Positioning screws for femoral nails

Abstract

A set screw for use in an intramedullary fracture fixation device having a longitudinal axis includes a housing and a set screw. The set screw may include a body having an external thread and an elastic member extending from the body, the elastic member having an uncompressed state and a compressed state. The housing may include a side wall partially surrounding the longitudinal axis, the side wall defining a cavity for accommodating the set screw, so that when the set screw is at least partially disposed in the cavity and in an uncompressed state, the set screw is fastened to the housing and can rotate relative to the housing.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 065,208, filed on August 13, 2020, and U.S. Provisional Application No. 62 / 986,138, filed on March 6, 2020, both of which are entitled “Positioning Screw for Femoral Nail,” the disclosures of which are each incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to intramedullary devices for internal fixation of fractured long bones. Background Art

[0004] Femoral fractures often occur in the femoral neck and trochanteric region. This type of fracture is usually treated with an intramedullary intertrochanteric fracture fixation device, which includes an intramedullary rod (sometimes referred to as an intramedullary nail or femoral nail) with an angled opening to receive a neck screw. The neck screw is designed to transfer the load from the femoral head to the shaft of the femoral nail while bridging the fracture line, so that the broken bone parts are compressed together and stabilized during osteogenesis.

[0005] Intramedullary nail is intended to be inserted into the medullary canal of femur by guide wire.When nail is inserted into the medullary canal of bone, guide wire helps to keep the correct placement of the bone part of fracture.Once intramedullary nail arrives its expected position in medullary canal, guide wire can be removed, thereby allowing neck screw to be inserted through the angled opening of femoral nail and enter into intertrochanteric bone.Then fastener (such as set screw etc.) is inserted through the axial hole defined in the proximal part of intramedullary nail to fasten neck screw to nail.

[0006] Postoperative rotational movement of the fractured bone fragments can lead to complications, such as shortening of the femoral neck, which can lead to reduced physical function. Therefore, it is desirable to compress the fracture site during surgery and then stabilize the bone parts to minimize their postoperative rotational movement during bone healing. It is sometimes also advantageous to allow limited axial sliding of the neck screw relative to the intramedullary nail to account for load transfer, which can occur, for example, when the patient's weight is applied to his or her hip.

[0007] Although improvements have been made to intramedullary intertrochanteric fracture fixation devices, various disadvantages still exist. For example, conventional set screws block the axial hole so that the set screw cannot be inserted into the intramedullary nail until the intramedullary nail has been implanted in the medullary canal of the bone and the guide wire has been removed. This is problematic because it may be a time-consuming process to fasten the set screw to the cervical screw when performed intraoperatively because soft tissue often overlaps the proximal end of the axial hole. Bone fragments of the expanded hole set in the axial hole may further aggravate the already difficult task of engaging the thread of the set screw with the corresponding thread in the femoral nail. In addition, improperly twisting the set screw may damage the thread of the set screw or the intramedullary nail, making the set screw easy to withdraw, which may cause postoperative rotation of the bone part of the fracture. Summary of the invention

[0008] According to a first aspect of the present disclosure, a sleeve-shaped set screw assembly for use in an intramedullary intertrochanteric fracture fixation device is provided. The sleeve-shaped set screw assembly allows the manufacturer or other users to pre-operate and tighten the set screw assembly to the corresponding thread in the femoral nail, thereby reducing errors and operation time.

[0009] The set screw assembly has a longitudinal axis and includes a set screw and a housing. The set screw includes a body having an external thread and a resilient member extending from the body, the resilient member having an uncompressed state and a compressed state. The housing includes a side wall partially surrounding the longitudinal axis, the side wall defining a cavity for accommodating the set screw, so that when the set screw is at least partially disposed in the cavity, the set screw is fastened to the housing and can rotate relative to the housing.

[0010] According to another aspect of the present disclosure, an intramedullary intertrochanteric fracture fixation device includes an intramedullary nail, a neck screw, and a positioning screw assembly. The intramedullary nail may include a proximal portion adjacent to the proximal end and a distal portion adjacent to the distal end. The proximal portion may define an angled opening, an axial hole, an internal thread, and a groove extending substantially parallel to the longitudinal axis, the axial hole having a longitudinal axis extending through the proximal end of the intramedullary nail and entering the angled opening. The neck screw may extend through the angled opening and have an outer surface with a groove, and the positioning screw may be disposed in the axial hole of the intramedullary nail. The positioning screw may include a housing having an upper portion and a lower portion, the upper portion including a first end wall, a second end wall, and a side wall that jointly define a cavity. The positioning screw may include an external thread engaged with the internal thread, and the positioning screw is at least partially disposed in the cavity of the housing, so that rotation of the positioning screw causes the positioning screw to rotate relative to the housing and causes the positioning screw and the housing to move together in the longitudinal direction.

[0011] In another aspect of the present disclosure, an intramedullary intertrochanteric fracture fixation device comprises an intramedullary nail, a neck screw and a positioning screw assembly. The intramedullary nail may have a proximal portion adjacent to a proximal end and a distal portion adjacent to a distal end. The proximal portion may define an angled opening, an axial hole, an internal thread and a groove extending through the proximal end of the intramedullary nail and entering the angled opening, and the axial hole has a longitudinal axis. The neck screw may extend through the angled opening, and the positioning screw assembly may be assembled in the proximal portion of the intramedullary nail before surgery so that the positioning screw assembly is cannulated to receive a guide wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a cross-sectional view of a femur.

[0013] 2 is an anterior-posterior elevation view of the proximal femur with a femoral neck fracture.

[0014] Figure 3 is a cross-sectional view of an intramedullary intertrochanteric fracture fixation device including an intramedullary nail, a neck screw, and a positioning screw assembly according to an embodiment of the present disclosure.

[0015] Figure 4 yes Figure 3 Side perspective view of the intramedullary nail shown in .

[0016] Figure 5A It is along Figure 4 A cross-sectional view taken along line AA of the intramedullary nail shown in FIG.

[0017] Figure 5B It is along Figure 4 A cross-sectional view taken along line BB of the intramedullary nail shown in FIG.

[0018] Fig. 6A yes Figure 3 Side elevation view of the set screw assembly shown in .

[0019] Figure 6B yes Figure 3 Top elevation view of the set screw assembly shown in .

[0020] Figure 7 yes Fig. 6A and Figure 6B Exploded view of the set screw assembly shown in .

[0021] Figure 8 is a depiction of a line extending through Figure 3 A partial cross-sectional view of a positioning screw assembly and a guide wire for an intramedullary nail is shown in FIG.

[0022] Fig.9A is a perspective view of a set screw assembly according to another embodiment of the present disclosure.

[0023] Fig. 9B yes Fig.9A A plan view of the set screw assembly.

[0024] Fig. 9C is a cross-sectional view taken perpendicular to the longitudinal axis of an intramedullary nail according to another embodiment of the present disclosure, the intramedullary nail being configured to receive Fig.9A and Fig. 9B Set screw assembly.

[0025] Fig.9D and Fig.9E They are Fig.9A and Fig. 9B A perspective view and a rear-anterior elevation view of a modified embodiment of a set screw assembly.

[0026] Fig.9F and Figure 9G yes Fig.9D and Fig.9E A bottom perspective view of a housing of a modified embodiment of a set screw assembly.

[0027] Figure 9H It's a picture. Fig.9D and Fig.9E A cross-sectional view of the joint between the neck screw and the set screw assembly taken along the longitudinal axis.

[0028] Figures 10A-10F is a top elevation view of an exemplary set screw assembly according to other embodiments of the present disclosure. DETAILED DESCRIPTION

[0029] As used herein, when referring to the femur or intramedullary nail, the term "proximal" refers to the end of the femur or intramedullary nail closer to the heart when the intramedullary nail is implanted in the patient's medullary canal in its expected manner. The term "distal" refers to the end of the femur or intramedullary nail farther from the heart when the intramedullary nail is implanted in the patient's medullary canal as expected. The term "anterior" refers to the front or face toward the body, and the term "posterior" refers to the back toward the body. The term "medial" refers to the midline toward the body, and the term "lateral" means away from the midline of the body. When referring to the neck screw, the term "rear" refers to closer to the user, and the term "front" refers to farther away from the user. Also as used herein, the terms "substantially", "usually" and "about" are intended to mean that slight deviations from absolute values ​​are included in the scope of the terms so modified.

[0030] Throughout this disclosure, fractures refer to femoral neck fractures, however, the devices described below can be used to fix associated fractures of the femoral shaft as well as fractures in other long bones (such as the tibia or humerus, etc.), whether the fracture occurs naturally or is induced by a surgeon.

[0031] 1 illustrates a femur 10 and its six anatomical regions: the diaphragm or midshaft 12, the proximal metaphysis 14, the distal metaphysis 16, the proximal epiphysis or head 18, the distal epiphysis 20, and the femoral neck 22. The femur 10 includes a scleroderma 24 and a medullary cavity 26. The medullary cavity 26 includes a medullary canal 28 extending through the center of the shaft 12, proximal and distal metaphyseal regions 30 and 32, and proximal and distal epiphyseal regions 34 and 36.

[0032] Fig. 2 is an anterior-posterior view of the proximal portion of the femur 10 with a fracture 38 extending along the femoral neck 22. The fracture 38 divides the proximal femur into a first bone portion 40 positioned adjacent to the proximal metaphysis 14 and a second bone portion 42 positioned adjacent to the proximal epiphysis or head 18. The fracture 38 is an exemplary illustration of an unstable, extra-articular fracture (i.e., the fracture is located outside of the joint). This type of fracture, if not treated, may lead to long-term complications, including comminution (i.e., comminution of the bone), which may lead to shortening of the femoral neck 22 and severe pain.

[0033] Figure 3 An intramedullary intertrochanteric fracture fixation device 100 is illustrated in accordance with an embodiment of the present disclosure. The device 100 is designed to compress a first bone portion 40 and a second bone portion 42 (shown in FIGS. 1 and 2 ) during healing of a fracture 38 and maintain rotational stability between the first bone portion and the second bone portion. The device 100 includes an intramedullary nail 102 having an angled opening 104 extending through the nail in a lateral to medial direction (in the direction of the lateral to medial direction), a neck screw 106, and a positioning screw 200. Figure 4 ), a neck screw 106 may be inserted through the angled opening for compressing the fractured bone portions together, and a positioning screw 200 is used to rotationally stabilize the neck screw within the angled opening of the intramedullary nail.

[0034] refer to Figure 4 , the intramedullary nail 102 includes a rod-shaped body having a proximal portion 108, a distal portion 110, and a middle portion 112 located between and connecting the proximal portion and the distal portion. The rod-shaped body of the intramedullary nail 102 can be anatomically shaped to allow the intramedullary nail to be inserted into the medullary canal 28 of the femur 10 (shown in FIG. 1 ). Therefore, the middle portion 112 can be curved and thinned in a direction from the proximal side to the distal side.

[0035] The rod-shaped body of the intramedullary nail 102 is cannulated and defines a channel 114, which is configured to receive a surgical line (such as a K-wire, etc.) for guiding the intramedullary nail into a suitable position in the medullary canal 28 of the femur 10 (shown in FIG. 1 ). The intramedullary nail 102 can have a substantially circular cross-section over its entire length, so that the proximal portion 108 and the distal portion 110 are substantially cylindrical. The proximal portion 108 of the intramedullary nail 102 has a diameter sufficient to accommodate the angled hole 104. The distal portion 110 of the intramedullary nail 102 has a diameter less than the diameter of the proximal portion 108, and the distal portion 108 is anatomically shaped into the medullary canal 28 of the femur 10 to facilitate the distal portion of the intramedullary nail to be inserted into the medullary canal of the femur. For the same reason, the distal portion 110 of the intramedullary nail 102 has a conical tip 116 at its distal end. The distal portion 110 of the intramedullary nail 102 may also define an aperture 118 configured to receive a bone fastener, such as a locking screw or the like, for fastening the intramedullary nail to the shaft 12 of the femur 10 after implantation.

[0036] like Figure 5A and Figure 5B As shown, the intramedullary nail 102 has an axial hole 122 extending along the longitudinal axis L of the proximal portion 108 of the nail between the proximal end of the nail and the angled opening 104. The axial hole 122 includes an internal thread 126, which is configured to be disposed in the positioning screw assembly 200 ( Figure 3 The corresponding thread fits on the ).

[0037] The angled opening 104 defines a bore axis 124 that is transversely angled relative to the longitudinal axis L of the proximal portion 108, such that the bore axis of the angled opening has an inclined extension relative to the axial extension of the proximal portion. In other words, the bore axis 124 of the angled opening 104 is oriented obliquely relative to the longitudinal axis L of the proximal portion 108. Thus, the bore axis 124 of the angled opening 104 is inclined relative to the longitudinal axis L of the proximal portion 108 at an angle α. The angle α may be between about 90° and about 140°, and may be, for example, about 126°.

[0038] Return to Figure 3 , the cervical screw 106 extends through the angled opening 104 in a lateral to medial direction. As will be explained in more detail below, the cervical screw 106 is positioned via a set screw 200 in a manner that prevents the cervical screw from rotating in the angled opening 104 and in a manner that allows the cervical screw to be rotated along the hole axis 124 (at Figure 5A ) is coupled to the intramedullary nail 102 in a manner that allows limited sliding to account for load offset.

[0039] The cervical screw 106 includes a rear end 128 and a front end 130. The rear end 128 of the cervical screw 106 includes a recess 132, for example, a hexagonal internal drive feature configured to receive a tool tip such as a screw driver or a wrench. The front portion of the cervical screw 106 includes threads 134, such as coarse threads, for anchoring the cervical screw into the intertrochanteric bone. The outer peripheral surface of the cervical screw 106 defines a plurality of grooves 136 extending in a direction generally parallel to the longitudinal axis of the cervical screw. For example, the cervical screw 106 may include four grooves 136 circumferentially spaced around the outer peripheral surface of the cervical screw at intervals of 90°. Each groove 136 defines an ascending ramp having a shallow end and a deep end. The ascending ramp extends from the rear of the cervical screw 106 toward the front of the cervical screw. Because the longitudinal axis of the neck screw 106 is substantially coaxial with the bore axis 124 of the angled opening 104 , the neck screw is configured to transfer loads placed on the femoral head to the intramedullary nail 102 and simultaneously bridge the fracture 38 and compress the first and second bone portions 40 , 42 together.

[0040] like Figure 6A-Figure 8 As shown in , the positioning screw assembly 200 is sleeve-shaped and thus overcomes the disadvantages associated with the positioning screws described in the prior art, namely the difficulties associated with assembly during surgery. Because the positioning screw assembly 200 is sleeve-shaped, the positioning screw assembly can be assembled in the intramedullary nail 102 before surgery and is configured to receive a guide wire while being disposed in the nail. That is, during surgery, the surgeon can insert the intramedullary nail 102 containing the positioning screw assembly 200 through the guide wire and into a position in the patient's medullary canal. As used herein, the term "preoperative assembly" refers to assembling the positioning screw assembly 200 in the intramedullary nail 102 by the manufacturer before transporting the intertrochanteric fracture fixation device 100, or alternatively, assembling the positioning screw assembly in the nail by the user before the nail is implanted in the patient's medullary canal.

[0041] The set screw assembly 200 includes a housing 202 and a set screw 204. Figure 6B and Figure 8 As shown, cannula 206 extends along the longitudinal axis of set screw assembly 200 and completely through housing 202 and set screw 204 of the set screw assembly such that the set screw assembly is configured to receive a guide wire when the set screw is disposed within the housing and preoperatively assembled within intramedullary nail 102.

[0042] refer to Figure 7, the housing 202 includes an upper portion 208 and a lower portion 210. The upper portion 208 of the housing 202 includes a first end wall 212, a second end wall 214 spaced a distance from the first end wall, and a side wall 216 extending between the first end wall and the second end wall and partially surrounding the cannula 206 of the upper portion. In other words, the side wall 216 only partially surrounds the longitudinal axis of the positioning screw assembly 200. In this way, the combination of the first end wall 212, the second end wall 214, and the side wall 216 of the upper portion 208 defines a cavity 218 that is sized and configured to receive the positioning screw 204. In a preferred embodiment, the first end wall 212 includes a lip 219, such as Figure 8 As shown, it is used to retain the set screw 204 in the cavity 218.

[0043] The upper portion 208 of the housing 202 has a larger cross-section than the cross-section of the lower portion 210 of the housing, so that a lug 220 is formed at the junction of the upper and lower portions. In addition, the cross-section of the upper portion 208 of the housing 202 can be polygonal in shape. As used herein, the term "polygonal" or "polygonal" is defined as any shape that is not completely circular and includes one or more vertices 222. The vertices 222 can form a sharp point or be rounded. For example, Figure 6B As shown, the cross-section of the upper portion 208 of the housing 202 may be substantially triangular and include rounded vertices.

[0044] Additional references Figure 5B , the proximal portion 108 of the intramedullary nail 102 includes a seat 138 extending inwardly from the wall defining the axial hole 122 of the intramedullary nail. The wall defining the axial hole 122 also defines a longitudinal slot 140 extending generally parallel to the longitudinal axis of the axial hole. The longitudinal slot 140 is shaped and sized to receive the corresponding vertex 222 of the housing 202, and thus can act as a track for stabilizing the positioning screw assembly 200 when the positioning screw assembly is loaded into the intramedullary nail 102. In addition, after the positioning screw assembly 200 has been fixed to the intramedullary nail 102, the positioning of the vertex 222 within the longitudinal slot 140 will inhibit the positioning screw assembly from rotating undesirably within the axial hole 122 after surgery.

[0045] The lower portion 210 of the housing 202 is substantially cylindrical in shape and includes one or more protrusions 224 extending from a distal end 226 of the housing. The protrusions 224 are sized and shaped to extend into the angled opening 104 and into one of the recesses 136 of the neck screw 106. The distal end 226 of the lower portion 210 can be angled obliquely relative to the longitudinal axis of the set screw assembly 200. In a preferred embodiment, the angle is approximately equal to α (e.g., the angle between the bore axis 124 of the angled opening 104 and the longitudinal axis L of the proximal portion 108 of the nail 102) so that when the lugs 220 of the housing 202 contact the seat 138, only the protrusions 224 extend into the angled opening 104 of the intramedullary nail 102. In other words, the distal end 226 of the lower portion 210 of the housing 202 does not extend into the angled opening 104 of the intramedullary nail 102 and will not contact the outer peripheral surface of the neck screw 106 .

[0046] The set screw 204 has a substantially cylindrical body 228 provided with external threads 230 disposed about the body. The set screw 204 is sized to allow the threads 230 of the set screw to be inserted from a cavity (eg, Figure 6B 2) is at least partially received in the cavity 218 of the housing 202 and engages the internal thread 126 of the intramedullary nail 102 (as shown). Figure 8 ) to threadably engage the positioning screw assembly 200 into the intramedullary nail.

[0047] The set screw 204 includes an elastic member 232 that can be switched between an expanded state (e.g., uncompressed) and a compressed state. In the compressed state, the length of the set screw 204 in the axial direction is equal to or less than the distance between the first end wall 212 and the second end wall 214 of the housing 202. Therefore, when the elastic member 232 is in the compressed state, the set screw 204 can be inserted into the cavity 218. On the other hand, when the elastic member 232 is expanded, the axial length of the set screw 204 is greater than the distance between the first end wall 212 and the second end wall 214 of the housing 202. Therefore, when the set screw 204 is disposed in the cavity 218 and the elastic member 232 is expanded into friction fit engagement with the first end wall 212 and the second end wall 214 of the housing 202, the set screw is securely coupled to the housing and lateral movement of the set screw relative to the housing is prevented. The engagement between the set screw 204 and the housing 202 also prevents the set screw from being rotated unintentionally within the housing and requires increased torque to intentionally rotate the set screw.

[0048] The resilient member 232 can have a smaller cross-section than the cross-section of the body 228 of the set screw 204, so that a retaining step 242 is formed around the resilient member. The retaining step 242 can engage with the lip 219 of the housing to prevent lateral movement of the set screw 204 relative to the housing 202 and help securely couple the set screw within the cavity 218.

[0049] like Figure 7 As shown, the resilient member 232 is a flange that is integrally formed or otherwise attached to the end of the set screw 204. The flange has a first end or attached end 234 and a second end or unattached end 236. The first end 234 of the flange extends from the end of the body 228 of the set screw 204 on a first side of the cannula 206, and the flange extends across the cannula of the set screw so that the second end or unattached end 236 is disposed above the end of the set screw on the opposite side of the cannula. Because the second end 236 of the flange is not attached to the body 228 of the set screw 204, a gap 238 is formed between the second end (e.g., the unattached end) of the flange and the end of the body to form a cantilever.

[0050] The flange may be formed of any material that exhibits elasticity, such as metal, metal alloy, or rubber, etc. In this manner, when a distally directed force is applied to the second end 236 of the flange through the first end wall 212 of the housing 202 during insertion of the set screw 204 into the cavity 218, for example, the second end of the flange will be compressed toward the distal end of the body 228 of the set screw 204, thereby reducing the size of the gap 238 and the axial length of the set screw 202. After the set screw 204 has been inserted into the cavity 218 (beyond the lip 219), the elastic material will expand to secure the set screw within the cavity.

[0051] The above-described flanges are merely examples of resilient members 232, and it will be appreciated that any other resilient member, such as a spring, rubber, silicon, etc., may be substituted for the flange. Furthermore, the resilient member 232 may be integrally formed as a component of the integral set screw 204, or otherwise attached to a separate body or housing 202 of the set screw 204, as long as compression and expansion of the resilient member securely couples the set screw within the cavity 218 of the housing and allows the set screw to rotate within the cavity when a rotational force is applied to the set screw.

[0052] refer to Figure 6B, the resilient member 232 and / or the cannula 206 of the set screw 204 define a drive feature 240, such as a recessed hexagonal internal drive feature, etc., which is adapted to receive a tool tip, such as a screw driver or a hexagonal wrench (not shown), to rotate the set screw in a first direction and screw the set screw assembly 200 into the axial hole 122 in the distal direction and connect with the intramedullary nail 102. Of course, the tool tip can also be inserted into the drive feature 240 and rotated in a second direction opposite to the first direction to move the set screw 204 in the proximal direction through the axial hole 122 to loosen the set screw from the intramedullary nail 102.

[0053] The use of the intramedullary intertrochanteric fracture fixation device 100 to heal the fracture 38 is now described. First, the set screw assembly 200 is assembled by inserting the set screw 204 into the cavity 218 of the housing 202. During insertion, the elastic member 232 of the set screw 204 will transition from an uncompressed state to a compressed state when the elastic member contacts the first end wall 212 of the housing 202. More specifically, the first end wall 212 of the housing 202 will apply a distal guiding force to the unattached end 236 of the flanged elastic member 232 and compress the unattached end toward the end of the body 228 of the set screw 204. This compression reduces the size of the gap 238, thereby reducing the axial length of the set screw 204 (e.g., measured from the unattached end 236 of the flange to the opposite end of the body 228), and allows the set screw to enter the cavity 218. After the set screw 204 has passed through the lip 219 of the upper portion 208 of the housing 202, the elastic member 232 elastically expands. In the uncompressed state, the lip 219 is located within the retaining step 242 and frictionally secures the set screw 204 within the cavity 218. The engagement between the lip 219 and the retaining step 242 inhibits lateral movement of the set screw 204 relative to the housing 202 while allowing the set screw to rotate within the cavity 218 about the longitudinal axis of the set screw when a rotational force is applied to the set screw.

[0054] The positioning screw assembly 200 can then be assembled within the proximal portion 108 of the intramedullary nail 102 prior to surgery. First, the manufacturer or another user can position one of the apexes 222 of the housing 202 into the longitudinal slot 140 of the intramedullary nail 102. Once positioned, the positioning screw assembly 200 can be slid in the distal direction until the outer threads 230 of the positioning screw 204 engage the inner threads 126 of the intramedullary nail 102. As described, sliding the positioning screw assembly 200 into the axial bore 122 of the intramedullary nail 102 will prevent the positioning screw assembly from tilting relative to the longitudinal axis and thus help properly align the outer threads 230 of the positioning screw 204 and the inner threads 126 of the intramedullary nail. The likelihood that either thread will be damaged during the screwing of the screw 204 into the intramedullary nail 102 is thereby reduced.

[0055] A driving tool (not shown) can then be inserted into the recessed drive feature 240 of the set screw 204 and rotated in a first direction (e.g., clockwise) to threadably engage the set screw and the intramedullary nail 102 and cause the set screw assembly 200 to move in the distal direction within the axial bore 122. During rotation of the set screw 204, components of the set screw assembly 200 and the intramedullary nail 102 can interact in several ways: 1) engagement between the apex 222 of the housing 202 and the longitudinal slot 140 of the intramedullary nail prevents rotation of the housing within the axial bore; 2) engagement between the expanded set screw 204 and the housing (including engagement between the lip 219 of the housing and the retaining step 242 of the set screw) prevents movement of the set screw in the axial or lateral direction relative to the cavity 218 of the housing (while allowing rotational movement of the set screw within the cavity); and 3) engagement between the external threads 230 of the set screw 204 and the internal threads 126 of the intramedullary nail 102 causes the set screw, and thus the housing 202, to move in the distal direction within the axial bore 122. Rotation of the set screw 204 may be stopped before the protrusion 224 of the lower portion 210 extends into the angled opening 104 of the intramedullary nail 102 .

[0056] After preparing the intramedullary intertrochanteric fracture fixation device 100 for surgery, the surgeon can then advance the intramedullary nail 102 over the guide wire 244, through the cannulated positioning screw assembly 200 (eg, Figure 8 ), and into position within the patient's medullary canal 28. After the intramedullary nail 102 has been positioned within the medullary canal 28 of the femur 10, the surgeon can remove the guide wire 244 and insert the neck screw 106 through the angled opening 104 of the intramedullary nail to compress the fractured bone parts together.

[0057] After the surgeon has confirmed that the cervical screw 106 is properly positioned within the intertrochanteric bone, the driving tool can be used again to rotate the set screw 204 and drive the set screw assembly 200 in the distal direction until the lug 220 of the housing 202 engages the seat 138 of the intramedullary nail 102 so that the protrusion 224 extends into the angled opening 104 of the intramedullary nail and into one of the grooves 136 of the cervical screw 106. Once positioned within the groove 136, the protrusion 224 prevents the cervical screw 106 from rotating about the bore axis 124 and effectively prevents the cervical screw 106 from rotating within the angled opening 104.

[0058] The surgeon can then optionally select to limit the axial movement of the neck screw 106 relative to the intramedullary nail 102. In order to set this limit, the surgeon can use a driving tool to rotate the positioning screw 204 during surgery until the desired limit has been reached. If the surgeon wishes to reduce the axial movement of the neck screw 106, the surgeon can rotate the driving tool in a first direction (e.g., clockwise) so that the positioning screw assembly 200 moves distally in the axial hole 122, as described above. Therefore, the projection 224 will further protrude into the inclined groove 136 of the neck screw 106 and limit the distance that the neck screw can slide. If the projection 224 is fastened to the surface of the neck screw 106 that defines the groove 136, firmly engage, then the movement of the neck screw can be prevented together.

[0059] On the other hand, if the surgeon wishes to allow or increase axial sliding of the neck screw 106, the surgeon can intraoperatively rotate the positioning screw 204 in a second direction (e.g., counterclockwise), causing the positioning screw assembly 200 to move in the proximal direction. This movement will cause the protrusion 224 to retract away from the neck screw 106 and allow the neck screw to slide relatively further in the axial direction before contacting the ramp groove 136 of the neck screw.

[0060] Figure 9A-9C A variant intramedullary nail 102' and a variant positioning screw assembly 200' are illustrated. The intramedullary nail 102' and the positioning screw assembly 200' include all of the features described above with respect to the intramedullary nail 102 and the positioning screw assembly 200 of the intramedullary intertrochanteric fracture fixation device 100, and are further modified as described below. For example, the side wall 216' of the housing 202' includes a pair of recessed cutouts defining an orifice 225', and when the positioning screw assembly 200' is disposed within the axial bore 122', the orifice 225' allows the outer thread 230' of the positioning screw 204' to extend through the orifice and directly engage with the inner thread 126' of the intramedullary nail 102'. Specific reference Fig. 9B , the housing 202' has a substantially triangular and clover-leaf-shaped cross-sectional shape taken orthogonally to the longitudinal axis.

[0061] The lower portion of the housing 202' may be formed substantially similar to Figure 6A-Figure 8 Alternatively, as shown in the housing 202 Figure 9D-9HAs shown, the lower portion 210' of the housing 202' can be cylindrical in shape and include a distal end 226', which is formed by one or more outwardly tapered surfaces 223', which facilitate the insertion of the k-wire through the positioning screw assembly 200'. The distal end 226' of the housing 202' also includes a medial protrusion 224a' and a lateral protrusion 224b'. The medial protrusion 224a' and the lateral protrusion 224b' are curved, and more specifically, have a parabolic shape when viewed from a medial-lateral perspective. The curved shape is designed to reduce stress on the protrusions 224a', 224b' when the protrusions engage the neck screw 106'.

[0062] The outer protrusion 224b' extends farther in the distal direction than the inner protrusion 224a'. Figure 9H When the inner protrusion 224a' and the outer protrusion 224b' are assembled as shown and arranged in the groove 136' of the neck screw 106', the outer protrusion engages the bottom surface of the groove and causes the inner protrusion to float above the bottom surface of the groove. In other words, the inner protrusion 224a' partially extends into the groove 136' to prevent the neck screw 106' from rotating in the axial hole, but does not engage the bottom surface of the groove, and therefore, when the neck screw slides limitedly along the hole axis, it will not have to slide against the bottom surface of the groove. Therefore, the inner protrusion 224a' will not be deformed.

[0063] The lateral protrusion 224b' includes a chamfer 246' extending in the lateral to medial direction. The chamfer 246' of the lateral protrusion 224b' is designed to anticipate and prevent plastic deformation of the lateral protrusion as it slides laterally against the bottom surface of the groove 136' of the neck screw 106'.

[0064] refer to Fig. 9C , it should be understood that the axial bore 122' of the intramedullary nail 102' can be modified (relative to the axial bore 122 of the intramedullary nail 102) to correspond to the cloverleaf shape of the housing 202'. For example, the axial bore 122' can include three longitudinal slots 140', which are shaped and sized to receive corresponding leaves or vertices 222' of the housing 202'. Similar to the longitudinal slots 140, when the set screw assembly is loaded into the intramedullary nail 102', each of the longitudinal slots 140' can act as a track for stabilizing the set screw assembly 200' and inhibiting undesirable postoperative rotation of the set screw assembly after the set screw assembly has been positioned in the axial bore 122'. In addition, the axial bore 122' includes an internal thread 126' disposed between each pair of adjacent longitudinal slots 140'. In this way, the alignment and threading of the set screw assembly 200' with the intramedullary nail 102' can be improved. Figure 9A-9HThe improved fracture fixation device shown in can be used as described above with respect to the intramedullary intertrochanteric fracture fixation device 100 and therefore will not be described in detail herein.

[0065] Figure 10A-10C 202A-202F, is a top elevation view of exemplary set screw assemblies 200A-200F according to other embodiments of the present disclosure. Each of the set screw assemblies 200A-200F includes all of the features of the set screw assembly 200 and / or the set screw assembly 200', with the only difference being the shape of the housing. The term "shape" as used below with respect to the housing 202A-202F refers to the shape of a cross-section of the housing taken perpendicular to the longitudinal axis.

[0066] Each positioning screw assembly 200A-200F is preferably designed to be used with a different intramedullary nail (not shown) having an axial hole corresponding in shape to the shape of the corresponding housing 202A-202F. More specifically, each housing 202A-202F has a polygonal shape having a number of vertices equal to the number of longitudinal slots in the axial hole of the corresponding intramedullary nail. In this regard, each of the vertices can be positioned in a corresponding one of the longitudinal slots to stabilize the positioning screw assembly when the positioning screw assembly is loaded into the corresponding intramedullary nail and to inhibit undesirable postoperative rotation of the positioning screw assembly after the positioning screw assembly has been positioned in the axial hole of the intramedullary nail.

[0067] For example, Fig. 10A The illustrated positioning screw assembly 200A has a housing 202A shaped into a substantially oval shape, and more specifically, shaped into an ellipse having two diametrically opposed vertices 222A. Thus, the axial hole of its corresponding intramedullary nail (not shown) can be formed with two longitudinal grooves, which are positioned on opposite sides of the axial hole.

[0068] like Fig. 10B As shown, the shape of the housing 202B of the positioning screw assembly 200B is similar to the housing 202' of the positioning screw assembly 200'. That is, the housing 202B of the positioning screw assembly 200B is shaped substantially like a clover and includes three vertices 222B. However, compared to the side wall 216' of the positioning screw assembly 200', the housing 202B of the positioning screw assembly 200B has a slightly thicker side wall 216B. Nevertheless, the corresponding intramedullary nail can be substantially the same as Fig. 9C as shown in , where three longitudinal slots are angularly spaced around the axial hole.

[0069] Fig. 10CA third exemplary housing 202C is illustrated, which is substantially triangular in shape and is similar to the housing 202 of the positioning screw assembly 200. The primary difference is that the side wall 216C of the housing 202C defines an arcuate cutout between each of the three vertices 222C. Thus, an intramedullary nail corresponding to the positioning screw assembly 200C may have an axial bore provided with three longitudinal slots angularly spaced about the axial bore.

[0070] Reference now Fig. 10D , the shape of the housing 202D is substantially rectangular, and more specifically, square. The side wall 216D of the housing 202D can define an arcuate cut between any of the four adjacent vertices 222D. In this regard, the intramedullary nail corresponding to the positioning screw assembly 200D will define four longitudinal slots spaced 90 degrees from each other around the axial hole.

[0071] like Fig. 10E As shown in , the housing 202E of the set screw assembly 200E is shaped as an ellipse having two diametrically opposite vertices 222E. The side wall 216E of the housing 202E can define two arcuate cutouts positioned along the short axis of the housing. Therefore, the corresponding intramedullary nail can define two longitudinal grooves, which are positioned on opposite sides of the axial hole.

[0072] Go to Fig.10F , the housing 202F of the positioning screw assembly 200F is substantially shaped as a rectangle having four vertices 222F and a thickened sidewall 216F along its width and a thinner sidewall along its length. Of course, the thickness of the sidewall 216F can be changed and / or varied along the width and / or length of the housing 202F. Therefore, the corresponding intramedullary nail preferably has four longitudinal grooves that are spaced 90 degrees apart from each other around the axial hole.

[0073] although Figures 10A-10F The housing is illustrated as a specific shape, but it should be understood that the shape of the housing can be alternatively formed into any polygonal shape. In addition, although the number of vertices of the corresponding housing is preferably equal to the number of longitudinal grooves formed in the axial hole of the corresponding intramedullary nail, it should be understood that the number of vertices of the corresponding housing does not have to be equal to the number of longitudinal slots defined in the axial hole of the specific intramedullary nail. As long as one of the multiple vertices of the housing is positioned in a single longitudinal groove of the intramedullary nail, the positioning screw assembly will exhibit a certain degree of stability during loading and the ability to withstand postoperative rotational forces, although to a lesser extent than the case where the number of vertices is equal to the number of longitudinal grooves.

[0074] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are only illustrative of the principles and applications of the present invention. Therefore, it should be understood that various modifications may be made to the exemplary embodiments and other arrangements may be designed without departing from the spirit and scope of the present disclosure as defined by the appended claims.

Claims

1. A positioning screw assembly having a longitudinal axis for use in an intramedullary fracture fixation device, comprising: A set screw comprising a body having external threads and an elastic member extending from the body, the elastic member having an uncompressed state and a compressed state; as well as a housing including a sidewall and a first end wall and a second end wall extending from the sidewall in a transverse direction relative to the longitudinal axis, the sidewall only partially surrounding the longitudinal axis of the set screw assembly, and a combination of the first end wall, the second end wall and the sidewall defining a cavity sized and configured to receive the set screw; wherein, when the set screw is at least partially disposed within the cavity and the resilient member is in the uncompressed state, the set screw is secured to the housing and is rotatable relative to the housing about the longitudinal axis; and When the positioning screw is fixed to the housing, a portion of the external thread of the positioning screw extends outside the cavity.

2. The set screw assembly according to claim 1, wherein: The housing and the set screw are cannulated such that the set screw assembly is configured to receive a guide wire.

3. The set screw assembly according to claim 1, wherein: The resilient member includes a cantilever flange having a first end attached to a distal end of the body and a second end disposed above the distal end of the body such that a gap is formed between the second end of the cantilever flange and the distal end of the body.

4. The set screw assembly according to claim 1, wherein: When the elastic member is in the uncompressed state, the length of the positioning screw in the direction along the longitudinal axis is greater than the distance between the first end wall and the second end wall, and when the elastic member is in the compressed state, the length of the positioning screw in the direction along the longitudinal axis is equal to or less than the distance between the first end wall and the second end wall.

5. The set screw assembly according to claim 1, wherein: At least one of the first end wall and the second end wall includes a lip.

6. The set screw assembly according to claim 5, wherein: The set screw defines a stepped retaining surface configured to engage the lip.

7. The set screw assembly according to claim 1, wherein: The side wall of the housing defines a plurality of discrete apertures, and a portion of the external threads of the set screw extends through each of the apertures when the set screw is secured to the housing.

8. The set screw assembly according to claim 1, wherein: The lower portion of the housing includes at least one projection extending from a distal end of the housing.

9. The set screw assembly according to claim 8, wherein: The at least one protrusion includes an inner protrusion having a first length and an outer protrusion having a second length longer than the first length.

10. The set screw assembly according to claim 9, wherein: The outer protrusion includes a chamfer extending in an outer side to an inner side direction.

11. The set screw assembly according to claim 8, wherein: The at least one protrusion includes an inner protrusion and an outer protrusion, each of which forms a curved shape when viewed from an inner direction and an outer direction, respectively.

12. The set screw assembly according to claim 11, wherein: The curved shape substantially comprises a parabola.

13. An intramedullary fracture fixation device, comprising: an intramedullary nail having a proximal portion adjacent a proximal end and a distal portion adjacent a distal end, the proximal portion defining an angled opening and an axial bore extending through the proximal end of the intramedullary nail and into the angled opening, the axial bore having a longitudinal axis, internal threads, and at least one slot extending substantially parallel to the longitudinal axis; a neck screw configured to extend through the angled opening and having an outer surface with a groove; as well as A positioning screw assembly having a longitudinal axis and configured to be disposed within an axial bore of the intramedullary nail, the positioning screw assembly comprising: a set screw having a body having external threads and a resilient member extending from the body, the resilient member having an uncompressed state and a compressed state; and a housing including an upper portion and a lower portion, the upper portion including a sidewall and a first end wall and a second end wall extending from the sidewall in a transverse direction relative to the longitudinal axis of the set screw assembly and together defining a cavity sized and configured to receive the set screw, wherein the sidewall only partially surrounds the longitudinal axis of the set screw assembly; and wherein, when the set screw is at least partially disposed within the cavity and the resilient member is in the uncompressed state, the set screw is secured to the housing and is rotatable relative to the housing about the longitudinal axis of the set screw assembly; wherein, when the set screw is fixed to the housing, a portion of the external thread of the set screw extends outside the cavity, and Wherein, when the positioning screw is partially disposed in the cavity of the shell and the positioning screw assembly is disposed in the axial hole of the intramedullary nail, the external thread of the positioning screw engages with the internal thread of the axial hole, so that rotation of the positioning screw causes the positioning screw to rotate around the longitudinal axis of the positioning screw assembly and relative to the shell, and causes the positioning screw assembly to move along the longitudinal axis of the axial hole of the intramedullary nail.

14. The device according to claim 13, wherein: The cross-section of the upper portion of the housing is a polygon having at least one vertex positioned within the at least one slot to prevent the housing from rotating relative to the intramedullary nail when the set screw is rotated.

15. The device according to claim 14, wherein: The polygon comprises "n" vertices, and wherein the at least one slot comprises a number of slots equal to "n".

16. The device according to claim 13, wherein: The cross section of the upper portion of the housing is larger than the cross section of the lower portion of the housing, and a lug is formed at a junction between the upper portion and the lower portion of the housing.

17. The device according to claim 16, wherein: The proximal portion of the intramedullary nail includes a seat extending inwardly into the axial bore for contacting the lug of the housing and limiting movement of the distal end of the housing within the axial bore.

18. The device according to claim 17, wherein: The lower portion of the housing further comprises a protrusion, and wherein, The lower portion of the housing includes a distal end that is angled relative to the longitudinal axis of the set screw assembly such that when the lug of the housing is in contact with the seat of the intramedullary nail, only the projection extends into the angled opening.

19. The device according to claim 13, wherein: The set screw is sized such that insertion of the set screw into the cavity causes the resilient member to contact one of the first end wall or the second end wall and transition the set screw into the compressed state.

20. An intramedullary fracture fixation device, comprising: an intramedullary nail having a proximal portion adjacent a proximal end, the proximal portion defining an angled opening and an axial bore extending through the proximal end of the intramedullary nail and into the angled opening, the axial bore having a longitudinal axis and internal threads; a cervical screw configured to extend through the angled opening; as well as The set screw assembly of claim 1, said set screw assembly being pre-operably assembled within said proximal portion of said intramedullary nail, said set screw assembly being cannulated to receive a guide wire.

21. The apparatus of claim 20, further comprising a guide wire configured to extend into the axial bore of the intramedullary nail and through the set screw assembly.

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