trial head component 210 is fully seated on the sizing instrument 160, the distal end of each of the bosses 226 formed in the trial head component 210 is received into a corresponding punch guide hole 170 of the sizing instrument 160 thereby aligning the guide bores 230 in the proper location.

0041Like the other instruments and implants described herein, the trial head component 210 may be provided in a number of different sizes. In the example, described herein, the trial head component 210 may be embodied in different diameters (e.g., 15 mm, 18 mm, or 21 mm) so as to mimic the diameter of the selected humeral head component.

0042<figref idref="f0007">FIG. 14</figref> shows a surgical punch 240 that is used to punch holes in the patient's surgically-prepared humeral surface to receive the legs 16 of the stemless humeral component 10 (see <figref idref="f0013">FIGS. 29 and 30</figref>). Similarly to the other instruments described herein, the surgical punch 240 may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used.

0043The surgical punch 240 is generally fork-shaped and includes a metal body 242 that includes an attachment shaft 244. The proximal end of the attachment shaft 244 has a D-shaped socket 260 formed therein. The D-shaped socket 260 is sized, shaped, and positioned to receive the D-shaped connecting pin 104 of the attachment mechanism 86 of the impaction handle 80 (see <figref idref="f0004">FIG. 6</figref>). The outer surface of the attachment shaft 244 has a channel 246 formed therein. The sidewalls of the shaft 244 into which the channel 246 is formed define an undercut 248 that extends along the length of the channel 246. The undercut 248 takes the form of a lip 250 positioned at the top of the channel 246. When the impaction handle's connecting pin 104 is inserted in the D-shaped socket 260 of the surgical punch 240 and thereafter advanced downwardly, the lip 250 is engaged by the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to secure the surgical punch 240 to the impaction handle 80.

0044At the end of the shaft 244 opposite the channel 246, the surgical punch's body 242 includes a number of tines 252. Each of the tines 252 is secured to the shaft 244 by a strut 268. The tines 252 function to punch holes in the patient's surgically-prepared humeral surface to receive the legs 16 of the stemless humeral component 10 (see <figref idref="f0013">FIGS. 29 and 30</figref>) and, as such, correspond in shape, size, and location with the legs 16 of the stemless humeral component 10. Like the legs 16 of the stemless humeral component 10, each of the surgical punch's tines 252 is generally T-shaped when viewed from a bottom elevation view (i.e., a view that is orthogonal to the longitudinal axis of the tine 252). In such an arrangement, each of the tines 252 has a bone-shaping plate 254 and an elongated rib 256. The elongated rib 256 extends along the length of the engaging plate 254 and, as such, forms the "trunk" of the T-shaped tine 252, with the engaging plate 254 forming the "cross bar" of the T-shaped tine 252. Specifically, the outer surface of the engaging plate 254 faces outwardly from the other tines (and hence the longitudinal axis of the surgical punch), with the rib 256 being secured to the backside of the tine's engaging plate 254 and extending inwardly in the direction toward the other tines 252. The longitudinal axis of the rib 256 is parallel with the longitudinal axis of the engaging plate 254. As can be seen in <figref idref="f0007">FIG. 14</figref>, each of the tines 252 includes a bevelled distal end 258 that functions as a lead punch surface. The bevelled distal end 258 also functions as a lead-in surface to facilitate insertion of the tine 252 into a pre-drilled hole in the surgically-prepared humeral surface.

0045The position of the tines 252 coincides with the position of the punch guide holes 170 of the sizing instrument 160. As such, the punch guide holes 170 function to guide the advancement of the tines 252 to punch holes in the patient's surgically-prepared humeral surface to receive the legs 16 of the stemless humeral component 10 (see <figref idref="f0013">FIGS. 29 and 30</figref>). As such, each of the tines 252 may be aligned with, and advanced through, the punch guide holes 170.

0046The surgical punch's body 242 also includes a centre spike 262 extending downwardly from the shaft 244 into the area between the tines 252. The centre spike 262 is centred on the longitudinal axis of the surgical punch 240. The centre spike 262 includes a pointed distal tip 264. The tip 264 of the centre spike 262 makes a divot in the patient's surgically-prepared humeral surface during use of the surgical punch 240 to punch holes to receive the legs 16 of the stemless humeral component 10. Such a divot is positioned to receive the elongated sleeve 36 of the stemless humeral component 10.

0047<figref idref="f0007">FIGS. 15 and 16</figref> show a centre drill bit 270 and a peripheral drill bit 272. The centre drill bit 270 is used to surgically drill a hole in the patient's surgically-prepared humeral surface to receive the elongated sleeve 36 of the stemless humeral component 10. The peripheral drill bit 272, on the other hand, is used to drill (or pre-drill) the holes in the patient's surgically-prepared humeral surface to receive the legs 16 of the stemless humeral component 10 (see <figref idref="f0014">FIGS. 31 and 32</figref>). Each of the drill bits 270, 272 includes an elongated shank 274 having a proximal end 276 that fits into the chuck of a rotary power tool (not shown) or a manual handle (not shown). The drill bits 270, 272 also include a cutting head 278 located at the opposite, distal end of the shank 274. The cutting head 278 of the drill bits 270, 272 includes a sharp cutting tip 280 with a plurality of helical cutting flutes 282 extending therefrom.

0048Each of the drill bits 270, 272 also includes an annular collar 284 positioned above the cutting head 278 at the upper end of the cutting flutes 282. The collar 284 functions as a depth stop to ensure the drill bits 270, 272 drill their respective holes at the desired depths. In the case of the centre drill bit 270, the collar has an outer diameter that is larger than the diameter of the elongated bore 168 of the sizing instrument 160. Hence, the centre drill bit 270 may be advanced into the bone tissue until the lower surface 286 of the collar 284 bottoms out or otherwise engages the flattened upper surface 164 of the sizing instrument 160. Likewise, the peripheral drill bit 272 may be advanced into the bone tissue until the lower surface 286 of the collar 284 bottoms out or otherwise engages a rim or shelf within the sleeves 228 of the trial head component 210.

0049The drill bits 270, 272 may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, in some embodiments, rigid polymers such as polyetheretherketone (PEEK) may also be used.

0050<figref idref="f0008">FIGS. 17 to 19</figref> show a head resection guide 290 which is used as a cutting guide to guide the advancement of a bone saw blade to resect the humeral head of the patient. The head resection guide 290 includes a base 292 having a pair of rails 294 extending outwardly therefrom. An arcuate-shaped, stationary cutting guide 296 is secured to the end of the rails 296 opposite the base 292. Specifically, one end of the stationary cutting guide 296 is secured to one of the rails 294, with the other end of the stationary cutting guide 296 being secured to the other rail 294.

0051A movable cutting guide 298 is captured on the rails 294 and is movable back and forth along the rails 294. Specifically, the movable cutting guide 298 includes a guide body 302 having a pair of holes 304 formed therein. One of the guide rails 294 is positioned in one of the holes 304, with the other rail 294 being positioned in the other hole 304. As such, the movable cutting guide 298 may be moved along the rails 294 in a direction toward and away from the stationary cutting guide 296.

0052A biassing element, such as a coiled spring 306, is captured on each of the rails 294. The springs 306 are positioned between an upper surface 308 of the base 292 and the lower surface 310 of the movable cutting guide's body 302. As such, the springs 306 assert a spring bias on the movable cutting guide 298 so as to urge it in the direction toward the stationary cutting guide 296.

0053The movable cutting guide's body 302 also has a finger grip 312 formed therein. In the example described herein, the finger grip 312 is embodied as a flange extending outwardly in a direction that is generally orthogonal to the rails 294. A surgeon or other user may grip the finger grip 312 and the lower surface 314 of the base 292 and thereafter squeeze his or her fingers. Doing so overcomes the spring bias of the springs 306 and urges or otherwise moves the movable cutting guide 298 in the direction away from the stationary cutting guide 296 (i.e., in a direction toward the base 292). Once the surgeon releases the finger grip 312, the spring bias of the springs 306 urges or otherwise moves the movable cutting guide 298 in the direction away back toward the stationary cutting guide 296 (i.e., in a direction away from the base 292).

0054As can be seen best in <figref idref="f0008">FIG. 18</figref>, both the stationary cutting guide 296 and the movable cutting guide 298 include rounded surfaces that cooperate to define a circular-shaped surface for capturing the patient's humeral head therein. Specifically, the stationary cutting guide 296 includes a rounded, generally semicircular-shaped posterior surface 318 that faces an rounded, generally semicircular-shaped anterior surface 320 of the movable cutting guide 298. As can be seen in <figref idref="f0008">FIGS. 17 and 18</figref>, a number of spikes 322 extend outwardly from each of the semicircular-shaped surfaces 318, 320 toward the opposite semicircular-shaped surface 318, 320. The spikes 322 engage the bone tissue of the patient's humerus to maintain the head resection guide 290 in a desired location and orientation during its use. As such, when a surgeon squeezes the finger grip 312 and the lower surface 314 of the base 292, the semicircular-shaped surfaces 318, 320 are moved away from one another thereby creating clearance to position the patient's humeral head between them. Thereafter, when the surgeon releases the finger grip 312 and the lower surface 314 of the base 292, the semicircular-shaped surfaces 318, 320 are toward one another thereby capturing the patient's humeral head therebetween with the spikes 322.

0055As can be seen in <figref idref="f0008">FIGS. 17 and 18</figref>, the movable cutting guide 298 has a number of pin holes 324 formed therein. The axis of each of the pin holes 324 extends in a direction that is oblique or angled relative to the rails 294 and the spikes 322. As will be discussed in more detail, surgical pins may be inserted through the pin holes 324 to pin the head resection guide 290 to the patient's humerus during resection of the patient's natural humeral head.

0056As can be seen best in the side view of <figref idref="f0008">FIG. 19</figref>, both the stationary cutting guide 296 and the movable cutting guide 298 include planar surfaces that cooperate to define a cutting guide surface for guiding a bone saw blade to resect the patient's natural humeral head. Specifically, the stationary cutting guide 296 includes a planar posterior guide surface 326 that aligns in a coplanar relationship with a planar anterior guide surface 328 of the movable cutting guide 298. Collectively, the two guide surfaces 326, 328 define a cutting surface upon which a bone saw blade may be supported (i.e., guided) during a cutting operation to resect the patient's natural humeral head. As can be seen in <figref idref="f0008">FIG. 19</figref>, the two guide surfaces 326, 328 lie in a plane that is generally parallel to the rails 294 and perpendicular to the finger grip 312 and the lower surface 314 of the base 292.

0057The head resection guide 290 may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used.

0058<figref idref="f0009">FIGS. 20 to 23</figref> show an implant insertion tool 330 which may be secured to the stemless humeral component 10 to facilitate implantation of the stemless humeral component 10 into the patient's surgically-prepared humeral surface. The implant insertion tool 330 includes an elongated body 332 that defines a cylindrically-shaped shaft 334 having a connector 336 on its proximal end. The connector 336 includes a D-shaped socket 338 formed in its proximal end. The D-shaped socket 338 is sized, shaped, and positioned to receive the D-shaped connecting pin 104 of the attachment mechanism 86 of the impaction handle 80 (see <figref idref="f0004">FIG. 6</figref>). The outer surface of the body's connector 336 has a channel 340 formed therein. The sidewalls of the connector 336 into which the channel 340 is formed define an undercut 342 that extends along the length of the channel 340. The undercut 342 takes the form of a lip 344 positioned at the top of the channel 340. When the impaction handle's connecting pin 104 is inserted in the D-shaped socket 338 of the implant insertion tool 330 and thereafter advanced downwardly, the lip 344 is engaged by the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to secure the implant insertion tool 330 to the impaction handle 80.

0059The end of the of the implant insertion tool's body 332 opposite its connector 336 has an alignment flange 346 formed therein. The alignment flange 346 is embodied as an annular face having a number of protrusions or alignment keys 348 extending downwardly therefrom. The alignment keys 348 are sized, shaped, and positioned to be received into the viewing windows 30 formed in the stemless humeral component 10. The alignment flange 346 also has an alignment pin 350 extending downwardly from its annular face. The alignment pin 350 is sized, shaped, and positioned to be received into the tapered bore 40 formed in the stemless humeral component 10.

0060As can be seen in <figref idref="f0009">FIGS. 20 and 21</figref>, a pair of locking arms 352 are pivotally coupled to the insertion tool's body 332. Each of the locking arms 352 has a cam follower 354 formed in its proximal end, and a generally L-shaped locking pawl 356 formed in its opposite, distal end. Each of the locking arms 352 is pivotally coupled to the implant insertion tool's body 332 at a location near its annular face 346 by a pivot pin 358 positioned in a bore 360 formed in the body 332. The locking arms 352 pivot about the pivot pins 358 such that movement of the cam followers 354 in the direction toward one another, and hence toward the shaft 334 of the insertion tool's body 332, causes movement of the locking pawls 356 in the direction away from one another, and hence away from the alignment pin 350 of the insertion tool's body 332. On the other hand, movement of the cam followers 354 in the direction away from one another, and hence away from the shaft 334 of the insertion tool's body 332, causes movement of the locking pawls 356 in the direction toward one another, and hence toward the alignment pin 350 of the insertion tool's body 332.

0061Such movement of the locking arms 352 may be used as part of a "quick connect" arrangement to selectively lock and release the stemless humeral component 10 from the implant insertion tool 330. In particular, when the insertion tool's alignment flange 346 is engaged with the stemless humeral component 10 such that its alignment pin 350 and alignment keys 348 are positioned in the stemless humeral component's tapered bore 40 and viewing windows 30, respectively, the locking pawls 356 of the locking arms 352 are positioned in the stemless humeral component's remaining viewing windows 30 (i.e., the viewing windows 30 not occupied by the alignment keys 348). So positioned, the locking pawls 356 may be moved into and out of engagement with the lips 74 of the undercuts 70 formed in the bottom surface 18 of the stemless humeral component's support flange 14 (see <figref idref="f0001">FIGS. 2</figref> and <figref idref="f0002">4</figref>). Specifically, the locking pawls 356 may be moved in the direction toward one another (i.e., toward the alignment pin 350 of the insertion tool's body 332) such that the locking pawls 356 engage the lips 74 of the undercuts 70 formed in the bottom surface 18 of the stemless humeral component's support flange 14 thereby securing the stemless humeral component 10 to the implant insertion tool 330. Oppositely, the locking pawls 356 may be moved in the direction away from one another (i.e., away from the alignment pin 350 of the insertion tool's body 332) such that the locking pawls 356 disengage the lips 74 of the undercuts 70 formed in the bottom surface 18 of the stemless humeral component's support flange 14 thereby releasing the stemless humeral component 10 from the implant insertion tool 330.

0062As can be seen in <figref idref="f0009">FIGS. 20 and 21</figref>, a rotating locking collar 362 is captured on the shaft 334 of the insertion tool's body 332. In particular, the locking collar 362 has a bore 364 extending through its centre, with the shaft 334 of the insertion tool's body 332 being received (i.e., positioned) in the bore 364. As such, the locking collar 362 may be rotated both clockwise and counterclockwise about the shaft 334 of the insertion tool's body 332. As can be seen best in <figref idref="f0009">FIG. 20</figref>, the locking collar 362 has a pair of channels 366 formed in its underside. The cam followers 354 of the locking arms 352 ride in the channels 366 as the locking collar 362 is rotated about the shaft 334. The sidewall defining the inner side of the channels 366 defines a cam surface 368. As can be seen in <figref idref="f0009">FIG. 20</figref>, one end 370 of the cam surface 368 is nearer the locking collar's bore 364 (and hence the shaft 334 of the insertion tool's body 332) than the other end 372 of the cam surface 368. As such, as each of the cam followers 354 rides along its corresponding cam surface 368 in the direction from its inner end 370 to its outer end 372, the cam followers 354 move in the direction away from one another, and hence away from the shaft 334 of the insertion tool's body 332, thereby causing the locking arms 352 to pivot such that the locking pawls 356 are moved in a direction toward one another, and hence toward the alignment pin 350 of the insertion tool's body 332. As described above, such movement of the locking pawls 356 is used to lock the stemless humeral component 10 to the implant insertion tool 330. As can be seen in <figref idref="f0009">FIG. 20</figref>, in the example described herein, clockwise rotation of the locking collar 362 causes the cam followers 354 to move along the cam surfaces 368 in such a direction (i.e., in a direction from the cam surface's inner end 370 to its outer end 372).

0063Oppositely, as each of the cam followers 354 rides along the corresponding cam surface 368 in the direction from its outer end 372 to its inner end 370, the cam followers 354 move in the direction toward one another, and hence toward the shaft 334 of the insertion tool's body 332, thereby causing the locking arms 352 to pivot such that the locking pawls 356 are moved in a direction away from one another, and hence away from the alignment pin 350 of the insertion tool's body 332. As described above, such movement of the locking pawls 356 is used to release the stemless humeral component 10 from the implant insertion tool 330. As can be seen in <figref idref="f0009">FIG. 20</figref>, in the example described herein, counterclockwise rotation of the locking collar 362 causes the cam followers 354 to move along the cam surfaces 368 in such a direction (i.e., in a direction from the cam surface's outer end 372 to its inner end 370).

0064As can be seen in <figref idref="f0009">FIGS. 20 and 21</figref>, the locking collar 362 has a pair of guide pins 374 extending through it. The outer end of the guide pins 374 is positioned near the outer surface of the locking collar 362, with its inner end (not shown) positioned in an annular channel (not shown) formed on the outer surface of the shaft 334 of the insertion tool's body 332. The inner end of the guide pins 374 rides in such a channel during rotation of the locking collar 362. The shaft 334 of the insertion tool's body 332 also has a pair of linear channels 376 formed in its outer surface. The linear channels 376 are arranged parallel to both one another and the longitudinal axis of the shaft 334 of the insertion tool's body 332. When the inner ends of the guide pins 374 are aligned with, and received into, the linear channels 376, the locking collar 362 may be slid along the shaft 334 of the insertion tool's body 332 in the direction toward the connector 336 (i.e., away from the alignment flange 346). In doing so, each of the cam followers 352 of the locking arms 350 escape from their respective channels 366 of the locking collar 362. Such an arrangement allows the cam followers 352 and the channels 366 of the locking collar 362 to be fully exposed to cleaning fluid during cleaning of the implant insertion tool 330 between uses. The cam followers 352 may be slipped back into their respective channels 366 of the locking collar 362 by aligning them with the inner ends 370 of channels 366 as the locking collar 362 is slid along the shaft 334 of the insertion tool's body 332 in the direction away from the connector 336 (i.e., toward the alignment flange 346). Thereafter, the locking collar 362 may be rotated to recapture the cam followers 352 in their respective channels 366 of the locking collar 362.

0065The components of the implant insertion tool 330 (e.g., its body 332, locking arms 352, and locking collar 362) may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used.

0066<figref idref="f0010">FIG. 24</figref> shows an head impaction tool 380 which may be used to impact, and hence taper lock, the head component 12 to the stemless humeral component 10. The head impaction tool 380 includes a generally conically-shaped body 382 having a connector 384 formed in its proximal end. The connector 384 includes a round opening 386 that is sized, shaped, and positioned to receive the connecting pin 104 of the attachment mechanism 86 of the impaction handle 80 (see <figref idref="f0004">FIG. 6</figref>). The connector 384 of the head impaction tool 380 also has three channels 388 formed therein. The sidewalls of the head impaction tool's body 382 into which the channels 388 are formed define undercuts 390 that extend along the length of the channels 388. Each of the undercuts 390 takes the form of a lip 392 positioned at the top of the respective channels 388. The lips 392 may be selectively engaged by the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to secure head impaction tool 380 to the impaction handle 80.

0067The end of the head impaction tool's body 382 opposite the connector 384 has a rounded, concave impact surface 396 formed therein. The concave impact surface 396 is sized, shaped, and positioned to closely conform to the convex, nearly generally hemispherically-shaped outer surface of the head component 12. As described below with reference to <figref idref="f0016">FIG. 35</figref>, when installing the head component 12 to the stemless humeral component 10, the head impaction tool 380 is first coupled to the impaction handle 80 and thereafter positioned such that the impact surface 396 of the head impaction tool 380 is placed in contact with the outer surface of the head component 12. The surgeon may then strike the impact handle's metal strike plate 90 with a surgical mallet, sledge, or other impaction tool to drive the head component 12 into taper lock attachment to the stemless humeral component 10. It should be appreciated that the head impaction tool 380 may be constructed from a polymer such as polyetheretherketone (PEEK), acetal, radel, or other polymer.

0068<figref idref="f0011 f0012 f0013 f0014 f0015 f0016 f0017">FIGS. 25 to 36</figref> show features of a surgical procedure in which the various instruments described with reference to <figref idref="f0004 f0005 f0006 f0007 f0008 f0009 f0010">FIGS. 6 to 24</figref> are used to prepare the patient's humerus 400 for implantation of the stemless humeral prosthesis 10 of <figref idref="f0001 f0002 f0003">FIGS. 1 to 5</figref>. The surgical procedure begins with preoperative planning in which, amongst other things, a CT scan (2D or 3D) or other type of preoperative image (e.g., X-ray) may be obtained to plan the placement location and orientation of the stemless humeral component 10 and humeral head component. If the procedure being planned is a shoulder replacement procedure, the CT scan or other type of preoperative images will also be used to plan the placement location and orientation of a prosthetic glenoid component (not shown) to be implanted in the patient's glenoid. With the preoperative planning complete, the patient's soft tissue is dissected and retracted in order to allow access to the shoulder joint. Full (i.e., 360°) exposure of the patient's humeral head 402 is typically achieved.

0069Once the patient's humeral head 402 has been surgically exposed, the surgeon may then begin the process of resecting it. As shown in <figref idref="f0011">FIG. 25</figref>, the surgeon first installs the head resection guide 290 on the patient's humerus 400. To do so, the surgeon grips the finger grip 312 and the lower surface 314 of the head resection guide's base 292 and thereafter squeezes his or her fingers. Doing so overcomes the spring bias of the springs 306 and urges or otherwise moves the movable cutting guide 298 in the direction away from the stationary cutting guide 296 (i.e., in a direction toward the base 292) thereby creating clearance to position the patient's humeral head 402 between their respective semicircular-shaped surfaces 318, 320.

0070The surgeon then positions the head resection guide 290 around the patient's humeral head 402 such that the stationary cutting guide 296 rests on the posterior cuff insertion site of the patient's rotator cuff. Doing so protects the posterior rotator cuff during head resection and is a step in placing the guide 296 at the correct height and version. The surgeon then positions the anterior surface 320 of the movable cutting guide 298 against the anterior surface 404 of the patient's humerus 400 at the desired resection angle and height. The surgeon positions cutting guide 298 on the patient's humeral head 402 such that the anterior guide surface 328 is aligned with the articular margin of the humeral head 402. The surgeon then gently releases the finger grip 312 and the lower surface 314 of the base 292. In doing so, the respective semicircular-shaped surfaces 318, 320 of the movable cutting guide 298 and the stationary cutting guide 296 are moved toward one another thereby capturing the patient's humeral head 402 therebetween with the spikes 322.

0071Once the surgeon has placed the movable cutting guide 298 in the desired resection angle and height, the surgeon may insert a surgical pin 406 through each of the pin holes 324 to pin the head resection guide 290 to the patient's humerus 400 to maintain the anterior guide surface 328 of the movable cutting guide 298 in its desired position, as shown in <figref idref="f0011">FIG. 25</figref>.

0072As shown in <figref idref="f0011">FIG. 26</figref>, the surgeon then operates a bone saw, such as an oscillating power saw 408, to resect the patient's humeral head 402. To do so, the surgeon positions the saw blade 410 of the power saw 408 on the planar anterior guide surface 328 of the movable cutting guide 298. The surgeon then activates the oscillating power saw 408 and applies pressure on it so that it advances posteriorly and into contact with the anterior surface 404 of the patient's humerus 400. As the saw blade 410 is advanced posteriorly into contact with the anterior surface 404 of the humerus 400 and thereafter through its mid-section in the direction toward its posterior surface 412, the oscillating motion of the bone saw 408 abrades the bone tissue of the humeral head 402.

0073The surgeon continues to advance the power saw 408 posteriorly until the saw blade 410 exits the bone. Specifically, the surgeon continues to operate the bone saw 408 until the distal tine of its blade 410 passes beyond the posterior surface 412 of the humeral head 402. Upon exit from the posterior surface 412 of the bone, the saw blade 410 is supported and guided by the posterior guide surface 326 of the stationary cutting guide 296. In such a way, the posterior guide surface 326 of the stationary cutting guide 296 prevents the saw blade 410 from contacting the patient's posterior rotator cuff. Once the saw blade 410 has exited the bone and advanced onto the posterior guide surface 326 of the stationary cutting guide 296, the surgeon may deactivate the bone saw 408 and thereafter then lift away the resected portion of the patient's humeral head 402. As can be seen in <figref idref="f0011">FIG. 26</figref>, the surgically resected surface 414 of the humerus 400 is substantially planar.

0074As shown in <figref idref="f0012">FIG. 27</figref>, the surgeon now determines the appropriate size stemless humeral component 10 to implant on the surgically resected surface 414 of the humerus 400. To do so, the surgeon uses the sizing instrument 160. Specifically, as will now be described in more detail, the sizing instrument 160 may be secured to the patient's surgically resected surface 414 of the humerus 400 to function as both a sizing trial and a punch and drill guide. To do so, the surgeon selects an initial one of the differently-sized sizing instruments 160 that the surgeon estimates is the proper size for the patient. The surgeon then couples the selected sizing instrument 160 to the alignment handle 120. Specifically, the surgeon inserts and advances the keying pin 144 formed in the distal end of the alignment handle's body 122 into the key-hole shaped opening 184 formed in the sizing instrument 160 until the lip 190 of the sizing instrument's connector 182 is engaged by the locking pawl 142 of the alignment handle's attachment mechanism 126 (see <figref idref="f0005">FIGS. 8 and 9</figref>) thereby securing the sizing instrument 160 to the alignment handle 120. The surgeon then places the selected sizing instrument 160 onto the surgically resected surface 414 of the humerus 400 and assesses coverage. If the surgeon determines the selected sizing instrument 160 is not the proper size, the initial sizing instrument 160 is removed and a sizing instrument 160 having a different diameter is attached to the alignment handle 120 and assessed.

0075Once the sizing instrument 160 of the proper diameter has been determined, the surgeon secures the sizing instrument 160 to the surgically resected surface 414 of the humerus 400. To do so, the surgeon utilizes the alignment handle 120 to position the sizing instrument 160 in a desired location and orientation for the final implant (i.e., the stemless humeral component 10) with the spikes 174 of the sizing instrument 160 facing downwardly toward the surgically resected surface 414 of the humerus 400. The surgeon then presses or otherwise urges the sizing instrument 160 downwardly into the cancellous bone of the surgically-resected surface 414 of the humerus 400 thereby securing it in place as shown in <figref idref="f0012">FIG. 27</figref>. The surgeon may utilize the sizing instrument's viewing windows 180 to visualize the surgically-resected surface 414 of the humerus 400 to ensure the sizing instrument 160 is fully seated thereon.

0076Once the sizing instrument 160 has been installed on the surgically resected surface 414 of the humerus 400, the surgeon may then perform a pre-trial of the fit of the final humeral head component 12. To do so, the surgeon selects an initial one of the differently-sized trial head components 210 that the surgeon estimates is the proper size for the patient and thereafter installs the selected trial head component 210 to the sizing instrument 160 (see <figref idref="f0012">FIG. 28</figref>). The surgeon installs the trial head component 210 on the sizing instrument 160 by inserting its centre lug 218 (see <figref idref="f0006">FIGS. 12 and 13</figref>) into the sizing instrument's elongated bore 168 and thereafter pressing or otherwise urging the trial head component 210 downwardly until it fully seats on the sizing instrument 160.

0077The trial head component 210 is used to ensure proper size selection of the ultimate humeral head component 12 (i.e., the humeral head component 12 that is ultimately implanted in the patient's humerus). As such, once the trial head component 210 is installed on the sizing instrument 160, the surgeon can visually assess its size and fit to get a sense of the size and fit of the final implant (i.e., the stemless humeral component 10 and the humeral head component 12). If the surgeon is not satisfied with the assessed size and fit, either one or both of the trial head component 210 and the sizing instrument 160 may be replaced. If the surgeon is satisfied with the assessed size and fit, the trial head component 210 is removed from the sizing instrument 160 and subsequent bone preparation of the patient's surgically resected humeral surface 414 is performed.

0078As shown in <figref idref="f0013">FIG. 29</figref>, the surgeon may then use the surgical punch 240 to punch holes in the patient's surgically-resected humeral surface 414 to receive the legs 16 and the elongated sleeve 36 of the stemless humeral component 10. It should be appreciated that the surgeon may utilize a number of fixation pins (not shown) inserted through the pin holes 178 to secure the sizing instrument 160 to the bone tissue of the patient's surgically-resected humeral surface 414 prior to use of the surgical punch 240. To perform the punching procedure, the surgeon first secures the surgical punch 240 to the impaction handle 80 by inserting the D-shaped connecting pin 104 into the D-shaped socket 260 formed in the attachment shaft 244 of the surgical punch 240 until the lip 250 formed in the attachment shaft 244 is engaged by the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to secure the surgical punch 240 to the impaction handle 80.

0079Thereafter, the surgeon uses the impaction handle 80 to position the surgical punch 240 such that each of its tines 252 is aligned with one of the punch guide holes 170 of the sizing instrument 160. Doing so also aligns the surgical punch's centre spike 262 with the elongated bore 168 of the sizing instrument 160. In such a way, the punch guide holes 170 and the elongated bore 168 function to guide the advancement of the tines 252 and the centre spike 262, respectively.

0080Once the surgical punch 240 is positioned in the sizing instrument 160 in such a manner, the surgeon strikes the metal plate 90 of the impaction handle 80 with a surgical mallet, sledge, or other impaction tool to drive the surgical punch 240 into the patient's surgically-resected humeral surface 414 until the surgical punch bottoms out on the sizing instrument 160. As shown in <figref idref="f0013">FIG. 30</figref>, doing so creates a number of punched holes 416 in the patient's surgically-resected humeral surface 414 corresponding in shape, size, and location with the legs 16 of the stemless humeral component 12. As also shown in <figref idref="f0013">FIG. 30</figref>, impacting the surgical punch 240 in such a manner also creates a recess in the form of a divot 418 in the patient's surgically-resected humeral surface 414 corresponding in shape, size, and location to the elongated sleeve 36 of the stemless humeral component 10.

0081The surgeon then backs out the surgical punch 240 from the patient's surgically-resected humeral surface 414 to expose the surgically created holes 416 and divot 418, as shown in <figref idref="f0013">FIG. 30</figref>. If necessary, the surgeon may strike the underside of the impaction handle's extraction flange 92 to facilitate such extraction of the surgical punch 240.

0082<figref idref="f0014">FIGS. 31 and 32</figref> show features of a pre-conditioning procedure to the punching procedure described with reference to <figref idref="f0013">FIGS. 29 and 30</figref>. In other words, the drilling procedure may be performed as a pre-drilling procedure in which holes are pre-drilled in the patient's surgically-prepared humeral surface 414, with such pre-drilled holes then being punched by use of the surgical punch 240 in the manner described above to receive the legs 16 of the stemless humeral component 10. To perform such a drilling procedure, the surgeon utilizes the trial head component 210 with the installed sizing instrument 160. In bone preparation (as opposed to trialing), the trial head component 210 is used as a drill guide for guiding drill bits used to drill (or pre-drill) holes in the patient's surgically-prepared humeral surface 414 to receive the legs 16 and the elongated sleeve 36 of the stemless humeral component 10. To begin such a drilling procedure, the surgeon first selects the trial head component 210 corresponding in size to the installed sizing instrument 160 and thereafter installs the selected trial head component 210 to the sizing instrument 160 (see <figref idref="f0014">FIG. 31</figref>). The surgeon installs the trial head component 210 on the sizing instrument 160 by inserting its centre lug 218 (see <figref idref="f0006">FIGS. 12 and 13</figref>) into the sizing instrument's elongated bore 168 and thereafter pressing or otherwise urging the trial head component 210 downwardly until it fully seats on the sizing instrument 160.

0083When the trial head component 210 is installed to the sizing instrument 160, the position of each of the trial head component's guide bores 230 coincides with, and is received into, the punch guide holes 170 of the sizing instrument 160. In particular, when the trial head component 210 is fully seated on the sizing instrument 160, the distal end of each of the bosses 226 formed in the trial head component 210 (see <figref idref="f0006">FIGS. 12 and 13</figref>) is received into a corresponding punch guide hole 170 of the sizing instrument 160 thereby aligning the guide bores 230 in the proper location.

0084The proximal end of the peripheral drill bit 272 is then inserted into the chuck of a rotary power tool (not shown) or a manual handle (not shown). The surgeon then inserts the tip 280 of the peripheral drill bit's cutting head 278 into one of the guide bores 230 of the trial head component 210 and activates the power drill (or turns the manual handle). The surgeon advances the peripheral drill bit 272 into the bone tissue of the patient's surgically-resected humeral surface 414 until the lower surface 286 of the bit's collar 284 bottoms out or otherwise engages the rim or shelf in the sleeve 228 of the trial head component 210. The surgeon then removes the drill bit 272 from the guide bore 230 corresponding to the newly drilled peripheral hole and repeats the process in the remaining guide bores 230. The surgeon then removes the trial head component 210 from the sizing instrument 160 to expose the surgically-drilled peripheral holes 420 corresponding in location to where the legs 16 of the stemless humeral component 10 (see <figref idref="f0014">FIG. 32</figref>) will be implanted.

0085With the trial head component 210 removed, the surgeon then drills a hole in the patient's surgically-resected humeral surface 414 to receive the elongated sleeve 36 of the stemless humeral component 10. To do so, the surgeon secures the proximal end of the centre drill bit 270 in the chuck of a rotary power tool (not shown) or a manual handle (not shown). The surgeon then inserts the tip 280 of the centre drill bit's cutting head 278 into the elongated bore 168 of the sizing instrument 160 and activates the power drill (or turns the manual handle). The surgeon advances the centre drill bit 270 into the bone tissue of the patient's surgically-resected humeral surface 414 until the lower surface 286 of the bit's collar 284 bottoms out or otherwise engages the flattened upper surface 164 of the sizing instrument 160. The surgeon then removes the drill bit 270 from the elongated bore 168 of the sizing instrument 160.

0086As shown in <figref idref="f0014">FIG. 32</figref>, the surgeon then removes the sizing instrument 160 to expose the surgically-drilled peripheral holes 420 corresponding in location to where the legs 16 of the stemless humeral component 10 will be implanted, along with the surgically-drilled centre hole 422 corresponding in location to where the elongated sleeve 36 of the stemless humeral component 10 will be implanted.

0087Once the patient's surgically-resected humeral surface 414 has been prepared, the surgeon may then implant the stemless humeral component 10. To do so, as shown in <figref idref="f0015">FIG. 33</figref>, the surgeon first secures the implant insertion tool 330 to the impaction handle 80 by inserting the handle's D-shaped connecting pin 104 into the D-shaped socket 338 of the implant insertion tool's connector 336 until the connector's lip 344 is engaged by the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to secure the implant insertion tool 330 to the impaction handle 80.

0088Thereafter, the surgeon secures the appropriately sized stemless humeral component 10 (i.e., a component having a diameter selected through trialing as described above) to the implant insertion tool 330. The surgeon first positions the locking collar 362 of the implant insertion tool 330 in an unlocked or release position in which the cam followers 354 of implant insertion tool's locking arms 352 are positioned near the inner end 370 of the locking collar's cam surface 368 thereby positioning the locking pawls 356 at their greatest distance away from one another. The surgeon then positions the insertion tool's alignment flange 346 in engagement with the stemless humeral component 10 such that its alignment pin 350 and alignment keys 348 are positioned in the stemless humeral component's tapered bore 40 and viewing windows 30, respectively. Doing so positions the locking pawls 356 of the implant insertion tool's locking arms 352 in the stemless humeral component's remaining viewing windows 30 (i.e., the viewing windows 30 not occupied by the alignment keys 348).

0089The surgeon rotates the locking collar 362 clockwise to move the locking collar 362 from its unlocked position to its locked position. Such rotation of the locking collar 362 causes each of the cam followers 354 of the implant insertion tool's locking arms 352 to ride along its corresponding cam surfaces 368 in the direction from its inner end 370 to its outer end 372. Doing so causes the cam followers 354 to move in the direction away from one another thereby causing the locking arms 352 to pivot such that the locking pawls 356 are moved in a direction toward one another. Such movement of the locking pawls 356 in the direction toward one another causes the locking pawls 356 to engage the lips 74 of the undercuts 70 formed in the bottom surface 18 of the stemless humeral component's support flange 14 thereby securing the stemless humeral component 10 to the implant insertion tool 330.

0090Thereafter, as shown in <figref idref="f0015">FIG. 33</figref>, the surgeon uses the impaction handle 80 to position the stemless humeral component 10 such that each of its legs 16 is aligned with, and inserted into, one of the punched holes 416 formed in the patient's surgically-resected humeral surface 414. Doing so also aligns the elongated sleeve 36 of the stemless humeral component 10 with the divot 418/drilled hole 422 formed in the patient's surgically-resected humeral surface 414 (or the drilled centre).

0091Once the stemless humeral component 10 is positioned in the punched holes 416 and the divot 418/drilled hole 422 in such a manner, the surgeon strikes the metal plate 90 of the impaction handle 80 with a surgical mallet, sledge, or other impaction tool to drive the stemless humeral component 10 into the bone tissue until the stemless humeral component 10 is fully seated on the patient's planar surgically-resected humeral surface 414. The surgeon may use the viewing windows 30 to visualize the surgically-resected humeral surface 414 to ensure the stemless humeral component 10 is fully seated thereon.

0092The surgeon then releases the stemless humeral component 10 from the implant insertion tool 330. To do so, the surgeon rotates the locking collar 362 of the implant insertion tool 330 counterclockwise from its locked position to its unlocked position. Such rotation of the locking collar 362 causes each of the cam followers 354 of the implant insertion tool's locking arms 352 to ride along its corresponding cam surfaces 368 in the direction from its outer end 372 to its inner end 370. Doing so causes the cam followers 354 to move in the direction toward one another thereby causing the locking arms 352 to pivot such that the locking pawls 356 are moved in a direction away from one another. Such movement of the locking pawls 356 in the direction away from one another causes the locking pawls 356 to release the lips 74 of the undercuts 70 formed in the bottom surface 18 of the stemless humeral component's support flange 14 thereby releasing the stemless humeral component 10 from the implant insertion tool 330. As shown in <figref idref="f0016">FIG. 34</figref>, the surgeon then lifts the impaction handle 80, and hence the implant insertion tool 330, away thereby exposing the implanted stemless humeral component 10.

0093Once the stemless humeral component 10 has been implanted on the surgically resected surface 414 of the humerus 400, the surgeon may then perform a trial of the fit of the final humeral head component 12. To do so, the surgeon installs an appropriately sized trial head component 210 (i.e., the size selected during the earlier trialing steps) to the implanted stemless humeral component 10. The surgeon installs the trial head component 210 on implanted stemless humeral component 10 by inserting its centre lug 218 (see <figref idref="f0006">FIGS. 12 and 13</figref>) into the tapered bore 40 of the implanted stemless humeral component 10 and thereafter pressing or otherwise urging the trial head component 210 downwardly until it fully seats on the implanted stemless humeral component 10. The centre lug's annular bands 222 frictionally engage the sidewalls of the tapered bore 40 to frictionally secure the centre lug, and hence the trial head component 210, to the implanted stemless humeral component 10. The surgeon then utilizes the trial head component 210 to assess coverage, soft tissue tension, and range of motion.

0094Once the surgeon is satisfied, the trial head component 210 is then removed and replaced with the ultimate humeral head component 12. In particular, as shown in <figref idref="f0016">FIG. 35</figref>, the surgeon then installs an appropriately sized humeral head component 12 (i.e., the size selected during the earlier trialing steps) to the implanted stemless humeral component 10. The surgeon installs the humeral head component 12 on implanted stemless humeral component 10 by inserting its tapered post 42 into the tapered bore 40 of the stemless humeral component's elongated sleeve 36 (see <figref idref="f0017">FIG. 36</figref>).

0095The head impaction tool 380 may be used to impact, and hence taper lock, the head component 12 to the stemless humeral component 10. To do so, as shown in <figref idref="f0016">FIG. 35</figref>, the surgeon first secures the head impaction tool 380 to the impaction handle 80 by inserting the handle's D-shaped connecting pin 104 into the round opening 386 of the head impaction tool's connector 384 until one of the connector's lip 392 is engaged by the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to secure the head impaction tool 380 to the impaction handle 80.

0096The surgeon then positions the impaction handle 80 that the head impaction tool's concave impact surface 396 is placed in contact with the generally hemispherically-shaped outer surface of the head component 12. The surgeon then strikes the impact handle's metal strike plate 90 with a surgical mallet, sledge, or other impaction tool to drive the humeral head component 12 downwardly so as to urge the tapered post 42 of the humeral head component 12 into contact with the sidewall defining the tapered bore 40 of the elongated sleeve 36 thereby taper locking the humeral head component 12 to the stemless humeral component 10. Such final assembly of the humeral head component 12 to the stemless humeral component 10 is shown in <figref idref="f0017">FIG. 36</figref>.

0097<figref idref="f0018">FIG. 37</figref> shows another implant insertion tool 540 that may be secured to the stemless humeral component 10 to facilitate implantation of the stemless humeral component 10 into the patient's surgically-prepared humeral surface 414. The implant insertion tool 540 includes a body 542 having an elongated bore 544 extending through it. A locking rod 548 is captured in the bore 544. In such an arrangement, the locking rod 548 rotates freely within the bore 544.

0098A knob 550 is secured to the proximal end of the locking rod 548. In addition to being used to secure the implant insertion tool 540 to the stemless humeral component 10, the knob 550 is also used as an impact surface. Namely, the surgeon strikes the upper surface 552 of the knob 550 to drive the stemless humeral component 10 into the bone tissue of the patient's surgically-prepared humeral surface 414.

0099The locking rod 548 has a set of locking threads 556 formed in its distal end (i.e., the end opposite the knob 550). The threads 556 are sized to be received into the complimentary threads 50 of the threaded bore 48 formed in the elongated sleeve 36 of the stemless humeral component 10. When a surgeon or other user rotates the knob 550, the locking screw's threads 556 are likewise rotated. Rotation in one direction (e.g., clockwise) may be used to tighten, and hence secure, the implant insertion tool 540 to the humeral component 10, with rotation in the opposite direction (e.g., counterclockwise) being used to loosen, and hence, uncouple the implant insertion tool 540 from the humeral component.

0100As can be seen in <figref idref="f0018">FIG. 37</figref>, a number of straight flutes or ridges 558 are formed in the end of the of the implant insertion tool's body 542 near the knob 550 of the locking rod 548. The ridges 558 function as a grip for allowing the surgeon to hold the implant insertion tool 540 during implantation of the stemless humeral component 10.

0101The end of the of the implant insertion tool's body 542 near the threads 556 of the locking rod 548 has an alignment collar 560 formed therein. The alignment collar 560 is embodied as an annular flange extending outwardly from the longitudinal axis of implant insertion tool's body 542. The alignment collar 560 has a number of protrusions or alignment keys 562 extending downwardly from its lower surface 564. As can be seen in <figref idref="f0018">FIG. 37</figref>, the alignment keys 562 are sized, shaped, and positioned to be received into the viewing windows 30 formed in the stemless humeral component 10. With the alignment keys 562 positioned in the viewing windows 30, the stemless humeral component 10 is prevented from rotating relative the implant insertion tool 540 during rotation of the implant insertion tool's knob 550 thereby allowing the implant insertion tool's threads 556 to engage (or disengage) the stemless humeral component's threads 50.

0102In a manner similar to that described with reference to <figref idref="f0015">FIG. 33</figref>, the surgeon secures the stemless humeral implant 10 to the implant insertion tool 540 then uses the implant insertion tool 540 to align the stemless humeral component's legs 16 and elongated sleeve 36 to the punched holes 416 and the divot 418/drilled hole 422, respectively, formed in the surgically-resected humeral surface 414. Once the stemless humeral component 10 is positioned in the punched holes 416 and the divot 418/drilled hole 422 in such a manner, the surgeon strikes the upper surface 552 of the knob 550 with a surgical mallet, sledge, or other impaction tool to drive the stemless humeral component 10 into the bone tissue until the stemless humeral component 10 is fully seated on the patient's planar surgically-resected humeral surface 414. The surgeon may use the viewing windows 30 to visualize the surgically-resected humeral surface 414 to ensure the stemless humeral component 10 is fully seated thereon.

0103The components of the implant insertion tool 540 (i.e., its body 542 and the locking rod 548) may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used.

0104<figref idref="f0019">FIG. 38</figref> shows another implant insertion tool 580 which may be secured to the stemless humeral component 10 to facilitate implantation of the stemless humeral component 10 into the patient's surgically-prepared humeral surface. The implant insertion tool 580 includes a body 582 having an elongated bore 584 extending through it. A locking rod such as a locking screw 588 is captured in the bore 584. In such an arrangement, the locking screw 588 rotates freely within the bore 584, but is prevented from being removed from the bore 584 (i.e., it is not removable from the implant insertion tool's body.

0105A D-shaped drive head 590 is formed in the proximal end of the locking screw 588, with a number of locking threads 592 being formed in its opposite, distal end. The threads 582 are sized to be received into the complimentary threads 50 of the threaded bore 48 formed in the elongated sleeve 36 of the stemless humeral component 10. The D-shaped drive head 590 is sized, shaped, and positioned to receive a D-shaped head of a rachet or other surgical tool. As such, when the head of the racket is inserted in the implant insertion tool's drive head 590 and rotated, the locking screw's threads 592 are likewise rotated. Rotation in one direction (e.g., clockwise) may be used to tighten, and hence secure, the implant insertion tool 580 to the stemless humeral component 10, with rotation in the opposite direction (e.g., counterclockwise) being used to loosen, and hence, uncouple the implant insertion tool 580 from the stemless humeral component 10.

0106The end of the of the implant insertion tool's body 582 near the drive head 590 of the locking screw 588 has a channel 596 formed therein. The sidewalls of the insertion tool's body 582 into which the channel 596 is formed define an undercut 598 that extends along the length of the channel 596. The undercut 598 takes the form of a lip 602 positioned at the top of the channel 596. The lip 602 is engaged by the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to secure the implant insertion tool 580 to the impaction handle 80.

0107In a manner similar to as described above in <figref idref="f0015">FIG. 33</figref>, the surgeon secures the implant insertion tool 580 to the impaction handle 80 and thereafter secures the stemless humeral implant 10 to the implant insertion tool 580 or vice versa. The surgeon then uses the impaction handle 80 to align the stemless humeral component's legs 16 and elongated sleeve 36 to the punched holes 416 and the divot 418/drilled hole 422 formed in the surgically-resected humeral surface 414. Once the stemless humeral component 10 is positioned in the punched holes 416 and the divot 418/drilled hole 422 in such a manner, the surgeon strikes the metal plate 90 of the impaction handle 80 with a surgical mallet, sledge, or other impaction tool to drive the stemless humeral component 10 into the bone tissue until the stemless humeral component 10 is fully seated on the patient's planar surgically-resected humeral surface 414. The surgeon may use the viewing windows 30 to visualize the surgically-resected humeral surface 414 to ensure the stemless humeral component 10 is fully seated thereon.

0108The components of the implant insertion tool 580 (i.e., its body 582 and the locking screw 588) may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used. In other examples, the implant insertion tool 580 may be formed as a single monolithic component. In such examples, the implant insertion tool 580 may be threaded onto the implant or clipped onto the impaction handle for threading onto the implant. In other examples, the implant insertion tool 580 may include a connecting collar that surrounds the D-shaped drive socket. As such, the D-shaped drive socket 630 may be rotated relative to the collar.

0109<figref idref="f0019">FIGS. 39 and 40</figref> show another implant insertion tool 620 which may be secured to the stemless humeral component 10 to facilitate implantation of the stemless humeral component 10 into the patient's surgically-prepared humeral surface 414. The implant insertion tool 620 includes a somewhat ring-shaped body 622 having an upper bore 624 extending through an upper portion of its body 622 and lower bore 626 extending through a lower portion of its body 622. The two bores 624, 626 are coaxial with one another (i.e., they share a common central axis). A locking rod 628 is captured in the bores 624, 626. In such an arrangement, the locking rod 628 rotates freely within the bores 624, 626, but is prevented from being removed from the bores 624, 626 (i.e., it is not removable from the implant insertion tool's body 622).

0110A D-shaped drive socket 630 is formed in the proximal end of the locking rod 628, with a number of locking threads 632 being formed in its opposite, distal end. The threads 632 are sized to be received into the complimentary threads 50 of the threaded bore 48 formed in the elongated sleeve 36 of the stemless humeral component 10 (see <figref idref="f0003">FIG. 5</figref>). The D-shaped drive socket 630 is sized, shaped, and positioned to receive the D-shaped connecting pin 104 of the attachment mechanism 86 of the impaction handle (see <figref idref="f0004">FIG. 6</figref>).

0111As can be seen in <figref idref="f0019">FIGS. 39 and 40</figref>, the ring-shaped body 622 of the implant insertion tool 620 includes a connecting collar 634 that surrounds the D-shaped drive socket 630 of the locking rod 628. As such, the D-shaped drive socket 630 of the locking rod 628 is rotatable relative to the connecting collar 634 of the implant insertion tool's ring-shaped body 622. The outer surface of the connecting collar 634 has a number of ratchet slots 636 formed therein. One end 638 of the ratchet slots 636 is wider than its other end 640 thereby giving the ratchets slots 636 a generally L-shaped configuration. The sidewall 642 defining the narrow end 640 of the ratchet slots 636 defines a ramped-shaped or otherwise angled cam surface 644, whereas the sidewall 646 defining the wide end 638 of the ratchet slots 636 defines a vertical stop surface 648. When the impaction handle's connecting pin 104 is inserted in the implant insertion tool's D-shaped drive socket 630, the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) is positioned in one of the ratchet slots 636. The configuration of the ratchet slots 636 permits rotation of the impaction handle 80 (and hence the locking rod 628) relative to the ring-shaped body 622 of the implant insertion tool 620 in one direction (e.g., clockwise), but prevents rotation in the opposite direction (e.g., counterclockwise). In particular, rotation of the impaction handle 80 (and hence the locking rod 628) relative to the ring-shaped body 622 in the clockwise direction causes the leading edge of the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to contact the ramped-shaped cam surface 644 that defines the narrow end 640 of the ratchet slot 636 in which the locking pawl 102 is captured. Continued clockwise rotation causes the locking pawl 102 to ride up the ramped-shaped cam surface 644 (as the spring bias of the spring impaction handle's 110 is overcome) and out of the ratchet slot 636. The locking pawl 102 rides on the outer surface of the connecting collar 634 between two adjacent ratchet slots 636 until the trailing edge of the locking pawl 102 clears the vertical stop surface 648 of the ratchet slot 636 adjacent to the one just exited by the locking pawl 102 at which point the spring bias of the spring impaction handle's 110 urges the locking pawl 102 downwardly into the ratchet slot 636.

0112Conversely, rotation of the impaction handle 80 (and hence the locking rod 628) relative to the ring-shaped body 622 in the counterclockwise direction causes the leading edge of the locking pawl 102 of the impaction handle's attachment mechanism 86 (see <figref idref="f0004">FIGS. 6 and 7</figref>) to contact the vertical stop surface 648 of the ratchet slot 636 that defines the wide end 638 of the ratchet slot 636 in which the locking pawl 102 is captured. Such contact with the vertical stop surface 648 prevents further rotation of the impaction handle 80 (and hence the locking rod 628) relative to the ring-shaped body 622 in the counterclockwise direction.

0113Such ratchet-type clockwise rotation of the impaction handle 80 (and hence the locking rod 628) relative to the ring-shaped body 622 is used to secure the stemless humeral component 10 to the implant insertion tool 620. In particular, when the impaction handle 80 is installed on the implant insertion tool 620 and rotated, the locking rod's threads 632 are likewise rotated. Rotation in one direction (e.g., clockwise) may be used to tighten, and hence secure, the implant insertion tool 580 to the stemless humeral component 10. Rotation in the opposite direction (e.g., counterclockwise) is used to loosen, and hence, uncouple the implant insertion tool 620 from the stemless humeral component 10. In order to perform such counterclockwise rotation, the surgeon presses and holds down on the actuation arm 98 of the impaction handle's lever 94 thereby lifting the impaction handle's locking pawl 102 out of the ratchets slots 636 of the implant insertion tool 620.

0114The end of the of the implant insertion tool's ring-shaped body 622 near the threads 632 of the locking rod 628 has an alignment collar 652 formed therein. The alignment collar 652 is embodied as an annular flange formed in the distal end 654 of the implant insertion tool's body 622. The alignment collar 652 has a number of protrusions or alignment keys 656 extending downwardly from its lower surface 658. As can be seen in <figref idref="f0019">FIG. 40</figref>, the alignment keys 656 are sized, shaped, and positioned to be received into the viewing windows 30 formed in the stemless humeral component 10. With the alignment keys 656 positioned in the viewing windows 30, the stemless humeral component 10 is prevented from rotating relative the implant insertion tool 620 during rotation of the implant insertion tool's locking rod 628 thereby allowing the implant insertion tool's threads 632 to engage (or disengage) the stemless humeral component's threads 50.

0115In a manner similar to that described above with reference <figref idref="f0015">FIG. 33</figref>, the surgeon secures the implant insertion tool 620 to the impaction handle 80 and thereafter secures the stemless humeral implant 10 to the implant insertion tool 620. The surgeon then uses the impaction handle 80 to align the stemless humeral component's legs 16 and elongated sleeve 36 to the punched holes 416 and the divot 418/drilled hole 422 formed in the surgically-resected humeral surface 414. Once the stemless humeral component 10 is positioned in the punched holes 416 and the divot 418 in such a manner, the surgeon strikes the metal plate 90 of the impaction handle 80 with a surgical mallet, sledge, or other impaction tool to drive the stemless humeral component 10 into the bone tissue until the stemless humeral component 10 is fully seated on the patient's planar surgically-resected humeral surface 414. The surgeon may use the viewing windows 30 to visualize the surgically-resected humeral surface 414 to ensure the stemless humeral component 10 is fully seated thereon.

0116The components of the implant insertion tool 620 (i.e., its body 622 and the locking rod 628) may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used.

0117<figref idref="f0020">FIGS. 41 and 42</figref> show another head resection guide 670 that may be used as a cutting guide to guide the advancement of a bone saw blade to resect the humeral head of the patient. Unlike the head resection guide 290 described above with reference to <figref idref="f0008">FIGS. 17 to 19</figref>, the head resection guide 670 is not adjustable, but rather is provided in a number of varying sizes (i.e., varying diameters) to fit the needs of a given patient. The head resection guide 670 includes a generally rectangular-shaped base 672 having a circular-shaped ring 674 secured thereto. The ring 674 extends outwardly from the base 672 and defines a circular-shaped opening 676. As described below, the patient's humeral head is captured in the opening 676 during resection thereof.

0118The head resection guide 670 has a connector 678 that may be engaged by the attachment mechanism 126 of the alignment handle 120 to secure the head resection guide 670 to the alignment handle 120. The connector 678 has a key-hole shaped opening 680 formed therein. The key-hole opening 680 is sized and shaped to receive the keying pin 144 formed in the distal end of the alignment handle's body 122. The connector 678 also has a channel 682 formed therein. An undercut 684 is formed along the length of the channel 682. The undercut 684 takes the form of a lip 686 positioned at the top of the channel 682 and extending outwardly into the channel 682. The lip 686 is engaged by the locking pawl 142 of the alignment handle's attachment mechanism 126 (see <figref idref="f0005">FIGS. 8 and 9</figref>) to secure the head resection guide 670 to the alignment handle 120.

0119The head resection guide's base 672 has a number of pin holes 692 formed therein. As discussed below, surgical pins may be inserted through the pin holes 692 to pin the head resection guide 670 to the patient's humerus during resection of the patient's humeral head.

0120As can be seen in <figref idref="f0020">FIG. 42</figref>, both the base 672 and the ring 674 include planar surfaces that cooperate to define a cutting guide surface for guiding a bone saw blade to resect the patient's natural humeral head. Specifically, the base 672 includes a planar anterior guide surface 694 that aligns in a coplanar relationship with a planar posterior guide surface 696 of the ring 674. As described above, in the example described herein, the head resection guide 670 is embodied as a monolithic structure. Hence, the two guide surfaces 694, 696 are embodied as a common surface that collectively defines a cutting surface upon which a bone saw blade may be supported (i.e., guided) during a cutting operation to resect the patient's natural humeral head.

0121In use, the surgeon installs the head resection guide 670 to the alignment handle 120 by inserting the keying pin 144 formed in the distal end of the alignment handle's body 122 into the key-hole opening 680 of the head resection guide's connector 678. In doing so, the connector's lip 686 is engaged by the locking pawl 142 of the alignment handle's attachment mechanism 126 (see <figref idref="f0005">FIGS. 8 and 9</figref>) thereby securing the head resection guide 670 to the alignment handle 120.

0122In a similar manner to that described with reference to <figref idref="f0011">FIG. 26</figref>, the surgeon then uses the head resection guide 670 as a cutting guide to facilitate the surgical resection of the patient's humeral head 402. To do so, the surgeon uses the alignment handle 120 to position the head resection guide 670 around the patient's humeral head 402 such that the posterior section 702 of the ring 674 rests on the posterior cuff insertion site of the patient's rotator cuff. Doing so protects the posterior rotator cuff during head resection and acts as a step in placing the guide at the correct height and version. The surgeon then positions the anterior guide surface 694 of the base 672 relative to the anterior surface 404 of the patient's humerus 400 at the desired resection angle and height. The surgeon may then make any necessary minor adjustments to the positions of the anterior surface of the base relative to the anterior surface 404 and the anterior guide surface 694 relative to the articular margin to finalize the desired resection angle and height. Thereafter, the surgeon may insert a surgical pin 406 (see <figref idref="f0011">FIG. 26</figref>) through each of the pin holes 692 to pin the head resection guide 670 to the patient's humerus 400 to maintain the anterior guide surface 694 in its desired position. Once pinned in place, the surgeon disconnects the alignment handle 120 from the head resection guide 670.

0123Similar to as described with reference to <figref idref="f0011">FIG. 26</figref>, the surgeon then operates a bone saw, such as an oscillating power saw 408, to resect the patient's humeral head 402. To do so, the surgeon positions the saw blade 410 of the power saw 408 on the planar anterior guide surface 694 of the head resection guide's base 672. The surgeon then activates the oscillating power saw 408 and applies pressure on it so that it advances posteriorly and into contact with the anterior surface 404 of the patient's humerus 400. As the saw blade 410 is advanced posteriorly into contact with the anterior surface 404 of the humerus 400 and thereafter through its mid-section in the direction toward its posterior surface 412, the oscillating motion of the bone saw 408 abrades the bone tissue of the humeral head 402.

0124The surgeon continues to advance the power saw 408 posteriorly until the saw blade 410 exits the bone. Specifically, the surgeon continues to operate the bone saw 408 until the distal end of its blade 410 passes beyond the posterior surface 412 of the humeral head 402. Upon exit from the posterior surface 412 of the bone, the saw blade 410 is supported and guided by the posterior guide surface 696 of the ring 674. In such a way, the posterior guide surface 696 of the ring 674 prevents the saw blade 410 from contacting the patient's posterior rotator cuff. Once the saw blade 410 has exited the bone and advanced onto the posterior guide surface 696 of the ring 674, the surgeon may deactivate the bone saw 408 and thereafter then lift away the resected portion of the patient's humeral head 402.

0125The head resection guide 670 may be constructed from a medical-grade metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. Moreover, rigid polymers such as polyetheretherketone (PEEK) may also be used.

0126<figref idref="f0021">FIGS. 43 and 44</figref> show another stemless humeral component 10 having features which are substantially similar to those discussed above with reference to <figref idref="f0001 f0002 f0003">FIGS. 1 to 5</figref>. Such features are designated in <figref idref="f0021">FIGS. 43 and 44</figref> with the same reference numbers as those used in <figref idref="f0001 f0002 f0003">FIGS. 1 to 5</figref>. In essence, the component of <figref idref="f0021">FIGS. 43 and 44</figref> is substantially the same as the component of <figref idref="f0001 f0002 f0003">FIGS. 1 to 5</figref> with a few exceptions. For example, the suture holes 26 have been removed from the stemless humeral component of <figref idref="f0021">FIGS. 43 and 44</figref>. In such a case, the surgeon may use the viewing windows 30 instead of the removed suture holes 26 to suture bone wafers or soft tissue to the stemless humeral component 10. To accommodate such use of the viewing windows 30, the edges of the stemless humeral component's support flange 14 defining the viewing windows 30 may be rounded.

0127<figref idref="f0022">FIGS. 45 and 46</figref> show another sizing instrument 160 having features which are substantially similar to those discussed above with reference to <figref idref="f0006">FIGS. 10 and 11</figref>. Such features are designated in <figref idref="f0022">FIGS. 45 and 46</figref> with the same reference numbers as those used in <figref idref="f0006">FIGS. 10 and 11</figref>. In essence, the instrument of <figref idref="f0022">FIGS. 45 and 46</figref> is substantially the same as the instrument of <figref idref="f0006">FIGS. 10 and 11</figref> with a few exceptions. For example, the viewing windows 180 have been removed from the sizing instrument 160 of <figref idref="f0022">FIGS. 45 and 46</figref>.

0128Moreover, the geometry of the punch guide holes 170 has been altered. In particular, the punch guide holes 170 are substantially T-shaped in the embodiment of the sizing instrument 160 shown in <figref idref="f0022">FIGS. 45 and 46</figref>. In such a way, the geometry of the punch guide holes 170 more closely corresponds with the geometry of the T-shaped tines 252 of the surgical punch 240.

0129In addition, the geometry of the connector 182 has been altered in the embodiment of the sizing instrument 160 shown in <figref idref="f0022">FIGS. 45 and 46</figref>. To accommodate such a change, the attachment mechanism 126 of the alignment handle 120 may also be altered to secure the sizing instrument 160 thereto.

0130<figref idref="f0023">FIG. 47</figref> shows another surgical punch 240 having features which are substantially similar to those discussed above with reference to <figref idref="f0007">FIG. 14</figref>. Such features are designated in <figref idref="f0023">FIG. 47</figref> with the same reference numbers as those used in <figref idref="f0007">FIG. 14</figref>. In essence, the punch of <figref idref="f0023">FIG. 47</figref> is substantially the same as the punch of <figref idref="f0007">FIG. 14</figref> with a few exceptions. For example, the centre spike 262 has been removed from the surgical punch 240 of <figref idref="f0023">FIG. 47</figref>. In such a case, the surgeon may use the centre drill 270 to drill a hole in the patient's surgically-prepared humerus to accommodate the elongated sleeve 36 of the stemless humeral component 10 in the manner discussed above.

0131Moreover, the struts 268 have been removed such that the tines 252 are more integrally formed in the surgical punch's body 242. In addition, the geometry of the surgical punch's connecting socket 260 and connecting channel 246 have been altered in the embodiment of the surgical punch 240 shown in <figref idref="f0023">FIG. 47</figref>. To accommodate such a change, the attachment mechanism 86 of the impact handle 80 may also be altered to secure the surgical punch 240 thereto.

0132Moreover, as can be seen in <figref idref="f0023">FIG. 47</figref>, the proximal end 266 of each of the ribs 256 of the tines 252 (i.e., the end secured to the punch's shaft 244) is wider than the opposite, distal end 288 of each rib 256. As such, the corresponding shape of the punched holes formed in the patient's surgically-prepared humerus is wider at its open end than at its blind end. Such a widened opening facilitates insertion of the cantilevered legs 16 of the stemless humeral component 10.

0133<figref idref="f0024">FIG. 48</figref> show another implant insertion tool 540 having features which are substantially similar to those discussed above with reference to <figref idref="f0018">FIG. 37</figref>. Such features are designated in <figref idref="f0024">FIG. 48</figref> with the same reference numbers as those used in <figref idref="f0018">FIG. 37</figref>. In essence, the tool of <figref idref="f0024">FIG. 48</figref> is substantially the same as the tool of <figref idref="f0018">FIG. 37</figref> with a few exceptions. For example, the size of the knob 552 is larger in the embodiment of <figref idref="f0024">FIG. 48</figref> to facilitate use thereof by the surgeon. Moreover, the implant insertion tool's grip is over-moulded to the tool's body 542.

0134<figref idref="f0025 f0026 f0027">FIGS. 49 to 52</figref> show a drill guide 710 that may be used to pre-drill the patient's surgically-prepared humeral surface prior to implantation of the stemless humeral component 10. In such a case, the surgeon may opt to subsequently punch the patient's surgically-prepared humeral surface prior to implantation of the stemless humeral component 10 in the manner described above (i.e., use the surgical punch 240 after such pre-drilling). Alternatively, the surgeon may drill the patient's surgically-prepared humeral surface in lieu of the punch procedure.

0135As described above, the stemless humeral component 10 may be provided in various sizes (i.e., diameters) to fit the needs of a given patient. For example, the stemless humeral component 10 may be provided in nine different sizes. Each of such differently-sized components 10 has legs of different thicknesses and lengths. As such, if discrete drill guides are used for each differently-sized stemless humeral component 10, multiple differently-sized drill guides would be required (e.g., nine differently sized drill guides would be required for nine differently-sized stemless humeral components 10). Moreover, to avoid overly thick drill guides for the smaller sizes of stemless humeral components 10, multiple different drill sizes may be required. As discussed below, the drill guide 710 avoids the need for such differently-sized drill guides and drills.

0136The drill guide 710 includes a body 712 having a generally planar lower surface 714, and an opposite, stepped upper surface 716. As can be seen in <figref idref="f0025">FIG. 49</figref>, the stepped upper surface 716 is spiral shaped and, being stepped, includes a plurality of discrete generally planar drill-stop surfaces 718. Each of the drill-stop surfaces 718 is spaced apart from the lower surface 714 of the drill guide's body 712 by a different length. As a result, the drill guide's body 712 has a different thickness at the locations corresponding to each of the different drill-stop surfaces 718.

0137As can be seen in <figref idref="f0025">FIGS. 49</figref> and <figref idref="f0026">50</figref>, each of the drill-stop surfaces 718 has a number of guide bores 730 formed therein. The guide bores 730 are configured to guide the peripheral drill bit 272 during drilling of the patient's surgically-prepared humeral surface. As such each of the guide bores 730 extends throughout the entire thickness of the guide body 712. In other words, one end of each of the guide bores 730 opens into the drill-stop surface 718, with the other end opening into the lower surface 714. As described above, the collar 284 of the peripheral drill bit 272 functions as a depth stop to ensure the drill bit 272 drills surgically-prepared holes at a desired depth. As such, the peripheral drill bit 272 may be advanced through one of the guide bores 730 and into the bone tissue until the lower surface 286 of the collar 284 bottoms out or otherwise engages the selected drill-stop surface 718.

0138Each of the drill-stop surfaces 718 corresponds to a differently-sized stemless humeral component 10. For example, a drill-stop surface 720 at the "bottom" end 722 of the spiral-shaped stepped upper surface 716 corresponds to the largest size of stemless humeral component 10, with the a drill-stop surface 724 at the "top" end 726 of the spiral-shaped stepped upper surface 716 corresponding to the smallest size of stemless humeral component 10. The remaining drill-stop surfaces 718 correspond to the remaining sizes of the stemless humeral component 10 with the size of the corresponding component 10 increasing along the stepped upper surface 716 in the direction from its top end 726 to its bottom end 722.

0139Because each of the drill-stop surfaces 718 is spaced apart from the lower surface 714 of the drill guide's body 712 by a different length, the peripheral drill bit 272 will drill to different depths of the patient's surgically-prepared humeral surface depending on which drill-stop surface 718 is used by the surgeon. For example, if the surgeon utilizes the guide holes 730 of the drill-stop surface 724 at the "top" end 726 of the spiral-shaped stepped upper surface 716, shallower drilled holes will be produced than if the surgeon utilizes the guide bores 730 of the drill-stop surface 720 at the "bottom" end 722 of the spiral-shaped stepped upper surface 716 since the collar 284 of the drill bit 272 will bottom out on the drill-stop surface 724 prior to when it will bottom out on the lower-positioned drill-stop surface 720. As such, the drill bit 272 will progressively drill deeper at the drill-stop surfaces 718 along stepped upper surface 716 in the direction from its top end 726 to its bottom end 722.

0140As can be seen in <figref idref="f0026">FIGS. 50 and 51</figref>, the guide bores 730 of each of the drill-stop surfaces 718 are arranged in a unique hole pattern relative to the remaining drill-stop surfaces 718. For example, the drill-stop surface 720 at the "bottom" end 722 of the spiral-shaped stepped upper surface 716 corresponding to the largest size of stemless humeral component 10 has a relatively large hole pattern (i.e., the guide bores 730 are more spread out relative to the other hole patterns), whereas the drill-stop surface 724 at the "top" end 726 of the spiral-shaped stepped upper surface 716 corresponding to the smallest size of stemless humeral component 10 has a relatively small hole pattern (i.e., the guide bores 730 are more compact relative to the other hole patterns). In such a way, the hole pattern corresponds to the size of the cantilevered legs 16 of the differently-sized stemless humeral components 10, with larger hole patterns corresponding to larger component legs 16 and smaller hole patterns corresponding to smaller component legs 16. That is, the drill-stop surfaces 718 correspond to the sizes of the stemless humeral component 10 with the size of the corresponding component 10 increasing along the stepped upper surface 716 in the direction from its top end 726 to its bottom end 722.

0141As can be seen in <figref idref="f0025">FIGS. 49</figref> and <figref idref="f0026">51</figref>, the guide body 712 has an elongated boss 732 secured to, and extending downwardly from, its lower surface 714. The elongated boss 732 is configured to be received into the elongated bore 168 of the sizing instrument 160 to secure the drill guide 710 thereto. An elongated grip 734 is secured to, and extends upwardly from, the stepped upper surface 716. The grip 734 has a number of grooves 736 formed therein and is used by the surgeon to grasp the drill guide 710.

0142As shown in <figref idref="f0026">FIG. 51</figref>, the guide body 712 has a number of alignment keys 738 formed in its lower surface 714. The alignment keys 738 are received into a number of alignment slots 740 formed in the sidewall of the sizing instrument's elongated bore 168 (see <figref idref="f0027">FIG. 52</figref>) to correlate the proper drill-stop surface 718 with the correct size of the sizing instrument 160. In particular, the alignment slots 740 of each of the differently-sized sizing instruments 160 are placed in annular locations unique to the particular sizing instrument 160 (i.e., each of the differently-sized sizing instruments has a unique slot configuration). When the alignment keys 738 of the drill guide 710 are advanced into the uniquely-positioned alignment slots 740, the proper drill-stop surface 718 corresponding to the particular size of the sizing instrument 160 will be positioned over one of the sizing instrument's guide punch holes 170 thereby "keying" the stepped upper surface 716 of the drill guide 710 to the particular size of the sizing instrument 160.

0143Like other of the instruments described herein, the drill guide 710 may be constructed with a biocompatible metal such as stainless steel, cobalt chrome, or titanium, although other metals or alloys may be used. The drill guide 710 may also be embodied as a polymer instrument. As such, drill guide 710 may be made of any suitable medical-grade polymeric material such as polyetheretherketone (PEEK). In such an example, the polymer drill guide 710 may include metallic inserts (e.g., sleeves) positioned in the drill guide bores 730.

0144In operation, the surgeon may use the drill guide 710 to drill a number of holes in the patient's surgically-prepared humeral surface. To do so, the surgeon first selects a size of the stemless humeral component 10 to implant in the patient's humerus in the manner described above. Such a selection may be performed preoperatively or as a result of intraoperative changes based on use of the sizing instrument 160. The surgeon then secures a sizing instrument 160 that corresponds to the selected size of the stemless humeral component 10 to the surgically-prepared surface of the patient's humerus in the manner described above in regard to <figref idref="f0012">FIG. 27</figref>.

0145The surgeon then selects a drill-stop surface 718 of the drill guide 710 that corresponds to the selected size of the stemless humeral component 10 from the plurality of drill-stop surfaces 718 formed in the drill guide's stepped upper surface 716. The surgeon may then attach the drill guide 710 to the sizing instrument 160 by advancing the drill guide's elongated boss 732 into the elongated bore 168 of the sizing instrument 160. During such advancement, the alignment keys 738 of the drill guide 710 are advanced into the uniquely-positioned alignment slots 740 of the sizing instrument 160 thereby causing the drill-stop surface 718 corresponding to the particular size of the selected sizing instrument 160 to be positioned over one of the sizing instrument's guide punch holes 170.

0146The surgeon may then advance the peripheral drill 272 through each of the guide bores 730 of the selected drill-stop surface 718 and into the bone tissue until the drill's collar 284 bottoms out or otherwise engages the selected drill-stop surface 718. The surgeon may then rotate the drill guide 710 such that the selected drill-stop surface 718 is positioned over a different one of the remaining punch guide holes 170 of the sizing instrument 160. Thereafter, the surgeon advances the peripheral drill 272 through each of the guide bores 730 and repeats the process at each of the remaining guide holes 170.

0147The surgeon may then utilize the surgical punch 240 in a similar manner to as described above in regard to <figref idref="f0013">FIG. 29</figref> to punch the now pre-drilled surgically-prepared surface of the patient's humerus and thereafter implant the stemless humeral component 10 in a similar manner to as described above in regard to <figref idref="f0015">FIG. 33</figref>. Alternatively, the surgeon may implant the stemless humeral component 10 into the drilled surgically-prepared surface of the patient's humerus without first utilizing the surgical punch 240.