Bone plate

Abstract

The bone plate (1) has a long strip-shaped main body (3) disposed on the side of the bone shaft (D), a transverse part (4) disposed on the side of the epiphysis (C1) and at one end of the main body (3), and a connecting part (5) connecting the transverse part (4) and the main body (3). The main body (3) is twisted relative to the transverse part (4) about an axis parallel to the long axis of the main body (3). When viewed along the short side of the main body (3), the bone plate (1) is bent into a crank shape in which the connecting part (5) is inclined relative to the long side of the main body (3) and the main body (3) and the transverse part (4) are offset from each other in the thickness direction of the plate, and has a shape that conforms to the shape of the side of the tibia (A) that protrudes from the side of the epiphysis (C1) relative to the side of the bone shaft (D).

Description

Technical Field

[0001] This invention relates to a bone plate. Background Technology

[0002] Currently, a bone plate for orthopedic surgery is known (for example, see Patent Documents 1-3).

[0003] Patent documents 1 and 2 disclose a bone plate for high tibial osteotomy (HTO) as one of the treatment methods for osteoarthritis of the knee. In HTO, the tibia is corrected by making an incision from the medial to the lateral side of the tibia and opening the incision, thereby shifting the weight line of varus knee from the medial to the lateral side. During the period until bone healing, the corrected tibia is fixed by the bone plate and bone screws.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5505767

[0007] Patent Document 2: Japanese Patent No. 4322039

[0008] Patent Document 3: Japanese Patent No. 6250836 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] At the joint surface B of the knee is Figure 12A In the case of the Pagoda type shown, sometimes simply moving the load line via HTO cannot improve knee sway. That is, it is not possible to simultaneously bring both the medial and lateral sides of the knee joint surface B into contact with the joint surface of the femur, thus creating a gap between the joint surfaces on either the medial or lateral side.

[0011] As a treatment for this condition, tibial condyle valgus osteotomy (TCVO) has been proposed. For example... Figure 12B As shown, in TCVO, the medial epiphysis is cut into an L-shape to the articular surface, and the articular surfaces B on both the medial and lateral sides are brought into contact with the articular surface of the femur by opening the cut portion.

[0012] In the case of HTO, the osteotomy portion is opened by rotating the epiphysis relative to the diaphysis, centered on the hinge portion near the lateral surface of the tibia A. On the other hand, in the case of TCVO, the osteotomy portion is opened by rotating the medial epiphysis relative to the diaphysis, while lifting it, centered on the center of the articular surface B. Therefore, compared to HTO, in the case of TCVO, the medial surface of the epiphysis extends more medially relative to the medial surface of the diaphysis.

[0013] Thus, the morphology of the tibia A after the osteotomy is opened differs in HTO and TCVO, making the bone plate used in HTO unsuitable for TCVO. Specifically, the bone plate used in HTO cannot correspond to the height difference between the medial surface of the epiphysis and the medial surface of the diaphysis, and will float above the bone surface. To reduce the impact of the bone plate on the surrounding tissues of the tibia A, it is preferable that there is no bone plate floating above the bone surface, or that the floating is minimal.

[0014] The present invention was made in view of the above circumstances, and its object is to provide a bone plate that can be suitably used on the side of the tibia where the side of the epiphysis protrudes relative to the side of the shaft.

[0015] Solution for solving the problem

[0016] To achieve the above objectives, the present invention provides the following solutions.

[0017] One aspect of the present invention is a bone plate suitable for the side of the tibia where the epiphysis protrudes relative to the diaphysis, and is fixed to the side of the tibia by means of a bone fixation member. The plate comprises: a long, strip-shaped main body disposed on the side of the diaphysis, having at least one through hole for inserting the bone fixation member; a transverse portion disposed on the side of the epiphysis, located at one end of the main body, and having at least one through hole for inserting the bone fixation member; and a connecting portion connecting the transverse portion to the main body. The main body is twisted relative to the transverse portion about an axis parallel to the long axis of the main body. When viewed along the short side of the main body, the bone plate is bent into a crank shape where the connecting portion is inclined relative to the long side of the main body, and the main body and the transverse portion are offset from each other in the thickness direction of the bone plate, and has a shape conforming to the morphology of the side of the tibia.

[0018] The bone plate of this design has a crank shape with the transverse portion offset relative to the main body in the thickness direction. Therefore, by positioning the bone plate on the side of the tibia in a manner where the offset direction of the transverse portion relative to the main body aligns with the protrusion direction of the epiphysis relative to the diaphysis, the shape of the bone plate can conform to the morphology of the tibial side. That is, the main body and the transverse portion can be simultaneously positioned on the sides of both the diaphysis and the epiphysis, thus allowing for appropriate use on the side of the tibia where the epiphysis protrudes relative to the diaphysis. Furthermore, because the main body is twisted relative to the transverse portion, when the side of the diaphysis is positioned anteriorly or posteriorly and twisted relative to the side of the epiphysis, the main body and the transverse portion can be appropriately positioned on the sides of both the diaphysis and the epiphysis.

[0019] In the above manner, the torsion angle of the transverse portion relative to the main body portion about the axis can also be 8° to 30°.

[0020] In the above manner, the offset between the main body and the transverse section in the plate thickness direction can also be 9mm ± 3mm.

[0021] In the above manner, the transverse portion may also extend relative to the main body portion in a direction corresponding to the posterior side of the tibia and in a direction intersecting the long side direction of the main body portion.

[0022] According to this structure, when the side of the epiphysis is offset posteriorly relative to the side of the diaphysis, the main body and the transverse portion can be more appropriately positioned on the side of the diaphysis and the side of the epiphysis, respectively. In this structure, when viewed along the short side of the transverse portion, the lower surface of the transverse portion positioned on the side of the tibia can also be located between two arcs having radii of curvature of 20 mm and 40 mm, respectively, passing through the two ends of the long side of the transverse portion.

[0023] In the above-described manner, the angle between the short axis of the transverse portion and the long axis of the connecting portion in the longitudinal section of the bone plate is 155°±10°, the angle between the long axis of the connecting portion and the long axis of the main body is 160°±10°, and the length between the center of the nearest through hole in the main body and the center of the farthest through hole in the transverse portion in the direction along the connecting portion is 38.5mm±5mm.

[0024] According to this structure, an appropriate offset, for example, 9mm ± 3mm, can be achieved between the main body and the transverse section.

[0025] In the above manner, when viewed along the short side of the horizontal section, the central axes of all the through holes in the horizontal section can also face different directions.

[0026] Depending on the position of the transverse portion relative to the side of the epiphysis, the direction in which the bone fixation member is inserted into the epiphysis through the through-hole varies. Because the central axes of all the through-holes in the transverse portion are oriented differently, the bone fixation member can be inserted more reliably to a sufficient depth from the side of the epiphysis.

[0027] In the above manner, the transverse portion may also have three through holes not arranged in a straight line, the central axes of the three through holes being inclined to each other such that the three bone fixation members passing through the three through holes are in contact with each other inside the epiphysis.

[0028] The three bone screws that contact each other at their front ends form a three-dimensional truss structure, which bears the load as a whole. Compared with the case where the three bone screws bear the load independently, the bone screws with this three-dimensional truss structure can withstand a greater load.

[0029] In the above manner, the transverse portion may also have two or more through holes arranged in the long side direction of the transverse portion, and the central axis of the two or more through holes is inclined toward the insertion direction of the bone fixation member and toward the side corresponding to the front side of the epiphysis.

[0030] The transverse portion can be positioned near the anterior side relative to the epiphysis. Because the through hole of the transverse portion is tilted anteriorly, even when the transverse portion is positioned near the anterior side relative to the epiphysis, a longer bone fixation member can be inserted into the epiphysis without protruding from the surface of the epiphysis.

[0031] In the above manner, the transverse portion may also have two or more through holes arranged in the long side direction of the transverse portion, with the central axis of the two or more through holes facing the insertion direction of the bone fixation member and inclined at the same angle to the side corresponding to the distal side of the tibia.

[0032] When the transverse portion is positioned closer to the distal side relative to the epiphysis and when it is positioned closer to the proximal side, the insertion direction of the bone fixation member into the epiphysis differs considerably. Since the central axis of the through-holes is inclined distally at the same angle, interference between the anterior end of the bone fixation member and the articular surface can be prevented. In this structure, the central axis of the two or more through-holes is preferably inclined at an angle of 77° ± 5° relative to the line segment connecting the proximal end of the transverse portion and the boundary between the transverse portion and the connecting portion.

[0033] In the above manner, the gap between the through hole on the side of the main body closest to the horizontal section and the through hole on the side of the horizontal section closest to the main body can also be 28.5 mm to 45.0 mm.

[0034] The bone fixation members inserted into the through holes on the outermost side of the main body and the outermost side of the main body of the transverse section pass near the osteotomy surface. The gap is 28.5 mm or more, thereby preventing interference between the bone fixation member and the osteotomy surface. Furthermore, the gap is 45.0 mm or less, thereby preventing the bone fixation member from excessively disengaging from the osteotomy surface.

[0035] In the above-described manner, the bone plate may have a lower surface disposed on the side of the tibia and an upper surface opposite to the lower surface and disposed on the opposite side of the side of the tibia. The central axis of at least one through hole of the main body and the transverse portion is inclined relative to the normal of the tangent plane of the upper surface of the at least one through hole. The upper surface has a raised portion disposed around the at least one through hole, which is located on the side where the angle between the central axis and the tangent plane is obtuse.

[0036] Without the raised portion, the corner of the head inside the through hole, where the central axis is inclined relative to the normal of the tangent plane, protrudes from the upper surface at the obtuse angle. By providing the raised portion, the obtuse angle side of the head inside the through hole is covered, thus preventing the corner of the head from protruding from the upper surface.

[0037] The effects of the invention are as follows.

[0038] According to the present invention, the side of the tibia that protrudes appropriately from the side of the epiphysis relative to the side of the diaphragm has the effect of being suitable for use. Attached Figure Description

[0039] Figure 1A This is a front view of a bone plate according to one embodiment of the present invention.

[0040] Figure 1B yes Figure 1A Rear view of the bone plate.

[0041] Figure 1C yes Figure 1A Top view of the bone plate.

[0042] Figure 1D yes Figure 1A A bottom view of the bone plate.

[0043] Figure 1E yes Figure 1A Right view of the bone plate.

[0044] Figure 1F yes Figure 1A Left view of the bone plate.

[0045] Figure 2A This is a front view of a bone fixation member according to one embodiment of the present invention.

[0046] Figure 2B yes Figure 2A A longitudinal sectional view of the bone fixation member along line II-II.

[0047] Figure 3A This is a diagram showing the bone plate and bone fixation components in use, viewed from the front of the tibia.

[0048] Figure 3B This is a diagram showing the bone plate in use, viewed from the inside of the tibia.

[0049] Figure 3C This is a diagram of the tibia in its working state, viewed from the articular surface side, illustrating the positional relationship between the main body and the transverse portion relative to the tibia.

[0050] Figure 4 This is the right view illustrating the design values ​​of the bone plate.

[0051] Figure 5A It is a diagram illustrating the offset between the main body and the transverse portion of the bone plate, and it is Figure 1A A longitudinal sectional view of the bone plate along line II.

[0052] Figure 5B It is a diagram illustrating the design values ​​of the bone plate, and it is Figure 1A A longitudinal sectional view of the bone plate along line II.

[0053] Figure 5C This is a diagram illustrating another design value for the bone plate, and it is... Figure 1A A longitudinal sectional view of the bone plate along line II.

[0054] Figure 6 This is a right view of the bone plate illustrating the direction of the central axis of the through hole in the transverse section.

[0055] Figure 7 This is a diagram illustrating the placement of the bone plate relative to the tibia.

[0056] Figure 8A It is a bottom view illustrating the direction of the central axis of the through hole in the transverse section and the positional relationship of the bone fixation member inserted into the through hole in the transverse section.

[0057] Figure 8B yes Figure 8A Rear view of the bone plate and bone fixation components.

[0058] Figure 9 This is another diagram illustrating the placement of the bone plate relative to the tibia.

[0059] Figure 10A This is an enlarged front view of the horizontal section.

[0060] Figure 10B This is an enlarged bottom view of the horizontal section.

[0061] Figure 11A It is a partial longitudinal sectional view of the transverse section with raised parts.

[0062] Figure 11B This is a partial longitudinal sectional view of the transverse section without any raised portion.

[0063] Figure 12A This is a diagram illustrating HTO.

[0064] Figure 12B This is a diagram illustrating TCVO. Detailed Implementation

[0065] Hereinafter, a bone plate 1 and a bone plate system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0066] Figures 1A to 1F Bone plate 1 is shown. Figure 2A and Figure 2B The bone fixation member 2 is shown, which is inserted into the through holes 6a-6d and 7a-7d of the bone plate 1 and is used to fix the bone plate 1 to the tibia A. Figure 3A and Figure 3B This illustrates an example of the usage of the bone plate 1 and the bone fixation member 2. For example... Figures 1A to 3B As shown, the bone plate system includes a bone plate 1 and multiple bone fixation members 2.

[0067] The bone plate system is suitable for the lateral aspect of the tibia A where the epiphysis C protrudes relative to the lateral aspect of the diaphysis D. In this embodiment, the use of the bone plate system is described in a tibial condyle eversion osteotomy (TCVO) in which the medial epiphysis C of the tibia A is osteotomized into an L-shape.

[0068] like Figure 3A and Figure 3B As shown, in TCVO, the medial epiphysis C of the tibia A is osteotomized in an L-shape from the medial surface to the articular surface B, cutting the bone fragment C1 of the medial epiphysis C. Next, the osteotomy section E is opened by lifting and rotating the bone fragment C1, so that the lateral articular surface B contacts the lateral articular surface of the femur. If necessary, artificial bone is inserted into the opened osteotomy section E. Then, a bone plate 1 is positioned on the medial surface of the tibia A, and the bone plate 1 is fixed to the epiphysis C and the shaft D using bone fixation devices 2.

[0069] Thus, in TCVO, the severed bone fragment C1 is lifted by rotating it approximately around the center of the articular surface B. Therefore, compared to HTO, the bone fragment C1 protrudes more medially relative to the bone shaft D. Furthermore, depending on individual differences in the shape of the articular surface B, the position of the bone fragment C1 is corrected so that the medial articular surface B conforms to the articular surface of the femur, thus lifting the bone fragment C1 either anteriorly or posteriorly. Sometimes, a gap is also created between the bone fragment C1 at the articular surface B and the lateral epiphysis C2.

[0070] Thus, unlike HTO, the bone morphology after TCVO correction is significantly different from that of a normal knee.

[0071] like Figures 1A to 1F As shown, the bone plate 1 includes a long, strip-shaped main body 3, a transverse section 4 disposed at one end of the main body 3, and a strip-shaped connecting section 5 extending between the main body 3 and the transverse section 4 and connecting the main body 3 and the transverse section 4. The transverse section 4 is a strip-shaped part that extends in a direction intersecting the long side of the main body 3 and is shorter than the main body 3. Therefore, the bone plate 1 is a plate-shaped component that is approximately L-shaped or approximately T-shaped when viewed from the front view along the thickness direction of the main body 3. Furthermore, the bone plate 1 has an upper surface 1a and a lower surface 1b that are opposite each other in the thickness direction.

[0072] The bone plate 1 has proximal, distal, anterior, posterior, medial, and lateral sides corresponding to the proximal, distal, anterior, posterior, superior, and inferior sides of the tibia A, respectively. The bone plate 1 shown in the attached figure is for the tibia A of the left leg. The transverse portion 4 is positioned proximal to the main body 3, with the upper surface 1a and lower surface 1b positioned superiorly and inferiorly, respectively. The bone plate 1 is positioned on the medial surface of the tibia A such that its lower surface 1b contacts the surface of the tibia A.

[0073] In one design example of the bone plate 1, the width of the main body 3 is 11mm to 18mm, the width of the transverse portion 4 is 20mm to 40mm, preferably 25mm to 35mm, and the width of the connecting portion 5 is 12mm to 25mm. To achieve both high strength and thinness, the thickness of the bone plate 1 is preferably 3mm ± 1mm. The width is the dimension along the shorter side of the main body 3.

[0074] The main body 3 has a plurality of through holes 6a to 6d arranged at intervals and penetrating the main body 3 in the thickness direction. The transverse section 4 has a plurality of through holes 7a to 7d arranged at intervals and penetrating the transverse section 4 in the thickness direction. The connecting section 5, except at the boundary with the main body 3 and the boundary with the transverse section 4, does not have through holes for the bone fixation member 2. In the illustrated example, the main body 3 has four through holes 6a, 6b, 6c, and 6d arranged in the long side direction of the main body 3, and the transverse section 4 has four through holes 7a, 7b, 7c, and 7d arranged in two rows.

[0075] The number of through holes in the main body 3 and the horizontal section 4 can be one, two, three, or five or more, respectively. Furthermore, the multiple through holes in the horizontal section 4 can be arranged in a single row along the long side of the horizontal section 4.

[0076] like Figure 3A and Figure 3BAs shown, the main body 3 is positioned on the inner surface of the bone shaft D along the long side of the bone shaft D and is fixed to the bone shaft D by multiple bone fixation members 2. The transverse part 4 is positioned on the inner surface of the bone plate C1 along the anterior-posterior direction of the epiphysis C and is fixed to the epiphysis C by multiple bone fixation members 2. The connecting part 5 is positioned on the opened osteotomy part E.

[0077] The boundary between the transverse portion 4 and the connecting portion 5 is located near the corner of the distal end of the bone fragment C1. In order to incorporate the corner of the distal end of the bone fragment, the boundary between the transverse portion 4 and the connecting portion 5 may also bulge upward.

[0078] like Figure 1E and Figure 1F As shown, the bone plate 1 is curved along its entire length from the proximal end to the distal end in the width direction (the direction of the short side of the main body 3), and the lower surface 1b becomes a concave surface along the convex surface of the tibia A. To ensure a more proper fit between the lower surface 1b of the transverse portion 4 and the medial surface of the bone plate C1, as shown... Figure 4 As shown, in a side view of the bone plate 1 viewed from the proximal side along the short axis of the transverse portion 4, the lower surface 1b of the transverse portion 4 preferably passes between two arcs Q1 and Q2. Arcs Q1 and Q2 pass through the front and rear ends of the transverse portion 4, respectively, with arc Q1 having a radius of curvature of 20 mm and arc Q2 having a radius of curvature of 40 mm.

[0079] Bone fixation component 2 is a rod-shaped part, such as a bone screw or bone pin. For example... Figure 2A As shown, the bone fixation member 2 has a rod-shaped shaft portion 2a that is inserted into the tibia through through holes 6a-6d and 7a-7d, and a head 2b that is fixed to the base end of the shaft portion 2a and has a larger diameter than the shaft portion 2a.

[0080] It can also be like Figure 2B As shown, the bone fixation member 2 has a hollow portion 2c that extends through the long axis of the axial portion 2a.

[0081] External threads are provided on the outer peripheral surface of the head 2b. The external threads are fastened to the internal threads formed on the inner peripheral surfaces of the through holes 6a-6d and 7a-7d, and the shaft portion 2a is coaxially arranged with the through holes 6a-6d and 7a-7d. When the bone fixation member 2 is a bone screw, external threads are also provided on at least a portion of the outer peripheral surface of the shaft portion 2a.

[0082] In TCVO, since bone fragment C1 is completely severed from the diaphysis D and the lateral epiphysis C2, bone fragment C1 needs to be securely fixed to the lateral epiphysis C2, which is continuous with the diaphysis D, using bone fixation piece 2. Furthermore, sometimes a gap is left between bone fragment C1 and the lateral epiphysis C2.

[0083] Therefore, a bone fixation member 2 with a longer axial portion 2a that can reach the lateral surface or near the lateral surface of the bone shaft D is used for fixing the transverse portion 4.

[0084] In TCVO, in addition to bone fixation member 2, rod-shaped components such as metal wires are also used. Rod-shaped components other than bone fixation member 2 can also be inserted into each of the through holes 6a-6d and 7a-7d. Depending on the purpose of the through holes 6a-6d and 7a-7d, a portion of the through holes 6a-6d and a portion of the through holes 7a-7d may not have internal threads.

[0085] The connecting portion 5 is twisted forward from the proximal side toward the distal side about an axis parallel to the long axis of the main body portion 3, and the main body portion 3 is positioned in a position that is twisted forward relative to the transverse portion 4. Figure 3B and Figure 3C As shown, with the osteotomy section E open, the inner surface of the bone shaft D is offset anteriorly relative to the inner surface of the bone fragment C1. By twisting the main body 3 anteriorly relative to the transverse section 4, the main body 3 and the transverse section 4 can be appropriately positioned on the inner surface of the bone shaft D and the inner surface of the bone fragment C1, respectively.

[0086] like Figure 1E As shown, in a side view observed along the short axis of the transverse portion 4, considering individual differences in the bone morphology of the diaphragm D, the angle γ between plane P1 and plane P2 is preferably 8° to 30°. Angle γ corresponds to the torsional angle between the main body portion 3 and the transverse portion 4. Plane P1 is a plane parallel to the short axis of the transverse portion 4 and connected to the front and rear ends of the lower surface 1b of the main body portion 3; plane P2 is a plane parallel to the short axis of the transverse portion 4 and connected to the front and rear ends of the lower surface 1b of the transverse portion 4.

[0087] like Figure 1C and Figure 1D As shown, in a top or bottom view of the bone plate 1 along the short side of the main body 3, the main body 3 and the transverse portion 4 are parallel or substantially parallel to each other, and the connecting portion 5 is inclined downward from the proximal side to the distal side relative to the long side of the main body 3. Using this connecting portion 5, the bone plate 1 is bent into a crank shape in which the main body 3 and the transverse portion 4 are offset from each other in a direction parallel to the plate thickness direction; in particular, the transverse portion 4 is offset upward relative to the main body 3.

[0088] Figure 5A It is a longitudinal section of the bone plate 1 along the short axis of the transverse portion 4. For example... Figure 5AAs shown, the offset Δ between the main body 3 and the transverse section 4 is preferably 9mm ± 3mm, more preferably 9mm ± 1mm. The offset Δ is the distance between two intersection points Pi and Pj in a direction orthogonal to the major axis of the main body 3. Intersection point Pi is the intersection of the central axis of the nearest through hole 6a of the main body 3 and the lower surface 1b, and intersection point Pj is the intersection of the central axis of the nearest through hole 7a of the transverse section 4 and the lower surface 1b.

[0089] and Figure 5A same, Figure 5B and Figure 5C This is a longitudinal section of the bone plate 1 along the short axis of the transverse portion 4, showing a design example of the bone plate 1 used to make the offset Δ between the main body portion 3 and the transverse portion 4 appropriate.

[0090] exist Figure 5B In the longitudinal section, angle α is 155°±10° and angle β is 160°±10°. More preferably, angle α is 160°±5° and angle β is 165°±5°.

[0091] Angle α is the angle formed by the minor axis of the transverse section 4 and the major axis of the connecting section 5, and angle β is the angle formed by the major axis of the connecting section 5 and the major axis of the main body section 3.

[0092] Furthermore, in Figure 5C In the longitudinal section, length L2 is 38.5mm ± 5mm, the sum of lengths L1 and L2 is 59mm ± 5mm, and the sum of lengths L1, L2, and L3 is 104mm to 135mm. Length L1 is the length between the proximal end of the transverse section 4 and the central axis of the farthest through hole 7d in the transverse section 4. Length L2 is the length between the central axis of the farthest through hole 7d in the transverse section 4 and the central axis of the nearest through hole 6a in the main body section 3. Length L3 is the length between the central axis of the nearest through hole 6a in the main body section 3 and the farthest end of the main body section 3.

[0093] Next, the function of the bone plate 1 and the bone plate system will be explained.

[0094] To perform TCVO using a bone plate system, the medial epiphysis C is osteotomized into an L-shape. While lifting the bone plate C1 of the medial epiphysis C, approximately centering on the articular surface B, it is rotated, thereby opening the osteotomy section E between the bone plate C1 and the bone shaft D. Artificial bone is then inserted into the opened osteotomy section E as needed.

[0095] Next, the bone plate 1 is placed on the medial side of the tibia A across the opened osteotomy section E. The transverse section 4 is fixed to the epiphysis C by inserting the bone fixation member 2 through the through holes 7a to 7d, and the main body 3 is fixed to the bone shaft D by inserting the bone fixation member 2 through the through holes 6a to 6d.

[0096] With the osteotomy portion E open, the medial surface of the tibia A has a shape in which the medial surface of the bone plate C1 protrudes significantly medially relative to the medial surface of the bone shaft D. The bone plate 1 of this embodiment has a crank shape in which the transverse portion 4 is offset relative to the main body portion 3 in a direction corresponding to the protrusion direction of the bone plate C1 relative to the bone shaft D, and has a shape that conforms to the shape of the medial surface of the tibia A when the osteotomy portion E is open. Therefore, the bone plate 1 can be appropriately used in TCVO. Specifically, the bone plate 1 can be positioned on the tibia A such that the main body portion 3 and the transverse portion 4 respectively contact the medial surface of the bone shaft D and the medial surface of the epiphysis C, thereby preventing the bone plate 1 from floating off the bone surface.

[0097] In particular, since the soft tissue covering the medial side of the tibia A is relatively thin, the bone plate that floats off the surface of the tibia A can cause tension in the skin on the medial side of the knee. According to this embodiment, it is possible to prevent the bone plate from floating off the surface of the tibia A and affecting the soft tissue.

[0098] In this embodiment, the through holes 7a to 7d of the transverse section 4 are preferably arranged in at least two rows along the short axis of the transverse section 4. In the reference drawings, three through holes 7a to 7c are arranged in the first row on the proximal side, and one through hole 7d is arranged in the second row on the distal side. The through holes 7a to 7c in the first row are preferably arranged at equal intervals.

[0099] In this way, by arranging the through holes 7a to 7d in two rows, the bone pieces C1, which are raised to a greater extent proximal to the proximal side, can be more stably fixed in the longitudinal direction using the two rows of bone fixation pieces 2.

[0100] Since bone fixation member 2 is sometimes inserted near osteotomy section E, the through hole 7d of the second column of transverse section 4 is preferably located at or near the boundary between transverse section 4 and connecting section 5, and the through hole 6a of the main body section 3 closest to the side is preferably located at or near the boundary between connecting section 5 and main body section 3.

[0101] Furthermore, to prevent interference between the shaft portion 2a and the osteotomy surface, the shortest distance on the lower surface 1b between the bone fixation member 2 passing through the first row of through holes 7a, 7b, and 7c and the bone fixation member 2 passing through the second row of through holes 7d is preferably 3mm to 15mm. Furthermore, the gap between the second row of through holes 7d and the through hole 6a closest to the side of the main body portion 3 is preferably 28.5mm to 45.0mm. This gap is the distance between the proximal edge of the through hole 6a and the distal edge of the through hole 7d, corresponding to the shortest distance between the lower neck portion of the bone fixation member 2 passing through the through hole 7d and the lower neck portion of the bone fixation member 2 passing through the through hole 6a. Moreover, from a strength point of view, the outer diameter of the shaft portion 2a is preferably 4.4mm to 6.5mm.

[0102] In this embodiment, such as Figure 1A As shown, in the front view, the bone plate 1 is preferably in a generally L-shape, with the transverse portion 4 extending rearward relative to the connecting portion 5 and the main body portion 3. In the generally L-shaped bone plate 1, all the through holes 7a to 7d of the transverse portion 4 are preferably relatively... Figure 1A The long axis of the main body 3, indicated by the double-dotted line, is positioned at the rear. Furthermore, when viewed along the long axis of the main body 3, the extension lines of at least two central axes within the through holes 6a to 6d of the main body 3 preferably intersect the extension lines of the central axes of all the through holes 7a to 7d of the transverse section 4 at both ends of the front and rear sides of the bone plate 1 in the short side direction of the main body 3.

[0103] like Figure 3B and Figure 3C As shown, the medial surface of the epiphysis C is offset posteriorly relative to the medial surface of the diaphysis D. Compared to a roughly T-shaped bone plate 1, the approximately L-shaped bone plate 1 allows for easier placement of the main body 3 and the transverse portion 4 on the medial surfaces of the diaphysis D and the epiphysis C, respectively. Furthermore, this arrangement facilitates the appropriate insertion of bone fixation members 2 with longer axial portions 2a into both the epiphysis C and the diaphysis D.

[0104] In the main view of the roughly L-shaped bone plate 1, the long axis of the main body 3 and the long axis of the connecting part 5 may form an angle with each other, and the long axis of the connecting part 5 and the short axis of the transverse part 4 may form an angle with each other. Figure 1A In the example, the connecting portion 5 is tilted forward from the proximal side to the distal side relative to the short axis of the transverse portion 4, and the angle between the long axis of the main body portion 3 and the long axis of the connecting portion 5 is approximately 165°.

[0105] In the transverse section 4 of the roughly L-shaped bone plate 1, the through hole 7d of the second column is preferably disposed between the two through holes 7a and 7b on the front side of the first column.

[0106] In order to improve the strength of the bone plate 1, the width and thickness of the transverse portion 4 are increased, which puts a burden on the soft tissue around the epiphysis C. Considering the burden on the soft tissue, when the through hole 7d of the second row is located near the center in the width direction of the transverse portion 4, the through hole 7d is preferably located between the two through holes 7a and 7b on the front side.

[0107] In this embodiment, such as Figure 6 As shown, in a side view taken from the proximal side along the short axis of the transverse section 4, the directions of the central axes of all the through holes 7a to 7d in the transverse section 4 are preferably different from each other. Figure 6 In the middle, the solid line represents the central axis of the through holes 7a to 7d.

[0108] Specifically, the central axis of the central through hole (second through hole) 7b in the first column is inclined forward from the upper surface 1a toward the lower surface 1b relative to the normal of the tangent plane of the lower surface 1b of the through hole 7b, preferably by 8.5° ± 5° relative to the normal. The central axis of the front through hole (first through hole) 7a in the first column is inclined forward from the upper surface 1a toward the lower surface 1b relative to the normal of the tangent plane of the lower surface 1b of the through hole 7a, preferably by 23° ± 5° relative to the normal. The central axis of the rear through hole (third through hole) 7c in the first column is inclined backward from the upper surface 1a toward the lower surface 1b relative to the normal of the tangent plane of the lower surface 1b of the through hole 7c, preferably by 9.5° ± 5° relative to the normal. The central axis of the through hole 7d in the second column is inclined forward from the upper surface 1a toward the lower surface 1b relative to the normal of the tangent plane of the lower surface 1b of the through hole 7d, preferably by 5° ± 5° relative to the normal.

[0109] Figure 6 In the diagram, the single-dot dashed line represents the normal to the tangent plane of the lower surface 1b of each of the through holes 7a, 7b, and 7c.

[0110] In TCVO, the skin incision is often located towards the front of the knee, therefore in most cases, such as Figure 7 As shown in the left figure, the bone plate 1 is positioned near the anterior side of the tibia A. As described above, the central axis of the through holes 7a-7d of the transverse portion 4 is tilted anteriorly towards the insertion direction of the bone fixation member 2, thereby allowing the longer shaft portion 2a to be properly inserted into the epiphysis C without protruding from the surface of the epiphysis C, even when the bone plate 1 is positioned near the anterior side of the tibia A. Furthermore, as... Figure 7 As shown in the right figure, even when the bone plate 1 is positioned near the posterior side on the tibia A, the longer shaft portion 2a can be inserted in a manner that does not protrude from the surface of the epiphysis C.

[0111] Furthermore, the central axes of the through holes 7a, 7b, and 7c in the first row are preferably inclined relative to each other in the front-rear direction as they approach each other towards the lower side. Preferably, the central axes of the through holes 7a, 7b, and 7c are inclined relative to each other at the angle such that the shaft portion 2a of the bone fixation member 2 passing through the central through hole 7b contacts the shaft portion 2a of the bone fixation member 2 passing through the front and rear through holes 7a and 7c at a position 80mm to 120mm away from the lower surface 1b.

[0112] In this structure, the axial portions 2a of the three bone fixation members 2, passing through through holes 7a, 7b, and 7c, converge within the epiphyseal portion C. Thus, as... Figure 7 As shown in the left and right figures, even when the bone plate 1 is positioned near the anterior or posterior side relative to the tibia A, the longer shaft portion 2a can be inserted into the vicinity of the lateral surface or the lateral surface of the epiphysis C without protruding from the bone surface.

[0113] When the directions of the central axes of the through holes 7a, 7b, and 7c are different from each other, it is preferable to use a bone fixation member 2 with a hollow portion 2c.

[0114] When the central axes of the through holes 7a to 7d are not aligned, it can be difficult for surgeons to accurately visualize the insertion direction of the bone fixation member 2 into the epiphysis C. The bone fixation member 2, having a hollow portion 2c, can be used in combination with a wire that guides the insertion of the bone fixation member 2 into the tibia A. That is, while observing an X-ray image of the tibia A, the wire is inserted from the medial to the lateral side of the bone fragment C1 and the lateral epiphysis C2, and then the bone fixation member 2 is inserted into the bone fragment C1 and the lateral epiphysis C2 along the guide wire. Thus, each bone fixation member 2 can be inserted into the epiphysis C in the desired direction.

[0115] Furthermore, in a side view taken from the proximal side along the short axis of the transverse section 4, the direction of at least one central axis within the through holes 6a-6d of the main body 3 is preferably different from the direction of all the through holes 7a-7d of the transverse section 4. Specifically, as Figure 6 As shown, at least one central axis within the through holes 6a to 6d is preferably inclined downwards and backwards at a larger angle than that of the through holes 7c and 7d.

[0116] According to this structure, the shaft portion 2a can be properly inserted using the diaphysis D, which is offset anteriorly relative to the epiphysis C.

[0117] In this embodiment, such as Figure 8A and Figure 8B As shown, in a top or bottom view along the width direction, the central axes of the three through holes that are not arranged on the same straight line as the horizontal section 4 are preferably inclined to each other in a direction that approaches each other as they move downwards.

[0118] Specifically, the direction of the central axis of the through holes 7a to 7d is designed as follows: the front end of the shaft portion 2a of the bone fixation member 2 passing through the second row of through holes 7d contacts the front end of the shaft portion 2a of the bone fixation member 2 passing through two of the three through holes 7a, 7b, and 7c in the first row, preferably contacts the front end of the shaft portion 2a of the bone fixation member 2 passing through the rear and central through holes 7c and 7b.

[0119] The anterior ends of the three axial portions 2a are preferably in contact with each other inside the outer epiphyseal portion C2. Specifically, as Figure 8A As shown, the shaft portion 2a of the bone fixation member 2 through the through hole 7d is preferably in contact with the other two shaft portions 2a at a position 50mm to 80mm away from the lower surface 1b.

[0120] According to this structure, a three-dimensional truss structure is formed by three bone fasteners 2 that are in contact with each other at a single point. This improves load-bearing capacity compared to the case where the three bone fasteners 2 bear the load independently. Furthermore, with external threads provided at least at the front end of the shaft portion 2a, the external threads mesh with each other at the contact point, thereby making the three-dimensional truss structure more stable.

[0121] The load-bearing capacity of the three-dimensional truss structure depends on the outer diameter of the shaft portion 2a. Considering the load on the tibia A, the outer diameter of the shaft portion 2a is preferably 4.4 mm to 6.5 mm to ensure the load-bearing capacity of the three-dimensional truss structure.

[0122] like Figure 8A and Figure 8B As shown, in top or bottom view, the central axes of the three through holes 7a, 7b, and 7c arranged in a row along the long side of the transverse section 4 are inclined at the same angle toward the proximal or distal side. The three bone fixation members 2 passing through the three through holes 7a, 7b, and 7c in the first row are preferably arranged on the same plane.

[0123] When the through holes 7a, 7b, and 7c in the first row are inclined at different angles towards the proximal or distal side, the three bone fixation members 2 in the first row are inserted into the epiphysis C at different insertion angles relative to the articular surface B. Therefore, it is possible to use bone fixation members 2 with different lengths of the shaft portion 2a depending on the insertion angle. When the central axes of the three through holes 7a, 7b, and 7c are inclined at the same angle, bone fixation members 2 with the same length of the shaft portion 2a can be used.

[0124] In this case, the central axes of the three through holes 7a, 7b, and 7c are preferably inclined distally from the upper surface 1a toward the lower surface 1b, so that the three bone fixation members 2 on the same plane are positioned distally relative to the proximal end of the bone plate 1. Preferably, as shown... Figure 8AAs shown, the central axes of the three through holes 7a, 7b, and 7c are inclined at an angle ε = 5° ± 3° relative to the normal of the tangent plane of the upper surface 1a of the center of the transverse section 4. Furthermore, preferably, in top or bottom views, the central axes of the through holes 7a, 7b, and 7c are inclined at δ = 77° ± 5° relative to the line segment (refer to the thick dashed line) connecting the proximal end of the transverse section 4 and the boundary between the transverse section 4 and the connecting section 5.

[0125] like Figure 9 As shown, depending on the configuration of the bone plate 1 relative to the tibia A, the insertion direction of the bone fixation member 2 relative to the tibia A varies. Furthermore, in most cases, the medial articular surface B is higher than the lateral articular surface B. By tilting the distal side of the central axis of the through holes 7a, 7b, and 7c, interference between the bone fixation member 2 inserted in the epiphysis C and the articular surface B can be prevented regardless of the configuration of the bone plate 1 relative to the tibia A.

[0126] On the other hand, to avoid interference between the transverse portion 4 and the osteophytes (not shown) present near the medial articular surface B, the transverse portion 4 is positioned distally from the articular surface B. Therefore, it is not recommended that the three bone fixation members 2 in the first row be excessively tilted distally, but rather inserted as parallel to the articular surface B as possible. Thus, as described above, the tilt angle ε of the three through holes 7a, 7b, and 7c is 5°±3°, and the tilt angle δ is preferably 77°±5°.

[0127] In this embodiment, such as Figure 10A and Figure 10B As shown, in order to prevent a portion of the head 2b inside the through holes 7a, 7c, and 7d of the transverse section 4 from protruding from the upper surface 1a, a raised portion 8 may be provided around the through holes 7a, 7c, and 7d. The raised portion 8 is a portion that bulges upward relative to the upper surface 1a around the raised portion 8 and its thickness is locally increased.

[0128] Figure 11A and Figure 11B These are partial cross-sectional views of the transverse portions 4 with and without raised portions 8, along the central axis of the through holes 7d in the second column. The normal to the tangent plane of the curved upper surface 1a or lower surface 1b relative to the position of the through hole 7d is inclined distally from the upper surface 1a toward the lower surface 1b. In one design example, the inclination angle of the central axis of the through hole 7d relative to the normal is 20° ± 5°.

[0129] like Figure 11BAs shown, without the raised portion 8 around the through hole 7d, the corner of the head 2b protrudes from the upper surface 1a on the obtuse angle side where the angle between the central axis of the through hole 7d and the upper surface 1a or the aforementioned tangential plane is obtuse. Since the head 2b protruding from the upper surface 1a may come into contact with surrounding tissue, the head 2b is preferably not protruding beyond the smooth upper surface 1a. The same applies to the through holes 7a and 7c.

[0130] The raised portion 8 is provided on the obtuse angle side of each of the through holes 7a, 7c, and 7d, but not on the acute angle side of each of the through holes 7a, 7c, and 7d. Specifically, the raised portion 8 is provided on the front side of the through hole 7a on the front side of the first row, the rear side of the through hole 7c on the rear side of the first row, and the distal side of the through hole 7d in the second row. Figure 11A As shown, the raised portion 8 is used to eliminate the height difference between the upper surface 1a and the top surface of the head 2b inside the through holes 7a, 7c, and 7d.

[0131] In this way, by providing a raised portion 8 around the through holes 7a, 7c, and 7d to cover the obtuse angle side of the head 2b, it is possible to prevent the corner of the head 2b from protruding from the upper surface 1a.

[0132] If necessary, raised portions 8 may also be provided around the through holes 6a to 6d on the upper surface 1a of the main body 3 and around the through holes 7b on the upper surface 1a of the transverse portion 4.

[0133] As another means to prevent the head 2b from protruding from the upper surface 1a, a method is to provide a countersinking hole in the upper surface 1a to accommodate the head 2b. When ensuring the fastening length between the head 2b and the bone plate 1 and providing the countersinking hole, it is necessary to increase the thickness of the bone plate 1 near the through hole. Furthermore, when the curvature of the bone plate 1 is large, and the central axis of the through hole is significantly inclined relative to the normal of the upper surface 1a, it is necessary to make the countersinking hole deeper, resulting in an increase in the thickness of the bone plate 1. To reduce the impact of the bone plate 1 on surrounding tissues, the bone plate 1 is preferably thinner.

[0134] Based on the aforementioned raised portion 8, the head 2b can be prevented from protruding from the upper surface 1a without increasing the overall thickness of the transverse portion 4, thereby making it easy to achieve a thinner bone plate 1. Furthermore, internal threads are also provided on the surfaces of the through holes 7a, 7c, or 7d of the raised portion 8, which ensures the fastening length between the head 2b and the bone plate 1, thereby improving the fixation force between the bone fixation member 2 and the bone plate 1.

[0135] In one configuration example, the inclination angle of the central axis of each through hole 7a, 7c, 7d relative to the corresponding normal is 5° to 25°, the outer diameter of the head 2b is 4.5mm to 8mm, the thickness of the bone plate 1 excluding the raised portion 8 is 3mm ± 1mm, the maximum width of the raised portion 8 in the direction intersecting the normal is 12mm or less, and the maximum protrusion of the raised portion 8 from the upper surface 1a is 1.2mm or less.

[0136] The fastening structure with the raised portion 8 can be provided not only on the bone plate 1, but also on any component with a through hole that houses the head of a screw. That is, when the through hole extends from the upper surface to the lower surface of the component and the central axis of the through hole is inclined relative to the normal to the tangent plane of the curved upper surface of the through hole, the raised portion 8 is provided in the obtuse-angled region of the peripheral area of ​​the through hole on the upper surface. The screw is inserted into the through hole from the upper surface side toward the lower surface side, and the external thread of the head is fastened to the internal thread of the through hole.

[0137] In this embodiment, the use of the bone plate system in TCVO has been described, but the application of the bone plate system is not limited to this, and it can be used in any treatment of the tibia where the epiphysis protrudes from the side of the tibia relative to the side of the shaft. Therefore, bone plate 1 can also be applied to locations other than the medial surface of the tibia A.

[0138] Symbol Explanation

[0139] 1—Bone plate, 1a—Upper surface, 1b—Lower surface, 2—Bone fixation component, 2a—Axis portion, 2b—Head, 2c—Hollow portion, 3—Main body portion, 4—Transverse portion, 5—Connecting portion, 6a, 6b, 6c, 6d, 7a, 7b, 7c, 7d—Through holes, 8—Raised portion, A—Tibia, B—Articular surface, C—Epiphyseal portion, C1—Bone plate, C2—Lateral epiphyseal portion, D—Bone shaft, E—Osteotomy portion.

Claims

1. A bone plate for tibial condyle eversion osteotomy, suitable for use on the side of the tibia where the epiphysis protrudes relative to the shaft, and fixed to the side of the tibia using a bone fixation device, the bone plate being characterized by comprising: The long, strip-shaped main body portion, which is disposed on the side of the aforementioned bone shaft, has at least one through hole for inserting the aforementioned bone fixation member. A transverse portion, which is a transverse portion disposed on the aforementioned side of the epiphysis, disposed at one end of the aforementioned main body, and having at least one through hole for inserting the aforementioned bone fixation member; and The connecting part connects the aforementioned transverse part to the aforementioned main body part. The aforementioned main body portion is twisted relative to the aforementioned transverse portion about an axis parallel to the major axis of the aforementioned main body portion. When viewed along the short side of the main body, the bone plate is bent into a crank shape, with the connecting portion inclined relative to the long side of the main body and the main body and the transverse portion offset from each other in the thickness direction of the bone plate. It also has a shape that conforms to the morphology of the side surface of the tibia. The torsion angle of the aforementioned transverse portion relative to the aforementioned main body portion about the aforementioned axis is 8° to 30°. The offset in the thickness direction between the main body and the transverse section is 9mm ± 3mm.

2. The bone plate according to claim 1, characterized in that, The aforementioned transverse portion extends relative to the aforementioned main body portion in a direction corresponding to the posterior side of the tibia and in a direction intersecting the long side direction of the aforementioned main body portion, and curves in the direction intersecting the long side direction. When viewed along the short side of the transverse section, the transverse section is positioned on the lower surface of the lateral side of the tibia, between two arcs having radii of curvature of 20 mm and 40 mm respectively, and passing through both ends of the long side of the transverse section.

3. The bone plate according to claim 1, characterized in that, In the longitudinal section of the bone plate along the short axis of the transverse portion, the angle between the short axis of the transverse portion and the long axis of the connecting portion is 155°±10°, the angle between the long axis of the connecting portion and the long axis of the main body is 160°±10°, and the length along the direction of the connecting portion between the center of the nearest through hole in the main body and the center of the farthest through hole in the transverse portion is 38.5mm±5mm.

4. The bone plate according to claim 1, characterized in that, When viewed along the short side of the aforementioned transverse section, the central axes of all the aforementioned through holes in the transverse section face different directions.

5. The bone plate according to claim 1, characterized in that, The aforementioned transverse section has three through holes that are not arranged in a straight line. The central axes of the three through holes are inclined to each other in such a way that the three aforementioned bone fixation members passing through the three through holes are in contact with each other inside the aforementioned epiphysis.

6. The bone plate according to claim 2, characterized in that, The aforementioned transverse section has two or more of the aforementioned through holes arranged along the long side direction of the transverse section. The central axes of the two or more through holes are inclined toward the insertion direction of the bone fixation member and toward the side corresponding to the anterior side of the epiphysis, and are inclined at the same angle toward the distal side of the tibia.

7. The bone plate according to claim 4, characterized in that, The aforementioned transverse portion has, sequentially from the side corresponding to the front of the aforementioned epiphysis to the side corresponding to the rear of the aforementioned epiphysis, a first through hole, a second through hole, and a third through hole arranged in the long side direction of the transverse portion. The central axis of the first through hole is inclined at 23°±5° relative to the normal of the tangent plane of the lower surface of the first through hole. The central axis of the second through hole is inclined at 8.5° ± 5° relative to the normal of the tangent plane of the lower surface of the second through hole. The central axis of the third through hole is inclined at 9.5°±5° relative to the normal of the tangent plane of the lower surface of the third through hole.

8. The bone plate according to claim 1, characterized in that, The gap between the through hole on the side of the main body closest to the horizontal section and the through hole on the side of the horizontal section closest to the main body is 28.5 mm to 45.0 mm.

9. The bone plate according to claim 1, characterized in that, The aforementioned bone plate has a lower surface disposed on the lateral side of the tibia and an upper surface opposite the lower surface and disposed on the opposite side of the lateral side of the tibia. The central axis of at least one of the through holes in the main body and the transverse section is inclined relative to the normal of the tangent plane of the upper surface of the at least one through hole. The aforementioned upper surface has a raised portion surrounding the at least one through hole. The raised portion is located on the side where the angle between the central axis and the tangent plane is obtuse.

10. The bone plate according to claim 9, characterized in that, The central axis of at least one of the aforementioned through holes is inclined at 5° to 25° relative to the aforementioned normal. The outer diameter of the head of the bone fixation member disposed in the aforementioned through hole is 4.5 mm to 8 mm. The maximum width of the aforementioned raised portion in the direction intersecting the aforementioned normal is 12 mm or less. The maximum protrusion of the aforementioned raised portion from the surrounding upper surface is less than 1.2 mm.

11. The bone plate according to claim 1, characterized in that, The width of the main body is 11mm to 18mm. The width of the aforementioned horizontal section is 20mm to 40mm. The width of the aforementioned connecting part is 12mm to 25mm. The thickness of the aforementioned bone plate is 3mm ± 1mm. In the longitudinal section along the short axis of the transverse portion of the aforementioned bone plate, the aforementioned bone plate has a shape that satisfies the following conditions: 33.5mm≤L2≤43.5mm 54mm≤L1+L2≤64mm 104mm≤L1+L2+L3≤135mm in, L1 is the length between the proximal end of the aforementioned transverse section and the central axis of the farthest through hole in the aforementioned transverse section. L2 is the length between the central axis of the farthest through hole in the aforementioned horizontal section and the central axis of the nearest through hole in the aforementioned main body section. L3 is the length between the central axis of the nearest through hole in the main body and the far end of the main body.

12. The bone plate according to any one of claims 1 to 11, characterized in that, All the aforementioned through holes in the transverse section are arranged on the side corresponding to the posterior side of the tibia, relative to the long axis of the main body. When viewed along the long axis of the main body, the extension lines of the central axes of at least two of the through holes in the main body intersect the extension lines of the central axes of all the through holes in the transverse section between the two ends of the bone plate in the short side direction of the main body.

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