JP2018075128A - Bone anchor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bone anchor enabling reliable fixation without any seizure of a locking part to a plate and capable of shortening a fixing time.SOLUTION: A bone anchor 1 for use in the femur 100 includes: a lug screw 2 that is screwed so as to pass through a fracture line; a plate 3 that is disposed along the longitudinal direction of the femur 100, and provided with a lug screw holding part 3B at a proximal side of the femur 100, and fixing holes 31 and 32 at a distal side of the femur 100; and locking pins 5 and 6 provided with screw parts 5S and 6S at head parts, and fixing the plate 3 to the femur 100. The lug screw 2 is held by the lug screw holding part 3B, and the locking pins 5 and 6 are inserted and fixed in the fixing holes 31 and 32 so as to become a different direction from that of the lug screw 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bone anchor (implant) for fixing bone.

  Conventionally, as a bone fixing tool used in osteosynthesis, fixing a plate with a screw has been the mainstream. As a screw in this case, it is common to use a normal screw (tapping screw, non-locking screw) in which a threaded portion is formed only in the main body and no threaded portion is formed in the head. In such a bone fixing device, when the plate is pressed when the screw is fixed, the plate may be warped. Therefore, the bone fixing device is often used in a portion where the load is relatively unrelated.

  In addition to the normal screw, the plate fixing member is provided with a threaded portion on the main body (thread portion) to be screwed into the bone and the head portion (locking portion) to be fixed to the plate. A locking screw that can be locked is also known. Since the screw portion of the head is fastened to the plate, the locking screw is superior in fixing force to a normal screw.

  On the other hand, CHS (Compression Hip Screw) is known as a bone fixing tool used in osteosynthesis of proximal femoral fractures. In osteosynthesis using CHS, a lag screw is inserted to the head of the femur so as to penetrate the fracture, and a plate coupled with this is attached to the outside of the femoral shaft to join and fix the fracture, and bone fusion Is to promote. In this case, in addition to the lag screw, a fixing member for fixing the plate and the bone is used.

  As the CHS fixing member, a normal screw having no threaded portion at the head is generally used. In order to further increase the fixing force, a technique using a locking screw as a CHS fixing member has also been developed (see, for example, Patent Document 1).

  In addition, a locking pin provided with a screw only on the head of the pin is known as a fixing member of the bone fixing device, but as a main fixing member of the plate, it is mainstream to use a normal screw as described above. Even if a locking pin is used, it has always been used in combination with a normal screw or a locking screw.

  This is because the locking pin is generally superior in strength and easier to insert than a normal screw or a locking screw, but has no fixing force in the axial direction of the locking pin.

JP 2009-125553 A

  However, when a locking screw is used instead of a normal screw as the CHS fixing member, the post-operative fixing force can be increased, but it has been found to be a problem particularly in long-term use.

  As for the locking screw, since the screw thread of the screw provided in each of the tip (thread part) fitted to the bone and the head (locking part) fitted to the plate does not necessarily match, a deviation occurs, Unintended stress occurs between the thread portion and the locking portion.

  Due to this stress, the screw of the locking part that is tightened later is squeezed into the fixing hole of the plate at the time of insertion, and the fixation becomes insufficient, and at the time of removal, the load is squeezed for a long time. As a result of this, it becomes fixed and a problem arises that the locking screw cannot be removed.

  In addition, when a plurality of locking screws are used in order to obtain a sufficient fixing force, the distal locking screws may be inserted at an angle with respect to the plate so that a large number of the locking screws remain in the bone. If the distance is long, it takes time to insert the screw (screwing), which increases the burden on the patient and the operator.

  Furthermore, a case has been reported in which a fracture is newly performed below a fractured part by embedding a bone fixing tool such as CHS using a normal screw or a locking screw for a long time. In such a case, it is necessary to replace it with a larger bone fixing device, but when using a screw in which a screw part is formed in a main body part embedded in bone, such as a normal screw or a locking screw, as a fixing member, In this case, problems are likely to occur.

  That is, when replacing the bone anchor, if the old locking screw is removed and a new locking screw is inserted at the same position, the thread formed on the bone will be broken due to the stress caused by the misalignment between the thread portion and the locking portion. May not be able to obtain a sufficient fixing force. For this reason, it is necessary to re-drill a new hole in another part of the bone and shift the position of the bone anchor, but the incision part becomes large and the original strength of the bone may be weakened. The burden will be large.

  Further, in the case of a normal screw, there is no deviation between the thread portion and the locking portion, but if the screw thread once formed on the bone is used again, there is a possibility that a sufficient fixing force cannot be obtained. That is, even if it is a normal screw, the same problem arises in that it is necessary to reopen a hole in another part of the bone.

  In view of such circumstances, the present invention increases the fixing force as compared with the case where a normal screw is used as a CHS fixing member, and does not bite the locking portion to the plate, and can be reliably fixed. An object of the present invention is to provide a bone anchor that can shorten the fixing time.

  (1) The present invention is a bone anchor used for a femur, which is disposed along a longitudinal direction of the femur, and a lag screw that is screwed so as to pass through the fracture line. A plate having a lag screw holding portion on the proximal side and a fixing hole on the distal side of the femur, and a locking pin having a screw portion on the head and fixing the plate to the femur. The bone is characterized in that the lag screw is held by the lag screw holding portion, and the locking pin is inserted and fixed in the fixing hole so as to be in a different direction from the lag screw. It is a fixture.

  According to such a configuration, the plate can be fixed without using a locking screw as the fixing member, and therefore, between the tip (thread portion) and the head (locking portion) generated when the locking screw is used. Can avoid unintended stress caused by.

  Therefore, it is possible to avoid problems such as no squeezing of the locking portion into the fixing hole at the time of insertion, and insufficient fixation or difficulty in removing the locking screw at the time of removal.

  Further, in the case of the locking pin, the fixing time can be greatly shortened as compared with the locking screw, so that the burden on the patient and the operator can be reduced.

  Furthermore, since the screw holes are not formed in the hole for inserting the locking pin formed in the bone, even if the bone fixing device may be replaced, a new hole is remade in another part of the bone, It is not necessary to shift the position of the bone anchor, and the burden on the patient can be reduced.

  (2) In the present invention, a plurality of the fixing holes are provided along a longitudinal direction of the plate, and the locking pin inserted into at least a part of the plurality of fixing holes is formed on the surface of the plate. The bone fixing device according to (1), wherein the bone fixing device is fixed so as to be inclined from a substantially vertical direction.

  According to such a configuration, during normal walking or the like, a load is applied in a direction in which the locking pin is difficult to be removed (vertically below), so that even the locking pin can be sufficiently fixed. Since a plurality of pins are inserted in different directions and their orientations are held by a locking mechanism with the plate, it is extremely difficult to pull out even the pins. Accordingly, even a locking pin can be sufficiently fixed.

  (3) The bone according to (2) above, wherein the locking pin is fixed so that a tip is located on a distal side of the femur from a screw portion of the head. It is a fixture.

  (4) The bone according to (2) or (3) above, wherein the angle of inclination of the locking pin is 10 degrees to 70 degrees with respect to the longitudinal direction of the femur. It is a fixture.

  (5) In the present invention, the locking pin inserted into a part of the plurality of fixing holes may have a direction substantially perpendicular to the surface of the plate or a tip of the thigh from a screw portion of the head. The bone fixing device according to any one of (2) to (4), wherein the bone fixing device is fixed in an inclined direction so as to be positioned on a proximal side of the bone.

  According to such a configuration, even a locking pin can be fixed more reliably.

  (6) In any one of the above (1) to (5), all the fixing members that fix the plate to the femur except for the lag screw are the locking pins. The bone anchor described.

  According to the bone fixing device of the present invention, the fixing force is increased as compared with the case where a normal screw is used as a CHS fixing member, and the locking portion is not squeezed into the plate, and it is possible to perform secure fixing. It is possible to provide an excellent effect that it is possible to provide a bone anchor that can shorten the fixing time.

It is a side view which shows the usage example of the bone fixing tool 1 of this embodiment. It is a figure which shows the bone fixing tool 1 of this embodiment, (A) The side view which shows the whole structure, (B) The side view which shows the plate 3, (C) The side view which extracts and shows the lag screw 2 and the fixing member 4 It is. It is a figure which shows the bone fixing tool 1 of this embodiment, (A) The external appearance front view which extracts and shows a part of structure, (B) It is the sectional view on the AA line of (A). It is a figure which shows the method of attaching the bone fixing tool 1 of this embodiment to the femur 100. FIG. It is sectional drawing in the transversal direction of the femur 100 of the state (modified example) to which the bone fixing tool 1 was attached. It is a figure which shows the result of the load test of the bone fixing tool 1 of this embodiment, and a comparative example. It is a figure which shows the result of the load test of the bone fixing tool 1 of this embodiment, and a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing the bone anchor 1 of the present embodiment attached to the femur. FIG. 2 is a view showing the bone anchor 1 of the present embodiment. FIG. 2A is a side view showing the overall configuration, and FIG. 2B is a front view of the bone anchor 1. (C) is a side view showing the plate 3, FIG. (D) is a side view showing the lag screw 2 and the fixing member 4 in a fixed state, and FIG. FIG.

  With reference to FIGS. 1 and 2, the bone anchor 1 of the present embodiment is used to jointly fix the femoral head 102 of the femur 100 fractured at the proximal portion of the femoral neck 101 to the femoral shaft 104. A lag screw 2 that is screwed so as to pass (straddle) the fracture line of the fracture portion F of the femur 100 from the metaphyseal end portion of the femur 100 toward the bone neck portion 101; It has the plate 3 arrange | positioned along the longitudinal direction of the femur 100, and the fixing member 4 which fixes the plate 3 to the femur 100. FIG. All of these members are made of biocompatible materials such as a titanium alloy, a cobalt chromium alloy, and stainless steel as an example.

  The plate 3 is provided on the body 3 </ b> A disposed along the longitudinal direction of the femur 100 (side surface of the femoral trunk 104) and the proximal side of the plate 3, and the lag screw 2 is inserted and held therein. It has a lag screw holding part 3B and a collar part 3C provided at the proximal end of the femur 100 of the main body part 3A.

  The main body 3 </ b> A is an elongated plate-like member having a surface 35 facing the femur 100 and a surface 36 opposite to the surface 35, and the longitudinal direction thereof is arranged along the longitudinal direction of the diaphysis 104. .

  The lag screw holding portion 3B is a cylindrical portion (barrel 3B) that protrudes from the surface 35 of the main body portion 3A so as to be inclined from a direction substantially perpendicular to the surface 35 of the plate (main body portion 3A). The lag screw 2 inserted from the end (opening) on the connection side with the portion 3A is held. In this example, the lag screw holding part 3B is formed integrally with the main body part 3A.

  Further, the main body 3A has first fixing holes 31 and 32 located on the distal side of the femur 100, and a second fixing hole 33 provided in the immediate vicinity of the barrel 3B.

  The lag screw 2 is held by the barrel 3B so that the screw portion 2A provided at the tip protrudes from the barrel 3B and is inclined from a direction substantially perpendicular to the surface 35 of the plate (main body portion 3A). Specifically, the lag screw 2 is held inclined such that the screw portion 2A is closer to the proximal side of the femur 100 than the fitting portion 2 'with the barrel 3B.

  The fixing member 4 is inserted into the first fixing holes 31 and 32 and the second fixing hole 33 and fastened. A part of the fixing member 4 is a first fixing pin that is inserted into the first fixing holes 31 and 32 and fixes the plate 3 to the femur 100, and the other part is a second fixing pin. This is a second fixing pin that is inserted into the use hole 33 and mainly prevents the rotation of the femoral head 102 or enhances the fixing force of the proximal bone fragment.

  As shown in FIGS. 2D and 2E, the fixing member 4 of the present embodiment is the locking pins 5, 6, and 7 provided with screw portions 5S, 6S, and 7S on the heads, respectively. The first fixing pins of the fixing member 4 are the locking pins 5 and 6, and are inserted and fixed in the first fixing holes 31 and 32 so as to be in a different direction from the lag screw 2. Further, the second fixing pin is the locking pin 7 and is inserted and fixed in the second fixing hole 33 in the immediate vicinity of the lag screw 2 so as to be in the same direction. In this example, the case of fixing with two locking pins 7 (7, 7 ') is described. However, the second fixing pin (locking pin 7) on the most proximal side (collar portion C) of the plate 3 is described. ′) Is a fixing pin that contributes to distal fixation if it is a stable trochanteric fracture, but a pin that contributes little to distal fixation in an unstable trochanteric fracture. That is, in the case of an unstable trochanter fracture, the most proximal second fixing pin (locking pin 7 ') may not be provided.

  Specifically, as shown in FIG. 2B, as an example in the present embodiment, a plurality (five in this example) of fixing holes 31 (in this example) along the longitudinal direction of the plate 3 (main body portion 3A). 31A, 31B), 32, 33 are provided.

  Of these, the three fixing holes on the distal side are the first fixing holes 31 (31A, 31B) and 32, and the two fixing holes on the proximal side are the second fixing holes 33.

  Of the three first fixing holes 31, 32, the first fixing hole 31 (distal side first fixing hole 31 (31A, 31B)) located on the distal side of the femur 100 is inserted. The locking pin 5 (5A, 5B) is fixed to the main body 3A of the plate 3 so as to be inclined in a direction different from that of the lag screw 2.

  Of the three first fixing holes 31, 32, the locking pin 6 inserted through the first fixing hole 32 (proximal first fixing hole 32) located on the proximal side of the femur 100 is The locking pin 5 is fixed in a different direction. Here, as an example, the locking pin 6 is shown as being fixed in a substantially vertical direction with respect to the surface 35 of the plate 3 (main body portion 3A). The configuration may be such that it is inclined and fixed from a substantially vertical direction with respect to the surface 35 of the plate 3 (main body portion 3A) so as to be located on the proximal side of 6S.

  The locking pins 7 (7, 7 ') inserted through the second fixing holes 33 provided in the immediate vicinity of the barrel 3B (in this example, front and rear in the longitudinal direction of the plate 3) are respectively in the same direction as the lag screw 2. The second fixing hole 33 is inserted and fixed so as to be inclined (see FIGS. 2A and 2D).

  3A and 3B are views showing the bone anchor 1 of the present embodiment, in which FIG. 3A is a front view of the bone anchor 1, and FIG. 3B is an AA line in FIG. It is sectional drawing and the figure (C) is sectional drawing which extracts and shows the plate 3 and the lag screw 2 of the figure (B). 3A and 3B, only the locking pins 5A and 6 are shown as the plate 3, the lag screw 2, and the fixing member 4. FIG.

  The main body 3A of the plate 3 is provided with a collar portion 3C at a position that becomes a proximal end portion (left direction in the drawing) of the femur 100, and from the proximal end portion of the collar portion 3C to the distal direction of the femur 100. The main body 3A extends substantially horizontally toward the surface. The collar portion 3C is provided with one second fixing hole 33. Thereafter, the barrel 3B and the locking pin 7 to which the lag screw 2 is fixed are fixed toward the distal end portion (right direction in the drawing). The second fixing hole 33, the proximal first fixing hole 32 to which the locking pin 6 is fixed, the distal first fixing hole 31B to which the locking pin 5B is fixed, and the far side to which the locking pin 5A is fixed. The position side first fixing holes 31A are provided in this order.

  The barrel 3B is inclined so that the tip is located on the proximal side of the femur 100, protrudes from the surface 35 of the main body portion 3A, and holds the fitting portion 2 'of the lag screw 2.

  The lag screw 2 has a cylindrical shaft portion 2B and a screw portion 2A provided at the tip of the shaft portion 2B, and a through hole 2C is formed along the axis of the shaft portion 2B. On the thread of the threaded portion 2A, teeth are formed to advance while threading the femur 100 when screwed into the femur 100. That is, the lag screw 2 of this embodiment is a self-tapping screw. The base end portion of the shaft portion 2B is a fitting portion 2 'that fits with the barrel 3B. That is, the locking portion 2D is screwed into the rear end (the end opposite to the screw portion 2A) of the shaft portion 2B, and the lag screw 2 is attached to the tip of the barrel 3B on the outer periphery of the locking portion 2D. A stopper 2E is attached to prevent the stopper 2E from falling off. As shown by a chain line in FIG. 5B, the axis of the barrel 3B and the axis center of the shaft portion 2B of the lag screw 2 coincide.

  In addition, the lag screw 2 of the present embodiment is configured to be slidable inside the barrel 3 </ b> B and is a sliding screw that is not fixed to the plate 3.

  In addition, each dimension of the plate 3 (barrel 3B), the lag screw 2, and the fixing member 4 is suitably selected according to the dimension etc. of the femur 100.

  The pin of the locking pin 5 (5A, 5B) is positioned with respect to the surface 35 of the body portion 3A of the plate 3 so that the tip thereof is located on the distal side of the femur 100 from the screw portion 5S of the head. Inclined from a substantially vertical direction, it is fixed to the distal first fixing hole 31 (31A, 31B). In other words, the distal-side first fixing hole 31 has a main body portion of the plate 3 such that the tip of the locking pin 5 (5A, 5B) is located on the distal side of the femur 100 from the screw portion 5S of the head. The threaded portion 5S is received in a state inclined from a direction substantially perpendicular to the surface 35 of 3A, and can be fastened. That is, when the screw portion 5S of the locking pin 5 is substantially cylindrical (substantially circular in the axial top view), the opening on the surface 36 side of the body portion 3A of the distal first fixing hole 31 is It is a substantially oval shape larger than that (see FIG. 3A).

  As shown in FIG. 3B, the angle α of the locking pin 5 (5A, 5B) inclined from the direction substantially perpendicular to the surface 35 of the main body 3A is, for example, 10 degrees to 70 degrees. Yes, preferably 30 to 60 degrees, more preferably 40 to 50 degrees. In the present embodiment, as an example, the angle α is 45 degrees).

  Further, in this example, the pin of the locking pin 6 is in a direction substantially perpendicular to the surface 35 of the main body 3 </ b> A of the plate 3 so that the locking pin 6 is in a different direction from the locking pin 5 and the lag screw 2. The proximal first fixing hole 32 is fixed. In other words, the proximal-side first fixing hole 32 is configured to be able to receive and fasten the screw portion 6S in a state where the axis of the locking pin 6 is substantially perpendicular to the surface 35 of the main body portion 3A of the plate 3. Yes. That is, when the screw portion 6S of the locking pin 6 is substantially cylindrical (substantially circular in the axial top view), the opening on the surface 36 side of the main body portion 3A of the proximal first fixing hole 32 is It has a substantially equivalent (slightly larger) substantially circular shape. The length of the locking pin 6 is shorter than the length of the locking pin 5.

  The pin of the locking pin 7 is positioned from a direction substantially perpendicular to the surface 35 of the main body portion 3A of the plate 3 so that the tip thereof is located on the proximal side of the femur 100 from the screw portion 7S of the head. Inclined and fixed to the second fixing hole 33. In other words, the second fixing hole 33 is approximately with respect to the surface 35 of the main body 3 </ b> A of the plate 3 so that the tip of the locking pin 7 is positioned on the proximal side of the femur 100 from the screw 7 </ b> S of the head. The screw part 7S is received in a state inclined from the vertical direction, and can be fastened.

  The direction of inclination of the locking pin 7 is the same as the direction of inclination of the barrel 3B so as to allow sliding of the lag screw 2, and the angle of inclination is also the same.

  As described above, in this embodiment, the locking pins 5, 6, and 7 are employed for all of the fixing members 4 for fixing the plate 3 to the femur 100 except for the lag screw 2.

  The locking pins 5 and 6 do not have a fixing force in the axial direction. However, the fixing force in the axial direction can be compensated by inserting and fixing the plurality of locking pins 5 and 6 with respect to the surface 35 of the plate 3 (main body portion 3A) at different angles. Therefore, even if the locking screw does not have a fixing force in the axial direction, the pin can be prevented from being pulled out and loosened, and sufficient fixing can be achieved.

  That is, since the plate 3 can be fixed to the femur 100 without using any locking screw, the screw between the tip (thread portion) and the head (locking portion) generated when the locking screw is used is not synchronized. Unintended stress due to can be avoided.

  In the case of the locking screw, when the screw at the tip (thread portion) advances, the screw at the head (locking portion) does not align with the rotation, and stress is easily applied to the screw at the locking portion. If these are mechanically matched, the plate may float from the femur and may not be fixed. In bone fixation devices, titanium alloys having biocompatibility and the like are often used, but there is a problem that the titanium alloys are easily squeezed with each other and promoted by a load.

  According to this embodiment, there is no galling into the fixing hole of the locking part at the time of insertion, avoiding problems such as insufficient fixing and difficulty in removing the locking screw at the time of removal, Can be fixed.

  In particular, since the length of the locking pin 5 in the distal direction can be increased, the fixing force can be increased. And the locking pin 5 can be fixed only by fastening the screw part 5S of the head. That is, even when the pin shaft is long, the fixing time (operation time) can be shortened as compared with the case where the locking screw (of the same length) is screwed into the bone. And by making all the fixing members 4 rocking pins 5, 6, 7, the fixing time (operation time) can be greatly shortened.

  In the case of a fracture of the proximal femur, since the bone supports the weight, a relatively large load is applied to the bone fixing device 1 employed for the osteosynthesis of the fracture. On the other hand, the load in the walking or standing state is repeatedly related to the load from a certain direction.

  The locking pins 5 and 6 that support this load are subjected to a force in the direction of pulling out along the axial direction of the pin due to the bending of the plate 3 due to the load. At this time, in the case of a locking screw that engages and is fixed to the bone, it can be prevented from coming off in the short term, but if a repeated load is applied in the long term, stress concentration occurs at the meshing part and normal There is a problem that destroys the bone.

  In the bone fastener 1 of the present embodiment, all the fixing members 4 (locking pins 5, 6, 7) are not engaged with the bone and are pulled out along the axial direction of the pin even when a load is applied. The direction force can be released. That is, unlike the locking screw, even if a load from a substantially constant direction is repeatedly applied, the stress concentration is smaller than that of the locking screw.

  The lag screw 2 of the present embodiment has a threaded portion 2A at the tip and meshes with the bone at the tip, but is slidable within the barrel 3B, so that the fixing force in the axial direction is against the locking screw. Therefore, the occurrence of stress concentration in the screw portion 2A is small as in the case of the locking pins 5, 6, and 7.

  Further, since the screw holes are not formed in the holes for inserting the locking pins formed in the bone, the holes formed in the bone can be shared even when the bone fixing device 1 is replaced. There is no need to re-drill a new hole in the area or shift the position of the bone anchor.

  For these reasons, the amount of incision is minimized, and the operation time can be shortened. Therefore, the burden on the patient and the operator can be reduced.

  With reference to FIG. 4, an example of a method for attaching the bone anchor 1 to the femur 100 will be described below.

  First, the patient's skin 106 and muscles are incised, and in order to define the position where the lag screw 2 is attached from the incision portion toward the neck portion 101 of the femur 100, In this example, two guide pins 108A and 108B are inserted so as to pass through F and the bone head 102. The proximal guide pin 108A defines the insertion position of the lag screw 2, and the distal guide pin 108B defines the insertion position of the locking pin 7 (distal side). The insertion of the guide pin 108 is performed using a dedicated instrument so as to be performed at a predetermined angle and a predetermined depth with respect to the longitudinal direction of the diaphysis 104 (FIG. 4A).

  Next, the insertion depth of the proximal guide pin 108A is measured to determine the screwing depth of the lag screw 2, and reaming is performed along the proximal guide pin 108A. Reaming includes, for example, a dedicated tool such as a hollow drill through which the proximal guide pin 108A can be inserted, and a predetermined guide that regulates the progress of the drill so that the drill stops at the measured screwing depth of the lag screw 2. (Not shown).

  Next, the plate 3 is inserted from the incised portion of the skin 106, and the barrel 3B is placed in the hole formed by reaming.

  Next, the lag screw 2 is inserted into the barrel 3B so that the proximal guide pin 108A is inserted into the through hole 2C of the lag screw 2, and screwed into the femur 100 along the proximal guide pin 108A. Since the screw cutting teeth are formed on the screw portion 2A of the lag screw 2, the lag screw 2 advances through the femur 100 while cutting the screw. Screwing the lag screw 2 into the femur 100 is performed by attaching a dedicated instrument to the rear end portion (the end portion opposite to the screw portion 2A) of the lag screw 2 (FIG. 4B).

  Thereafter, the guide pins 108A and 108B are removed, and drilling for the locking pin 7 is performed. For the drilling hole for the locking pin 7, for example, a drill guide means (not shown) capable of maintaining parallelism with the lag screw 2 is attached to the plate 3, and the locking pin 7 (in this example, the distal side locking) Hole for pin 7) is formed. Then, the locking pin 7 is inserted into the second fixing hole 33, and the screw portion 7S is fastened and fixed. Here, the axis of the pin of the locking pin 7 is set so that the tip thereof is located on the proximal side of the femur 100 from the screw portion 7S of the head (so as to be parallel to the lag screw 2). The second fixing hole 33 is fixed by being inclined from a direction substantially perpendicular to the surface 35 of the main body 3A. When the proximal locking pin 7 (7 ′) is used, a hole is drilled in the same manner and fixed to the second fixing hole 33 (FIG. 4C).

  Next, in order to make a hole for the locking pin 6, a guide means for drill (not shown) is attached to the proximal first fixing hole 32 of the plate 3 to form a hole for the locking pin 6. . Then, the locking pin 6 is inserted into the proximal first fixing hole 32, and the screw portion 6S is fastened and fixed. As an example, the locking pin 6 is positioned in a direction different from that of the locking pin 5. Fix to the use hole 32.

  Further, a drill guide means (not shown) is attached to the distal first fixing hole 31 of the plate 3 to form a hole for the locking pin 5. Then, the locking pin 5 (5A, 5B) is inserted into the distal first fixing hole 31 (31A, 13B), and the screw portion 5S is fastened and fixed.

  The pin of the locking pin 5 (5A, 5B) is positioned with respect to the surface 35 of the body portion 3A of the plate 3 so that the tip thereof is located on the distal side of the femur 100 from the screw portion 5S of the head. It is made to incline from a substantially vertical direction and is fixed to the distal first fixing hole 31 (31A, 31B). As an example, the inclination angle α of the locking pin 5 (5A, 5B) is 45 degrees (FIG. 4D).

  FIG. 5 is a schematic cross-sectional view of the femur 100 in the short direction (cross-sectional schematic view seen from the axial direction). All of the fixing members 4 of the present embodiment are inserted in the diameter direction when the femur 100 has a substantially cylindrical shape. Thereby, it can fix with necessary and sufficient maximum length.

  Not limited to this, the fixing member 4 may be inserted in a direction shifted by a predetermined angle from the diameter direction of the femur 100 as indicated by a broken line in FIG. In this case, although the length of the fixing member 4 may be inevitably shortened depending on the part, as shown in FIG. It may be ensured.

  The bone fixing device of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

  For example, the number of the distal first fixing holes 31 (and the locking pins 5 inserted therethrough) may be one or plural. Moreover, when providing with two or more, the direction of a pin may differ in each.

  Further, the number of the proximal first fixing holes 32 (and the locking pins 6 inserted therethrough) may be one or plural. Moreover, when providing with two or more, the direction of a pin may each differ.

  Further, only one locking pin 7 as the second fixing pin and its fixing hole (second fixing hole 33) may be provided on the distal side of the lag screw 2. In this case, the plate 3 A configuration in which the collar portion 3C is not provided is possible.

  In the above example, the case where the barrel 3B is provided integrally with the main body 3A has been described as an example, but the barrel 3B may be separate from the main body 3A. As an example of the configuration in that case, for example, a substantially rectangular connecting portion formed in a shape along the main body portion 3A of the plate 3 is provided at the base end portion of the barrel 3B, and the main body portion 3A includes the connecting portion. (For example, a long hole along the longitudinal direction of the main body 3A) is provided. The hole is formed at a position communicating with the internal space of the barrel 3B when the main body 3A and the barrel 3B are connected. And a connection part and a hole part are piled up and both are fixed with a screw etc.

  The first fixing pins (locking pins 5, 6) are not limited to the above example as long as they are configured to be fixed in a direction different from the lag screw 2. Further, when the first fixing pins (locking pins 5 and 6) are fixed to be in different directions, the fixing force is increased, and either of the first fixing pins (locking pins 5 and 6) is used. In this case, it is preferable that the tip is inclined and fixed so that the tip is located on the distal side of the screw portion of the head. If so, the first fixing pins (locking pins 5 and 6) may be fixed in the same direction.

  For example, in the above example, the distal first fixing hole 31 and the locking pin 5 inserted through the first fixing hole 31 are tilted and fixed so that the tip thereof is located proximal to the screw portion 5S of the head. A direction in which the axis of the pin is substantially perpendicular to the surface 35 of the main body portion 3A of the plate 3 as in the case of the first proximal fixing hole 32 and the locking pin 6 inserted through the proximal first fixing hole 32. You may make it become.

  <Example>

  About the bone fixing tool 1 (1A, 1B) of this embodiment, the load test was done using the bone model. FIG. 6 and FIG. 7 show the method and results.

  First, in FIG. 1, the bone anchor 1 </ b> A of the present embodiment has one distal first fixing hole 31 (one locking pin 5) and one proximal first fixing hole 32. This is a configuration (one locking pin 6), and the bone fastener 1B has the configuration shown in FIG.

  On the other hand, the bone fastener 50 of Comparative Example 1 is a conventional general CHS as schematically shown in FIG. That is, all the fixing members other than the lag screw 51 are ordinary screws (non-locking screws) 52 having no threaded portion at the head, and the three screws 52 are set substantially perpendicular to the surface of the plate 53. It is a fixed configuration. Moreover, the bone fixing tool 55 of the comparative example 2 has a configuration in which the number of the three screws 52 shown in FIG.

  In addition, in the comparative examples 1 and 2, it is the structure which does not provide the fixing member corresponding to the locking pin 7 (2nd fixing pin) of this embodiment and fixed in the same direction as the lag screw 51. However, in the load test of this example, the fracture of the bone fixing devices 50 and 55 or the bone occurred only in the distal direction with respect to the lag screw 51. Therefore, in this experiment, the fixing member in the same direction as the lag screw 51 was used. The presence or absence of the (second fixing pin) is considered to have no effect.

  With reference to FIG. 6 (B), the content and result of the load test will be described. The load test includes a static load test in which the load is gradually increased by one pressurization and a dynamic load test in which a constant load (for example, 400 N) is repeatedly applied. This is a result of measuring the load and the number of times when the detachment from the model occurs or the bone model is destroyed or broken.

  Regarding bone model B (see FIG. 7), the bones of the fractured portion remain, and the bones of the fractured portion can contact each other (can also be supported by the bone surface of the fractured portion); A comparison was made of “unstable” bone models in which bones at the fractured part were missing and bones could not contact each other (the bone surface of the fractured part could not be supported, but only supported by a bone anchor).

  As shown in FIG. 5B, in the static load test of the “stable” bone model, the bone anchor 1A of the present embodiment and the bone anchor 50 of the comparative example 1 are numerically comparable. However, it can be said that the bone anchor 1A of the present embodiment is superior to the bone anchor 50 of Comparative Example 1 in that the number of fixing members (locking pins 5 and 6) is smaller. Further, in the static load test of the “unstable” bone model, the bone fastener 1B of the present embodiment is the bone of Comparative Example 2 even though the number of fixing members (locking pins 5 and 6) is small. The result exceeded the breaking load of the fixture 55 by about twice.

  In the dynamic load test, neither the bone fastener 1A nor 1B of the present embodiment is damaged or damaged by the bone model even after 1 million repetitive loads. It became clear that it was very superior to the use of period.

  FIG. 7 is a photograph showing the appearance of the bone anchor 1B (FIG. (A)) of the present embodiment and the bone anchor 55 (Compare B) of Comparative Example 2 after the end of the dynamic load test. As shown in FIG. 6A, in the bone anchor 1B of the present embodiment (same for 1A), the bone anchor 1B is damaged even after being subjected to a repeated load of 1 million times. Neither damage nor destruction occurred. On the other hand, in Comparative Example 2 (as in Comparative Example 1) as shown in FIG. 5B, the number of times shown in FIG. Or destruction of bone model B) occurred. Thereby, in the dynamic load test, the remarkable superiority of the bone anchor 1 of this embodiment became clear.

  The bone anchor of the present invention can be used in fields such as osteosynthesis surgery.

1, 1A, 1B Bone Fixing Tool 2 Lag Screw 2B Shaft 2C Through Hole 2D Locking Part 2E Stopper 3 Plate 3A Body 3B Lag Screw Holding Part 3C Collar 3D Pin Fixing Hole 4 Fixing Member 5, 5A, 5B, 6 , 7 Locking pins 31, 31A, 31B Distal first fixing hole 32 Proximal first fixing hole 33 Second fixing hole 35 Surface 36 Surface 50, 55 Bone fixing tool 51 Lag screw 52 Locking screw 53 Plate DESCRIPTION OF SYMBOLS 100 Femur 102 Femoral head 104 Femoral trunk 106 Skin 108 Guide pin

Claims (6)

A bone anchor used for the femur,
A lag screw screwed to pass through the fracture line;
A plate disposed along the longitudinal direction of the femur, provided with a lag screw holding portion on the proximal side of the femur, and provided with a fixing hole on the distal side of the femur;
A threaded portion provided on the head, and a locking pin for fixing the plate to the femur;
The lag screw is held by the lag screw holding part,
The locking pin is inserted and fixed in the fixing hole so as to be in a different direction from the lag screw.
A bone anchor characterized by that. A plurality of the fixing holes are provided along the longitudinal direction of the plate,
The locking pin inserted into at least a part of the plurality of fixing holes is fixed so as to be inclined from a direction substantially perpendicular to the surface of the plate.
The bone anchor according to claim 1. The locking pin is fixed so that the tip is located on the distal side of the femur from the screw portion of the head.
The bone anchor according to claim 2. The angle of inclination of the locking pin is 10 degrees to 70 degrees with respect to the longitudinal direction of the femur.
The bone anchor according to claim 2 or claim 3, wherein The locking pin that is inserted into a part of the plurality of fixing holes has a direction substantially perpendicular to the surface of the plate or a tip that is closer to the proximal side of the femur than the screw portion of the head. Fixed in a tilting direction,
The bone fixation device according to any one of claims 2 to 4, wherein the bone fixation device is provided. Except for the lag screw, all the fixing members that fix the plate to the femur are the locking pins.
The bone fixing device according to any one of claims 1 to 5, wherein the bone fixing device is provided.