Headless compression screw with integrated reduction-compression instrument

(54) Title: INSTALLATION INSTRUMENT, DEVICE FOR ADJUSTING, COMPRESSING, AND / OR FIXING BONE FRAGMENTS, METHOD FOR SELECTIVELY CONFERING STRENGTH TO A SCREW, AND, DEVICE FOR CONFIRMING A STRENGTH FOR A SCREW (30) Unionist Priority: I6 / 08/2005 us 11 / 205,829 (73) Owner (s): synthes gmbh (72) Inventor (s): André Frenk, Florian Beutter, Franco Cicoira, Walter Pistoia, Yan Yevmenenko (74) Attorney (s): Tavares Intellectual Property Ltda (86) International Order: pct us200603i977de 15/08/2006 (87) International Publication: wo 2007/022261 de 22/02/2007 (57) Summary: installation instrument, device FOR ADJUSTING, COMPRESSING, AND / OR FIXING BONE FRAGMENTS, METHOD FOR SELECTIVELY CHECKING STRENGTH TO A SCREW, AND, DEVICE FOR CONFIRMING A STRENGTH TO A SCREW. A bone screw is provided having first and second threaded portions of different diameters separated by a non-threaded intermediate portion so that a bone screw can be inserted into a pair of adjacent bone fragments and used to compress the fragments together The screw into a hole drilled in the fragments. Also shown is an installation tool for threaded engagement of one end of the bone screw and used to initially drive the screw into the hole in the bone. After that, a screwdriver can be inserted through the tool and plugging it into a recess in the bone screw can be used to insert the screw completely into the bone and to separate it from the installation tool. In addition, an installation method is provided.

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140130

100

150

158 “INSTALLATION INSTRUMENT, ADJUSTMENT DEVICE,

COMPRESS, AND / OR FIX BONE FRAGMENTS, METHOD

TO SELECTIVELY GIVE STRENGTH TO A SCREW, AND,

DEVICE FOR CONFERRING A STRENGTH TO A SCREW ”

REFERENCECONDUCTED TO REQUESTS

<img file="BRPI0615212A2_D0002.tif" />

This application is partly a continuation of the US patent application 10 / 861,818 to Frenk et al, filed on June 4, 2004, which is a continuation of the international application PCT / CHO1 / 00698 for Frenk et al, filed on 04 December 2001, the two requests being here fully incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a bone screw for engaging two bone fragments, a device for implanting this bone screw, and a method for adjusting, compressing and / or fixing bone fragments.

BACKGROUND OF THE INVENTION

Bone screws are used in various ways in osteosynthesis, for example, to adjust bone fragments, such as compression screws or to fix bone fragments.

A bone screw with two axially threaded end segments 20 and a median segment without a distaff is known as U.

S. 5,019,079 to Ross. The diameter of the median segment corresponds essentially to the outer diameter of the outer thread of the threaded distal segment, but it is larger than the diameter of the outer thread core of the threaded proximal segment, so that the middle segment can be used to stabilize the two fragments laterally. of fracture bones. It may be a disadvantage of this particular construction of bone screws that the two external threads have different steps, so that different stages of the implant, the adjustment of bone fragments, the compression of bone fragments and the removal of the screw head do not can be performed separately from each other.

SUMMARY OF THE INVENTION

Pursued by the invention, this objective is achieved with a bone screw and with a device to implant it, as well as with a method to adjust, compress and / or fix bone fragments.

The bone screw of the invention essentially comprises two threaded segments which are arranged coaxially on the longitudinal axis and terminally on the bone screw, steps S_v and S_Hof the front and rear segments, respectively, which can be identical or different from each other. After these two bone segments have been adjusted and compressed, where only the front threaded segment is screwed into the distal bone fragment while the rear threaded segment is screwed, for example, into an implant instrument and not yet into the fragment of proximal bone, the bone screw can be further screwed into the bone fragments until the rear threaded segment is also fully seated in the proximal bone fragment. This can be achieved without at the same time changing the position of the bone fragments in relation to each other and without changing the compression of the two bone fragments. The two threaded segments are constructed so that the outside diameter of the front threaded segment is less than, or equal to the diameter of the outer thread core in the threaded rear segment.

An advantage of the bone screw of the invention and the invented device is that because the steps of the external thread of the front threaded segment and the rear threaded segment are the same, the steps of adjusting the bone fragments, compressing the bone fragments and positioning the screw head can be performed separately and in a controlled manner.

Because the rear threaded segment is configured with a core diameter that can be greater than or equal to the outer diameter of the front threaded segment, the interaction of the rear threaded segment with the thread already cut in the bone fragments for the front threaded segment can be avoided.

Preferably, the external threads of the front and rear threaded segments are self-cutting threads.

A preferred embodiment of the invented bone screw includes, between the two threaded segments, a median segment, without thread, which has an outside diameter that is less than, or equal to, the diameter of the core of the external thread of the front threaded segment . With this, the frontal threaded segment can be screwed completely into the distal bone fragment and the hole in the proximal bone fragment does not have to be enlarged in relation to the distal bone fragment hole to adjust and compress the bone fragments. Compared to known bone screw embodiments, the front threaded segment that joins directly to the rear threaded segment in the axial direction and for which the hole in the proximal bone fragment would have to be increased so that the front threaded segment can be screwed only within the distal bone fragment, moreover, with the present device, greater stability of the engagement between the bone screw and the proximal bone segment can be achieved.

The device of the invention serves to adjust, compress and fix bone fragments by means of a bone screw and includes a surgical implant instrument that has a central hole through which a screwdriver can be passed extending coaxially through the instrument. implant. In addition, the central hole is expanded from the front end of the implant instrument to a depth T, so as to form a shoulder at depth T. In the expanded part of the central hole there is an internal thread that is complementary to the external thread of the rear threaded segment of the bone screw, so that the rear external segment of the bone screw can be screwed into the central hole to a depth T. The depth T is selected so that T must be greater than L, where L is the length of the rear threaded segment of the bone screw. This ensures that the rear threaded segment of the bone screw can be completely screwed into the central hole of the implant instrument. However, T can also be equal to or less than L which can have the effect of partially inserting the rear threaded segment of the bone screw into the central hole.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and further developments of the invention are explained in more detail below, by means of partially diagrammatic representations of various examples. In the drawings,

Figure 1 shows a cross-sectional view of an embodiment of the bone screw of the invention;

Figure 2 shows a cross-sectional view of the embodiment shown in Figure 1, an implant instrument and a screwdriver;

Figure 3 A shows a side view of an embodiment of a compression sleeve;

Figure 3B shows a cross-sectional view of the compression sleeve of Figure 3A;

Figure 3C shows an enlarged partial cross-sectional view of the compression sleeve of Figures 3A-3B;

Figure 4A shows a side view of an embodiment of a cannulated screwdriver.

Figure 4B shows a cross-sectional view of the screwdriver of Figure 4A;

Figure 5A shows a side view of an embodiment of a protective grip;

Figure 5B shows a cross-sectional view of the protective handle of Figure 5 A;

Figure 6A shows a side view of a coupling member for use with the protective grip of Figures 5A-5B;

Figure 6B shows a cross-sectional view of the coupling member of Figure 6A;

Figure 7A shows a side view of a combined instrument;

Figures 7B-7C show cross-sectional views of the combined instrument of Figure 7A;

Figure 8A shows a cross-sectional view of a compression sleeve for use with the combined instrument of Figure 7 A;

Figure 8B shows an enlarged cross-sectional view of the compression sleeve of Figure 8 A;

Figure 9A shows a side view of a handle for use with the combined instrument of Figure 7A;

Figure 9B shows a cross-sectional view of the handle of Figure 9A;

Figure 10A shows a side view of a cannulated screwdriver and locking collar for use with the combined instrument of Figure 7A;

Figure 10B shows a cross-sectional view of the cannulated screwdriver and locking collar of Figure 10A;

Figure 10C shows an enlarged side view of the engagement portion of the cannulated screwdriver of Figures 10A-10B;

Figure 10D shows a cross-sectional view of the engagement portion of Figure 10C;

Figure 11A shows a side view of a locking ring for use with the combined instrument of Figure 7A;

Figure 11B shows a cross-sectional view of the locking ring of Figure 11 A;

Figure 12A shows a side view of a locking collar for use with the combined instrument of Figure 7A;

Figure 12B shows an end view of the locking collar of Figure 12 A;

Figure 13 A shows a side view of an embodiment of a compression sleeve having a hexagonal inlet for use with a screw sealed with plastic;

Figure 13B shows an enlarged side view of the compression sleeve of Figure 13 A;

Figure 13C shows an enlarged partial cross-sectional view of the compression sleeve of Figure 13 A;

Figure 14A shows a side view of a plastic seal for use with a screw; and

Figure 14B shows a cross-sectional view of the plastic seal of Figure 14A.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the bone screw 1 of the invention is shown in Figure 1. This bone screw 1 includes a rear threaded segment 7 with an outer thread 9 having a core diameter Dkh, an outer diameter D_Hif a step S_H, a threadless middle segment 6 with an outer diameter Dms> that coaxially joins the rear threaded segment 7 to the longitudinal axis 2, and the front threaded segment 5 with an external thread 8, which has a diameter of the core D_Kv, an outer diameter D_Vif a step Sy. The two threaded segments 5, 7 have different diameters, that is, the diameter of the core Dkh of the rear threaded segment 7 is greater than, or equal to the outside diameter D_Vs of the front threaded segment 5. The pitches of the two external threads 8,9 can be identical or they can be different from each other. Furthermore, the guide of the front threaded segment 5 can be the same as, or different from the guide of the threaded segment 7. The outer diameter D_MS of the median segment 6 is less than, or equal to the diameter of the nucleus D_Kv of the front threaded segment 5. In addition, at the front end 3 of the bone screw 1 and in the transition between the rear threaded segment 7 and the middle segment 6, several indentations 23 are arranged distributed on the periphery of the two threaded segments 5, 7 which must be axially aligned, with cutting edges 12 essentially parallel to the longitudinal axis 2 so that these two external threads 8, 9 are constructed as self-cutting threads. At the rear end 4 of the bone screw 1, means 11 are coaxially arranged to accommodate a screwdriver, for example, a hexagonal, Torx® or Philips recess. Furthermore, the bone screw 1 is equipped with a central hole 10 which extends from the front end 3 to the rear end 4 and serves, for example, to accommodate a guide wire (not shown).

In Figure 2 the device of the invention is shown together with the bone screw 1, a portion of the rear threaded segment is screwed into the implant instrument 15 and the front threaded segment 5 which is screwed completely into the distal bone fragment 14. The implant instrument includes a continuous central hole 17 which is expanded from the front end 18 to a depth T and, in the expanded part 24 it has an internal thread 20 which is complementary to the external thread 9. At depth T between the expanded part 24 of the central hole 17 and the narrower part 25 of the central hole 17 has a shoulder 22 against which the rear end 4 of the bone screw 1 rests when the rear threaded segment 7 is screwed completely into the implant instrument 15. A screwdriver 16 can be passed through the narrowest part 25 of the central hole 17 from the rear end 19 of the implant instrument 15 so that it can be inserted into the means 11, which are arranged at the rear end 4 of the screw for bone 1 to accommodate a screwdriver, and that the bone screw 1 can be rotated through it in relation to the implant instrument 15.

To adjust, compress and fix the two bone fragments 13, 14, a hole 21 must be drilled through the proximal bone fragment 13 and into the distal bone fragment 14. The diameter of hole 21 corresponds to the diameter of the core Dkv (Figure 1) of the external thread 8 of the front threaded segment 5 of the bone screw 1. However, hole 21 may be optional, particularly when the bone screw 1 is self-drilling.

At the beginning of the implantation process, the bone screw 1 is completely screwed down to a depth T in the internal thread 20 inside the central hole of the implant instrument 15. By turning the implant instrument 15 over the longitudinal axis 2, the screw for bone it can then be screwed into pre-drilled holes 21 in bone fragments 13, 14. Since the rear threaded segment 7 of the bone screw 1 is completely contained in the implant instrument 15, the external thread 9 of the rear threaded segment 7 cannot engage the bone fragment 13 so that when the implant instrument 15 is rotated , only the front threaded segment 5 of the bone screw 1 can be screwed into the distal bone fragment 14. In this phase, the front end 18 of the implant instrument 15 takes on the task of a screw head so that after the bone screw 1 has been taken into the two bone fragments 13, 14 enough that the front end 18 of the implant instrument 15 rests against the proximal bone fragment 14, the two bone fragments 13, 14 are moved towards each other by the posterior rotation of the implant instrument 15. As soon as the two bone fragments 13, 14 are in contact with each other, compression of the two bone fragments 13, 14 begins. As soon as the desired compression of the two bone fragments 13, 14 is achieved by the posterior rotation of the implant instrument 15, the screwdriver 16 is inserted through the central hole 17 of the implant instrument 15 into the means 11 to accommodate the key screw and the bone screw 1 is subsequently turned by the screwdriver 16 so that while the implant instrument 15 is held in place, the bone screw 1 is unscrewed from the internal thread 20 of the front end 10 of the implant instrument 15 and the rear threaded segment 7 is screwed into the proximal bone fragment 13 until the rear threaded segment 7 is brought completely under the surface of the proximal bone fragment 13. Since the two bone fragments 13, 14 did not move relative to each other during the last process, the compression remains unchanged after the rear threaded segment 7 is activated into the proximal bone fragment 13.

Preferably, the bone screw 1 is used where a screw head could interfere, for example, for fractures in the vicinity of a joint, for intra-articular fixation such as scaphoid fractures, for small fragments and for fixations in the vicinity of tendons, nerves and vessels. Bone screw 1 can also be used in conjunction with, or adjacent to, a bone plate (not shown).

FIGS. 3A-3C show an embodiment of a compression sleeve 30 for use with a bone screw 1. As shown in the side view of FIG. 3A, the compression sleeve 30 may have a front end 32, a rear end 34, and a handle portion 36 arranged near the rear end 34. As shown in the cross-sectional view of FIG. 3B, the compression sleeve 30 may have a hole 38 running through the sleeve 30 and extending between the front opening 40 and the rear opening 42. An enlarged view of the front end 32 of the compression sleeve 30 is shown in FIG. 3C. The internal threads 44 can be arranged at and / or near the front end 32 and the front opening 40 of the sleeve 30. The sleeve 30 can also have a shoulder 46 disposed adjacent to the internal threads 40. Shoulder 46 must be dimensioned to prevent a bone screw 1 from protruding too far from hole 38 of sleeve 30. The shoulder 46 must be positioned inside hole 38 so that the rear threaded segment 7 of bone screw 1 can fully engage the internal threads 40. The compression sleeve 30 can be used in a manner substantially similar to that of the implant instrument 15, discussed above.

FIGS. 4A-4B show an embodiment of a screwdriver 50 for use with a bone screw 1. As shown in the side view of FIG. 4A, the screwdriver 50 may also have a depressed portion 58 in, or near the rear end 54, which can assist in engaging a handle. As shown in the cross-sectional view of FIG. 4B, the screwdriver 50 may have a hole 60 running between a front opening 62 and a rear opening 64. The screwdriver may also have an engagement portion 66 for engaging a bone screw 1 in a manner similar to that described above with respect to the screwdriver 16. The engagement portion 66 may have any shape chosen to effectively engage a bone screw 1.

Indicator marks 56a, 56b, 56c can help determine the depth of insertion of a bone screw 1 into bone or tissue. When inserted into a compression sleeve or other implant instrument, the indicator marks 56a, 56b, 56c may be fully or partially visible during use. When the engagement portion 66 of the screwdriver 50 connects a receiving portion (an embodiment of which is shown above as means 11) of a bone screw 1, it is subsequently inserted into a bone or tissue and can be disengaged with the internal threads 40 of a compression sleeve 30. When the screwdriver is inserted further into hole 38 of sleeve 30, the indicator marks 56a,

56b, 56c can be progressively covered so that when the indicator mark 56c is covered by the sleeve 30, the bone screw 1 must be fully inserted into a bone or tissue.

FIGS. 5A-5B show an embodiment of a handle 70 for use with an instrument described herein. As shown in the side view of FIG. 5A, the handle may have a handle portion 72 and a coupling member 74 having a front opening 76 and expandable fingers 82. Coupling member 74 may be a separate and distinct component (as shown in FIGS. 6A-6B) and it can be inserted, at least partially, into a compression sleeve 30 via opening 42. The expandable fingers can be useful for contracting elastically within hole 38 of the compression sleeve 30 to create a more secure fit. As shown in the cross-sectional view of FIG. 5B, the handle 70 can also have a hole 78 for receiving the coupling member 74. The receiving portion 74 can also have a hole 80 for receiving a portion of a guide wire (not shown) through it.

FIGS. 6A-6B show, in more detail, an embodiment of a coupling member 74. As shown in the side view of FIG. 6A and in cross-sectional view 6B, the coupling member 74 may have a front opening 76, a rear opening 86 with a hole 80 extending between them. Coupling member 74 can also have a front end 85 and a stop end 86. Hole 80 may be of a particular size and sized to fit a guidewire (not shown).

When in use, the handle 70 can be useful to provide an ergonomic and safe means for the user to insert the bone screw 1 into a bone segment. First, a guidewire can be inserted into a bone segment at a desired location. The compression sleeve 30 with the bone screw 1 already attached to the internal threads 40 can be engaged with the handle 70 and then inserted over the guide wire so that the front end 3 of the bone screw 1 is adjacent to the surface of the bone. In this arrangement, the coupling portion 74 connects the compression sleeve 30 via its rear opening 42 and the free end of the guide wire is housed in the hole 78 of the handle 70. The bone screw 1 can then be inserted into the bone surface with the exposed, free end of the guidewire, securely lodged in the handle. After the bone screw 1 is inserted into the bone surface to a desired depth, the handle 70 and the coupling portion 74 can be disengaged from the compression sleeve 30 and the screwdriver 50 can be engaged to further tighten the bone screw 1 inside the bone surface and / or disengage the bone screw 1 from the compression sleeve 30. Thus, the configuration and removable engagement of the handle 70 with the compression sleeve 30 offer protection to the user of the free end of the guidewire and provide, in addition, an ergonomic method to insert the bone screw 1, at least partially, into of the bone surface.

FIGS. 7A-7C show an embodiment of another type of instrument, the combined instrument 100, which can be used with the bone screw 1. As shown in the side view of FIG. 7A, and viewed in cross section 7B-7C, the combined instrument 100 may have a handle 110, a locking collar 115, a locking ring 120, a compression sleeve 130 having a handle portion 135 and a stem portion 140 , a screwdriver 150 having a guide portion 158, and a hole 160 extending therethrough.

When in use, the combined instrument 100 can function substantially similar to the other devices described herein. A difference between the combined instrument 100 and the other devices described here is that the combined instrument 100 may have a selective engagement feature that allows a bone screw 1 to be inserted, at least partially, with and without the use of a screwdriver. 150. As described in more detail below, the selective locking arrangement between the locking collar 115 and the locking ring 120 can selectively determine whether the compression sleeve 130 is fixed in relation to the grip 110 and the screwdriver 150. Since the hole 160 passes through the entire combined instrument 100, a guidewire (not shown) can be used for a more accurate and accurate location and use of the instrument 100.

FIGS. 8A-8B show an embodiment of a compression sleeve 130 for use with the combined instrument 100. The compression sleeve 130 can be substantially similar in design and function to the compression sleeve 30 and the implant instrument 15 described above. The compression sleeve 130 can have a hole 131 extending between a front opening 133 and a rear opening 132. The sleeve 130 can also have a handle portion 135 and a stem 140. As with the compression sleeve 30 discussed above, the sleeve 130 may also have internal threads 134 to engage a bone screw 1, and a shoulder 136 to restrict the movement of a bone screw 1 into the hole 131. The compression sleeve 130 may, in addition, have an auxiliary stem portion 139 that is polygonal, or of another non-circular shape, to receive a locking ring 120 so that when it is received on the auxiliary stem, it cannot rotate in relation to the compression sleeve 120. Thus, the compression sleeve 130 and the locking ring 120 are fixed by rotation during use, although the locking ring can be slidably associated with the auxiliary stem portion 139.

FIGS. 9A-9B show an embodiment of a handle 110 for use with the combined instrument 100. It can have a hole 111 extending between a front opening 113 and a rear opening 114. The handle 110 can also have a handle portion 190 with 192 indentations to enhance the user's grip capacity. The handle 110 may additionally have an enlarged chamber 112, at least partially concurrent with the hole 114 which can receive at least a portion of a locking collar 115. The handle 110 is fixedly engaged, preferably with the locking collar. locking 115 by means of fasteners (not shown) inserted in the fixing holes 194.

FIGS. 10A-10D show an embodiment of a cannulated screwdriver 150 for use with the combined instrument 100. The screwdriver 150 can be substantially similar to the screwdrivers 16, 50 described above. The screwdriver 150 may have a front end 152, a rear end 154, a hole 156, and a guide portion 158 at and / or near the front end 152. As shown in FIGS. 10A-10B, the screwdriver 150 can be dimensioned to interact with the locking collar 115. The guide portion 158 is shown in greater detail in FIGS. 10C-10D. The guide portion 158 may have an engaging portion 157 for engaging a bone screw 1. The guide portion 158 may also have a hole 159 coaxial with, but with a reduced diameter in relation to the hole 156 of the screwdriver 150. Any one, and all the features of the guide portion 158 can also be used with the screwdriver 16, 50. The screwdriver 150 can be fixedly engaged with the handle 110 during use.

FIGS. 11A-11B show an embodiment of a locking ring 120 for use with the combined instrument 100. As shown in the side view of FIG. 11A and viewed in cross-section 11B, the locking ring 120 may have indentations 122 to aid in the grip, a first end 124, a second end 126, a first opening 125, and a second opening 123. The locking ring may also have locking elements 127a, 127b projecting into cavity 129 of locking ring 120. Locking elements 127a, 127b can fit indentations 118 of locking collar 115 as discussed below. Locking ring 120 may have one, two, three or more locking elements. The inner surface 121 of the locking ring 120 corresponds, preferably, to the shape and dimensions of the auxiliary shaft portion 139 of the compression sleeve 130.

FIGS. 12A-12C show an embodiment of a locking collar 115 for use with the combined instrument 100. As shown in the side view of FIG. 12A, front view of FIG. 12B and a cross-sectional view of FIG. 12C, the locking collar 115 can have an insertion end 117 for insertion into a handle 110, and an engagement end 119 for engaging a locking ring 120. Locking collar 115 can also have a hole 116 extending between ends 117, 119. As seen in detail in FIG. 12B, the engaging end 119 of the locking collar 115 may have a plurality of indentations 118 arranged around the hole 116. Some indentations 118 may engage the locking elements 127a, 127b of the locking ring 120. Locking collar 115 is fixedly engaged with handle 110 by means of fasteners being inserted into the fixing holes 196 which must align with the fixing holes 194 of the handle 110. The fixing holes 194, 196 can be threaded.

Locking collar 115 may also have indicator marks 191a, 191b, 191c, which can be used in a substantially similar manner to the indicator marks 56a, 56b, 56c of the screwdriver 50 (discussed above) so that when inserting the screw for bone 1 in a bone or tissue progresses, the indicator marks 191a, 191b, 191c are progressively covered up. Indicator marks 56, 191 can be spaced apart by a variety of distances. Indicator marks 56, 191 are spaced apart, preferably about 2mm.

The engagement and release of the locking collar 115 with the locking ring 120 will now be described. After the bone screw 1 is threaded to the compression sleeve 130, connecting the internal threads 134 to the rear threaded segment 7 of the bone screw 1, the combined instrument 100 is arranged so that the locking elements 127 of the ring locking elements 120 connect the indentations 118 of the locking collar 115. In this configuration, the entire combined instrument 100 is essentially an integrated tool. The combined instrument 100 is then rotated and / or otherwise manipulated to insert the bone screw 1 into the bone or tissue to a desired depth, but preferably so that the front end 133 of the compression sleeve 130 stay close to the surface of the bone or tissue. At this point, the locking ring 120 can be moved towards the distal end of the device, so that the locking elements 127 are disengaged from the indentations 118 of the locking collar 115. The locking ring 120 is moved, preferably in this direction to the point where it rests on the compression sleeve 130. After the locking ring 120 is disengaged, the handle 110 (with the screwdriver 150 and the locking collar 115 fixedly engaged) can be rotated to further insert the bone screw 1 into the bone or tissue while concurrently disconnecting the rear threaded segment 7 of the internal threads 134 of the compression sleeve 130. This is achieved because the engagement portion 157 of the screwdriver 150 is now allowed to engage the bone screw 1 and turn it free of the compression sleeve 130 into its hole 131.

FIGS. 13A-13C show another embodiment of a compression sleeve 200 and a embodiment of a plastic seal 220 for use with the bone screw 1 and in accordance with the overall objectives of the invention described herein. As shown in the side view of FIG. 13A, in the enlarged side view of FIG. 13B and in partial cross-sectional view of FIG. 13C, the compression sleeve 200 may have a hole 202 extending between the front opening 204 and the rear opening 206. Hole 202 may have more than one diameter. The compression sleeve 200 may also have a shank portion 208 and a nose portion 209 having a front end 210. As shown in greater detail in FIGS 13A-13C, the nose portion 209 may have an inner surface 212 in the form of hexagon to receive a portion of a plastic seal 220 (see FIGS. 14A-14B below). The inner surface 212 can have other shapes as long as appropriate to restrict the rotational movement of the plastic seal 220 within the tip portion 209. The tip portion 209 may also have a ring 214 disposed near the front end 210 to elastically hold a portion of a 220 plastic seal. Ring 214 can be elastically deformable to allow a portion of a plastic seal 220 to be engaged with ring 214 while still allowing plastic seal 220 to slide out of the ring and forward into hole 202.

FIGS. 14A-14B show an embodiment of a plastic seal 220 for use with compression sleeve 200 and bone screw 1. As shown in the side view of FIG. 14A and in the cross-sectional view of FIG. 14B, seal 220 may have a front end 222, an insertion end 224 with a hole 226 extending between the front opening 230 and the rear opening 228. The seal 220 may also have a bulbous guide portion 234 for receiving a portion of a bone screw 1. The inner surface of the guide portion 234 may have a shoulder 232 similar in design and function to the shoulders 22, 46, 136 described above . The inner surface of the guide portion 234 may or may not be threaded. In one embodiment, the inner surface is not threaded and the bone screw 1 is inserted into the guide portion 234 by axial force. In another embodiment, the internal surface is threaded and the bone screw 1 can be received, by threading, inside the guide portion 234. The seal 220 can also be molded on at least a portion of the bone screw 1 The seal 220 may also have a hexagonal outer surface 236 at, or close to, the insertion end 224 that can be inserted into the hexagonal inner surface 212 of the compression sleeve 200. Shapes other than the hexagonal surface can be used. The seal 220 is preferably made of plastic and is preferably a single-use, disposable element.

When in use, bone screw 1 is inserted into front opening 230 of seal 220 and insertion end 224 is inserted into front opening 204 of compression sleeve 200, so that the outer hexagonal surface 236 of seal 220 connects the inner hexagonal surface 212 of compression sleeve 200. The bone screw 1 can then be partially inserted into the bone or tissue to a desired depth. The bone screw 1 can then be engaged by a screwdriver via hole 206 of the compression sleeve 200 to further insert the screw 1 into the bone or tissue and concurrently disengage the bone screw 1 with the seal 220. The bone screw 1 can be engaged in this way until it is completely disengaged with the seal 220. The plastic seal 220 can then be removed from the compression sleeve 200 and discarded.

The bone screw 1 can be totally or partially inserted into the instrument 15 or the compression sleeve 30, 130, 200 before engaging with a bone surface. Threaded portions of the bone screw 1 can have a variety of steps, lengths, diameters and, different threaded segments on a bone screw 1, can have the same steps, lengths and diameters, or different. The various combinations of features will be appreciated by those skilled in the art.

It is expressly contemplated that the characteristics of some embodiments can be combined, integrated or interchanged with characteristics of other embodiments. In this sense, the components described, of the instruments described here, are “modular in nature. These combinations will be appreciated by those skilled in the art in addition to their modifications.

Although the invention has been presented and described here with reference to particular embodiments, it should be understood that the various additions, substitutions or modifications of shape, structure, arrangement, proportions, materials and components and, moreover, used in practice and that they are particularly adapted for specific environments and operational requirements can be made in the described embodiments without departing from the spirit and scope of the present invention. Consequently, it should be understood that the embodiments presented here are merely illustrative of the principles of the invention and that various modifications can be made by those skilled in the art who will incorporate the principles of the invention and fall within its spirit and scope.