Bone plate system
The bone plate system with a third screw securing both sides of the osteotomy improves hinge stability, reducing fracture risk and promoting stable bone union in high tibial osteotomy surgeries.
Patent Information
- Application Number
- JP2024112252
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-07-12
- Publication Date
- 2026-01-23
AI Technical Summary
The hinge side in high tibial osteotomy surgeries is unstable, leading to a higher risk of fracture and subsequent instability at the osteotomy site, which can result in delayed union or false joint formation.
A bone plate system with a bone plate and multiple bone screws, including a third screw that penetrates the osteotomy portion to secure both proximal and distal bone portions, ensuring stability and reducing load on the hinge.
The bone plate system enhances stability at the hinge, reducing the risk of fracture and promoting proper bone union by dispersing stress and providing secure fixation.
Smart Images
Figure 2026011545000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a bone plate system. [Background technology]
[0002] High tibial osteotomy (HTO) has traditionally been performed as a treatment to correct the medial bias of loads due to bow-leg deformity caused by osteoarthritis of the knee, etc. In medial-opening HTO, the osteotomy is performed without a complete osteotomy, leaving a hinged portion of the bone, and the osteotomy surface is then opened around this hinged portion as the central axis. A bone plate is then placed on the lateral side of the tibia on the side of the opened osteotomy opening and fixed using bone screws.
[0003] In HTO, bone screws are inserted proximally and distally from the osteotomy opening side and fixed with bone plates, stabilizing the osteotomy area. On the other hand, the hinge side, which is the opposite side of the osteotomy opening, is in a less stable state of fixation than the osteotomy opening, and mechanical stimuli are applied during bone formation, promoting bone union. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Re-tabled publication 2017 / 195307 Summary of the Invention [Problem to be solved by the invention]
[0005] However, because the hinge is unstable, it may break (fracture) after surgery. If the hinge fractures, the osteotomy site is divided and discontinuous, significantly reducing stability, which can lead to delayed union or false joint. Therefore, it is desirable to reduce the load acting on the hinge, particularly for patients at high risk of postoperative hinge fracture. [Means for solving the problem]
[0006] One aspect of the present invention is a bone plate system comprising: a bone plate having a plurality of screw holes; and a plurality of bone screws fastened to each of the screw holes of the bone plate and to a bone; the bone plate comprising: a first portion positioned along an outer surface of a proximal bone portion proximal to an osteotomy portion; and a second portion connected to the first portion and positioned along an outer surface of a distal bone portion distal to the osteotomy portion; the plurality of bone screws comprising: a first screw for fixing the first portion to the proximal bone portion; a second screw for fixing the second portion to the distal bone portion; and a third screw for passing through the osteotomy portion to fix the first portion or the second portion to both the proximal bone portion and the distal bone portion; the third screw comprising: a body portion having a first external thread that is fastened to both the proximal bone portion and the distal bone portion; and a head portion having a second external thread that is fastened to the screw holes; and the first external thread and the second external thread have the same lead.
[0007] Another aspect of the present invention is a bone plate system comprising: a bone plate to be placed on a side of a bone; and a plurality of bone screws to secure the bone plate to the bone, wherein the bone plate comprises a first portion to be placed along the outer surface of a proximal bone portion proximal to an osteotomy portion; and a second portion connected to the first portion and to be placed along the outer surface of a distal bone portion distal to the osteotomy portion, wherein the plurality of bone screws comprise a first screw to secure the first portion to the proximal bone portion, a second screw to secure the second portion to the distal bone portion, and a third screw that passes through the osteotomy and secures the first portion or the second portion to both the proximal and distal bone portions, wherein the third screw secures the first portion to the bone at a position proximal to or closer to the distal end of the first screw, which is the most distal, or the second portion to the bone at a position proximal to or closer to the distal end of the second screw, which is the most proximal. [Brief explanation of the drawings]
[0008] [Figure 1] FIG. 1 is an anterior view of one embodiment of a bone plate system secured to a tibia. [Figure 2] 2 is a front view showing a bone plate included in the bone plate system of FIG. 1. FIG. [Figure 3] FIG. 2 is a rear view of the bone plate system of FIG. 1. [Figure 4] 3 is a partial longitudinal cross-sectional view showing the relationship between screw holes and bone screws provided in the bone plate of FIG. 2. FIG. [Figure 5] FIG. 2 is a view of the bone plate system of FIG. 1 from the medial side of the tibia. [Figure 6] 2 is a partial cross-sectional view showing a modified example of a bone plate included in the bone plate system of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION
[0009] A bone plate system 1 according to one embodiment of the present invention will be described below with reference to the drawings. As shown in Figure 1, the bone plate system 1 of this embodiment is a system for expanding and fixing an osteotomy section B formed at the epiphysis of a tibia A in a high tibial osteotomy (HTO), and comprises a bone plate 2 and a plurality of bone screws 3a, 3b, 3c, and 3d.
[0010] The bone plate 2 is a long, thin, strip-like member that is fixed to the high medial surface of the tibia A after osteotomy and expansion, and has a slightly curved shape so as to follow the typical curved surface shape of the lateral surface of the tibia at a position transitioning from the diaphysis toward the end of the tibia A. As shown in Figure 2, the bone plate 2 is strip-like and has a longitudinal direction X that is aligned along the length of the tibia A and a lateral direction Y that is aligned along the anterior-posterior direction of the tibia A, and has proximal, distal, anterior, and posterior sides that correspond to the proximal, distal, anterior, and posterior sides of the tibia A, respectively.
[0011] The bone plate 2 comprises a first portion 2a on the proximal side and a second portion 2b on the distal side of the first portion 2a, which is narrower than the first portion 2a and is integrally formed with the first portion 2a. The first portion 2a is provided with three screw holes 4a aligned in a row at intervals in the lateral direction Y, and two screw holes 4b and 4c positioned distal to the screw holes 4a at an interval in the lateral direction Y, for a total of five screw holes 4a, 4b, and 4c. The second portion 2b is also provided with, for example, four screw holes 4d spaced apart in the longitudinal direction X. These screw holes 4a, 4b, 4c, and 4d are tapered screw holes that taper in the plate thickness direction toward the surface facing the lateral surface of the tibia A when the bone plate 2 is placed on the lateral surface of the tibia A.
[0012] The three screw holes 4a arranged in a row at intervals in the lateral direction Y of the first portion 2a and the one rear screw hole 4b distal to the screw holes 4a have axes that extend substantially along the thickness direction of the bone plate 2. On the other hand, the one front screw hole 4c distal to the three screw holes 4a arranged in a row in the lateral direction Y of the first portion 2a has an axis that extends at an incline toward the distal side and the front side toward the tibia A with respect to the thickness direction of the bone plate 2.
[0013] In addition, the front screw hole 4c, which is distal to the three screw holes 4a lined up in the short direction Y of the first part 2a, is positioned proximal to the rear screw hole 4b, which is distal to the three screw holes 4a lined up in the short direction Y of the first part 2a.
[0014] The bone plate 2 is formed in a shape twisted in one direction from the first portion 2a to the second portion 2b around the longitudinal axis of the second portion 2b. As a result, when the first portion 2a of the bone plate 2 is placed on the high medial surface of the tibia A, the second portion 2b of the bone plate 2 is placed on the lateral surface of the tibia A in a position more anterior than the first portion 2a. Each portion of the bone plate 2 has a cross-sectional shape of an arc-shaped plate curved at a predetermined curvature that conforms to the outer surface shape of the tibia A.
[0015] As shown in FIG. 3 , each of the bone screws 3a, 3b, 3c, and 3d is a so-called locking screw, comprising a body 5 having a first external thread 5a to be fastened to the tibia A, and a head 6 provided at one end of the body 5 and having a second external thread 6a to be fastened to the screw holes 4a, 4b, 4c, and 4d of the bone plate 2. The first external thread 5a is a parallel thread formed over substantially the entire length of the body 5. The second external thread 6a has a larger outer diameter than the first external thread 5a and is a tapered external thread that gradually tapers toward the body 5. The first external thread 5a and the second external thread 6a have the same lead. The first external thread 5a and the second external thread 6a may have different thread numbers as long as they have the same lead.
[0016] As shown in Fig. 3, second male threads 6a of bone screws 3a, 3b, 3c, and 3d are fastened into the screw holes 4a, 4b, 4c, and 4d provided in the first portion 2a and the second portion 2b of the bone plate 2, respectively. As shown in Figs. 1 and 3, bone screws 3a and 3b (hereinafter also referred to as first screws 3a and 3b) are inserted into four of the five screw holes 4a, 4b, and 4c provided in the first portion 2a in the thickness direction of the bone plate 2. Bone screws 3d (hereinafter also referred to as second screws 3d) are also inserted into four of the screw holes 4d provided in the second portion 2b in the thickness direction of the bone plate 2.
[0017] That is, the axes D of these bone screws 3a, 3b, 3c, and 3d are arranged substantially along the thickness direction of the bone plate 2, as shown in FIG. Since the bone plate 2 has an arc-shaped cross section, the first screws 3a, 3b fastened to the screw holes 4a, 4b of the first part are inserted in a direction that brings the tips closer to each other, as shown in Figures 1 and 4.
[0018] On the other hand, in this embodiment, a bone screw (hereinafter also referred to as a third screw) 3c is inserted into the screw hole 4c provided on the distal and front side of the first portion 2a along a direction inclined distally and forwardly with respect to the thickness direction of the bone plate 2, as shown in FIGS. 1 and 4. More specifically, the axis of the screw hole 4c for fastening the third screw 3c is inclined at an angle of 30° to 60°, preferably 40° to 50°, with respect to the thickness direction of the bone plate 2 when viewed along the short direction Y, i.e., the front-to-rear direction. In this embodiment, for example, the screw hole 4c is inclined at an angle of 43° toward the distal side. Furthermore, the axis of the screw hole 4c is inclined at an angle of 20° to 50°, preferably 30° to 40°, with respect to the thickness direction of the bone plate 2 when viewed along the longitudinal direction X, i.e., the near-to-far direction. In this embodiment, for example, the screw hole 4c is inclined at an angle of 35° toward the front.
[0019] As a result, the third screw 3c is inclined in the direction in which it passes through the screw hole 4c provided in the first portion 2a, the proximal bone portion A1 and the osteotomy portion B, and is fastened to the distal bone portion A2, as shown in Figure 1.
[0020] In this embodiment, the screw hole 4c for fastening the third screw 3c is disposed proximally relative to the screw hole 4b, which is disposed distally and rearward, of the screw holes 4a and 4b for fastening the first screws 3a and 3b, as shown in Fig. 2. As a result, the third screw 3c extends obliquely distally from a position more proximal to the first portion 2a of the bone plate 2, i.e., a position distant from the osteotomy portion B, and penetrates the enlarged osteotomy portion B.
[0021] Furthermore, in the bone plate system 1 according to this embodiment, the tip of the third screw 3c fastened to the distal bone portion A2 is positioned distal to the hinge C at a distance d of 15 mm or less, preferably 10 mm or less, from the hinge C. The position of the hinge C varies depending on the procedure, but it is preferable to move the entire bone plate system 1 in the distal direction so that the tip of the third screw 3c is positioned at the distance d from the hinge C. Assuming that the hinge C is in a standard position, the position and angle of the screw hole 4c of the bone plate 2 are designed so that the tip of the third screw 3c is positioned at the distance d from the hinge C when the bone plate system 1 is positioned in the designed position.
[0022] As shown in Figure 1, the third screw 3c is a so-called bicortical screw that is fastened to the cortical bone of the proximal bone portion A1 at a position close to the head 6 of the main body portion 5 and fastened to the cortical bone of the distal bone portion A2 at the tip of the main body portion 5.
[0023] The operation of the bone plate system 1 according to this embodiment configured as described above will be described below. To fix the osteotomized tibia A using the bone plate system 1 according to this embodiment, a wedge-shaped artificial bone E is inserted into the osteotomy B formed at the epiphysis and opened up. In this state, the bone plate 2 is placed on the obliquely anterior medial surface of the tibia A so as to straddle the most opened part of the osteotomy B.
[0024] More specifically, as shown in Figure 1, the first part 2a of the bone plate 2 is placed along the outer surface of the proximal bone part A1, which is proximal to the osteotomy part B, and the second part 2b is placed along the outer surface of the distal bone part A2, which is distal to the osteotomy part B. In this state, bone screws 3a, 3b, 3c, and 3d are inserted into the screw holes 4a, 4b, 4c, and 4d of the bone plate 2, and the first male threads 5a of the bodies 5 of the bone screws 3a, 3b, 3c, and 3d are fastened to the tibia A. That is, the first screws 3a and 3b inserted into the screw holes 4a and 4b provided in the first portion 2a of the bone plate 2 are fastened to the proximal bone portion A1 facing the first portion 2a. Also, the second screws 3d inserted into the four screw holes 4d provided in the second portion 2b of the bone plate 2 are fastened to the distal bone portion A2 facing the second portion 2b.
[0025] Meanwhile, the third screw 3c inserted into the screw hole 4c provided in the first portion 2a of the bone plate 2 is inserted into the proximal bone portion A1 facing the first portion 2a, and then penetrates the osteotomy portion B in the proximal and distal directions and is inserted into the distal bone portion A2. As a result, the first male thread 5a provided in the main body portion 5 of the third screw 3c penetrates the osteotomy portion B and is fastened to both the proximal bone portion A1 and the distal bone portion A2.
[0026] Then, as the first male threads 5a of all the bone screws 3a, 3b, 3c, 3d are being fastened into the tibia A, the second male threads 6a provided on the heads 6 of the bone screws 3a, 3b, 3c, 3d reach and are fastened into the screw holes 4a, 4b, 4c, 4d of the bone plate 2. In this case, the first male threads 5a and the second male threads 6a of the bone screws 3a, 3b, 3c, 3d have the same lead, so the fastening of the first male threads 5a into the tibia A and the fastening of the second male threads 6a into the screw holes 4a, 4b, 4c, 4d proceed simultaneously without interfering with each other.
[0027] That is, the bone plate 2 is fixed in an appropriate position relative to the tibia A without being pressed (compressed and fixed) against the side surface of the tibia A by the bone screws 3a, 3b, 3c, and 3d. Then, when the second male screw 6a, which is a tapered male screw, has been completely fastened into the screw holes 4a, 4b, 4c, and 4d, which are tapered screw holes, the bone screws 3a, 3b, 3c, and 3d can no longer rotate, and the fastening operation is completed.
[0028] According to the bone plate system 1 of this embodiment, the four first screws 3a, 3b that fix the first part 2a of the bone plate 2 to the proximal bone part A1, the four second screws 3d that fix the second part 2b of the bone plate 2 to the distal bone part A2, and the artificial bone E can support a vertical load W applied in the direction of reducing the osteotomy part B.
[0029] Of the first screws 3a, 3b that fix the first portion 2a of the bone plate 2 to the proximal bone portion A1, the most distal bone screw 3b is fastened at a position close to the osteotomy portion B and extending along the osteotomy portion B. The tips of these first screws 3a, 3b extend in directions approaching each other, thereby forming a triangular truss-like structure. That is, the force from the proximal bone portion A1 is received by the triangular surface, and the force acting on the proximal bone portion A1 is dispersed, preventing stress concentration, which has the advantage of improving the fixation of the bone plate 2.
[0030] Furthermore, according to this embodiment, the osteotomy portion B can be more firmly fixed by the third screw 3c that penetrates the osteotomy portion B and fixes both the proximal bone portion A1 and the distal bone portion A2 to the bone plate 2. This reduces the possibility of the hinge C breaking (fracturing) after surgery, improves the stability of the hinge C, prevents delay in bone union, and prevents the occurrence of the inconvenience of a false joint. In particular, for patients who are at high risk of fracture of the hinge C after surgery, this has the advantage of significantly reducing the load acting on the hinge C.
[0031] In this case, the tip of the third screw 3c is fastened to the cortical bone of the distal bone portion A2 at a position close to the hinge C, thereby improving the fixation strength. Furthermore, it may be preferable to shift the entire bone plate system 1 distally so as to move the second screw 3d, which is arranged most proximally, away from the osteotomy B. In this case, according to this embodiment, the third screw 3c is fastened to the proximal bone portion A1 from a position relatively distant from the osteotomy B on the proximal side, thereby preventing the fastening position of the third screw 3c to the proximal bone portion A1 from coming close to the osteotomy B. In other words, there is an advantage in that the third screw 3c can be more reliably engaged with the cortical bone of the proximal bone portion A1.
[0032] Furthermore, by using the bone screws 3a, 3b, 3c, and 3d as locking screws, the bone screws 3a, 3b, 3c, and 3d can be fixed to three locations: the bone plate 2, the proximal bone portion A1, and the distal bone portion A2, thereby achieving a more secure fixation. Furthermore, by using bicortical screws for the bone screws 3a, 3b, 3c, and 3d, the first male thread 5a of the main body 5 can be firmly fixed to the proximal bone portion A1 and the distal bone portion A2, respectively.
[0033] Furthermore, since the third screw 3c is inclined obliquely toward the distal and anterior side in the thickness direction of the bone plate 2, the third screw 3c can be positioned in a direction away from the peroneal nerve, as shown in Figure 5. It is also possible to avoid interference between the artificial bone E inserted behind the osteotomy portion B and the third screw 3c.
[0034] In this embodiment, the screw hole 4c for fastening the third screw 3c is formed directly in the bone plate 2. However, as shown in FIG. 6, the screw hole 4c may be formed in a bridge member 7 that is movably fitted into the hole 2c of the bone plate 2. The bridge member 7 is, for example, a cylindrical member having a spherical outer surface 7a, and the inner surface has a tapered female thread 7b that tapers in one axial direction. The hole 2c of the bone plate 2 has an inner spherical surface with an inner diameter equal to the outer diameter of the bridge member 7. The bridge member 7 fitted into the hole 2c of the bone plate 2 can rotate in any direction around the center point O of the spherical outer surface 7a relative to the bone plate 2. This allows the axis F of the tapered female thread 7b of the bridge member 7 to be inclined in any direction with respect to the thickness direction of the bone plate 2.
[0035] For example, when the third screw 3c is fastened after the first screws 3a, 3b and the second screw 3d have been fastened, the insertion direction of the third screw 3c can be adjusted to any direction by rotating the bridge member 7 relative to the bone plate 2. This allows adjustment so that the third screw 3c does not reach the hinge C, move far away from the hinge C, or interfere with the artificial bone E. In other words, there is an advantage that the hinge C can be properly fixed by the third screw 3c even when the bone plate 2 is fixed to the tibia A.
[0036] Instead of making the inner surface of the hole 2c spherical and the outer surface 7a of the bridge member 7 spherical, allowing the angle of the third screw 3c to be adjusted in any direction, the bridge member 7 may be attached to the bone plate 2 so as to be rotatable about an axis (not shown) extending in the front-to-back direction. This allows the insertion direction of the third screw 3c to be adjusted only in the near-to-far direction. Reducing the degree of freedom of adjustment makes it easier for the surgeon to adjust the insertion direction of the third screw 3c.
[0037] In addition, in this embodiment, the second male threads 6a of the bone screws 3a, 3b, 3c, and 3d are tapered threads, but instead, the second male threads 6a of the bone screws 3a, 3b, 3c, and 3d may be parallel threads. It is sufficient that the first male thread 5a and the second male thread 6a have the same lead. Furthermore, the bone screws 3a, 3b, 3c, and 3d do not have to be locking screws.
[0038] Furthermore, although the bone screws 3a, 3b, 3c, and 3d are described as bicortical screws, they may also be monocortical screws. The bone screws 3a, 3b, 3c, and 3d may be solid or hollow. The use of solid bone screws 3a, 3b, 3c, and 3d increases rigidity and allows for stronger fixation. The use of hollow bone screws 3a, 3b, 3c, and 3d allows for the insertion of guide pins through the hollow holes to properly guide the fastening direction of the bone screws 3a, 3b, 3c, and 3d.
[0039] Furthermore, the bone plate 2 and bone screws 3a, 3b, 3c, and 3d are made of a highly biocompatible metal material. Such materials are relatively safe for the human body even when placed inside the body. Titanium alloys are the most suitable biocompatible materials for the bone plate 2 and bone screws 3a, 3b, 3c, and 3d, as they can ensure sufficient strength and elasticity over a long period of time. Of course, biocompatible materials are not limited to titanium alloys; other materials such as cobalt-chromium alloys and stainless steel can also be used.
[0040] Although the bone plate 2 has four screw holes 4a, 4b for the first screws 3a, 3b, four screw holes 4d for the second screw 3d, and one screw hole 4c for the third screw 3c, the number and arrangement of the bone screws 3a, 3b, 3c, 3d and screw holes 4a, 4b, 4c, 4d may be arbitrary. In particular, multiple third screws 3c may be provided. Increasing the number of third screws 3c allows for more secure fixation of the proximal bone portion A1 and the distal bone portion A2.
[0041] In this embodiment, the screw hole 4c for fastening the third screw 3c is positioned proximally relative to the screw hole 4b, which is positioned distally and rearward of the screw holes 4a and 4b for fastening the first screws 3a and 3b. Alternatively, the screw hole 4c may be positioned at the same distance from or further distally from the screw hole 4b. Even in this case, when the bone plate system 1 is positioned entirely proximally, the third screw 3c can be reliably engaged with the cortical bone of the proximal bone.
[0042] Furthermore, in this embodiment, the third screw 3c is inserted obliquely distally through the screw hole 4a provided in the first portion 2a of the bone plate 2. Alternatively, the third screw 3c may be inserted obliquely proximally through the screw hole 4c provided in the second portion 2b of the bone plate 2. In this case, the first thread 5a of the main body 5 of the third screw 3c is first fastened to the distal bone portion A2, penetrates the osteotomy portion B in the distal-proximal direction, and then fastened to the proximal bone portion A1. This also enables the distal bone portion A2 and the proximal bone portion A1 to be more firmly fixed together by the third screw 3c.
[0043] In this case, it is preferable that the screw hole 4c for the third screw 3c be provided distal to the screw hole 4d for the second screw 3d that is located most proximally among the screw holes 4d provided in the second portion 2b of the bone plate 2. This allows the most proximal second screw 3d to be brought sufficiently close to the osteotomy portion B, and the tip of the third screw 3c can be located at a proximal position within 10 mm from the hinge C while ensuring a relatively large angle of the third screw 3c relative to the osteotomy portion B.
[0044] Furthermore, although the present embodiment has been described with reference to the bone plate system 1 for fixing the tibia A, it may be applied to the case of fixing any other bone having a hinge C. [Explanation of symbols]
[0045] 1 Bone Plate System 2 bone plates 2a Part 1 2b 2nd part 3a, 3b First screw (bone screw) 3c Third screw (bone screw) 3d Second screw (bone screw) 4a,4b,4c,4d screw hole 5 Main body 5a First male screw 6 head 6a Second male thread 7b Tapered female thread (screw hole) A. Tibia (bone) A1 proximal bone A2 Distal bone B Osteotomy C hinge
Claims
1. a bone plate having a plurality of screw holes; a plurality of bone screws fastened to each of the screw holes of the bone plate and to the bone; the bone plate comprises a first portion disposed along an outer surface of a proximal bone portion proximal to the osteotomy portion, and a second portion connected to the first portion and disposed along an outer surface of a distal bone portion distal to the osteotomy portion; the plurality of bone screws comprising a first screw for fixing the first portion to the proximal bone portion, a second screw for fixing the second portion to the distal bone portion, and a third screw for fixing the first portion or the second portion to both the proximal bone portion and the distal bone portion through the osteotomy; the third screw includes a body portion having a first external thread that is fastened to both the proximal bone portion and the distal bone portion, and a head portion having a second external thread that is fastened to the screw hole; A bone plate system, wherein the first external thread and the second external thread have the same lead.
2. 2. The bone plate system of claim 1, wherein the screw holes for the third screws are positioned equidistant or farther from the screw holes for the second screws than any of the screw holes for the first screws.
3. a bone plate placed on the side of the bone; a plurality of bone screws for securing the bone plate to the bone; the bone plate comprises a first portion disposed along an outer surface of a proximal bone portion proximal to the osteotomy portion, and a second portion connected to the first portion and disposed along an outer surface of a distal bone portion distal to the osteotomy portion; the plurality of bone screws comprising a first screw for fixing the first portion to the proximal bone portion, a second screw for fixing the second portion to the distal bone portion, and a third screw for fixing the first portion or the second portion to both the proximal bone portion and the distal bone portion through the osteotomy; a third screw for fixing the first portion to the bone at a distal or more proximal position relative to the most distal first screw, or a second portion to the bone at a distal or more distal position relative to the most proximal second screw.
4. The bone plate system of claim 3 , wherein the third screw is a locking screw.
5. 4. The bone plate system according to claim 1, wherein the screw hole for the third screw allows the insertion direction of the third screw to be changed.
6. the bone plate having distal and proximal sides corresponding to distal and proximal sides of the bone; The bone plate system according to claim 5 , wherein the screw hole for the third screw allows the insertion direction of the third screw to be changed in the distal to proximal direction.
7. the osteotomy portion comprises a hinge; 4. The bone plate system according to claim 1, wherein the tip of the third screw when fixed to the bone is positioned at a distance of 15 mm or less, preferably 10 mm or less, from the hinge in the distal and proximal directions.
8. The bone plate system according to claim 1 or 3, wherein the third screw is a bicortical screw fastened to the cortical bone of each of the proximal bone portion and the distal bone portion.
9. The bone plate system according to claim 1 or claim 3, wherein the third screw is a solid screw.
10. the bone plate having an anterior side corresponding to an anterior side of the bone; 4. The bone plate system according to claim 1, wherein the third screw is inserted obliquely forward with respect to the thickness direction of the bone plate.
11. the bone plate having an anterior side corresponding to the anterior side of the bone and a posterior side corresponding to the posterior side of the bone; 4. The bone plate system according to claim 1, wherein the third screw is inclined at an angle of 30° to 60°, preferably 40° to 50°, relative to the thickness direction of the bone plate when viewed along the front-to-back direction of the bone plate.
12. the bone plate having a proximal side corresponding to a proximal side of the bone and a distal side corresponding to a distal side of the bone; 11. The bone plate system according to claim 10, wherein the third screw is inclined at an angle of 20° to 50°, preferably 30° to 40°, relative to the thickness direction of the bone plate when the bone plate is viewed along the perspective direction.
13. The bone plate system according to claim 1 or 3, comprising a plurality of said third screws.