Orthopaedic plate and bone screw assembly

ES 2 297 487 T3

DESCRIPTION

Orthopedic implant and bone screw assembly.

Field of the invention

The present invention relates generally to a system for engaging bone portions across a fracture, and more specifically to an intramedullary nail and screw assembly used to treat long bone fractures, such as the femur, humerus, and tibia. and various periarticular fractures of these and other bones.

Background of the invention

There are a variety of devices used to treat fractures of the femur, humerus, tibia, and other long bones. For example, fractures of the femoral neck, head, and intertrochanteric region have been successfully treated with a variety of compression screw assemblies, generally including a compression plate having a cylinder element, a set screw, and a lag screw. compression. Examples include the AMBI® and CLASSIC ™ hip compression screw systems offered by Smith & Nephew, Inc. In such systems, the compression plate is attached to the outside of the femur, and the cylinder element is inserted into a pre-drilled hole. in the direction of the femoral head. The set screw has a threaded end, or other mechanism for engaging the bone, and a smooth portion. The set screw is inserted through the cylinder member so that it extends through the interruption and into the femoral head. The threaded portion engages the femoral head. The compression screw connects the set screw to the plate. By adjusting the tension of the compression screw, the compression (reduction) of the fracture can be varied. The smooth portion of the set screw is free to slide through the cylinder member to allow adjustment of the compression screw. Some prior art assemblies use multiple screws to prevent rotation of the set screw relative to the compression plate and cylinder member and also to prevent rotation of the femoral head on the set screw.

Intramedullary nails have also been used successfully in combination with fixation screws or other screw assemblies to treat fractures of the femur, humerus, tibia, and other long bones. A significant application of such devices has been the treatment of femoral fractures. One such nail system is the IMHS® system offered by Smith & Nephew, Inc., and covered at least in part by US Patent No. 5,032,125, EPO 441,577, and various related international patents. Other key patents in the field include U.S. Patent Nos. 4,827,917, 5,167,663, 5,312,406, and 5,562,666, which are all assigned to Smith & Nephew, Inc. A typical prior art intramedullary nail may have one or more transverse openings through its distal end to allow distal bone pins or screws to be screwed or otherwise inserted through the femur at the distal end of the intramedullary nail. This is called “locking” and it secures the distal end of the intramedullary nail to the femur. In addition, a typical intramedullary nail may have one or more openings through its proximal end to allow a set screw assembly to be screwed or otherwise inserted through the proximal end of the intramedullary nail and into the femur. The fixation screw is placed through the break in the femur and an end portion of the fixation screw engages the femoral head. An intramedullary nail can also be used to treat fractures of the shaft of the femur or other long bones.

As with hip compression screw systems, intramedullary nail systems are sometimes designed to allow compression screws and / or lag screws to slide through the nail and thus allow contact between two or more fragments. bone. Contact resulting from sliding compression facilitates faster consolidation in some circumstances. In some systems, two separate screws (or a separate screw and pin) are used to prevent, among other things, the rotation of the femoral head relative to the rest of the femur, to prevent penetration of a single screw. beyond the femoral head and to prevent a single screw from ripping through the femoral neck and head. However, when an additional screw or dowel is used, the uneven forces applied to the separate screws or dowels can cause the separate screws or dowels to press against the sides of the holes through which the screws are intended to slide. or separate pins. This can result in bonding, reducing slippage of the screws or dowels through the nail. Conversely, a problem can result from excessive compression of the femoral head towards or at the fracture site. In extreme cases, excessive sliding compression can cause the femoral head to compress along the entire trochanteric region of the femur.

In addition, nails that are too rigid sometimes cause periprosthetic fractures in regions far from a fracture site. Therefore, it is important that intramedullary nails are adequately flexible compared to the bones into which they are implanted.

The hardest, usually outer portion of a typical bone is called the cortical bone. Cortical bone is typically a structurally sound load bearing material for implant support. A cross section of a long bone showing the typical anatomical shape of cortical bone generally reveals a non-circular ring of cortical bone surrounding a medullary canal. Consequently, the medullary canal generally has a non-circular cross section. However, prior art intramedullary nails are typically round or square in cross-section and therefore do not match the cortical bone or medullary canal anatomically. Some have treated this problem by reaming the medullary canal of the bone with a re2 reamer.

ES 2 297 487 T3 dondo in order to make the nail fix to the cortical bone. However, this approach can remove significant portions of healthy cortical bone.

The problem of providing an effective load bearing physical relationship between an implant and cortical bone in the proximal femur has been addressed in the art of hip arthroplasty devices. Various hip stems have been developed that have generally non-circular cross sections along their length in order to better fix the anatomically shaped cortical bone of the proximal femur and thus more evenly and efficiently distribute the load across the stem. and bone. However, none of these hip stems has been incorporated into a nail or configured to accept a screw or screws useful to repair substantially all portions of the treated bone. Instead, hip stems, as a general matter, have been viewed as a device for replacing portions of a long bone and have been designed and used for that purpose. For example, the typical application of a hip stem includes completely removing a femoral head and neck and implanting a hip stem, and using the hip stem to support an artificial femoral head.

In summary, and without limitation, the foregoing shows some of the shortcomings of the state of the art in this field. Among other things, what is needed is an orthopedic implant system that includes an upper lag screw or other mechanism to apply compression across a fracture. Some embodiments would also provide a lag screw or other mechanism that achieves adequate bone anchorage while reducing incidence of shear, rotational instability, and excessive slippage. An implant that is anatomically shaped appropriately to achieve improved contact with cortical bone would also be advantageous. When the implant is an intramedullary nail, the nail would provide reduced reaming and removal of healthy bone. An improved screw can also have a cross-section that provides a greater area of ​​material on the side of the nail that is placed under a higher tensile load when the nail is subjected to a typical bending load. Additionally, an improved implant system could include a lag screw in combination with intramedullary nails of various designs, or in combination with plates. Combinations of any of these with each other or combinations with each other and / or with other devices or combinations thereof also present opportunities for advancement beyond the state of the art according to certain aspects of the present invention.

Summary of the invention

An apparatus as defined in the claims allows the treatment of bone fractures using one or both of a structure configured to implant in or to stabilize a first bone fragment and a fixation assembly. The framework may take the form of an implant for implantation at least partially within the bone. Such implants can include a proximal section having a transverse opening and an opening substantially along its length. Preferably, they include at least one cross section in their proximal portions that is shaped to impart additional strength and tensile strength. Such shapes can be provided, for example, by one or both of (i) adding additional mass in the lateral portions of the cross section, and (2) strategically adding and reducing mass in the cross section to take advantage of flange effects so similar to the way flanges add structural benefits to I-beams and channels. One way to characterize such cross sections, which may be asymmetric, although not necessary, with respect to at least one axis, is that they generally exhibit a moment of inertia that extends in a lateral direction from a point that is the midpoint of a line from a lateral tangent to a mean tangent of the cross section. In some structures, that line is coplanar with the axis of the transverse opening and coplanar with the cross section and is therefore defined by the intersection of those planes. The end points of that line can be defined as the intersection of the line with tangents to the median aspect and the lateral aspect of the cross section, respectively. Such implants also typically include a distal section and a transition section that provides a coupling between the proximal section and the distal section.

The fixation assemblies are adapted to be accommodated in the transverse opening of the implant in a sliding relationship, so that the fixation assembly is adapted to slide with respect to the transverse opening and thus to apply compression to a fracture and to any other desired end. The engagement element is adapted to achieve anchoring in a second bone fragment. The latch and compression device are configured so that the compression device interacts with a portion of the implant and also with a portion of the latch so that the fit of the compression device controls the sliding of the latch with relative to the implant and thus allows controlled movement between the first and second bone fragments. In some embodiments, the compression device directly contacts, at least partially, the second bone fragment when implanted.

Declaration of the invention

The present invention provides an apparatus for treating bone fractures as defined in claim 1. Preferred embodiments are defined in dependent claims 2-7.

Brief description of the drawings

Figure 1 is a perspective view of an intramedullary nail shown installed in a femur.

Figure 1A is a perspective view of an intramedullary nail in greater detail.

ES 2 297 487 T3

Figure 1B is a perspective view of an intramedullary nail.

Figure 1C is a cross-sectional view of a portion of the nail of Figure 1B.

Figure 1D is a perspective view of an intramedullary nail.

Figure 2 is an elevation view of the intramedullary nail of Figure 1.

Figure 3 is a cross-sectional view of the intramedullary nail of Figure 2 taken through line 3-3.

Figure 4 is a side view of the intramedullary nail of Figure 2.

Figure 5 is a cross-sectional view of the intramedullary nail of Figure 4 taken through line 5-5.

Figure 6 is a cross section of the intramedullary nail of Figure 4 taken through line 6-6.

Figure 7 is a perspective view of an intramedullary nail.

Figure 8 is a perspective view of an intramedullary nail.

Figure 9 is a perspective view of an intramedullary nail.

Figure 10 is a perspective view of an intramedullary nail.

Figure 11 is a perspective view of an intramedullary nail.

Figure 12 is a perspective view of an intramedullary nail.

Figure 13 is a cross-sectional view of the intramedullary nail of Figure 7 taken through the line

13-13.

Figure 14 is a cross-sectional view of the intramedullary nail of Figure 8 taken through the line

14-14.

Figure 15 is a cross-sectional view of the intramedullary nail of Figure 9 taken through the line

15-15.

Figure 16 is a cross-sectional view of the intramedullary nail of Figure 10 taken through the line

16-16.

Figure 17 is a cross-sectional view of the intramedullary nail of Figure 11 taken through the line

17-17.

Figure 18 is a cross-sectional view of the intramedullary nail of Figure 12 taken through the line

18-18.

Figure 19 is a perspective view of a tool for preparing bone to accommodate certain devices.

Figure 20 is a perspective view of a device that includes one version of a fastener assembly.

Figure 21 is an exploded view of the intramedullary device and fixation element assembly shown in Figure 20.

Figure 22 is a perspective view of the fastener assembly shown in Figure 20.

Figure 23 is an exploded view of the fastener assembly of Figure 20.

Figure 24 is an elevation view of the latch member of the fixture assembly of Figure 23.

Figure 25 is a side view of the latch of Figure 24.

Figure 26 is a cross-sectional view of the latch of Figure 24 taken through line 26-26.

Figure 27 is an end view of one end of the latch member of Figure 24.

Figure 28 is an end view of the other end of the latch member of Figure 24.

ES 2 297 487 T3

Figure 29 is an elevation view of the compression device of the fastener assembly of Figure 22.

Figure 30 is a cross-sectional view of the compression device of Figure 29 shown through line 30-30.

Figure 31 is an end view of one end of the compression device of Figure 29.

Figure 32 is an end view of the other end of the compression device of Figure 29.

Figure 33 is a cross-sectional view of an intramedullary nail and screw assembly.

Figure 34 is a perspective view of a fastener assembly.

FIG. 35 is a perspective view of the set screw of the fastener assembly of FIG. 34.

Figure 36 is a perspective view of a fastener assembly.

FIG. 37 is a perspective view of the set screw of the fastener assembly of FIG. 36.

Figure 38 is a perspective view of a fastener assembly.

Figure 39 is an exploded view of the fastener assembly of Figure 38.

Figure 40 is a perspective view of a fastener assembly.

Figure 41 is an exploded view of the fastener assembly of Figure 40.

Figure 42 is a perspective view of a compression plate that includes a fastener assembly.

Figure 43 is a perspective view of a periarticular plate that includes a fastener assembly.

Figure 44 is a perspective view of a device according to one embodiment used in the context of repair of the humerus in a shoulder joint.

Detailed description

The apparatus according to embodiments of this invention seeks to provide improved treatment of femur fractures. Figures 1-6 illustrate various views of one embodiment of an intramedullary nail 100. The intramedullary nail 100 has a longitudinal bore 130 through it to aid in its insertion into the bone. Intramedullary nail 100 has a proximal section 102, a transition section 104, and a distal section 106.

The proximal section 102 of the particular framework shown in Figures 1-6 preferably exhibits an anatomically inspired shape that more precisely corresponds to a typical cortical bone. One version of such a shape is shown in cross-sectional view of proximal section 102 in Figure 6. The particular cross section of the proximal section 102 shown in Figure 6 is generally non-circular along at least some portions of its length, and has a lateral aspect or side 108 that is greater than a median aspect or side 109. The lateral side 108 and the middle side 109 are joined by a first side 110 and a second side 116. At the intersection of the first side 110 with the lateral side 108 there is a first rounded corner 112 and at the intersection of the second side 116 with the lateral side 108 there is a second rounded corner 114. The first side 110, the second side 116, and the lateral side 108 are of approximately equal length. The first side 110 and the second side 116 are oriented at acute angles with respect to the lateral side 108, so that the middle side 109 is less than the lateral side 108. By having the lateral side 108 larger than the medial side 109, the stability in rotation of the intramedullary nail 100 is increased and the resistance to bending and torsion can also be improved.

The middle side 109 shown in Figure 6 can be rounded. As can be seen in FIG. 4, the rounded medial side 109 projects out of the transition section 104 and continues to the proximal end of the intramedullary nail 100. The mid-side overhang 109 corresponds to the calcar region of the femur and improves the regularity of load distribution between bone and intramedullary nail 100. Furthermore, the general cross-sectional geometry of the proximal section reduces maximum stresses in the proximal section. More specifically, the typical failure mode of a screw assembly and intramedullary nail combination is failure of the nail with tension on its lateral side. Tension is created by the load-induced bending moment of body weight that is applied to the screw assembly. Therefore, it would be beneficial to reduce stress in the proximal section of a nail to include more material on the side of the nail that is in tension, the lateral side, to shape the cross section more effectively to improve strength and robustness in the nail. lateral zone, or both. The design illustrated in Figure 6 achieves this goal. The lateral side 108 is wider than the middle side 109, thus at least partially conferring

ES 2 297 487 T3 a flange type effect. The stress per unit area induced in the material on the lateral side 108 is less than it would be if the lateral side had a smaller cross-sectional area, such as the middle side 109.

A structure that benefits from the same principle is shown in Figures 1B and 1C which illustrate an intramedullary nail 1100 with a generally circular cross section whose generally circular opening 1128 is disposed non-concentrically with the periphery of the cross section. In the particular structure shown in these two figures, the off-center opening 1128 is offset towards the middle side 1109, so that a greater portion of material is available to carry load and reduce stress on the lateral side 1108. Also, any cross section that provides more material on the lateral side of the section reduces stress per unit area on the nail on that side.

Regardless of the particular way in which material or mass may be added to some portions of the lateral portions of the cross section of the proximal portion 102, material may be added and removed from some portions of the cross section in order to increase strength and the robustness of the side parts, or both, the effect being characterized as conferring a moment of inertia to the cross section oriented at least partially in the direction of the aspect or lateral side 108. The moment of inertia (shown indicated by the letter M in Figure 6) can be characterized as extending in a lateral direction, or at least partially towards the lateral aspect or side 108 from a point P which is the midpoint of a line L extending from the intersection I1 of that line with a tangent T1 to the lateral aspect 108, to the intersection I2 of that line with a tangent T2 to the middle aspect 109. In other words, the effect, at least in some cases, is to create a cross section exhibiting a moment of inertia extending in an at least partially lateral direction from a center of the cross section. Preferably, that center can be a midpoint between the lateral and middle edges of the cross section. Alternatively, that center can be the center of mass of the cross section. The radius of gyration reflected by the moment of inertia, which is a function of the square of the distance of the incremental mass from the center, reflects the additional force on the lateral portions of the proximal portion 102 produced by more mass or more strategically placed mass. on the. cross section. In some structures, the line L is coplanar with the axis of the transverse opening and coplanar with the cross section and is therefore defined by the intersection of those planes. As shown in Figures 1A, on the one hand, and 1B and 1C on the other, and taking into account that these are only two of the immense number of structures that can confer additional strength and lateral robustness of this type, the cross section can be asymmetric, although not necessary, with respect to at least one of its axes. Additionally, the longitudinal hole 130 may be positioned to share its central axis with that of the cross section, or it may be offset in order to help confer lateral force or for other purposes.

In the particular device shown in Figures 1-6, the first side 110, the second side 116, and the lateral side 108 are flat. Alternatively, these sides could be rounded or, in any case, not flat. In the embodiment shown in Figures 1-6, the middle side 109 is rounded, but as one skilled in the art would appreciate, the middle side could be flat.

Proximal section 102 has a transverse opening 118 that houses a screw or fixation assembly 200 (various versions of which are shown in Figures 19-41) through intramedullary nail 100. One embodiment of the proximal transverse opening 118, shown in Figures 1-4, is formed of two overlapping circular openings 120, 122, wherein the proximal circular opening 120 is smaller in diameter than the distal circular opening 122. The proximal circular opening 120 shown has a flange 132 to constrain the depth of insertion of the screw assembly as will be explained in more detail below. Various other openings could be used which allow the intersection of various screw assemblies as would be known to those skilled in the art. For example, Figure 33 illustrates the intramedullary nail with a circular opening. The embodiment of FIG. 33 is described in greater detail below.

The proximal section 102 illustrated in Figure 3 has a proximal end opening 128. Proximal end opening 128 is threaded to allow insertion of a set screw that can be used to fix the rotational and sliding position of a screw assembly. A set screw may also include mechanisms for encompassing a compression screw 204 (FIG. 19) and interfering with a set screw 202 (FIG. 19) to independently limit the rotation or sliding of the set screw 202.

As shown in Figures 1-6, transition section 104 is tapered from proximal section 102 to distal section 106. The tapered nature of transition section 104 creates a press fit in the intramedullary canal that controls sag. The tapered transition section 104 helps to prevent the nail 100 from being pressed into the intramedullary canal of the femur more than expected.

In the intramedullary nail 100 shown in Figures 1-6, the cross section of the transition section 104 is circular, but the cross section could vary as is known to those skilled in the art. The cross section could be derived from the anatomical, similar to the cross section of the proximal, oval or non-circular section 102. In the embodiment shown in Figures 1-6, the transition section 104 contains a distal transverse opening 124. Distal opening 124 allows intersection through intramedullary nail 100 of a distal locking screw to lock intramedullary nail 100.

The distal section 106 of the intramedullary nail 100 is generally cylindrical and is configured to provide reduced flexural stiffness. The embodiment shown in Figures 1-5 has a longitudinal slot 126 through

ES 2 297 487 T3 from the center of the distal section 106 which forms two sides 134, 136. The groove reduces flexural stiffness at the distal end of the intramedullary nail 100 and reduces the chances of periprosthetic fractures.

Figure 1D shows an intramedullary nail 100. This nail has, in its proximal portions, a non-circular cross section which is symmetrical with respect to its lateral-median axis (in this case, preferably but not necessarily, oval in cross section), and which has a longitudinal bore centered (in this case preferably but not necessarily circular in cross section). This nail achieves additional stability to the point that it resists twisting in the medullary canal. It also achieves the goal of placing more mass toward the aspect or lateral edge of the proximal cross section. Furthermore, it places additional mass towards the aspect or median edge, thus providing additional structure that acts as a fulcrum to lessen the mechanical advantage of the fastener assembly which when loaded is the component that imposes tensile stress on the aspect or side edge.

Figures 7-18 illustrate intramedullary nails 100. Figures 7 and 13 illustrate an intramedullary nail 100 that does not have a longitudinal bore through it.

Figures 8 and 14 illustrate an intramedullary nail 100 having stiffness reduction grooves 140 in transition section 104 and distal section 106. Stiffness reducing grooves 140 reduce flexural stiffness at the distal end of intramedullary nail 100 and could be used to accommodate locking screws in some embodiments.

Figures 9 and 15 illustrate an intramedullary nail 100 having three longitudinal grooves 138 in distal section 106 and a portion of transition section 104 that forms a cloverleaf pattern. This design more easily allows blood flow near intramedullary nail 100 and also reduces flexural stiffness at the distal end of nail 100.

Figures 10 and 16 illustrate an intramedullary nail 100 in which the distal section 106 and a portion of the transition section 104 have a series of longitudinal grooves 146. Longitudinal grooves 146 reduce flexural stiffness at the distal end, provide resistance to rotation, and improve blood flow near intramedullary nail 100.

Figures 11 and 17 illustrate an intramedullary nail 100 in which the transition section 104 and distal section 106 have fins 144. The fins 144 provide resistance to rotation for the intramedullary nail 100.

Figures 12 and 18 illustrate an intramedullary nail 100 having barbs 142 located in the distal section 106 and a portion of the transition section 104. Barbs 142 provide resistance to rotation for intramedullary nail 100.

Intramedullary nails can be inserted into a patient by any suitable known technique. Generally, the intramedullary canal of the bone is prepared with an appropriate tool to create a hole for the insertion of the nail. Portions of the gap can be prepared to be approximately 1 millimeter larger than the perimeter of the nail to allow sufficient room for blood flow after nail insertion. A guide wire or pin is optionally inserted into the prepared medullary canal. The nail is then inserted into the desired position. If the nail is cannulated, the nail can be inserted over the guide wire. Nail position can be confirmed by image intensification.

Figure 19 shows one embodiment of a tool 300 for preparing a medullary canal. The tool has a drill bit 302 for reaming and also a chisel 304. In operation, the drill 302 reams the medullary canal of the femur and the chisel 304 cuts a larger section at the most proximal end of a bone. As shown in FIG. 19, chisel 304 has an anatomically derived cross section of approximately the same shape as the proximal section of the intramedullary nail. By applying this type of shaped chisel, the proximal end of the nail will be allowed to better seat in cortical bone that has only been minimally disturbed. Chisel 304 can be of a wide variety of shapes, including complicated asymmetrical shapes. This is advantageous because it enables a device and method for preparing holes that can accept a wide variety of shapes of intramedullary nails without merely reaming circular holes excessively. Preparing a precisely shaped hole is valuable to prevent unnecessary removal of healthy bone, and to ensure stable seating of the nail.

In operation, tool 300 of the embodiment shown is advanced as a unit, reaming bit 302 and cutting chisel 304 simultaneously. The bit 302 can be rotated with an electric actuator or by hand. Also, the entire tool 300 may be manually advanced in a medullary canal, or advanced with the aid of electrical equipment or mechanical advantage. In other configurations, drill 302 can be cannulated (not shown) so that the entire tool 300 can be driven over and guided by a guide wire that has been inserted into the medullary canal.

In other embodiments, the reaming bit is a more traditional reamer that is separate from a cutting tool such as chisel 304. The method of preparing a hole in such a case would first include reaming a hole with a traditional reamer. Then, a device such as a chisel or reamer, shaped similar to the intramedullary nail to be implanted, would be used to prepare the hole. The chisel or reamer can ac

ES 2 297 487 T3 be used by hand, with the aid of a hammer or mallet, or with the use of other electrical equipment. A nail would then be implanted that matches the prepared hole.

Other standard instruments could also be used such as a contoured reamer or standard router bit and jig. Reamers have long been used to prepare holes for hip stems, and one of ordinary skill in the art will be familiar with the use of a reamer. Indeed, a router bit and template could be used to mill the desired shape into the bone. Such a method could also be used in combination with reaming or widening to create the desired gap.

The intramedullary nail can be used to treat proximal femoral and shaft fractures, among other long bone fractures. When used to treat femoral shaft fractures, the intramedullary nail is held in the femur by one or more fixation devices. When used for the treatment of proximal femoral fractures, the intramedullary nail is preferably used in conjunction with a proximal screw assembly.

Figures 20 and 21 illustrate an intramedullary nail 100 used in conjunction with a fixation element assembly 200. This type of fixation assembly can be used in various other bones and to treat various other indications, but for the purpose of providing an example, it is being described herein in use with the proximal femur. In general, the screw assembly is useful in any situation where a piece of bone is to be withdrawn into or pushed away from another piece of bone in a controlled manner. The fixation element assembly provides the additional advantage of being able to be configured to allow the assembly to slide in a desired direction after movement of the bone fragments.

As shown in FIG. 21, the axis of the proximal transverse opening 118 in the intramedullary nail 100 is angled relative to the proximal section 102 and in use, is directed toward the femoral head. In this embodiment of the clamp assembly 200, a latch such as a clamp screw 202 is used in conjunction with a compression device, such as a compression screw 204 or a compression pin. The screws are configured so that, when in use, the circumference of the set screw 202 partially intersects the circumference of the compression screw 204, so that the compression screw 204 is partially nested within the circumference of the set screw 202. This particular combination of set screw 202 and compression screw 204 is further illustrated in Figures 22 to 32. Briefly, the set screw 202 shown in these figures is intended to engage the femoral head and to slide into the transverse opening 118 of the nail 100. Compression screw 204 engages a flange or other structure in transverse opening 118 of nail 100 and also threads into the portion of set screw 202 into which compression screw 204 is engaged, so that rotation The compression screw 204 controls the sliding of the fixation screw 202 relative to the nail 100 and thus the compression of the femoral head against the fracture site.

The set screw 202 shown in these drawings includes an elongated body 206 and a threaded end 208. As shown in Figures 24 and 25, the threaded end 208 does not include a sharp end, which reduces the possibility of cutting through the femoral head. Elongated body 206 includes a channel 212 that allows placement of compression screw 204 partially within the circumference of set screw 202. Channel 212 includes a threaded portion 210 that complements and cooperates with a threaded section 214 of compression screw 204. Compression screw 204 includes a threaded section 214 and a head section 215. The threaded section 214 of the compression screw 204 is configured so that the threads are relatively flat and smooth on the outer surface so that they can easily slide into the opening and also reduce the possibility of cutting.

Set screw 202 is housed in proximal transverse opening 118 and in a pre-drilled hole in the femur such that set screw 202 extends through the interruption and into the femoral head. The threaded end 208 of the set screw 202 engages the femoral head as the set screw 202 is rotated within the opening 118 causing its threaded end 208 to engage the femoral head. Threaded end 208 can be any device for obtaining anchorage in the femoral head, and includes, but is not limited to, threads of any desired configuration including helixes, barbs, blades, hooks, expansion devices, and the like. The depth of placement of the fixation screw 202 in the femoral head differs depending on the desired compression of the fracture.

Compression screw 204 may also be housed through proximal transverse opening 118 in a pre-drilled hole in the femoral head. The threaded section 214 of the compression screw 204 engages with the threaded portion of the channel 212 of the set screw 202. Proximal transverse opening 118 has an interior flange 132 (FIG. 21) to limit sliding of compression screw 204 in the general median direction, and thus set screw 202, through opening 118. When the compression screw 204 is tightened, the threads 214 of the compression screw engage with the threaded portion 210 of the set screw channel and the compression screw 204 moves in the general middle direction downward from the set screw 202. Head section 215 of compression screw 204 engages flange 132 of proximal transverse opening 118 preventing compression screw 204 from moving further in the general median direction. As compression screw 204 is tightened, fixation screw 202 is pulled in the general lateral direction toward the intramedullary nail providing compression to the fracture. Compression screw 204 that partially cuts the circumference of set screw 202 provides increased surface strength and helps prevent rotation of the set screw.

ES 2 297 487 T3 the femoral head. Therefore, the compression screw 204 acts not only as part of the mechanism to move the fractured bone fragments relative to each other, but also directly contacts the femoral head bone to help prevent the femoral head from rotating. around the axis of the set screw 202.

In one embodiment, a set screw (not shown), positioned in opening 128 in the proximal end of the intramedullary nail, is used to engage compression screw 204 and lock compression screw 204 and set screw 202 in place. . The use of the set screw to secure the fastener assembly 200 in place depends on the fracture pattern. If a set screw is not used to engage the fixation element assembly, the fixation element assembly 200 may slide into the proximal opening limited by flange 132.

In the embodiment of the set screw and compression screw shown in Figures 20-32, the diameter of the compression screw 204 is less than the diameter of the set screw 202. The diameters of the set screw and compression screw could be the same or the diameter of the set screw could be less than the diameter of the compression screw. The set screw and compression screw threads could be a variety of different shapes as is known to those skilled in the art. In general, the purpose of the set screw is to obtain anchorage in the bone, and the purpose of the compression screw is to engage with and pull or move the set screw. Any configuration that allows these functions is within the scope of the invention.

The fixation element assembly could be further configured to allow the addition of a prosthetic femoral head and neck. In such an embodiment, the fixation screw 202 would be replaced with a prosthetic head and neck. The neck would lock into proximal transverse opening 118 in nail 100. The design would be beneficial when degeneration or re-injury to a hip joint and repaired femoral fracture would later necessitate total hip arthroplasty (TCA). The decision to carry out an ATC could be made between operations, or after a certain period of time. Rather than having to prepare a femur to accommodate a hip stem as is known in association with TCA, only a small portion of bone would need to be removed, along with the fixation element assembly 200. The prosthetic head and neck could then be inserted into the proximal transverse opening 118, the acetabulum prepared, and the remainder of the CTA completed.

Figure 33 is a cross-sectional view of an intramedullary nail 100 with an alternate fastener assembly 400. The illustrated fastener assembly is very similar to the IMHS compression fastener assembly.^® from Smith & Nephew, as disclosed in more detail in US Patent No. 5,032,125. The improvement of the illustrated device is that it includes the intramedullary nail 100 with an anatomically derived shape and its multiple advantages discussed above. In operation, a sleeve 401 is fixed through the intramedullary nail 100, and can be secured to the nail by the set screw or other effective mechanisms. A slide set screw 402 is movable axially within the sleeve 401. A compression screw 404 is threaded into the slide set screw 402 so that tightening of the compression screw 404 pulls the slide set screw 402 back. toward sleeve 401. With this mechanism, a bone fragment can be placed in a desired position, but still allows sliding compression once placed.

Figures 34-35 illustrate a fastener assembly 200 having a set screw 202 and a compression pin 502. As shown in Figure 34, set screw 202 and compression pin 502 are configured such that, when in use, the circumference of set screw 202 partially intersects the circumference of compression pin 502, although in some embodiments the circumferences could be adjacent rather than intersect. Set screw 202 includes an elongated body 206 and threaded end 208. Set screw 202 has a key 504 on channel 212. Compression pin 502 has a slot 503 that is adapted to receive key 504 of set screw 202. Key 504 and slot 503 can be a variety of complementary shapes, such as, when considered in cross-section, triangular, D-shaped, keyhole, and other shapes as are apparent to those skilled in the art. In operation, compression pin 502 can be moved relative to set screw 202 by a compression tool (not shown) that applies disparate forces between compression pin 502 and set screw 202, or between the entire assembly and the nail 100 intramedullary.

In the fixation element assembly 200 shown in Figures 34-35, the fixation screw 202 is housed to slide into a proximal opening of the intramedullary nail so that the fixation screw 202 extends through the interruption and into the socket. femoral head. The threaded end 208 of the set screw 202 engages the femoral head. Once the fixation screw 200 has been properly engaged with the femoral head, the compression pin 502 is inserted into the proximal opening into a pre-drilled hole in the femoral head, in order to further prevent rotation of the screw 202 from the femoral head. locking as the slot 503 of the compression pin 502 houses the key 504 of the locking screw 202. By providing more area for resistance, compression pin 502 helps prevent rotation of the femoral head on set screw 202. The compression pin 502 is secured in place in the intramedullary nail 100 by a set screw positioned in the opening at the proximal end of the nail. Set screw 202 can slide over compression pin 502 through the proximal opening. In another embodiment, compression pin 502 has barbs on its surface.

A fastener assembly 200 according to another embodiment is illustrated in Figures 36-37. The fastener assembly 200 of this embodiment has a compression pin 502 and a set screw 202 similar to

2 297 487 T3 those of the embodiment illustrated in Figures 34-35 except that the key 504 of the set screw 202 and the slot 503 of the compression pin 502 have complementary ratchet teeth 506. The compression pin 502 is fixed in place in the intramedullary nail by a set screw positioned in the opening at the proximal end. Compression of the fracture can be achieved by pushing the set screw in the general lateral direction. The ratchet teeth 506 allow the set screw 202 to move in the general lateral direction, but prevent the set screw 202 from moving in the general median direction. A compression tool similar to the tool described in association with Figures 34-35 can be used to achieve movement.

FIGS. 38-39 a fastener assembly 200 according to another embodiment of the invention having a set screw 602, a cross screw 610, and a compression screw 604. Set screw 602 includes an elongated body 606 and threaded end 608. The elongated body 606 is semicircular in cross-sectional shape. Screws 602, 604, 610 are configured so that the circumference of set screw 602 intersects the circumferences of cross screw 610 and compression screw 604. Elongated body 606 of set screw 602 is threaded to complement and cooperate with a threaded section 602 of cross screw 610. The cross screw 610 is threaded to engage with the set screw 602 and the compression screw 604. Compression screw 604 includes a threaded portion 614 and a head portion 612.

In this embodiment, set screw 602, cross screw 610, and compression screw 604 are simultaneously housed to slide into a proximal opening of an intramedullary screw. Set screw 602 extends through the interruption and into the femoral head. The threaded end 608 of the set screw 602 engages the femoral head. As compression screw 604 is tightened, the compression screw threads 614 engage the threads of cross screw 610 and set screw 602, thereby moving set screw 602 in the general lateral direction toward the intramedullary nail, providing compression to the femoral head. Then, screw 610 is rotated crosswise causing compression screw 604 to move in the distal direction away from set screw 602. The fixation element assembly 200 may alternatively be configured so that the compression screw 604 moves proximally with respect to the fixation screw 602. Separating compression screw 604 from set screw 602 helps prevent rotation of the femoral head on set screw 602 adding more area for strength.

Figures 40-41 illustrate a fastener assembly 200 according to another embodiment having a set screw 702 and a compression pin 704. Set screw 702 includes an elongated body 706 and a threaded end 708. Elongated body 706 is semi-circular in shape to allow compression pin 704 to be partially positioned within the circumference of set screw 702 for insertion into the femur and has a key 712 positioned on the inner side of elongated body 706 . The elongated body 706 also has a hole 710 through the body. The compression pin 704 is generally cylindrical and is sized to fit within the semi-circular body 706 of the set screw. Set screw key 712 is housed in slot 714 in compression pin 704. Key 712 and key 714 contain complementary ratchet teeth.

In this embodiment, fixation screw 702 and compression pin 704 are simultaneously housed to slide into a proximal opening of an intramedullary screw in a pre-drilled hole in the femur. Set screw 702 extends through the interruption and into the femoral head. The threaded end of the set screw 702 engages the femoral head. A compression tool similar to the tool described in association with Figures 34-35 can be used to achieve movement between compression pin 704 and set screw 702, or between the entire assembly and intramedullary nail 100. A set screw can be used to fix the position of the fastener assembly. The set screw is configured so that when the set screw is tightened, a protrusion on the set screw is received through the slot 710 of set screw 702 and the compression screw 704 is moved away from screw 702 away from the set screw. fixation. Separating the compression screw 704 from the set screw 702 helps prevent rotation of the femoral head on the set screw adding more area for strength.

Figure 42 illustrates another embodiment in which a fastener assembly 200 is employed in conjunction with a compression plate 150. As illustrated, the devices are being applied to a femur. The various embodiments of fixation element assembly 200 disclosed above can be used with a similar compression plate, and various compression plates can be configured to apply to other parts of the anatomy.

Figure 43 illustrates another embodiment in which a fixation element assembly 200 is being used with a periarticular plate 170. The plate and fastener assembly shown are being applied to the proximal portion of a tibia. The various embodiments of fixation element assembly 200 disclosed above can be used with a similar periarticular plate, and various periarticular plates can be configured to apply to other parts of the anatomy.

Figure 44 illustrates an embodiment in which a fixation element assembly 200 is used in combination with a humeral nail 190. As illustrated, a head section 212 of compression screw 204 abuts against the humerus to apply compression against the humerus. With compressive force applied to set screw 202, and set screw 202 secured to a bone fragment through its threaded end 208, the bone fragment can be brought into position for proper healing. In some circumstances, it will be advantageous to place a washer or bearing surface (not shown) between the head section 212 and the humerus bone against which it is

ES 2 297 487 T3 compresses the head section 212. In yet another variant, the hole in the humerus can be enlarged so as to allow the head section 212 to penetrate the humerus and bear against a portion of the humeral nail 190. In such an embodiment, the fixation element assembly 200 would be shorter than that illustrated in FIG. 45 to obtain anchoring in the same area of ​​the bone with the threaded end 208. The various embodiments of the fastener assembly 200 disclosed above can be used with a similar nail and various nails can be configured so that they can be applied to other parts of the anatomy.