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 on 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, Patent Document 1 below proposes a roughly T-shaped bone plate 1, as shown in Figure 6, which has a long, strip-like distal portion (main body portion) 3, a short proximal portion (transverse portion) 4, and a connecting portion (intermediate 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 same 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 placed on the medial 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, protruding portions 8 are provided around the through-holes 7a, 7c, and 7d of the proximal portion 4. 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 by the raised portion 8, the contact area between the head 2b and the proximal portion 4 is increased, thereby increasing 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 middle 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 bone plate 1 fixed to the tibia may inhibit the contraction and contraction of these muscles.

[0008] (2) The shank 2a of the fastener 2 inserted through 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 shank 2a may penetrate the diaphysis of the tibia and reach the area where the deep peroneal nerve or artery passes, possibly damaging these nerves or arteries.

[0009] (3) As shown in Figure 7, although the raised portion 8 prevents 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 still 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 fixing 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, the distal and middle portions 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 where the deep peroneal nerve or artery passes.

[0012] A third object of the present invention is to provide a bone plate device that can prevent the corners of the head of the fastener inserted through the through-hole in the proximal portion from protruding from the upper and lower surfaces of the proximal portion when the bone plate is positioned and fixed on the medial surface of the tibia, thereby ensuring sufficient 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. [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 that is placed 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 shank on which a screw thread is formed and a head on which a male screw thread is formed and which is larger in diameter than the shank, The bone plate includes a strip-shaped distal portion extending in a proximal-distal direction so as to be disposed on the medial surface of the diaphysis, a curved plate-shaped proximal portion extending in an anterior-posterior direction so as to be disposed on the medial surface of the epiphysis, and an intermediate portion connecting the distal portion and the proximal portion; The distal portion has a plurality of through holes arranged along the longitudinal direction (proximal-distal direction) of the distal portion, and the proximal portion has a plurality of through holes arranged along the longitudinal direction (front-rear direction) of the proximal portion, each of the through holes being capable of inserting the shank, and each of the through holes has a female thread formed therein to be threadedly engaged with the male thread formed on the head, In a top view of the bone plate, All The through hole whole is located posterior to the extension line of the posterior surface of the distal portion And, When viewed from above, the anterior surfaces of the intermediate portion and the proximal portion are on a straight line that slopes more anteriorly as it approaches the distal side, and the angle α between the straight line and an extension of the anterior surface of the distal portion is 25° or more. It is characterized by:

[0014] With a bone plate device of this configuration, 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 middle portions of the bone plate and the pes anserine.

[0016] Also, According to the bone plate device having such a configuration, the proximal and distal portions of the bone plate can be spaced apart sufficiently in the anterior-posterior direction.

[0017] (2) 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] (3) 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 of this configuration, the shaft of the fastener can be prevented from being directed toward the area where 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 the area.

[0020] (4) the above (3) In the bone plate device of , it is preferable that a protruding portion on which a partial internal thread is formed is provided around the upper opening of the through hole formed in the distal portion.

[0021] With a bone plate device of this configuration, when the bone plate is positioned and fixed on the medial surface of the tibia, the fixing strength of the distal part 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] (5) In the bone plate device of the present invention, it is preferable 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.

[0023] With a bone plate device configured in this manner, a protrusion 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 medial surface of the tibia, the fastening 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 epiphysis of the tibia, can be sufficiently ensured. [Effects of the Invention]

[0024] According to the bone plate device of the present invention, when the bone plate constituting the device is positioned and fixed on 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 shank of the fastener extending from the underside of the bone plate is inclined forward by 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 shank of the fastener inserted through the distal through-hole will not reach the area where the deep peroneal nerve or artery passes. 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 fixing strength of the bone plate to the epiphysis of the tibia, can be sufficiently ensured. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a perspective view of a bone plate device according to one embodiment of the present invention; [Figure 2] 2 is a perspective view showing a fastener that constitutes the bone plate device shown in FIG. 1. FIG. [Figure 3A] 2 is a plan view (top view) showing a bone plate that constitutes the bone plate device shown in FIG. 1. FIG. [Figure 3B] 2 is a bottom view (underside view) showing a bone plate that constitutes the bone plate device shown in FIG. 1. FIG. [Figure 3C] 2 is a side view (rear side view) showing a bone plate that constitutes the bone plate device shown in FIG. 1. FIG. [Figure 3D] 2 is an explanatory view of the bone plate device shown in FIG. 1 as seen from the distal side. [Figure 3E] 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. 3E. [Figure 3G] 2 is a perspective view showing the 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 the 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 view illustrating that the bone plates constituting the bone plate device shown in FIG. 1 do not interfere with the anserine pes. FIG. [Figure 5] FIG. 2 is an explanatory diagram showing, in a simplified manner, that the tip 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] FIG. 7 is a cross-sectional view showing a main part of the bone plate shown in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[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 placed with its underside 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 21 on which a screw thread 23 is formed, and a head 22 with a larger diameter than the shaft 21 and on which a male thread 24 is formed. The bone plate 10 has a strip-shaped distal portion 13 extending in the proximal-distal direction (X direction) so as to be placed 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 placed on the medial surface of the epiphysis. The distal portion 13 has through holes 16a to 16d arranged along the longitudinal direction (X direction) of the distal portion 13, and the proximal portion 14 has through holes 17a to 17c arranged along the longitudinal direction (approximately the Y direction) of the proximal portion 14, with through hole 17d formed on the distal side thereof. Each of the through holes 16a to 16d and 17a to 17d can receive a shank 21 of a fastener 20, and each of the through holes 16a to 16d and 17a to 17d receives a head 22 of the fastener 20. In a top view of the bone plate (10), the anterior surfaces of the intermediate portion (15) and the proximal portion (14) are substantially on a straight line (L1), and the angle (α) between this straight line (L1) and an extension line (L2) of the anterior surface of the distal portion (13) is 25° or more. All of the through holes (17a-17c) arranged along the longitudinal direction of the proximal portion (14) are located posterior to the extension line (L3) of the posterior surface of the distal portion (13). Fasteners are inserted into the through holes (16a-16d) of the distal portion (13) and extend from the underside (10B) of the bone plate (10). The shaft portion 21 of 20 is inclined forward by 20°±5° with respect to the Z axis extending in the vertical direction (Z direction); a raised portion 18A having a partial internal thread 19A is provided around the opening on the upper surface 10A of the through holes 17a and 17d formed in the proximal portion 14, and a raised portion 18B having a partial internal thread 19B is provided around the opening on the lower surface 10B of the through holes 17a and 17d; and a raised portion 18A having a partial internal thread 19B is provided around the opening on the upper surface 10A of the through holes 16a to 16d formed in the 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] As shown in Figure 2, fastener 20 is composed of shank 21 and head 22 having a larger diameter than shank 21. Shank 21 of fastener 20 is formed with a screw thread 23, and head 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 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 (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 that is placed on the medial surface of the diaphysis of the tibia, and is a strip-like plate that extends 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 placed along the proximal-distal direction of the diaphysis.

[0031] Four through holes 16a to 16d are arranged along the longitudinal direction of distal portion 13. Each of through holes 16a to 16d has an inner diameter that allows shank 21 of fastener 20 to be inserted therethrough, and each of through holes 16a to 16d has an internal thread 19 formed therein that screws together with external thread 24 formed on head 22 of 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 14 mm.

[0032] The proximal portion 14 of the bone plate 10 is a portion that is placed on the medial surface of the epiphysis of the tibia, which protrudes medially 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 placed along the anterior-posterior direction of the epiphysis.

[0033] Proximal portion 14 has three through holes 17a-17c arranged along its longitudinal direction, and through hole 17d formed distally thereto. Each of through holes 17a-17d has an inner diameter that allows shank 21 of fastener 20 to be inserted therethrough, and each of through holes 17a-17d has an internal thread 19 formed therein that screws together with external thread 24 formed on head 22 of 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 this intermediate portion 15 does not have a through-hole for attaching the fastener 20. The intermediate portion 15 is placed in the opened osteotomy site.

[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 moves toward the "distal" side. The angle α formed by 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 spaced apart sufficiently in the front-to-rear direction (Y direction). Furthermore, by ensuring a sufficient distance between the proximal portion 14 and the distal portion 13 in the anterior-posterior direction, all of the through holes 17a to 17c arranged along the longitudinal direction of the proximal portion 14 are located behind the extension line (extrapolated line) L3 of the rear side surface of the distal portion 13.

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

[0038] As shown in Figure 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 threadedly engaged with each other, and is inclined forward by 20° with respect to the axis extending vertically (the Z axis which is the normal to the XY plane).

[0039] This prevents the shank 21 of the fastener 20 from being directed toward the area where the deep peroneal nerve and artery pass (the area indicated by N in the figure), as shown in FIG. 5. Therefore, when the bone plate 10 is positioned and fixed to the medial surface of the tibia, the tip of the shank 21 is positioned in the center of the tibia without reaching the area.

[0040] 3A, raised portions 18A on which partial internal threads are formed 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 axes of the internal threads 19 formed in the through holes 16a to 16d form 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 also 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 on which a partial internal thread 19A is formed 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, protrusions 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. During surgery, bone plate 10 is positioned between the medial collateral ligaments (between the deep medial collateral ligament and the superficial medial collateral ligament). Specifically, only the superficial medial collateral ligament is cut, and bone plate 10 is placed on top of the deep medial collateral ligament. The cut superficial medial collateral ligament is then reattached and sutured. Furthermore, when fastener 20 is inserted into bone plate 10, it is inserted through the deep medial collateral ligament located on the lower surface 10B while avoiding the superficial medial collateral ligament located on the upper surface 10A, thereby securing bone plate 10 to the epiphysis. Therefore, when the knee is moved after surgery, the upper surface of bone plate 10 rubs against the superficial medial collateral ligament. If protrusion 18A has an extremely convex shape, the protruding portion rubs against the ligament, potentially damaging 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 friction resistance between the protuberance 18A and the superficial medial collateral ligament, preventing damage to the ligament. Furthermore, blood flows inside bones, and if protrusions or bumps on a metal plate are pressed against the bone, blood flow in that area may be obstructed, slowing bone regeneration. For this reason, no protrusions are provided on the underside of the distal portion 13 of the bone plate 10 (a portion that may come into contact with the diaphysis). 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 (the deep medial collateral ligament). Therefore, even if a protrusion 18B is provided on the underside 10B that is located on the medial surface of the epiphysis, the protrusion 18B will not obstruct blood flow.

[0044] In this way, protrusions 18A are provided around the openings on the upper surface 10A of through holes 17a and 17d, and protrusions 18B are also provided around the openings on 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 plates 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 formed 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 female 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 shank on which a screw thread is formed and a head on which a male screw thread is formed and which is larger in diameter than the shank, The bone plate includes a strip-shaped distal portion extending in a proximal-distal direction so as to be disposed on the medial surface of the diaphysis, a curved plate-shaped proximal portion extending in an anterior-posterior direction so as to be disposed on the medial surface of the epiphysis, and an intermediate portion connecting the distal portion and the proximal portion; The distal portion has a plurality of through holes arranged along the proximal-distal direction, which is the longitudinal direction of the distal portion, and the proximal portion has a plurality of through holes arranged along the anterior-posterior direction, which is the longitudinal direction of the proximal portion, each of the through holes being capable of inserting the shank, and each of the through holes has a female thread formed therein to be threadedly engaged with the male thread formed on the head, when viewed from above, all of the through holes arranged along the longitudinal direction of the proximal portion are located posterior to an extension line of a posterior side surface of the distal portion; A bone plate device characterized in that, when viewed from above, the anterior surfaces of the intermediate portion and the proximal portion lie on a straight line that slopes more anteriorly as it moves distally, and the angle α between this line and an extension of the anterior surface of the distal portion is 25° or more.

2. 2. 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.

3. 2. The bone plate device according to claim 1, wherein the shank of the fastener inserted through 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.

4. 4. The bone plate device according to claim 3, wherein a protuberance having a partial internal thread is provided around the upper opening of the through-hole formed in the distal portion.

5. The bone plate device according to claim 1, 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.

Images