Systems and methods for inserting intramedullary nails

Abstract

The intramedullary (IM) nail insertion assembly includes an IM nail extending longitudinally from a proximal end to a distal end. The proximal portion of the IM nail has internal threads. The IM nail insertion assembly also includes a connection screw extending longitudinally from the proximal end to the distal end. The distal portion of the connection screw has external threads for engaging the internal threads of the IM nail. One of the proximal portion of the IM nail and the distal portion of the connection screw has a feature that resists disengagement of the proximal portion from the distal portion.

Description

[Technical Field]

[0001] The present disclosure relates generally to a connection screw for mounting an intramedullary nail onto a device that allows for insertion of the nail, the connection screw having features that resist disengagement or loosening during nail insertion. [Background technology]

[0002] Bone defects can be repaired by inserting a permanent nail or rod into the medullary canal of the bone. A connecting screw can be attached to an intramedullary (IM) nail at one end, and force can be applied to the opposing end of the connecting screw to insert the IM nail into the medullary canal. The connecting screw may loosen during the nail insertion procedure as a result of the applied force and may need to be retightened. Summary of the Invention [Means for solving the problem]

[0003] The present disclosure relates to systems and methods for inserting an intramedullary (IM) nail. The IM nail insertion assembly includes an IM nail extending longitudinally from a proximal end to a distal end. The proximal portion of the IM nail has internal threading. The IM nail insertion assembly also includes a connection screw extending longitudinally from the proximal end to the distal end. The distal portion of the connection screw has external threading for engaging the internal threading of the IM nail. One of the proximal portion of the IM nail and the distal portion of the connection screw has a feature that resists disengagement of the proximal portion from the distal portion.

[0004] In one embodiment, the feature is a portion of the external threads of the connection thread having a first pitch that is distinct from the remainder of the external threads having a second pitch.

[0005] In one embodiment, the first pitch is greater than the second pitch.

[0006] In one embodiment, the second pitch is greater than the first pitch.

[0007] In one embodiment, the feature is a portion of the internal threads of the IM nail having a first pitch that is distinct from the remainder of the internal threads having a second pitch.

[0008] In one embodiment, the features are part of the external threads of the connection screw that form different detents.

[0009] In one embodiment, each of the detents extends radially from a central portion of the external threads.

[0010] In one embodiment, the externally threaded portion forms two detents.

[0011] In one embodiment, the feature is a portion of the internal threads of the IM nail that form different detents.

[0012] In one embodiment, each of the detents extends radially from a central portion of the internal threads.

[0013] In one embodiment, a portion of the internal threads forms one detent.

[0014] In one embodiment, the connection screw is cannulated.

[0015] In one embodiment, the IM nail insertion assembly further includes an insertion handle extending from a proximal end to a distal end, and a sleeve extending longitudinally from the proximal end to the distal end, the proximal end of the sleeve sized and shaped to receive the proximal end of the connection screw therein, the proximal end of the sleeve being tightly secured to the distal end of the insertion handle.

[0016] In one embodiment, the sleeve further includes a lumen sized and shaped to receive the shaft of the connection screw.

[0017] In one embodiment, the IM nail insertion assembly further includes a screwdriver extending from a proximal end to a distal end, the screwdriver having a tip at the distal end and a handle at the proximal end, the tip sized and shaped to engage a recess in the proximal end of the connection screw.

[0018] In one embodiment, the tip is hexagonal to engage a correspondingly shaped hexagonal recess in the proximal end of the connection screw.

[0019] In one embodiment, the IM nail insertion assembly further includes a tab extending radially from the proximal end of the connection screw, the tab being biased toward an undeformed state in which it engages the proximal end of the sleeve.

[0020] In one embodiment, the IM nail is made from a titanium alloy.

[0021] In one embodiment, the connection screw is made from a stainless steel alloy.

[0022] The present disclosure also relates to a method of inserting an IM nail insertion assembly into a medullary canal, the IM nail insertion assembly including: an IM nail, wherein a proximal portion of the IM nail has internal threads; and a connection screw, wherein a distal portion of the connection screw has external threads for engaging the internal threads of the IM nail, wherein one of the proximal portion of the IM nail and the distal portion of the connection screw has a feature to resist disengagement of the proximal portion from the distal portion; inserting a tip of a screwdriver into a recessed portion of a head of the connection screw; and rotating the screwdriver in a first direction to engage the external threads of the connection screw with the internal threads of the IM nail.

[0023] In one embodiment, the method further includes rotating the screwdriver in a second direction opposite the first direction, removing the connection screw, and placing an end cap on the proximal end of the IM nail. [Brief explanation of the drawings]

[0024] [Figure 1]1 illustrates a system for performing an intramedullary (IM) nail insertion procedure according to various exemplary embodiments of the present disclosure. [Figure 2] 2 shows an enlarged view of the system of FIG. 1. [Figure 3a] 2 shows an enlarged view of the proximal end of the IM nail engaged with the distal end of the connection screw of the system of FIG. 1. [Figure 3b] 2 shows an enlarged view of the proximal end of the connection screw of the system of FIG. 1. [Figure 4] 10 shows the distal end of a connection screw according to a second embodiment. [Figure 5] 10 shows the distal end of a connection screw according to a third embodiment. [Figure 6] 1 shows the proximal end of an IM nail according to a second embodiment. [Figure 7] 10 shows the proximal end of an IM nail according to a third embodiment. [Figure 8] 10 shows the distal end of a connection screw according to a fourth embodiment. [Figure 9] 9 shows an enlarged view of the connecting screw of FIG. 8. [Figure 10] 10 shows the proximal end of an IM nail according to a fourth embodiment. [Figure 11] 11 shows an enlarged view of the IM nail of FIG. 10. [Figure 12] 10 shows the proximal end of a connection screw according to a fifth embodiment. [Figure 13] 13 shows an enlarged view of the tab on the proximal end of the connection screw shown in FIG. 12 in an undeformed state. [Figure 14] 13 shows the proximal end of the connection screw of FIG. 12 with the tab in a deformed state with the driver tip inserted therein; DETAILED DESCRIPTION OF THE INVENTION

[0025] The present disclosure can be further understood with reference to the following description and the accompanying drawings, in which like elements are referred to with the same reference numerals. Exemplary embodiments describe a connection screw and / or intramedullary (IM) nail having features that resist disengagement or loosening therebetween during nail insertion. The connection screws and IM nails described herein can be implemented in a system for inserting IM nails. It should be noted that, as used herein, the terms "proximal" and "distal" are intended to refer to directions toward (proximal) and away from (distal) the user of the device.

[0026] 1-3b illustrate a system 100 for performing an intramedullary (IM) nail insertion procedure in accordance with various exemplary embodiments of the present disclosure. The system 100 includes an intramedullary (IM) nail 102 according to a first embodiment sized and shaped to be inserted into a medullary canal to repair a bone defect. Insertion of the IM nail 102 is implemented with a connection screw 104 according to the first embodiment, which is coupled to the IM nail 102 during insertion and detached therefrom once the IM nail 102 is fully inserted. During the insertion procedure, the connection screw 104 is further coupled to an insertion handle 106, which is grasped by the surgeon performing the procedure. As will be understood by those skilled in the art, a force, such as a striking force, is applied to the insertion handle 106 to force the attached IM nail 102 into the medullary canal. The applied force may be large and may stress the connection between the IM nail 102 and the connection screw 104.

[0027] Due to the magnitude of forces applied to the system 100 and to facilitate setup of the various components, the various elements involved are connected in multiple ways, in part to maintain a secure connection during the insertion procedure. The initial connection between the insertion handle 106 and the IM nail 102 is made via a sleeve 108 extending from the distal end of the insertion handle 106. The sleeve 108 has a proximal end 112 tightly connected to the distal end of the insertion handle 106. Because the sleeve 108 is part of the insertion handle 106 and tightly secured to its proximal end 112, the sleeve 108 cannot be removed from the handle 106. In this embodiment, the distal end 114 of the sleeve 108 has a feature shaped to snap-lock with a corresponding feature shaped on the proximal end 130 of the IM nail 102. For example, the proximal end 130 of the IM nail 102 may have a protrusion extending radially inward that engages a correspondingly sized and shaped recess in the distal end 114 of the sleeve 108. However, other attachment mechanisms between the sleeve 108 and the IM nail 102 can be used.

[0028] The sleeve 108 has a hollow interior sized and shaped to receive the longitudinal shaft 124 of the connect screw 104. Thus, when the sleeve 108 and IM nail 102 are initially attached together, the distal end 122 of the connect screw 104 is inserted into the proximal end 112 of the sleeve 108 and extends the length of the sleeve 108 to engage the proximal end 130 of the IM nail 102 to more securely connect the IM nail 102 to the sleeve 108, as described below. The proximal end 112 of the sleeve 108 has an increased diameter relative to the remainder of the sleeve 108, and the proximal end 112 has a recess 116 for receiving the head 126 of the connect screw 104 such that the head 126 seats in the recess 116 when the connect screw 104 and IM nail 102 are coupled.

[0029] The connection screw 104 is cannulated to allow for insertion of the IM nail 102 and insertion handle 106 over the reaming rod. The connection screw 104 has a channel that extends the entire length of the connection screw 104 from the proximal end 120 to the distal end 122. The distal end 122 has external threads 128 for engaging a corresponding threaded interior surface 134 at the proximal end 130 of the cannulated IM nail 102, as seen in FIG. 3 a.

[0030] The set screw 104 is inserted through the sleeve 108, and a T-arm screwdriver 110 is used to thread the distal end 122 of the set screw 104 into the proximal end 130 of the IM nail 102. The T-arm 110 has a longitudinal shaft 138 extending from a proximal handle 136 to a distal tip 140 that is sized and shaped to engage the countersunk head 126 of the set screw 104. In this embodiment, the tip 140 is hexagonal to engage a correspondingly shaped hexagonal recess in the head 126 of the set screw 104, although other shapes can be used for the tip 140 and head 126 of the T-arm 110. The T-arm screwdriver 110 is used to tighten the connecting screw 104 until the distal surface 127 of the head 126 of the connecting screw 104, i.e., the portion of the head 126 extending radially between the outer surface of the head 126 and the shaft 124, engages the proximal shoulder 118 of the recessed portion 116 of the sleeve 108, i.e., the portion of the sleeve 108 extending radially between the inner surface of the recessed portion 116 and the inner surface of the sleeve 108, as shown in FIG. 3b. This tightening creates a compressive force between the connecting screw 104 and the sleeve 108 that coincides with engagement of the connecting screw 104 and the IM nail 102 via the threads 128, 134, further strengthening the connection between the components.

[0031] Once the connection screw 104 and the IM nail 102 are mated, the operating physician can proceed to drive the distal end 132 of the IM nail 102 into the medullary canal. As will be appreciated by those skilled in the art, the connection between the distal end 122 of the connection screw 104 and the proximal end 130 of the IM nail 102 may be subjected to stress during this procedure. To prevent loosening of the connection, it will typically be necessary to re-tighten the connection with the T-arm 110 during the insertion procedure. The system 100 according to various exemplary embodiments includes features to provide a more secure connection that resists such loosening effects during the insertion procedure. The IM nail 102 in the exemplary embodiments may be made of a titanium alloy, such as TAN or TAV. The connection screw 104 in the above embodiments, as well as the connection screws in the following embodiments, may be made of a stainless steel alloy.

[0032] 4 shows the distal end 222 of a connect screw 204 according to a second embodiment. The connect screw 204 may be substantially similar to the connect screw 104 described above, except for the distal end 222. In this second embodiment, the distal end 222 has a threaded section 228 with a variable pitch, including a first thread 230 extending from a distal-most point of the threaded section 228 to a transition approximately midway along the threaded section 228, and a second thread 232 extending from the transition to a proximal-most point of the threaded section 228. Those skilled in the art will understand that the pitch of a thread relates to the angle of the helix through which the thread extends (i.e., the angle between the axial progression of the helix and the axis of the cylinder around which the helix wraps), with a smaller pitch representing a larger helix angle and, therefore, threads with a smaller pitch being closer together than threads with a larger pitch.

[0033] The first thread 230 has a first pitch that corresponds to the pitch of the internal threads 134 of the IM nail 102, while the second thread 232 has a second pitch that is smaller than the pitch of the first thread 230 and the internal threads 134, such that the second thread 232 generates interference with the internal threads 134. The ratio between the first pitch of the first thread 230 and the second pitch of the second thread 232 is between 0.5 and 0.99. As the threads 228 of the connecting screw 204 advance along the threads 134 of the IM nail 102, the second (smaller) thread 232 engages with the threads 134 of the IM nail 102.

[0034] Due to the different pitches, one or both of the mating threads deform, causing the distal end 222 of the connective screw 204 and the proximal end 130 of the IM nail 102 to fit more tightly together in a manner that resists loosening during the insertion procedure. Once the IM nail 102 is fully inserted despite the deformation caused by tightening, the mating threads can then be disengaged by rotating the connective screw 204 in the opposite direction to the tightening direction.

[0035] If the threads 134 of the IM nail 102 are deformed during advancement of the connecting screw 204, the first thread 230 of the connecting screw 204 can engage the deformed threads 134, substantially counteracting the deformation. That is, engagement of the first thread 230 with the inner threads 134 re-threads and compensates for the inner threads 134. Therefore, if an additional element is attached to the threads 134 of the IM nail 102, such as an end cap, the end cap will not encounter significant resistance when tightened thereon. Therefore, when the first thread 230 matches the threads 134 of the IM nail 102, the threads 134 of the IM nail 102 will not be deformed, and the end cap will have a tight fit within the IM nail 102.

[0036] 5 shows the distal end 322 of a connect screw 304 according to a third embodiment. The connect screw 304 may be substantially similar to either of the connect screws 104, 204 described above, except for the distal end 322. In this third embodiment, the distal end 322, like the connect screw 204 of the first embodiment, has a threaded portion 328 having a variable pitch, including a first thread 330 extending from a distal-most point of the threaded portion 328 to a transition approximately midway along the threaded portion 328, and a second thread 332 extending from the transition to a proximal-most point of the threaded portion 328.

[0037] However, in the third embodiment, the first thread 330 has a first pitch that corresponds to the pitch of the internal threads 134 of the IM nail 102, while the second thread 332 has a pitch that is greater than the pitch of the first thread 330 and the internal threads 134. As the threads 328 of the connecting screw 304 advance along the threads 134 of the IM nail 102, the second thread 332 engages with the threads 134 of the IM nail 102 in a manner similar to the connecting screw 204 described above. The ratio between the first pitch of the first thread 330 and the second pitch of the second thread 332 is between 1.01 and 2.

[0038] Due to the different pitches, one or both of the mating threads deform, causing the distal end 322 of the connect screw 304 and the proximal end 130 of the IM nail 102 to tightly fit together and resist loosening during the insertion procedure. If the threaded portion 134 of the IM nail 102 deforms during advancement of the connect screw 304, the first thread 330 of the connect screw 304 will engage the deformed threaded portion 134 and substantially correct the deformation. Thus, if an additional element is attached to the threaded portion 134 of the IM nail 102, such as an end cap, the end cap will not encounter significant resistance when tightened thereon.

[0039] By adjusting the pitch on the proximal end of the threads rather than the distal end, only the proximal portion of the corresponding threads on the IM nail 102 may deform as the connection screw advances rather than the entirety of the threads. In an alternative embodiment, a connection screw is provided that has the smaller / larger pitch of the connection screw 204, 304 but does not have distal threads that correspond to the threads on the IM nail 102. Thus, when the connection screw is threaded into the IM nail 102, only the smaller / larger pitch threads of the connection screw engage the threads 134 of the IM nail 102, and the distal portion of the threads 134 remains disengaged.

[0040] The principles described above with respect to the connective screws 204, 304 may alternatively be implemented in the IM nail 102. Specifically, a connective screw 104 having a uniform pitch for its threads 128 may be used with an IM nail having a variable pitch for its threads. In these embodiments, the distal portion of the IM nail threads has a smaller or larger pitch, deforming either the threads 128 of the connective screw 104 or the distal threads of the IM nail as the connective screw 102 is advanced.

[0041] 6 shows the proximal end 430 of an IM nail 402 according to a second embodiment. The IM nail 402 may be substantially similar to the IM nail 102 described above, except for the proximal end 430. The IM nail 402 has a threaded portion 434 with a variable pitch, including a first thread 436 extending from a distal-most point of the threaded portion 434 to a transition approximately midway along the threaded portion 434, and a second thread 438 extending from the transition to a proximal-most point of the threaded portion 434. The first thread 436 has a first pitch that is smaller than the pitch of the second thread 438, and the second thread 438 has a second pitch that corresponds to the pitch of the outer thread 128 of the connection screw 104.

[0042] 7 shows the proximal end 530 of an IM nail 502 according to a third embodiment for use in the system 100 of FIG. 1. The IM nail 502 may be substantially similar to the IM nail 102 or 402 described above, except for the proximal end 530. Like the IM nail 402, the IM nail 502 has a threaded portion 534 with a variable pitch, including a first thread 536 extending from a distal-most point of the threaded portion 534 to a transition approximately midway along the threaded portion 534, and a second thread 538 extending from the transition to a proximal-most point of the threaded portion 534. The first thread 536 has a first pitch that is greater than the pitch of the second thread 538, and the second thread 538 has a second pitch that corresponds to the pitch of the outer thread 128 of the connection screw 104.

[0043] Figure 8 shows a distal end 622 of a connect screw 604 according to a fourth embodiment. The connect screw 604 may be substantially similar to any of the connect screws 104, 204, 304 described above, except for the distal end 622. In this fourth embodiment, the distal end 622 has a threaded portion 628 that includes detents 630 at two locations on the threaded portion 628, as shown in Figure 9. The two detents 630 extend radially from a central portion of the threaded portion and are shaped differently from the remainder of the threaded portion.

[0044] Specifically, the threads are deformed axially such that the gap between adjacent portions of the threads becomes narrower or wider. Thus, the detents 630 cause mechanical interference with the threads 134 of the IM nail 102 when the IM nail 102 and the connect screw 604 are threaded together. The threads 628 shown in FIG. 8 have two detents 630, although more or fewer detents can be used. Similar to the connect screws 204, 304 described above, when the distal end 622 is threaded onto the proximal end 130 of the IM nail 102, the detents 630 engage the threads 134 of the IM nail 102, thereby creating a tighter mechanical interference between the connect screw 604 and the IM nail 102 to lock them together. The detent 630 may be on the proximal portion of the threads of 628 to interfere with only the proximal portion of the threads 134 of the IM nail, so that when an additional element is attached to the threads 134 of the IM nail 102, for example an end cap, the end cap fits tightly with the IM nail 102.

[0045] FIG. 10 illustrates the proximal end 730 of an IM nail 702 according to a fourth embodiment. The IM nail 702 can be substantially similar to the IM nails 102, 402, and 502 described above, except for the proximal end 730. In this fourth embodiment, the IM nail 702 has a threaded section 734 that includes a detent 736 extending laterally from a midsection of the threads. The detent 736 is a portion of the threads that is deformed relative to the remainder of the threads. Thus, due to the detent 736, the shape of the threads of the threaded section 734 differs from the shape of the gaps between the turns of the threads of the threaded section 128. When these components are threaded together, this difference in shape creates a mechanical interference between the threaded section 128 of the connecting screw 104 and the IM nail 702 that resists loosening during implantation of the IM nail 702. As shown in FIG. 11, the threaded section 734 has a single detent, although more detents can be used.

[0046] In addition to the features described above at either the distal end of the connection screw or the proximal end of the IM nail, further features can be implemented at the proximal end of the connection screw to resist disengagement of the tight connection between the connection screw and the IM nail.

[0047] FIG. 12 shows the proximal end 820 of a connect screw 804 according to a fifth embodiment. The connect screw 804 can be substantially similar to the connect screw 104 described above, except for the proximal end 820. In this embodiment, a countersunk head 826 at the proximal end 820 has a deformable tab 828 extending radially through the head 826. In its natural, or undeformed, state, the tab 828 is oriented such that an outer portion 830, e.g., a corner, of the tab 828 protrudes radially outward relative to the outer surface of the head 826, as shown in FIG. 13. Thus, when the connect screw 804 is inserted into the sleeve 108 of the insertion handle 106, the outer portion 830 engages the proximal end 112 of the sleeve 108.

[0048] This engagement acts to prevent movement, e.g., rotation, of the connection screw 804 relative to the sleeve 108. For example, during an insertion procedure, pressure created by an insertion force may act to remove the connection screw 804 from the IM nail 102 or the sleeve 108. In its undeformed state, the tab 828 provides a force that resists relative movement, e.g., rotation, between the connection screw 804 and the sleeve 108, which, given the rigid connection between the sleeve 108 and the IM nail 102 described above, further resists movement between the connection screw 804 and the IM nail 102.

[0049] In its undeformed state, the tab 828 also has an inner portion 832, or opposed corners of the outer portion 830, that protrude radially inward relative to the inner surface of the head 826. However, when the tip 140 of the T-arm 110 engages a recess in the countersunk head 826 of the connect screw 804, the tip 140 pushes the inner portion 832 radially outward, and the tab 828 deforms under pressure from the tip 140. The deformation causes the tab 828 to straighten so that the outer portion 830 no longer engages the proximal end 112 of the sleeve 108, as shown in FIG. 14 . Thus, the connect screw 804 can be rotated relative to the sleeve 108 as the tip 140 of the T-arm 110 is inserted into the countersunk head 826. This allows the connect screw 804 to be threaded into the IM nail 102 early in the nail insertion procedure and then removed from the IM nail 102 at the end of the insertion procedure without the tab 828 interfering with the sleeve 108. In other words, the connecting screw 804 is rotatable relative to the sleeve 108 when the tip 140 of the T-arm 110 is inserted into the countersunk head 826, and when the T-arm 110 is withdrawn, the tab 828 resists rotation, providing a more secure connection between the connecting screw 804 and the IM nail 102.

[0050] Those skilled in the art will appreciate that changes can be made to the above-described embodiments without departing from the inventive concept thereof. Furthermore, it will be understood that structural features and methods associated with one of the embodiments may be incorporated into other embodiments. Accordingly, it is understood that the invention is not limited to the specific embodiments disclosed, but rather that modifications are encompassed within the scope of the invention as defined by the appended claims.

[0051] [Embodiment] (1) An intramedullary (IM) nail insertion assembly, comprising: an IM nail extending longitudinally from a proximal end to a distal end, wherein a proximal portion of the IM nail has an internal thread; a connective screw extending longitudinally from a proximal end to a distal end, a distal portion of the connective screw having external threads for engaging the internal threads of the IM nail; An IM nail insertion assembly, wherein one of the proximal portion of the IM nail and the distal portion of the connection screw has a feature that resists disengagement of the proximal portion from the distal portion. (2) The IM nail insertion assembly of claim 1, wherein the feature is a portion of the external threaded portion of the connection screw having a first pitch and is a different portion from the remainder of the external threaded portion having a second pitch. (3) The IM nail insertion assembly of embodiment 2, wherein the first pitch is greater than the second pitch. (4) The IM nail insertion assembly of embodiment 2, wherein the second pitch is greater than the first pitch. (5) The IM nail insertion assembly of claim 1, wherein the feature is a portion of the internal thread of the IM nail having a first pitch and is a different portion from the remainder of the internal thread having a second pitch.

[0052] (6) The IM nail insertion assembly of claim 1, wherein the feature is a portion of the external threaded portion of the connection screw that forms a plurality of distinct detents. (7) The IM nail insertion assembly of embodiment 6, wherein each of the detents extends radially from a central portion of the external threaded portion. (8) The IM nail insertion assembly of embodiment 6, wherein the portion of the external threaded portion forms two detents. (9) The IM nail insertion assembly of claim 1, wherein the feature is a portion of the internal thread of the IM nail that forms a plurality of distinct detents. (10) The IM nail insertion assembly of embodiment 9, wherein each of the detents extends radially from a central portion of the internal threading portion.

[0053] (11) The IM nail insertion assembly of embodiment 9, wherein the portion of the internal threaded portion forms one detent. (12) The IM nail insertion assembly of embodiment 1, wherein the connecting screw is cannulated. (13) an insertion handle extending from the proximal end to the distal end; a sleeve extending longitudinally from a proximal end to a distal end, the proximal end of the sleeve sized and shaped to receive the proximal end of the connection screw therein; 2. The IM nail insertion assembly of claim 1, wherein the proximal end of the sleeve is tightly secured to the distal end of the insertion handle. (14) The IM nail insertion assembly of embodiment 13, wherein the sleeve further comprises a lumen sized and shaped to receive the shaft of the connection screw. (15) A screwdriver extending from a proximal end to a distal end, the screwdriver having a tip at the distal end and a handle at the proximal end; 14. An IM nail insertion assembly as described in claim 13, wherein the tip is sized and shaped to engage a recess in the proximal end of the connection screw.

[0054] (16) The IM nail insertion assembly of claim 15, wherein the tip is hexagonal to engage a correspondingly shaped hexagonal recess in the proximal end of the connection screw. (17) The IM nail insertion assembly of claim 13, further comprising a tab extending radially from the proximal end of the connection screw, the tab being biased toward an undeformed state in which it engages the proximal end of the sleeve. (18) The IM nail insertion assembly of embodiment 1, wherein the IM nail is made of a titanium alloy. (19) The IM nail insertion assembly of embodiment 1, wherein the connecting screw is made of a stainless steel alloy. (20) A method comprising: inserting an IM nail insertion assembly into a medullary canal, the IM nail insertion assembly including: an IM nail, wherein a proximal portion of the IM nail has internal threads; and a connection screw, wherein a distal portion of the connection screw has external threads for engaging the internal threads of the IM nail, wherein one of the proximal portion of the IM nail and the distal portion of the connection screw has a feature for resisting disengagement of the proximal portion from the distal portion; Inserting the tip of a screwdriver into a recessed portion of the head of the connecting screw; rotating the screwdriver in a first direction to engage the external threads of the connection screw with the internal threads of the IM nail.

[0055] (21) rotating the screwdriver in a second direction opposite to the first direction; removing the connecting screw; 21. The method of claim 20, further comprising placing an end cap on the proximal end of the IM nail.

Claims

1. 1. An intramedullary (IM) nail insertion assembly comprising: an IM nail extending longitudinally from a proximal end to a distal end, the proximal portion of the IM nail having an internal thread; a connection screw extending longitudinally from a proximal end to a distal end, a distal portion of the connection screw having external threads for engaging the internal threads of the IM nail; one of the proximal portion of the IM nail and the distal portion of the connection screw includes a feature that resists disengagement of the proximal portion from the distal portion; the feature is a portion of the external threads of the connection screw having a first pitch and a portion having a different pitch than the remainder of the external threads having a second pitch.

2. The IM nail insertion assembly of claim 1 , wherein the first pitch is greater than the second pitch.

3. The IM nail insertion assembly of claim 1 , wherein the second pitch is greater than the first pitch.

4. 1. An intramedullary (IM) nail insertion assembly comprising: an IM nail extending longitudinally from a proximal end to a distal end, the proximal portion of the IM nail having an internal thread; a connection screw extending longitudinally from a proximal end to a distal end, a distal portion of the connection screw having external threads for engaging the internal threads of the IM nail; one of the proximal portion of the IM nail and the distal portion of the connection screw includes a feature that resists disengagement of the proximal portion from the distal portion; 1. An IM nail insertion assembly, wherein the feature is a portion of the internal threads of the IM nail having a first pitch and a portion having a different pitch than the remainder of the internal threads having a second pitch.

5. 1. An intramedullary (IM) nail insertion assembly comprising: an IM nail extending longitudinally from a proximal end to a distal end, the proximal portion of the IM nail having an internal thread; a connection screw extending longitudinally from a proximal end to a distal end, a distal portion of the connection screw having external threads for engaging the internal threads of the IM nail; one of the proximal portion of the IM nail and the distal portion of the connection screw includes a feature that resists disengagement of the proximal portion from the distal portion; the feature is a portion of the external threads of the connection screw that forms a detent; The IM nail insertion assembly, wherein each of the detents extends radially from a central portion of the external threads.

6. The IM nail insertion assembly of claim 5 , wherein the portion of the external threads forms two detents.

7. 1. An intramedullary (IM) nail insertion assembly comprising: an IM nail extending longitudinally from a proximal end to a distal end, the proximal portion of the IM nail having an internal thread; a connection screw extending longitudinally from a proximal end to a distal end, a distal portion of the connection screw having external threads for engaging the internal threads of the IM nail; one of the proximal portion of the IM nail and the distal portion of the connection screw includes a feature that resists disengagement of the proximal portion from the distal portion; the feature is a portion of the internal threads of the IM nail that forms a detent; The IM nail insertion assembly, wherein each of the detents extends laterally from a central portion of the internal threads in an axial direction of the IM nail.

8. The IM nail insertion assembly of claim 7 , wherein the portion of the internal threads forms one detent.

9. The IM nail insertion assembly of claim 1 , wherein the connective screw has a channel extending from the proximal end of the connective screw to the distal end of the connective screw.

10. an insertion handle extending from a proximal end to a distal end; a sleeve extending longitudinally from a proximal end to a distal end, the proximal end of the sleeve sized and shaped to receive the proximal end of the connection screw therein; The IM nail insertion assembly of claim 1 , wherein the proximal end of the sleeve is tightly secured to the distal end of the insertion handle.

11. The IM nail insertion assembly of claim 10 , wherein the sleeve further includes a lumen sized and shaped to receive the shaft of the connection screw.

12. a screwdriver extending from a proximal end to a distal end, the screwdriver having a tip at the distal end and a handle at the proximal end; The IM nail insertion assembly of claim 10 , wherein the tip is sized and shaped to engage a recess in the proximal end of the connection screw.

13. The IM nail insertion assembly of claim 12 , wherein the tip is hexagonal to engage a correspondingly shaped hexagonal recess in the proximal end of the connect screw.

14. The IM nail insertion assembly of claim 10, further comprising a tab extending radially from the proximal end of the connective screw, the tab being biased toward an undeformed state in engagement with the proximal end of the sleeve.

15. The IM nail insertion assembly of claim 1 , wherein the IM nail is made of a titanium alloy.

16. The IM nail insertion assembly of claim 1 , wherein the connection screw is made of a stainless steel alloy.

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