Bone plate device

Abstract

To provide a bone plate device preventing a part of a bone plate from interfering with a goose's foot when the bone plate is arranged and fixed to an inside surface of the shank.SOLUTION: A bone plate device including a bone plate 10 and a plurality of fasteners 20 is configured such that the bone plate 10 comprises a band plate like distal part 13, a curved plate like proximal part 14, and an intermediate part 15 for connecting both of them; through holes 16a-16d are aligned along the longitudinal direction in the distal part 13; through holes 17a-17d are aligned along the longitudinal direction in the proximal part 14; each of the through holes is formed with a female screw 19 screwed with a male screw 24 formed in a head 22 of the fastener 20; and in a top face view of the bone plate 10, all the through holes 17a-17d aligned along the longitudinal direction in the proximal part 14 are positioned at a rear side more than an extension line L3 of the rear side of the distal part 13.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] The present invention relates to a bone plate system for use in high tibial osteotomy (HTO). [Background technology]

[0002] The bone plate device used in HTO consists of a bone plate that is placed and fixed to the medial surface of the tibia, and a fastener for fixing the bone plate to the tibia.

[0003] Conventionally, as a bone plate constituting a bone plate device, the following Patent Document 1 proposes a roughly T-shaped bone plate 1, as shown in FIG. 6, which has a long, strip-like distal portion (main body portion) 3, a short proximal portion (transverse portion) 4, and a connecting portion (middle portion) 5 connecting these, and in which the distal portion 3 is twisted relative to the proximal portion 4 around an axis parallel to the longitudinal axis of the distal portion 3.

[0004] As shown in the figure, the distal portion 3 has through holes 6a to 6d arranged along its longitudinal direction, and the proximal portion 4 has through holes 7a to 7c arranged along its longitudinal direction (a direction intersecting the longitudinal direction of the distal portion 3), and a through hole 7d is formed on the distal side thereof. The distal portion 3 and the proximal portion 4 are disposed on the inner surfaces of the diaphysis and epiphysis of the tibia, respectively, and are fixed to the tibia by fasteners attached to the through holes 6a to 6d and 7a to 7d.

[0005] Furthermore, proximal portion 4 has protruding portions 8 around through-holes 7a, 7c, and 7d. This raised portion 8 is said to be able to prevent the corners of the head 2b of the fastener 2, which is inserted at an angle relative to the normal to the tangent plane of the lower surface of the proximal portion 4, from protruding from the upper surface of the proximal portion 4, as shown in Figure 7. In addition, since the corner portion (part of the male thread) of the head 2b of the fastener 2 is covered with the protruding portion 8, the contact area between the head 2b and the proximal portion 4 is increased, thereby enhancing the fixing strength of the fastener 2 to the proximal portion 4 of the bone plate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2021 / 250853 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the bone plate described in Patent Document 1 has the following problems. (1) When the bone plate is placed on the medial surface of the tibia, the distal portion 3 and part of the intermediate portion 5 may interfere with the pes anserine, which is the attachment point of the tendons of the muscles (sartorius, semitendinosus, and gracilis), and the contraction and contraction of these muscles may be inhibited by the bone plate 1 fixed to the tibia.

[0008] (2) The shaft 2a of the fastener 2 inserted from the through-holes 6a to 6d of the distal portion 3 is usually inserted perpendicularly into the inner surface of the diaphysis with which the lower surface of the distal portion 3 is in contact. At this time, the tip of the inserted shaft 2a may penetrate the diaphysis of the tibia and reach the area where the deep peroneal nerve and artery pass, causing damage to these nerves and arteries.

[0009] (3) As shown in Fig. 7, although the raised portion 8 can prevent the corners of the head 2b of the fastener 2 inserted at an angle from protruding from the upper surface of the proximal portion 4, the corners of the head 2b protrude from the lower surface of the proximal portion 4. This results in an insufficient number of meshing pitches with the female thread formed in the through hole, reducing the fixing strength of the fastener 2 to the proximal portion 4 of the bone plate, and ultimately the fastening strength of the bone plate to the epiphysis of the tibia.

[0010] The present invention has been made based on the above circumstances. A first object of the present invention is to provide a bone plate device in which, when the bone plate is positioned and fixed on the medial surface of the tibia, a distal portion and a portion of the middle portion of the bone plate do not interfere with the pes anserine.

[0011] A second object of the present invention is to provide a bone plate device in which, when the bone plate is positioned and fixed on the medial surface of the tibia, the tip of the shaft of the fastener inserted through the distal through-hole does not reach the area through which the deep peroneal nerve or artery passes.

[0012] A third object of the present invention is to provide a bone plate device which can prevent the corners of the head of the fastener inserted through the through hole in the proximal part from protruding from the upper and lower surfaces of the proximal part when the bone plate is positioned and fixed on the medial surface of the tibia, and can sufficiently ensure the fixing strength of the fastener to the proximal part of the bone plate, and ultimately the fastening strength of the bone plate to the epiphysis of the tibia. [Means for solving the problem]

[0013] (1) The bone plate device of the present invention is a bone plate device for high tibial osteotomy, comprising a bone plate arranged with its underside facing the medial surface of the tibia, and a plurality of fasteners for fixing the bone plate to the tibia, The fastener has a shaft portion having a screw thread formed thereon and a head portion having a larger diameter than the shaft portion and having a male thread formed thereon, The bone plate includes a strip-shaped distal portion extending in a proximal-distal direction so as to be disposed on an inner surface of a diaphysis, a curved plate-shaped proximal portion extending in an anterior-posterior direction so as to be disposed on an inner surface of an epiphysis, and an intermediate portion connecting the distal portion and the proximal portion; The distal portion has a plurality of through holes arranged along a longitudinal direction (proximal-distal direction) of the distal portion, and the proximal portion has a plurality of through holes arranged along a longitudinal direction (front-rear direction) of the proximal portion, each of the through holes being capable of receiving the shaft portion, and each of the through holes has a female thread formed therein to be screwed with the male thread formed on the head portion, The bone plate is characterized in that, when viewed from above, all of the through holes arranged along the longitudinal direction of the proximal portion are located posterior to the extension line of the rear side surface of the distal portion.

[0014] With a bone plate device configured in this manner, the distal portion is located in front of the through holes arranged in the proximal portion of the bone plate, and the proximal and distal portions of the bone plate are sufficiently spaced apart in the anterior-posterior direction. Therefore, when the bone plate is positioned and fixed on the medial surface of the tibia, it is possible to avoid interference between the distal and part of the middle portion of the bone plate and the anserine pes.

[0015] (2) In a top view of the bone plate constituting the bone plate device of the present invention, it is preferable that the front surfaces of the intermediate portion and the proximal portion are substantially on a straight line, and that the angle α between the straight line and an extension line of the front surface of the distal portion is 25° or more.

[0016] According to a bone plate device configured in this manner, the proximal and distal portions of the bone plate can be spaced apart sufficiently in the front-rear direction.

[0017] (3) In the bone plate device of the present invention, it is preferable that the proximal portion has at least one through hole formed distal to the through holes arranged along the longitudinal direction of the proximal portion.

[0018] (4) In the bone plate device of the present invention, it is preferable that the shaft portion of the fastener inserted into the through hole of the distal portion and extending from the underside of the bone plate is inclined forward by 20°±5° relative to the axis (Z axis) extending vertically (the central axis of the female thread of the through hole is inclined).

[0019] With a bone plate device configured in this manner, it is possible to prevent the shaft of the fastener from being directed toward the area through which the deep peroneal nerve or artery passes, so that when the bone plate is positioned and fixed on the medial surface of the tibia, the tip of the shaft will not reach said area.

[0020] (5) In the bone plate device of (4) above, it is preferable that a protruding portion having a partial internal thread is provided around an upper opening of the through hole formed in the distal portion.

[0021] With a bone plate device configured in this manner, when the bone plate is positioned and fixed to the inner surface of the tibia, the fixing strength of the distal portion of the fastener whose shaft is inserted at an angle through the through hole, and ultimately the fastening strength of the bone plate to the diaphysis of the tibia, can be sufficiently ensured.

[0022] (6) In the bone plate device of the present invention, it is preferable that a raised portion having a partial female thread is provided around each of the upper and lower openings of at least one of the through holes formed in the proximal portion.

[0023] With a bone plate device configured in this manner, a protuberance is provided not only around the upper opening of the through hole but also around the lower opening of the through hole. Therefore, when the bone plate is positioned and fixed to the inner surface of the tibia, the fixing strength of the fastener, whose shaft is inserted at an angle through the through hole, to the proximal part, and ultimately the fastening strength of the bone plate to the bone end of the tibia, can be sufficiently ensured. Effect of the Invention

[0024] According to the bone plate device of the present invention, when the bone plate constituting the bone plate device is positioned and fixed to the medial surface of the tibia, the distal and middle portions of the bone plate do not interfere with the pes anserine. Furthermore, according to the bone plate device of the present invention, in which the shaft of the fastener extending from the underside of the bone plate is inclined forward at 20°±5° relative to the Z-axis extending up and down, when the bone plate is positioned and fixed on the medial surface of the tibia, the tip of the shaft of the fastener inserted through the distal through hole will not reach the area where the deep peroneal nerve or artery pass through. Furthermore, according to the bone plate device of the present invention, in which protrusions are provided around each of the upper and lower openings of the through hole formed in the proximal portion of the bone plate, when the bone plate is positioned and fixed to the medial surface of the tibia, the fixing strength of the fastener to the proximal portion of the bone plate, and ultimately the fastening strength of the bone plate to the epiphysis of the tibia, can be sufficiently ensured. [Brief description of the drawings]

[0025] [Figure 1] 1 is a perspective view of a bone plate device according to one embodiment of the present invention; [Diagram 2] 2 is a perspective view showing a fastener constituting the bone plate device shown in FIG. 1. [Figure 3A] 2 is a plan view (top view) showing a bone plate constituting the bone plate device shown in FIG. 1. FIG. [Figure 3B] 2 is a bottom view (underside view) showing a bone plate constituting the bone plate device shown in FIG. 1. FIG. [Figure 3C] 2 is a side view (rear side view) showing a bone plate constituting the bone plate device shown in FIG. 1. FIG. [Figure 3D] FIG. 2 is an explanatory view of the bone plate device shown in FIG. 1, viewed from the distal side. [Figure 3E] FIG. 2 is a cross-sectional view of the bone plate device (proximal portion of the bone plate) shown in FIG. 1. [Figure 3F] FIG. 3E is a detailed cross-sectional view of a portion of FIG. [Figure 3G] 2 is a perspective view showing a proximal portion (upper surface side) of a bone plate constituting the bone plate device shown in FIG. 1. FIG. [Figure 3H] 2 is a perspective view showing a proximal portion (lower surface side) of a bone plate constituting the bone plate device shown in FIG. 1. FIG. [Figure 4] 2 is an explanatory diagram showing a schematic diagram illustrating that the bone plate constituting the bone plate device shown in FIG. 1 does not interfere with the anserine pes. FIG. [Diagram 5] FIG. 2 is an explanatory diagram showing, in schematic form, that the tip portion of the shaft of the fastener constituting the bone plate device shown in FIG. 1 is not directed toward the area through which the deep peroneal nerve or artery passes. [Figure 6] FIG. 1 is a plan view showing a conventional bone plate. [Figure 7] 7 is a cross-sectional view showing a main part of the bone plate shown in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The bone plate device of this embodiment shown in FIG. 1 is a bone plate device for high tibial osteotomy, comprising a bone plate 10 arranged with its lower surface 10B facing the medial surface of the tibia, and eight fasteners 20 for fixing the bone plate 10 to the tibia. The fasteners 20 have a shaft portion 21 on which a screw thread 23 is formed, and a head portion 22 on which a male thread 24 is formed and has a diameter larger than that of the shaft portion 21. The bone plate 10 has a strip-shaped distal portion 13 extending in the proximal-distal direction (X direction) so as to be arranged on the medial surface of the diaphysis, and a strip-shaped distal portion 14 extending in the anterior-posterior direction (X direction) so as to be arranged on the medial surface of the epiphysis. The proximal portion 14 is made up of a curved plate-like proximal portion 14 extending in a direction (approximately the Y direction) and an intermediate portion 15 connecting the distal portion 13 and the proximal portion 14. The distal portion 13 has through holes 16a to 16d arranged along the longitudinal direction (X direction) of the distal portion 13. The proximal portion 14 has through holes 17a to 17c arranged along the longitudinal direction (approximately the Y direction) of the proximal portion 14, and through hole 17d is formed on the distal side thereof. Each of the through holes 16a to 16d, 17a to 17d can receive a shaft portion 21 of a fastener 20. Each of the through holes 16a to 16d, 17a to 17d can receive a head portion 22 of the fastener 20. a female thread 19 is formed on the proximal portion 14 and the intermediate portion 15 is threadedly engaged with a male thread 24 formed on the distal portion 13; when viewed from above, the front side surfaces of the intermediate portion 15 and the proximal portion 14 are substantially on a straight line L1, and an angle (α) between the straight line L1 and an extension line L2 of the front side surface of the distal portion 13 is 25° or more; all of the through holes 17a to 17c arranged along the longitudinal direction of the proximal portion 14 are located rearward of an extension line L3 of the rear side surface of the distal portion 13; fasteners are inserted into the through holes 16a to 16d of the distal portion 13 and extend from the lower surface 10B of the bone plate 10. Shaft portion 21 of 20 is inclined forward by 20°±5° with respect to the Z axis extending in the up-down direction (Z direction); raised portion 18A having partial female threads 19A is provided around the opening of upper surface 10A of through holes 17a and 17d formed in proximal portion 14, and raised portion 18B having partial female threads 19B is provided around the opening of lower surface 10B of through holes 17a and 17d; and raised portion 18A having partial female threads 19B is provided around the opening of upper surface 10A of through holes 16a to 16d formed in distal portion 13.

[0027] The bone plate device of this embodiment comprises a bone plate 10 and eight fasteners 20 for fixing the bone plate 10 to the tibia.

[0028] 2, fastener 20 is composed of a shaft portion 21 and a head portion 22 having a larger diameter than shaft portion 21. Shank portion 21 of fastener 20 is formed with a screw thread 23, and head portion 22 is formed with a male thread 24.

[0029] The bone plate 10 shown in FIGS. 3A to 3H is a plate for the tibia of the left leg, and is made up of a distal portion 13, a proximal portion 14, and an intermediate portion 15. When the bone plate 10 is placed on the medial surface of the tibia, the bone plate 10 has a lower surface 10B that faces the medial surface and an upper surface 10A on the opposite side. Therefore, the up-down direction (plate thickness direction) of the bone plate 10 corresponds to the medial-lateral direction of the tibia to which it is fixed.

[0030] The distal portion 13 of the bone plate 10 is a portion disposed on the medial surface of the diaphysis of the tibia, and is a strip-like plate extending in the proximal-distal direction (X direction). Here, the "proximal-distal direction" of the bone plate 10 corresponds to the proximal-distal direction of the tibia to which it is fixed, and therefore the distal portion 13 is disposed along the proximal-distal direction of the diaphysis.

[0031] Four through holes 16a to 16d are arranged along the longitudinal direction of the distal portion 13. Each of the through holes 16a to 16d has an inner diameter that allows a shaft portion 21 of a fastener 20 to be inserted therethrough, and each of the through holes 16a to 16d has a female thread 19 formed therein to screw together with a male thread 24 formed on a head 22 of the fastener 20. The width (length in the Y direction) of the distal portion 13 is set to 13 to 16 mm, and a suitable example is set to 14 mm.

[0032] The proximal portion 14 of the bone plate 10 is a portion that is disposed on the medial surface of the epiphysis of the tibia that protrudes inward relative to the diaphysis, and extends in the anterior-posterior direction (approximately the Y direction) while curving. Here, the "anterior-posterior direction" of the bone plate 10 corresponds to the anterior-posterior direction of the tibia to which it is fixed, and therefore the proximal portion 14 is disposed along the anterior-posterior direction of the epiphysis.

[0033] In the proximal portion 14, three through holes 17a to 17c are arranged along the longitudinal direction, and a through hole 17d is formed on the distal side thereof. Each of the through holes 17a to 17d has an inner diameter that allows a shaft portion 21 of a fastener 20 to be inserted therethrough, and each of the through holes 17a to 17d has a female thread 19 formed therein to screw together with a male thread 24 formed on a head 22 of the fastener 20. The length of the proximal portion 14 (length in the Y direction) is set to 25 to 30 mm, and a suitable example is 28 mm.

[0034] The intermediate portion 15 of the bone plate 10 is a portion that connects the distal portion 13 and the proximal portion 14, and no through-hole for attaching the fastener 20 is formed in the intermediate portion 15. The intermediate portion 15 is placed in the opened osteotomy portion.

[0035] In the top view of bone plate 10 shown in FIG. 3A, the anterior surfaces of intermediate portion 15 and proximal portion 14 are substantially on a single straight line L1, and this straight line L1 is inclined toward the "anterior" side as it approaches the "distal" side. The angle α between this straight line L1 and an extension line L2 of the front side surface of the distal portion 13 is preferably 25° or more, more preferably 25 to 45°, and a suitable example is 37°.

[0036] By setting this angle α to 25° or more, the proximal portion 14 and the distal portion 13 of the bone plate 10 can be sufficiently spaced apart in the front-rear direction (Y direction). Furthermore, by ensuring a sufficient distance between the proximal portion 14 and the distal portion 13 in the fore-aft direction, all of the through holes 17a to 17c arranged along the longitudinal direction of the proximal portion 14 are located rearward of the extension line (extrapolation line) L3 of the rear side surface of the distal portion 13.

[0037] In this manner, in the bone plate device of this embodiment, the distal portion 13 and the intermediate portion 15 of the bone plate 10 constituting it can be positioned at a position far forward from the position where the proximal portion 14 is positioned. As a result, as shown in FIG. 4, distal portion 13 and / or any part of intermediate portion 15 do not interfere with the pes anserine, which is located distal to the position of proximal portion 14 (position indicated by G in the same figure), and therefore the fixed bone plate 10 does not inhibit the contraction and stretching of muscles (sartorius, semitendinosus, and gracilis).

[0038] As shown in FIG. 3D, in the bone plate device of this embodiment, the shaft 21 of the fastener 20 is inserted into each of the through holes 16a to 16d in the distal portion 13 of the bone plate 10, and extends downward from the lower surface 10B of the bone plate 10 with the female threads 19 formed in the through holes and the male threads 24 formed in the head 22 screwed together, and is inclined 20° forward with respect to the axis extending vertically (the Z-axis which is normal to the XY plane).

[0039] As a result, as shown in FIG. 5, it is possible to avoid pointing the shaft 21 of the fastener 20 toward the area where the deep peroneal nerve and artery pass (the area indicated by N in the figure), so that when the bone plate 10 is positioned and fixed to the medial surface of the tibia, the tip portion of the shaft 21 is positioned in the center of the tibia without reaching the area.

[0040] 3A, raised portions 18A having partial female threads are provided around the openings of the upper surface 10A of the through holes 16a to 16d formed in the distal portion 13. These raised portions 18A are provided on the side where the central axis of the female threads 19 formed in the through holes 16a to 16d forms an obtuse angle with the XY plane, i.e., on the front side.

[0041] This prevents the corners (part of the male thread 24) of the head 22 of the fastener 20 inserted through the through holes 16a to 16d formed in the distal portion 13 from protruding from the upper surface of the distal portion 13, and ensures sufficient fixing strength of the fastener 20 to the distal portion 13 of the bone plate 10, and ultimately, the fastening strength of the bone plate 10 to the diaphysis of the tibia.

[0042] As shown in Figures 3A, 3F and 3G, a raised portion 18A having a partial internal thread 19A is provided around the opening of the upper surface 10A of the through holes 17a and 17d formed in the proximal portion 14.

[0043] As shown in Figs. 3B, 3F and 3H, raised portions 18B on which partial internal threads 19B are formed are also provided around the openings of the lower surface 10B of the through holes 17a and 17d. Incidentally, the bone plate 10 is placed in a state of being sandwiched between the medial collateral ligaments (between the deep medial collateral ligament and the superficial medial collateral ligament) during surgery. Specifically, only the superficial medial collateral ligament is cut, and the bone plate 10 is placed on the deep medial collateral ligament, after which the cut superficial medial collateral ligament is covered again and sewn up. In addition, when the fastener 20 is inserted into the bone plate 10, the fastener 20 is inserted through the deep medial collateral ligament located on the lower surface 10B side while avoiding the superficial medial collateral ligament located on the upper surface 10A side, and the bone plate 10 is fixed to the bone end. Therefore, when the knee is moved after surgery, the upper surface of the bone plate 10 and the superficial medial collateral ligament rub against each other, and if the protruding portion 18A has an extremely convex shape, the protruding portion rubs against the ligament, which may cause damage to the ligament. However, since the protuberance 18A of the bone plate 10 has a gentle slope and a smooth shape, when the knee is moved after surgery, there is very little frictional resistance between the protuberance 18A and the superficial medial collateral ligament, preventing damage to the ligament. In addition, there is blood flow inside the bone, and if the protrusions or bumps of the metal plate are pressed against the bone, the blood flow in that area may be obstructed, slowing down bone regeneration. For this reason, no protrusion is provided on the lower surface (a portion that may come into contact with the diaphysis) of the distal portion 13 of the bone plate 10. On the other hand, unlike the diaphysis where the distal portion 13 is located, the epiphysis where the proximal portion 14 is located has soft tissue (deep medial collateral ligament), so even if a protrusion 18B is provided on the lower surface 10B located on the medial surface of the epiphysis, the protrusion 18B will not obstruct the blood flow.

[0044] In this way, protrusions 18A are provided around the openings of the upper surface 10A of through holes 17a and 17d, and protrusions 18B are also provided around the openings of the lower surface 10B of through holes 17a and 17d, thereby making it possible to ensure a sufficiently high fixing strength of fastener 20 to proximal portion 14 of bone plate 10. [Explanation of symbols]

[0045] 10 Bone Plate 10A Top surface of bone plate 10B Underside of bone plate 13 Distal 14 Proximal 15 Middle section 16a to 16d: Through holes formed in the distal portion 17a to 17d Through holes formed in the proximal part 18A Raised portion on the top surface of the bone plate 18B A ridge formed on the underside of the proximal part of the bone plate 19 Female thread 19A, 19B Partial internal thread 20 Fasteners 21 Shaft 22 Head 23 Screw 24 Male thread

Claims

1. A bone plate device for high tibial osteotomy, comprising a bone plate arranged with its lower surface facing the medial surface of the tibia, and a plurality of fasteners for fixing the bone plate to the tibia, The fastener has a shaft portion having a screw thread formed thereon and a head portion having a larger diameter than the shaft portion and having a male thread formed thereon, The bone plate includes a strip-shaped distal portion extending in a proximal-distal direction so as to be disposed on an inner surface of a diaphysis, a curved plate-shaped proximal portion extending in an anterior-posterior direction so as to be disposed on an inner surface of an epiphysis, and an intermediate portion connecting the distal portion and the proximal portion; a plurality of through holes are arranged in the distal portion along a longitudinal direction of the distal portion, a plurality of through holes are arranged in the proximal portion along a longitudinal direction of the proximal portion, each of the through holes is capable of receiving the shaft portion, and each of the through holes is formed with a female thread that screws into the male thread formed in the head portion, A bone plate device characterized in that, when viewed from above, all of the through holes arranged along the longitudinal direction of the proximal portion are located posterior to the extension line of the rear side of the distal portion.

2. 2. The bone plate device according to claim 1, wherein, in a top view of the bone plate, the front surfaces of the intermediate portion and the proximal portion are substantially on a straight line, and the angle α between the straight line and an extension line of the front surface of the distal portion is 25° or more.

3. 3. The bone plate device according to claim 1, wherein the proximal portion has at least one through hole formed distal to the through holes arranged along the longitudinal direction of the proximal portion.

4. 3. The bone plate device according to claim 1, wherein the shaft portion of the fastener inserted into the through hole of the distal portion and extending from the underside of the bone plate is inclined forward by 20°±5° relative to an axis extending vertically.

5. 5. The bone plate device according to claim 4, wherein a protuberance having a partial internal thread is provided around an upper opening of the through hole formed in the distal portion.

6. The bone plate device according to claim 1 or 2, characterized in that a protruding portion having a partial internal thread is provided around each of the upper and lower openings of at least one of the through holes formed in the proximal portion.

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