System and method for inserting intramedullary nails

Abstract

An intramedullary (IM) nail insertion assembly is provided that includes an IM nail extending longitudinally from a proximal end to a distal end. A proximal portion of the IM nail has internal threads. The IM nail insertion assembly also includes a connecting screw extending longitudinally from a proximal end to a distal end. A distal portion of the connecting 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 connecting screw has a feature that resists disengagement of the proximal portion from the distal portion.

Description

Technical Field

[0001] This disclosure relates in its entirety to a connecting screw that attaches an intramedullary nail to a device that enables the insertion of the intramedullary nail, the connecting 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 is attached to one end of the intramedullary (IM) nail, and force is applied to the opposite end of the connecting screw to insert the IM nail into the medullary canal. During the nail insertion procedure, the connecting screw may loosen due to the applied force and needs to be tightened again. Summary of the Invention

[0003] This disclosure relates to a system and method 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 threads. The IM nail insertion assembly also includes a connecting screw extending longitudinally from the proximal end to the distal end. The distal portion of the connecting 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 connecting screw has features that resist disengagement between the proximal portion and the distal portion.

[0004] In one embodiment, the feature is part of the external thread of the connecting screw, and the first pitch of the feature is different from the second pitch of the rest of the external thread.

[0005] In one implementation, the first spacing is greater than the second spacing.

[0006] In one implementation, the second spacing is greater than the first spacing.

[0007] In one embodiment, the feature is part of the internal thread of the IM pin, and the first pitch of the feature is different from the second pitch of the rest of the internal thread.

[0008] In one implementation, the feature is part of the external thread of the connecting screw, and this part forms multiple pawls that are different from each other.

[0009] In one implementation, each of these pawls extends radially from the middle portion of the external thread.

[0010] In one implementation, this portion of the external thread forms two pawls.

[0011] In one implementation, the feature is part of the internal thread of the IM pin, and this part forms multiple pawls that are different from each other.

[0012] In one implementation, each of these pawls extends radially from the middle portion of the internal thread.

[0013] In one implementation, the portion of the internal thread forms a ratchet.

[0014] In one implementation, the connecting screw is hollow.

[0015] In one embodiment, the IM pin 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 being sized and shaped to receive the proximal end of the connecting screw therein. The proximal end of the sleeve is rigidly secured to the distal end of the insertion handle.

[0016] In one embodiment, the sleeve further includes an inner cavity whose dimensions and shape are configured to receive the shaft of the connecting screw.

[0017] In one embodiment, the IM pin insertion assembly further includes a screwdriver extending from a proximal end to a distal end, the screwdriver having an end at the distal end and a handle at the proximal end. The size and shape of the end are configured to engage a recess in the proximal end of the connecting screw.

[0018] In one embodiment, the end is hexagonal, used to engage a corresponding hexagonal recess in the proximal end of the connecting screw.

[0019] In one embodiment, the IM pin insertion assembly further includes a tab extending radially from the proximal end of the connecting screw, the tab being biased toward the undeformed state of the proximal end of the engaging sleeve.

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

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

[0022] This disclosure also relates to a method comprising inserting an IM nail insertion assembly into a medullary canal, the IM nail insertion assembly comprising: an IM nail having an internal thread on a proximal portion; a connecting screw having an external thread on a distal portion for engaging the internal thread of the IM nail, and one of the proximal portion of the IM nail and the distal portion of the connecting screw having features that resist disengagement from the proximal portion; inserting the tip of a screwdriver into a recess in the head of the connecting screw; and rotating the screwdriver in a first direction to engage the external thread of the connecting screw with the internal thread of the IM nail.

[0023] In one embodiment, the method further includes rotating the screwdriver in a second direction opposite to the first direction; removing the connecting screw; and placing an end cap on the proximal end of the IM nail. Attached Figure Description

[0024] Figure 1 A system for performing an intramedullary (IM) nail insertion procedure according to various exemplary embodiments of the present disclosure is shown.

[0025] Figure 2 It shows Figure 1 A magnified view of the system.

[0026] Figure 3a shows the relationship with Figure 1 A magnified view of the proximal end of the IM nail, which is engaged with the distal end of the connecting screw of the system.

[0027] Figure 3b shows Figure 1 An enlarged view of the proximal end of the connecting screw of the system.

[0028] Figure 4 The distal end of the connecting screw according to the second embodiment is shown.

[0029] Figure 5 The distal end of the connecting screw according to the third embodiment is shown.

[0030] Figure 6 The proximal end of the IM nail according to the second embodiment is shown.

[0031] Figure 7 The proximal end of the IM nail according to the third embodiment is shown.

[0032] Figure 8 The distal end of the connecting screw according to the fourth embodiment is shown.

[0033] Figure 9 It shows Figure 8 An enlarged view of the connecting screws.

[0034] Figure 10 The proximal end of the IM nail according to the fourth embodiment is shown.

[0035] Figure 11 It shows Figure 10 A magnified view of the IM pin.

[0036] Figure 12 The proximal end of the connecting screw according to the fifth embodiment is shown.

[0037] Figure 13 It shows Figure 12 The enlarged view of the proximal end tab of the connecting screw shown is in an undeformed state.

[0038] Figure 14 It shows Figure 12 The proximal end of the connecting screw, wherein the end of the screwdriver is inserted therein and the tab is in a deformed state. Detailed Implementation

[0039] This disclosure can be further understood with reference to the following description and accompanying drawings, wherein like reference numerals refer to similar elements. Exemplary embodiments describe connecting screws and / or intramedullary (IM) screws having features that resist disengagement or loosening during screw insertion. The connecting screws and IM screws described herein can be implemented in systems for inserting IM screws. It should be noted that, as used herein, the terms “proximal” and “distal” are intended to refer to the direction toward (proximal) and away from (distal) the device, respectively.

[0040] Figure 1 Figures 3b illustrate a system 100 for performing an intramedullary (IM) nail insertion procedure according to various exemplary embodiments of the present disclosure. System 100 includes an intramedullary (IM) nail 102 according to a first embodiment, the IM nail being sized and shaped for insertion into the medullary canal to repair a bone defect. Insertion of the IM nail 102 is achieved by a connecting screw 104 according to the first embodiment, which is engaged with the IM nail 102 during insertion and disengaged from it when the IM nail 102 is fully inserted. During the insertion procedure, the connecting screw 104 is further engaged with an insertion handle 106 grasped by the operator. As those skilled in the art will understand, a force, such as a hammering force, is applied to the insertion handle 106 to push the attached IM nail 102 into the medullary canal. The applied force may be substantial and may stress the connection between the IM nail 102 and the connecting screw 104.

[0041] Due to the magnitude of the force applied to system 100 and the ease of setting up various components, the various elements involved are connected in multiple ways, partly to maintain a secure connection during the insertion procedure. An initial connection is made between the insertion handle 106 and the IM pin 102 via a sleeve 108 extending from the distal end of the insertion handle 106. The sleeve 108 has a proximal end 112 rigidly connected to the distal end of the insertion handle 106. The sleeve 108 is part of the insertion handle 106 and rigidly fixed at its proximal end 112, therefore the sleeve 108 cannot be detached from the handle 106. In this embodiment, the distal end 114 of the sleeve 108 has a feature shaped to snap into a corresponding shape feature at the proximal end 130 of the IM pin 102. For example, the proximal end 130 of the IM pin 102 may have a radially inwardly extending protrusion that engages a correspondingly sized and shaped recess in the distal end 114 of the sleeve 108. However, other attachment mechanisms can be used between sleeve 108 and IM nail 102.

[0042] The sleeve 108 has a hollow interior whose dimensions and shape are configured to receive the longitudinal axis 124 of the connecting screw 104. Therefore, once the sleeve 108 and the IM pin 102 are initially attached to each other, the distal end 122 of the connecting screw 104 is inserted into the proximal end 112 of the sleeve 108 and extends through the length of the sleeve 108 to engage the proximal end 130 of the IM pin 102, as described below, to more securely attach the IM pin 102 to the sleeve 108. The proximal end 112 of the sleeve 108 has an increased diameter relative to the rest of the sleeve 108 and has a recessed portion 116 to receive the head 126 of the connecting screw 104, such that when the connecting screw 104 and the IM pin 102 are engaged, the head 126 is located within the recessed portion 116.

[0043] The connecting screw 104 is hollow to allow the IM pin 102 and the insertion handle 106 to be inserted into the reamer bar. The connecting screw 104 has a channel extending through its length from the proximal end 120 to the distal end 122. The distal end 122 has an externally threaded portion 128 for engaging a corresponding threaded inner surface 134 on the proximal end 130 of the hollow IM pin 102, as shown in FIG3a.

[0044] A connecting screw 104 is inserted through a sleeve 108, and a T-shaped screwdriver 110 is used to screw the distal end 122 of the connecting screw 104 into the proximal end 130 of the IM nail 102. The T-arm 110 has a longitudinal axis 138 extending from a proximal handle 136 to a distal end 140, the end 140 being sized and shaped to engage the countersunk head 126 of the connecting screw 104. In this embodiment, the end 140 is hexagonal to engage a corresponding hexagonal recess in the head 126 of the connecting screw 104; however, other shapes of the end 140 and head 126 of the T-arm 110 may be used. T-screwdriver 110 is used to tighten connecting screw 104 until the distal side 127 of the head 126 of connecting screw 104, i.e., the portion of head 126 extending radially between the outer surface of head 126 and shaft 124, engages the proximal shoulder 118 of recessed portion 116 of sleeve 108, i.e., the portion of sleeve 108 extending radially between the inner surface of recessed portion 116 and inner surface of sleeve 108, as shown in FIG. 3b. This tightening generates a compressive force between connecting screw 104 and sleeve 108 consistent with the engagement of connecting screw 104 and IM pin 102 via threaded portions 128, 134, which further strengthens the connection between components.

[0045] Once the connecting screw 104 and the IM nail 102 are engaged, the operator may continue to drive the distal end 132 of the IM nail 102 into the medullary canal. As those skilled in the art will understand, the connection between the distal end 122 of the connecting screw 104 and the proximal end 130 of the IM nail 102 may be subjected to stress during the procedure. To prevent loosening of the connection, this typically requires retightening the connection to the T-arm 110 midway through the insertion procedure. The system 100 according to various exemplary embodiments includes features that provide a more secure connection against 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 connecting screw 104 in the above embodiments and the connecting screw in the following embodiments may be made of a stainless steel alloy.

[0046] Figure 4 The distal end 222 of a connecting screw 204 according to a second embodiment is shown. Apart from the distal end 222, the connecting screw 204 may be substantially similar to the connecting screw 104 described above. In this second embodiment, the distal end 222 has a threaded portion 228 with a variable pitch, the threaded portion including a first thread 230 and a second thread 232, the first thread extending from the farthest point of the threaded portion 228 to a transition portion passing through approximately the middle of the threaded portion 228, and the second thread extending from the transition portion to the nearest point of the threaded portion 228. Those skilled in the art will understand that the thread pitch is related to the helical angle along which the thread extends (i.e., the angle between the axial progression of the helix and the axis of the cylinder around which it is wound), and a smaller pitch indicates a larger helical angle, such that threads with smaller pitch are closer to each other than threads with larger pitch.

[0047] The first thread 230 has a first pitch corresponding to the spacing of the internal thread portion 134 of the IM pin 102, while the second thread 232 has a second pitch smaller than that of the first thread 230 and the internal thread portion 134, causing the second thread 232 to interfere with the internal thread portion 134. The ratio between the first pitch of the first thread 230 and the second pitch of the second thread 232 is 0.5 to 0.99. When the thread portion 228 of the connecting screw 204 advances along the thread portion 134 of the IM pin 102, the second (smaller) thread 232 engages the thread portion 134 of the IM pin 102.

[0048] Due to the different spacing, one or both engagement threads will deform, causing the distal end 222 of the connecting screw 204 and the proximal end 130 of the IM pin 102 to engage more tightly against loosening during the insertion procedure. Although tightening causes deformation, once the IM pin 102 has been fully inserted, the engagement threads can be disengaged by subsequently rotating the connecting screw 204 in the opposite direction to the tightening direction.

[0049] If the threaded portion 134 of the IM pin 102 deforms during the advancement of the connecting screw 204, the first thread 230 of the connecting screw 204 will engage the deformed threaded portion 134 and substantially counteract the deformation—that is, the engagement of the first thread 230 with the inner threaded portion 134 will reposition and correct the threads of the inner portion 134. Therefore, if and when another component is attached to the threaded portion 134 of the IM pin 102, such as an end cap, the end cap will not encounter significant resistance when tightened onto it. Thus, if the first thread 230 matches the threaded portion 134 of the IM pin 102, the threaded portion 134 of the IM pin 102 will not deform, and therefore the end cap will have a tight fit within the IM pin 102.

[0050] Figure 5 The distal end 322 of a connecting screw 304 according to a third embodiment is shown. Apart from the distal end 322, the connecting screw 304 may be substantially similar to any of the connecting screws 104 and 204 described above. In this third embodiment, the distal end 322 has a threaded portion 328 with variable pitch, the threaded portion including a first thread 330 and a second thread 332, the first thread extending from the farthest point of the threaded portion 328 to a transition portion passing through approximately the middle of the threaded portion 328, and the second thread extending from the transition portion to the nearest point of the threaded portion 328, similar to the connecting screw 204 of the first embodiment.

[0051] However, in the third embodiment, the first thread 330 has a first pitch corresponding to the spacing of the internal thread portion 134 of the IM pin 102, while the second thread 332 has a larger pitch than the first thread 330 and the internal thread portion 134. Similar to the connecting screw 204 described above, the second thread 332 engages the thread portion 134 of the IM pin 102 as the thread portion 328 of the connecting screw 304 advances along the thread portion 134. The ratio between the first pitch of the first thread 330 and the second pitch of the second thread 332 is from 1.01 to 2.

[0052] Due to the varying spacing, one or both engagement threads will deform, causing the distal end 322 of the connecting screw 304 and the proximal end 130 of the IM pin 102 to engage tightly and resist loosening during insertion. If the threaded portion 134 of the IM pin 102 deforms during the advance of the connecting screw 304, the first thread 330 of the connecting screw 304 will engage the deformed threaded portion 134 and substantially correct the deformation. Therefore, if and when another element is attached to the thread 134 of the IM pin 102, such as an end cap, the end cap will not encounter significant resistance when tightened onto it.

[0053] By adjusting the spacing on the proximal end of the thread, rather than the distal end, the proximal portion of the corresponding thread of the IM pin 102 will potentially deform, rather than the entire thread, as the connecting screw advances. In an alternative embodiment, the provided connecting screws have smaller / larger spacing connecting screws 204, 304, but no distal thread corresponding to the thread of the IM pin 102. Therefore, when the connecting screw is screwed into the IM pin 102, only the smaller / larger spacing thread of the connecting screw engages the threaded portion 134 of the IM pin 102, and the distal portion of the threaded portion 134 remains unengaged.

[0054] The principles described above regarding connecting screws 204 and 304 can be alternatively implemented at IM pin 102. Specifically, connecting screw 104 with a uniform pitch for its threaded portion 128 can be used with IM pins with a variable pitch for their threaded portion. In these embodiments, the distal portion of the IM pin thread has a smaller or larger pitch, such that the thread 128 of the connecting screw 104 or the distal thread of the IM pin deforms as the connecting screw 102 is advanced.

[0055] Figure 6 The proximal end 430 of an IM pin 402 according to a second embodiment is shown. Apart from the proximal end 430, the IM pin 402 may be substantially similar to the IM pin 102 described above. The IM pin 402 has a threaded portion 434 with a variable pitch, the threaded portion including a first thread 436 and a second thread 438, the first thread extending from the farthest point of the threaded portion 434 to a transition portion passing through approximately the middle of the threaded portion 434, and the second thread extending from the transition portion to the nearest point of the threaded portion 434. The first thread 436 has a first pitch smaller than the second thread 438, and the second thread 438 has a second pitch corresponding to the pitch of the external threaded portion 128 of the connecting screw 104.

[0056] Figure 7 A third embodiment is shown for use Figure 1 The proximal end 530 of the IM pin 502 of system 100. Except for the proximal end 530, the IM pin 502 may be substantially similar to the IM pins 102 or 402 described above. Similar to IM pin 402, the IM pin 502 has a threaded portion 534 with a variable pitch, the threaded portion including a first thread 536 and a second thread 538, the first thread extending from the farthest point of the threaded portion 534 to a transition portion passing through approximately the middle of the threaded portion 534, and the second thread extending from the transition portion to the nearest point of the threaded portion 534. The first thread 536 has a first pitch greater than the second thread 538, and the second thread 538 has a second pitch corresponding to the pitch of the external threaded portion 128 of the connecting screw 104.

[0057] Figure 8 The distal end 622 of a connecting screw 604 according to a fourth embodiment is shown. Apart from the distal end 622, the connecting screw 604 may be substantially similar to any of the connecting screws 104, 204, and 304 described above. In this fourth embodiment, the distal end 622 has a threaded portion 628, which includes pawls 630 at two locations on the threaded portion 628, such as... Figure 9 As shown. Two pawls 630 extend radially from the middle portion of the thread and are shaped differently from the rest of the thread.

[0058] Specifically, axial deformation of the thread causes the gap between adjacent portions of the thread to become narrower or wider. Therefore, when the IM pin 102 and the connecting screw 604 are screwed together, the pawl 630 will mechanically interfere with the threaded portion 134 of the IM pin 102. Although Figure 8 The threaded portion 628 shown has two pawls 630, but more or fewer pawls can be used. In a manner similar to the connecting screws 204 and 304 described above, when the distal end 622 is screwed into the proximal end 130 of the IM pin 102, the pawls 630 engage the threaded portion 134 of the IM pin 102, such that the mechanical interference between them locks the connecting screw 604 and the IM pin 102 more tightly together. The pawls 630 can be located on the proximal portion of the threaded portion of 628 so as to interfere only with the proximal portion of the threaded portion 134 of the IM pin, so that if and when another element is attached to the threaded portion 134 of the IM pin 102, such as an end cap, that end cap will fit tightly with the IM pin 102.

[0059] Figure 10 The proximal end 730 of the IM nail 702 according to a fourth embodiment is shown. Apart from the proximal end 730, the IM nail 702 may be substantially similar to the IM nails 102, 402, and 502 described above. In this fourth embodiment, the IM nail 702 has a threaded portion 734, which includes a pawl 736 extending laterally from the middle portion of the thread. The pawl 736 is part of the thread that is deformed relative to the rest of the thread. Therefore, due to the pawl 736, the thread shape of the threaded portion 734 differs from the shape of the gap between the threaded rings of the threaded portion 128, and this difference in shape creates mechanical interference against loosening between the threaded portion 128 of the connecting screw 104 and the IM nail 702 when these components are screwed together. Although the threaded portion 734 has a single pawl, as Figure 11 As shown, more pawls can be used.

[0060] In addition to the mechanisms described above at the distal end of the connecting screw or the proximal end of the IM nail, an additional mechanism may be implemented at the proximal end of the connecting screw to resist disengagement of the tight connection between the connecting screw and the IM nail.

[0061] Figure 12 The proximal end 820 of a connecting screw 804 according to a fifth embodiment is shown. Apart from the proximal end 820, the connecting screw 804 may be substantially similar to the connecting screw 104 described above. In this embodiment, the countersunk head 826 of the proximal end 820 has a deformable tab 828 extending radially through the head 826. In its natural (i.e., undeformed state) state, the tab 828 is oriented such that the outer portion 830 (e.g., a corner) of the tab 828 projects radially outward relative to the outer surface of the head 826, as... Figure 13 As shown. Therefore, when the connecting 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.

[0062] This engagement serves to prevent the connecting screw 804 from moving, for example, rotating, relative to the sleeve 108. For example, during the insertion procedure, the stress generated by the insertion force can act to remove the connecting screw 804 from the IM pin 102 or the sleeve 108. Considering the rigid connection between the sleeve 108 and the IM pin 102 described above, the tab 828, in its undeformed state, provides a force to resist relative movement (e.g., rotation) between the connecting screw 804 and the sleeve 108, which further resists movement between the connecting screw 804 and the IM pin 102.

[0063] In its undeformed state, the tab 828 also has an inner portion 832, which is the opposite corner of the outer portion 830, thus protruding radially inward relative to the inner surface of the head 826. However, when the end 140 of the T-arm 110 engages in the recess of the countersunk head 826 of the connecting screw 804, the end 140 forces the inner portion 832 radially outward, and the tab 828 deforms under pressure from the end 140. This deformation straightens the tab 828, causing the outer portion 830 to no longer engage the proximal end 112 of the sleeve 108, as... Figure 14 As shown. Therefore, when the end 140 of the T-arm 110 is inserted into the countersunk head 826, the connecting screw 804 can rotate relative to the sleeve 108. This allows the connecting screw 804 to screw into the IM nail 102 at the start of the nail insertion procedure and out of the IM nail 102 at the end of the insertion procedure without interfering with the tab 828 and the sleeve 108. In other words, when the end 140 of the T-arm 110 is inserted into the countersunk head 826, the connecting screw 804 can rotate relative to the sleeve 108, and when the T-arm 110 is retracted, the tab 828 resists rotation, thereby providing a more secure connection between the connecting screw 804 and the IM nail 102.

[0064] Those skilled in the art will understand that modifications can be made to the above embodiments without departing from the inventive concept of the present invention. It should also be understood that a structural feature and method associated with one embodiment can be incorporated into other embodiments. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, but rather that modifications are also included within the scope of the invention as defined in the appended claims.

Claims

1. An intramedullary nail insertion assembly, comprising: An intramedullary nail, the intramedullary nail extending longitudinally from a proximal end to a distal end, the proximal portion of the intramedullary nail having internal threads; and A connecting screw, extending longitudinally from a proximal end to a distal end, the distal portion of the connecting screw having external threads for engaging the internal threads of the intramedullary nail. One of the proximal portion of the intramedullary nail and the distal portion of the connecting screw has a feature that resists disengagement between the proximal portion and the distal portion. The intramedullary nail insertion assembly further includes: Insertion handle, the insertion handle extending from the proximal end to the distal end; and A sleeve extending longitudinally from a proximal end to a distal end, the proximal end of the sleeve being sized and shaped to receive the proximal end of the connecting screw therein. The proximal end of the sleeve is rigidly fixed to the distal end of the insertion handle, and The intramedullary nail insertion assembly further includes: A tab extending radially from the proximal end of the connecting screw, wherein the tab is biased toward a non-deformed state in which it extends outward from the connecting screw to engage the proximal end of the sleeve, preventing the connecting screw from rotating relative to the sleeve, and the tab is configured to move into a deformed state in which it moves inward without engaging the proximal end of the sleeve, allowing the connecting screw to rotate relative to the sleeve.

2. The intramedullary nail insertion assembly according to claim 1, wherein, The feature portion is a part of the external thread of the connecting screw, and the first spacing of the portion is different from the second spacing of the rest of the external thread.

3. The intramedullary nail insertion assembly according to claim 2, wherein, The first spacing is greater than the second spacing.

4. The intramedullary nail insertion assembly according to claim 2, wherein, The second spacing is greater than the first spacing.

5. The intramedullary nail insertion assembly according to claim 1, wherein, The feature portion is part of the internal thread of the intramedullary nail, and the first spacing of the feature portion is different from the second spacing of the rest of the internal thread.

6. The intramedullary nail insertion assembly according to claim 1, wherein, The feature portion is part of the external thread of the connecting screw, and the portion forms multiple pawls that are different from each other.

7. The intramedullary nail insertion assembly according to claim 6, wherein, Each of the pawls extends radially from the middle portion of the external thread.

8. The intramedullary nail insertion assembly according to claim 6, wherein, The portion of the external thread forms two pawls.

9. The intramedullary nail insertion assembly according to claim 1, wherein, The feature portion is part of the internal thread of the intramedullary nail, and the portion forms multiple pawls that are different from each other.

10. The intramedullary nail insertion assembly according to claim 9, wherein, Each of the pawls extends radially from the middle portion of the internal thread.

11. The intramedullary nail insertion assembly according to claim 1, wherein, The feature portion is part of the internal thread of the intramedullary nail, and the portion forms a pawl.

12. The intramedullary nail insertion assembly according to claim 1, wherein, The connecting screw is hollow.

13. The intramedullary nail insertion assembly according to claim 1, wherein, The sleeve also includes an inner cavity whose dimensions and shape are configured to receive the shaft of the connecting screw.

14. The intramedullary nail insertion assembly according to claim 1, further comprising: A screwdriver extending from a proximal end to a distal end, the screwdriver having an end located at the distal end and a handle located at the proximal end. The size and shape of the end are set to engage the recess in the proximal end of the connecting screw.

15. The intramedullary nail insertion assembly according to claim 14, wherein, The end is hexagonal, used to engage the corresponding hexagonal recess in the proximal end of the connecting screw.

16. The intramedullary nail insertion assembly according to claim 1, wherein, The intramedullary nail is made of titanium alloy.

17. The intramedullary nail insertion assembly according to claim 1, wherein, The connecting screw is made of stainless steel alloy.

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