JP2007236568A - Fixing structure of nail and lug screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide fixing structure of a nail and a lug screw with which the nail and the lug screw can be easily and stably fixed to each other. <P>SOLUTION: In the structure fixing of the nail B and the lug screw 30 to each other by screwing a stopper screw 30 constituting the lug screw A, the lug screw is composed of a distal end member 10, a barrel member 20 connected with the proximal end of the distal end member, and a stopper screw which is screwed to enter the proximal end 23 of the barrel member. The barrel member 20 is formed with: a nail through-hole for putting the nail through obliquely with respect to the barrel member; and a screw groove to be screwed with the stopper screw on the inner circumferential surface of the proximal end 23. The stopper screw is composed of a distal end 31 and a screw bar part. The distal end face of the distal end is inclined so as to contact with the side face B1 of the nail with a surface, and the screw bar part is formed with, on its outer circumferential surface, a screw thread to be screwed with the screw groove formed on the inner circumferential surface of the proximal end of the barrel member formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure for fixing an nail and a lag screw for an implant mainly used for osteosynthesis of a trochanteric fracture.

Conventionally, as shown in Patent Document 1, a fixing structure for fixing a nail and a lag screw by a pressing force generated by screwing a stopper screw constituting the lag screw is known. In the fixing structure shown in the patent document, the nail is hollow and has a slit in the length direction, and the stopper screw pushes the slit of the nail by screwing the stopper screw into the slit. The nail and the lag screw are fixed by spreading and screwing until the tip of the stopper screw reaches the inner surface of the nail.
U.S. Pat. No. 4,697,585

  However, the fixing structure shown in Patent Document 1 is a point contact between the stopper screw and the nail inner surface and a point contact between the nail outer surface and the lag screw, both of which are point contact, so there is a risk of lack of stability and wobble. There is. In osteosynthesis, where high technical accuracy is required, it requires a high level of skill with a strong sense of tension because it requires considerable arm strength to reach the physical destructive force that spreads the slit of the nail with a stopper screw. Required technology.

  Therefore, as a result of intensive studies, the present inventor has developed a fixing structure of a nail and a lag screw that can easily fix the nail and the lag screw with a high degree of stability.

  The fixing structure of the nail and the lag screw according to the present invention is a fixing structure for fixing the nail and the lag screw by a pushing force by screwing a stopper screw constituting the lag screw, and the lag screw includes a tip member and The barrel member is connected to the base end portion of the tip member, and a stopper screw that is screwed into the base end portion of the barrel member, and the barrel member penetrates the nail obliquely with respect to the barrel member. Therefore, a nail through hole is formed from the substantially central position of one side surface to a position slightly rearward from the center of the other side surface, and the base end portion is a hollow communicating with the nail through hole, Are formed with a screw groove to be screwed with the stopper screw and a guide groove for guiding the stopper screw. And a screw rod portion, and the distal end surface of the distal end portion is inclined so as to come into surface contact with the side surface of the nail that penetrates obliquely with respect to the body member. Fits into a guide groove formed on the inner peripheral surface of the base end of the body member so that the tip of the tip of the stopper screw keeps in contact with the side surface of the nail when the tip of the stopper screw enters inside The guide protrusion is formed, and the screw rod portion is formed with a screw thread that is screwed into a screw groove formed on the inner peripheral surface of the trunk member base end portion on the outer peripheral surface thereof.

  The fixing structure of the nail and the lag screw having the above-described configuration is such that the tip end surface of the stopper screw in the lag screw is inclined so as to be in surface contact with the side surface of the nail that penetrates obliquely with respect to the body member. Therefore, when the stopper screw is screwed in, a pushing force that the tip end surface of the stopper screw comes into surface contact with the nail acts, and the nail comes into contact with the cut surface of the nail through hole by the pushing force. By these surface contacts, the nail and the lag screw are stably fixed, and there is no possibility of wobbling between the nail and the lag screw. Further, since the pushing force works with a force sufficient to screw the stopper screw, a large arm force that reaches a physical breaking force is not required, and the nail and the lag screw can be easily fixed.

  In the above-described configuration, the distal end member of the lag screw is formed in a cone shape with the distal end portion having a thread, the proximal end portion is configured to be able to advance and retreat relative to the body member, and the proximal end surface is fitted with a screwdriver. It is good also as a structure by which a joint groove is formed.

  Moreover, the said structure WHEREIN: The trunk | drum member of a lag screw is good also as a structure which is a cylindrical body.

  Furthermore, in the above-described configuration, the distal end portion of the stopper screw is rotatably coupled to the screw rod portion by a coupling shaft extending to the rear end surface thereof, and the connection between the distal end portion and the screw rod portion is achieved. It is good also as a structure by which a spring washer is distribute | arranged to the axis | shaft.

  In the above-described configuration, the screw rod portion of the stopper screw may be configured such that a concave portion into which a screwdriver for screwing the stopper screw into the base end portion of the body member is fitted is formed on the rear end surface.

  Furthermore, in the above configuration, the nail may be configured such that the contact surface with the stopper screw is smooth and the opposite surface protrudes to form a non-slip groove.

  As described above, the fixing structure of the nail and the lag screw according to the present invention allows the nail and the lag screw to be fixed easily and with a high degree of stability, and does not require a highly skilled technique. There is an advantage that the osteosynthesis can be performed more easily.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  1 is a partially sectional side view showing a fixed state of a nail and a lag screw according to the present embodiment, FIG. 2 is a partially sectional view excluding a stopper screw of the lag screw, and FIG. 3 is a front end of the lag screw. 4 is an exploded view of the member, FIG. 4 is a view of the body member in the lag screw, (a) is a cross-sectional view, (b) is a side view seen from the rear, FIG. 5 is a view of the stopper screw in the lag screw FIG. 6A is a view seen from the front, FIG. 6B is a view seen from the side, FIG. 6C is a view seen from the rear, and FIG. 6 is a side view seen from the rear end side of the stopper screw. FIG. 7 is an exploded side view of the nail, FIG. 8 is a perspective view of the nail with the nail cap removed, and FIG. 9 is a side view of a fixing screw inserted through the lower portion of the nail.

  As shown in FIG. 1, the lag screw A according to the present embodiment has a structure in which the nail B is penetrated and the lag screw A is fixed to the nail B by the pushing force generated by twisting the stopper screw 30.

  As shown in FIGS. 2 to 6, the lag screw A includes a tip member 10, a body member 20, and the stopper screw.

  As shown in FIG. 3 in particular, the distal end member 10 has a distal end portion 11 formed in a conical shape having a thread 11a, and the proximal end portion 12 has a slightly smaller shaft diameter than the central shaft portion 12a of the distal end member 10. The thin shaft portion 12b is small, and the rear end portion 12c is formed such that the shaft diameter is slightly smaller than that of the thin shaft portion 12b. Then, as shown in FIG. 2, the thin shaft portion 12b is inserted from the front end side of the body member 20, and an annular cap 12d is fitted into the rear end portion 12c. The members 10 and 20 are connected so as to be able to advance and retreat, and the members 10 and 20 are detachable. The proximal end surface 12e of the proximal end portion 12 is formed with a driver fitting groove 12f so that the distal end portion 11 can be screwed into the proximal femur by a screwdriver.

  As shown in FIG. 4, the body member 20 is a cylindrical body, and a central through hole 21 a is formed at a substantially central position on one side surface of the body member 20 in order to penetrate the nail B obliquely with respect to the body member 20. A rear through hole 21b is formed at a position slightly rearward from the center of the other side surface, and the nail through hole 21 is formed by the central through hole 21a and the rear through hole 21b. The distal end portion 22 of the body member 20 is formed such that the hole diameter of the distal end opening portion 22a is slightly smaller than the hole diameter of the distal end inner portion 22b, and the proximal end portion 12 of the distal end member 10 is connected to be able to advance and retract. ing. That is, as shown in FIG. 2, the hole diameter of the distal end port portion 22a is smaller than the shaft diameter 10 of the distal end member central shaft portion 12a at the proximal end portion 12, larger than the thin shaft portion 12b, and smaller than the outer diameter of the cap 12d. The hole diameter of the tip inside 22b is formed larger than the outer diameter of the cap 12d. With this configuration, the tip member 10 and the barrel member 20 slide within the length of the tip member thin shaft portion 12 b, and the tip member 10 can move forward and backward with respect to the barrel member 20. On the inner peripheral surface of the base end portion 23 of the body member 20, a screw groove 23a that is screwed with the stopper screw 30 and a guide groove 23b that guides the stopper screw 30 are formed. According to the configuration of the stopper screw 30 described below. The stopper screw 30 is screwed into the trunk member base end portion 23 as shown in FIG. 1 without changing the posture of the tip of the stopper screw 30.

  As shown in FIG. 5, the stopper screw 30 includes a tip portion 31 and a screw rod portion 32. The distal end surface 31 a of the distal end portion 31 is inclined so as to come into surface contact with the side surface B1 of the nail B that penetrates obliquely with respect to the body member 20. As shown in FIG. 6, a guide convex portion 31 b that fits into a guide groove 23 b formed on the inner peripheral surface of the trunk member base end portion 23 is formed on the outer peripheral surface of the distal end portion 31. The distal end portion 31 of the stopper screw 30 is configured to invade into the end portion 23 so as to maintain a posture in which the distal end portion distal end surface 31a is in surface contact with the side surface B1 of the nail B. The distal end portion 31 is coupled to the screw rod portion 32 in a freely loosely fitted state by a coupling shaft 31d extending to the rear end surface 31c, and a spring washer is coupled to the coupling shaft 31d between the distal end portion 31 and the screw rod portion 32. 33, the stopper screw 30 is screwed into the body member 20, the tip surface 31a of the stopper screw 30 comes into contact with the nail side surface B1, and further, when the stopper screw 30 is further screwed in, the spring washer 33 is compressed. The urging force that the compressed spring washer 33 tries to restore to the original state always presses the tip surface 31a of the stopper screw 30 in surface contact with the nail side surface B1. A screw thread 32a is formed on the outer peripheral surface of the screw rod portion 32 to be screwed with a screw groove 23a formed on the inner peripheral surface of the body member base end portion 23. The screw rod portion 32 has a stopper screw 30 on the rear end surface 32b. A recess 32c is formed in the body member base end portion 23 to be fitted with a screwing screwdriver.

  As shown in FIG. 7, the nail B has a smooth side B1 that is a contact surface with the stopper screw 30 and a non-slip groove B3 formed on the opposite side B2. B4 is a nail cap screwed on the nail head. A fixing screw C shown in FIG. 8 is inserted into the insertion hole B5 at the lower part of the nail, and the nail B is fixed to the distal part of the femur.

  Since the structure for fixing the nail B and the lag screw A according to the present embodiment is configured as described above, the tip end surface 31a of the stopper screw 30 in the lag screw A penetrates obliquely with respect to the body member 20. Since it is inclined so as to come into surface contact with the side surface B1 of the nail B to be pushed, when the stopper screw 30 is screwed in, a pushing force that the tip end surface 31a of the stopper screw 30 makes surface contact with the nail B acts. In addition, since the nail B comes into contact with the cut surface of the nail through hole 21 due to the pushing force, the nail B and the lag screw A are stably fixed by the surface contact, and the wobbling occurs between the nail B and the lag screw A. There is no risk of this. Moreover, since the said pushing force works only with the force of screwing the stopper screw 30, the nail B and the lag screw A can be fixed easily.

It is a partial cross section side view which shows the fixed state of the nail and lag screw which concern on a present Example. It is a partial cross section figure except for a stopper screw of a lag screw concerning this example. It is an exploded view of the tip member in the lag screw concerning this example. It is a figure of the trunk | drum member in the lag screw which concerns on a present Example, Comprising: (a) is sectional drawing, (b) is the side view seen from back. It is the figure of the stopper screw in the lag screw which concerns on a present Example, Comprising: (a) is the figure seen from the front, (b) is the figure seen from the side, (c) is the figure seen from back. It is the side view seen from the rear end side of the stopper screw which concerns on a present Example. It is a disassembled side view of the nail which concerns on a present Example. In the nail which concerns on a present Example, it is the perspective view which removed the nail cap. It is a side view of the fixation screw inserted in the lower part of the nail concerning this example.

Explanation of symbols

A ... Lug screw B ... Nail B1 ... Side surface where the nail stopper screw contacts B2 ... Side surface where the nail stopper screw contacts B3 ... Anti-slip groove B4 ··· Nail cap B5 ··· Fixing screw insertion hole C ··· Fixing screw 10 ··· Tip member 11 ··· Tip portion of tip member 11a ··· Screw thread at tip portion 12 ··· Base end portion 12a .. Central shaft portion 12b of the front end member 12b Thin shaft portion 12c Base end portion 12d Cap 12e Base end surface 12f Driver screw groove 20 Body member 21 Nail through hole 21a ... Central through hole 21b ... Back through hole 22 ... Tip 22a ... Tip mouth 22b ... Inside tip 23 ... Base end 23a ... Screw hole 23b on the inner peripheral surface of the base end 23b ... Guy on the inner peripheral surface of the base end Groove 30 .. Stopper screw 31... Tip portion 31a .. Tip end surface 31b .. Guide convex portion 31c .. Rear end surface 31d of tip end .. Connecting shaft 32 .. Screw rod portion 32a. Screw thread 32b .. rear end surface of screw rod portion 32c .. driver fitting recess 33... Spring washer

Claims (6)

A fixing structure that fixes the nail and the lag screw by the pushing force of the stopper screw constituting the lag screw,
The lag screw is composed of a tip member, a barrel member connected to the base end portion of the tip member, and a stopper screw that is screwed into the base end portion of the barrel member.
The body member is formed with a nail through hole extending from a substantially central position of one side surface to a position slightly rearward from the center of the other side surface in order to allow the nail to penetrate obliquely with respect to the body member. It is a hollow communicating with the nail through hole, and on its inner peripheral surface, a screw groove to be screwed with the stopper screw and a guide groove for guiding the stopper screw are formed,
The stopper screw includes a tip portion and a screw rod portion, and the tip surface of the tip portion is inclined so as to come into surface contact with the side surface of the nail that penetrates obliquely with respect to the body member, and the outer peripheral surface of the tip portion In the inner peripheral surface of the trunk member base end portion, the tip end surface of the tip end portion is in contact with the side surface of the nail when the tip end portion of the stopper screw enters the base end portion of the barrel member. A guide convex portion that fits into the formed guide groove is formed, and a screw thread that engages with a screw groove formed on the inner peripheral surface of the trunk member base end portion is formed on the outer peripheral surface of the screw rod portion. Fixed structure of nail and lag screw.   The distal end member of the lag screw is formed in a conical shape having a threaded portion at the distal end, the base end is configured to be able to advance and retract relative to the body member, and a driver fitting groove is formed on the proximal end surface. The structure for fixing a nail and a lag screw according to claim 1.   3. The structure for fixing a nail and a lag screw according to claim 1, wherein the body member of the lag screw is a cylindrical body.   The distal end portion of the stopper screw is coupled to the screw rod portion in a loosely fitted state by a coupling shaft extending on the rear end surface thereof, and a spring washer is disposed on the coupling shaft between the distal end portion and the screw rod portion. The structure for fixing a nail and a lag screw according to any one of claims 1 to 3, wherein the structure is a fixed structure.   The screw rod portion of the stopper screw is formed with a concave portion on the rear end surface thereof, into which a screwdriver for screwing the stopper screw into the base end portion of the body member is fitted. Fixing structure of nail and lag screw as described in 1.   The nail according to any one of claims 1 to 5, wherein the nail has a smooth contact surface with the stopper screw, the opposite surface protrudes from the nail, and a non-slip groove is formed. Fixed structure with lag screw.

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