Instrument for bone surgery

Abstract

To provide an instrument for a bone surgery which is capable of accurate and simple arc-shaped bone-cutting and hardly causes bone fracture near a bone-cutting surface (arc-cut surface) to be formed.SOLUTION: An instrument for a bone surgery for guiding a bone-cutting blade in an arc-shape includes a flat plate support pillar part (50), an arc-planar guide part (30), and a fixed part (60) fixed to the bone. In the support pillar part, an open hole (20) is formed, which penetrates between a first surface (10A) and a second surface (10B) and is positioned on a specific point of the bone. In the guide part, a through slit (40) is formed, which penetrates between the first surface and the second surface and is opened to an arc-shape on the first surface and a second surface. A central axis of the open hole is vertical to the first surface and the second surface. In a cross-sectional view including the central axis of the open hole, the through slit tilts toward the central axis so that a separation distance from the central axis of the open hole becomes short toward the first surface side.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to bone surgical instruments, and more particularly to instruments used as guides for guiding bone cutting blades in osteotomies. [Background technology]

[0002] Osteotomy is performed to improve the symptoms of knee osteoarthritis, and one of the osteotomy techniques is DTO (distal-tuberosity osteotomy). DTO differs from HTO (high tibial osteotomy) in the location of the osteotomy relative to the tuberosity; in DTO, the osteotomy is performed distal to the tuberosity.

[0003] In DTO, the tibia is cut from the inside toward the hinge point located on the outside proximal part to form a first osteotomy surface, the posterior side of the tibial tuberosity is cut parallel to the tibial axis to form a second osteotomy surface (descending cut surface), and the distal side of the tibial tuberosity is cut along an arc centered on the hinge point to form a third osteotomy surface (arc cut surface).

[0004] In DTAO, which is one form of DTO, Patent Document 1 below proposes a bone surgical instrument (a guide for guiding a bone cutting blade) as shown in Figure 8 as a bone surgical instrument that can be used to form an arc-cut surface. This bone surgery instrument 1 comprises a flat support part 5, an arc-shaped guide part 3, and a fixing part 6 provided on the opposite side of the guide part 3 from the support part 5.

[0005] The support post 5 of this bone surgery instrument 1 is formed with a through hole (pin hole 2a) that is positioned at the hinge point. Furthermore, the guide portion 3 is formed with an arc-shaped slit 4 that penetrates in a direction parallel to the central axis of the through-hole formed in the support portion 5 and has the center on the central axis. Furthermore, the fixing portion 6 is formed with a through-hole (fixing hole 6a) that penetrates in a direction parallel to the central axis of the through-hole formed in the support portion 5.

[0006] With the bone surgical instrument 1 configured as described above, a hinge pin is inserted in the anterior-posterior direction of the tibia (perpendicular to the tibial axis) at the hinge point and passed through the through hole (pin hole 2a), positioning the through hole at the hinge point; the guide portion 3 is placed on the bone so that the slit 4 is located at the site where the bone is to be cut (distal to the tuberosity portion); the fixing portion 6 is fixed to the bone using a fixing pin to prevent the bone surgical instrument 1 from moving relative to the bone; and the bone cutting blade is moved according to the guide of the slit 4 to perform the bone cutting, thereby forming an arc-shaped bone cutting surface (arc cut surface).

[0007] Here, the slit 4 penetrates in a direction parallel to the central axis of the through-hole (pin hole 2a) formed in the support part 5, and therefore the bone cutting blade guided by the slit 4 performs bone cutting in a direction perpendicular to the tibial axis. Therefore, the angle (valley angle) formed between the formed arc cut surface (surface perpendicular to the tibial axis) and the descending cut surface (surface parallel to the tibial axis) is approximately a right angle. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 7309911 Summary of the Invention [Problem to be solved by the invention]

[0009] However, there is a problem in that fractures are likely to occur near the arc-cut surface formed using a bone surgical instrument such as that described in Patent Document 1, particularly near the ridge line (valley ridge line) where the arc-cut surface and the descending cut surface come into contact.

[0010] The present invention has been made in light of the above circumstances, and its object is to provide a bone surgery instrument that can accurately and easily perform arc-shaped bone resection and is less likely to cause fractures near the bone resection surface (arc cut surface) that is formed. [Means for solving the problem]

[0011] In order to solve the above problems, the inventors conducted extensive research and found that when the angle between the arc-cut surface formed by the bone surgical instrument and the descending cut surface is a right angle, stress tends to concentrate on the bone area near the ridge where they come into contact, which can cause fractures; and that if an arc-cut surface can be formed so that the angle it forms with the descending cut surface is an obtuse angle, stress concentration on the bone area near the ridge can be alleviated, thereby suppressing the occurrence of fractures near the ridge. Based on this knowledge, the present inventors have completed the present invention.

[0012] That is, the bone surgical instrument of the present invention is a bone surgical instrument that guides a bone cutting blade in an arc shape, The bone support includes a flat support portion, an arc-shaped guide portion connected to one end of the support portion, and a fixing portion fixed to the bone, The support portion has a first surface (rear surface) that contacts the surface of the bone and a second surface (front surface) opposite to the first surface, and a through hole that is positioned on a specific point of the bone is formed in the support portion; The guide portion has a through slit formed therein, the through slit penetrating between the first surface and the second surface and opening in an arc shape on the first surface and the second surface, the central axis of the through hole is perpendicular to the first surface and the second surface; In a cross-sectional view including the central axis of the through hole, the through slit is inclined with respect to the central axis of the through hole so that the distance from the central axis becomes shorter toward the first surface side.

[0013] In a bone surgical instrument having such a configuration, in a cross-sectional view including the central axis of the through-hole formed in the support part, the through-slit formed in the guide part is inclined with respect to the central axis of the through-hole so that the distance from the central axis of the through-hole becomes shorter toward the first surface side, and therefore, by moving the bone-cutting blade according to the guidance of the through-slit to perform bone cutting, it is possible to form an arc-cut surface whose angle with the descending-cut surface (valley angle) is an obtuse angle. This reduces stress concentration on the bone near the ridge line (valley ridge line) where the formed arc-cut surface and the descending-cut surface meet, and makes it possible to suppress the occurrence of fractures near the ridge line.

[0014] In the bone surgical instrument of the present invention, it is preferable that the inclination angle (θ) of the through slit is 2° or more in a cross section including the central axis of the through hole.

[0015] Preferably, the through hole is formed at the other end of the support column.

[0016] It is also preferable that the fixing portion be provided at a position opposite the support portion across the guide portion. [Effects of the Invention]

[0017] The bone surgical instrument of the present invention enables accurate and easy arc-shaped bone resection, and is less likely to cause fractures near the bone resection surface (arc cut surface), particularly near the ridge where the arc cut surface and the descending cut surface come into contact. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view showing one embodiment of a bone surgical instrument of the present invention. FIG. [Figure 2] FIG. 2 is a plan view of the bone surgical instrument shown in FIG. 1. [Figure 3] FIG. 2 is a bottom view of the bone surgical instrument shown in FIG. 1. [Figure 4]FIG. 2 is a side view of the bone surgical instrument shown in FIG. 1. [Figure 5] FIG. 4 is a cross-sectional view of FIG. 3 . [Figure 6] 2 is an explanatory diagram showing a state in which an arc cut surface formed by osteotomy of a tibia using the bone surgical instrument shown in FIG. 1 comes into contact with a descending cut surface. FIG. [Figure 7] FIG. 10 is an explanatory diagram schematically showing a contact state between an arc-cut surface and a descending-cut surface. [Figure 8] FIG. 1 is a plan view showing a conventionally known bone surgical instrument. DETAILED DESCRIPTION OF THE INVENTION

[0019] The bone surgical instrument 10 of this embodiment shown in FIGS. 1 to 5 is a bone surgical instrument for guiding a bone cutting blade in an arc, and comprises a flat support post portion 50, an arc-plate-shaped guide portion 30 connected to one end of the support post portion 50, and a fixing portion 60 that is fixed to the bone using a fixing pin. The support post portion 50 has a first surface (rear surface) 10A that abuts against the surface of the bone and a second surface (front surface) 10B opposite to the first surface 10A, and a through-hole 20 that is positioned at a specific point. The guide portion 30 has a through slit 40 formed therein, which penetrates between the first surface 10A and the second surface 10B and opens in an arc shape on the first surface 10A and the second surface 10B, and the central axis 25 of the through hole 20 is perpendicular to the first surface 10A and the second surface 10B, and in a cross-sectional view including the central axis 25 of the through hole 20 (see Figure 5), the through slit 40 is inclined with respect to the central axis 25 of the through hole 20 so that the distance between the through slit 40 and the central axis 25 of the through hole 20 becomes shorter toward the first surface 10A.

[0020] The bone surgical instrument 10 of this embodiment is a bone surgical instrument that guides a bone cutting blade in an arc shape.

[0021] This bone surgery instrument 10 is for the left foot, and is composed of a flat plate-shaped support portion 50, an arc-shaped guide portion 30, and a fixing portion 60, which are integrally formed. The bone surgical instrument 10 may be made of stainless steel, titanium, or a titanium alloy.

[0022] The bone surgical instrument 10 has a first surface (posterior surface) 10A that comes into contact with the surface of the tibia, and a second surface (anterior surface) 10B opposite to the first surface 10A.

[0023] The support column 50 has a through-hole 20 formed therein, which penetrates between the first surface 10A and the second surface 10B and is positioned on a specific point (hinge point). When the bone surgical instrument 10 is used for DTO, the "specific bone point" is the hinge point located on the lateral proximal part of the tibia.

[0024] The central axis 25 of the through-hole 20 is perpendicular to the first surface 10A and the second surface 10B. By inserting the hinge pin inserted in the anterior-posterior direction of the tibia (perpendicular to the tibial axis) at the hinge point into the through hole 20, the through hole 20 is positioned on the hinge point and its central axis 25 extends in a direction perpendicular to the tibial axis.

[0025] The guide portion 30 is in the shape of an arcuate plate centered on the central axis 25 of the through-hole 20 . The guide portion 30 has a through slit 40 formed therein, which penetrates between the first surface 10A and the second surface 10B and opens in an arc shape (a substantially arc shape that follows the arc shape of the guide portion 30) on the first surface 10A and the second surface 10B.

[0026] As shown in FIG. 2, the through slit 40 opens in the second surface 10B of the guide part 30 in an arc shape centered near the central axis 25 of the through hole 20. As shown in FIG. 3, the through slit 40 opens in the first surface 10A of the guide part 30 in an arc shape centered near the central axis 25 of the through hole 20. In the cross-sectional view of the bone surgical instrument 10 shown in FIG. 40 indicates the center (axis) of the arc in the through slit 40. That is, the through slit 40 has the guide portion 30 aligned along this central axis L 40It penetrates in a direction parallel to the

[0027] The fixing portion 60 is located on the opposite side of the guide portion 30 from the support portion 50 . The fixing portion 60 has a fixing hole 70 formed therein, which penetrates the fixing portion 60 in a direction parallel to the central axis 25 of the through-hole 20 (in Figures 2, 3 and 5, 75 is the central axis of the fixing hole 70). With the through hole 20 of the support portion 50 positioned on the hinge point by the hinge pin, the fixation pin can be inserted into the tibia via the fixation hole 70, thereby fixing the bone surgical instrument 10 so that it does not move in a direction perpendicular to the central axis 25 of the through hole 20 relative to the tibia.

[0028] The bone surgical instrument 10 of this embodiment is characterized in that the through slit 40 formed in the guide portion 30 is inclined with respect to the central axis 25 of the through hole 20 . That is, in a cross-sectional view including the central axis 25 of the through hole 20 as shown in Figure 5, the through slit 40 penetrating the guide portion 30 (between the first surface 10A and the second surface 10B) is inclined with respect to the central axis 25 of the through hole 20 so that the distance from the central axis 25 becomes shorter from the second surface 10B toward the first surface 10A.

[0029] Here, the inclination angle (θ shown in FIG. 5) of the through slit 40 is preferably 2° or more, more preferably 2 to 45°, particularly preferably 5 to 15°, and a suitable example is 10°. If the inclination angle is too small, the effects of the present invention cannot be fully achieved, whereas if the inclination angle is too large, the amount of bone resection increases, which increases the burden of the procedure and also makes the bone surgical instrument 10 too large.

[0030] 6 shows the contact state between the arc cut surface AC formed by moving the bone cutting blade according to the guide of the through slit 40 to perform bone cutting and the descending cut surface DC (a surface parallel to the tibia axis). In the figure, P1 is a hinge pin inserted into the through hole 20 of the support part 50, and P2 is a fixing pin inserted into the fixing hole 70 of the fixing part 60.

[0031] By moving the bone cutting blade according to the guidance of the through slit 40 inclined relative to the central axis 25 and performing the bone cutting, an arc cut surface AC can be formed such that the angle (valley angle) it forms with the descending cut surface DC parallel to the tibial axis is an obtuse angle (90°+θ).

[0032] Here, as shown in Figure 7(A), if the angle (valley angle) between the descending cut surface DC and the arc cut surface AC is a right angle, stress is likely to concentrate in the bone area near the ridge where these surfaces meet (the area indicated by IA in the same figure), which can cause a fracture.

[0033] In contrast, as shown in Figure 7(B), when the angle (valley angle) between the descending cut surface DC and the arc cut surface AC is obtuse, stress concentration in the bone area near the ridge where these surfaces meet (the area indicated by IB in the same figure) is alleviated, and fractures in that area can be prevented.

[0034] In addition, in DTO, the tuberosity is screwed from the front to the back onto the distal fragment of the tibia, which causes a step between the cut bone portions on either side of the arc-cut surface AC. Here, the step portion shown in Figure 7(A) (the portion indicated by IIA in the figure) is a right angle, making it easy for a fracture to occur at that portion. In contrast, the step portion shown in Figure 7(B) (the portion indicated by IIB in the figure) is an obtuse angle, making it difficult for a fracture to occur at that portion.

[0035] As described above, the bone surgical instrument 10 of this embodiment makes it difficult for fractures to occur in the vicinity of the arc cut surface formed using the instrument.

[0036] In the bone surgical instrument 10 of this embodiment, the shortest distance between the central axis 25 of the through-hole 20 and the through-slit 40 on the first surface 10A (r shown in FIG. 5) is preferably 40 to 65 mm. In addition, this separation distance (r) is 40 and the distance between the through slit 40 (the radius of curvature of the through slit 40) preferably coincides with each other.

[0037] The width (w 30 ) is preferably 4 to 12 mm. The thickness (t) of the guide portion 30 is preferably 5 to 15 mm. Furthermore, it is preferable that the thickness (t) of the guide portion 30 (t / cosθ) is smaller than the length of the bone cutting blade, for example, by about 5 to 25 mm, so that the cutting edge of the bone cutting blade guided by the through slit 40 can protrude from the through slit 40.

[0038] The width (w 40 ) is preferably 1 to 3 mm. In addition, the width (w 40 ) is preferably larger than the thickness of the bone cutting blade by 0.5 to 1.5 mm to prevent the bone cutting blade from rattling inside the through slit 40.

[0039] The minimum thicknesses (d1) and (d3) of the edge portions of the guide portion 30 surrounding the through slit 40 are preferably 0.5 to 2.5 mm, and the maximum thicknesses (d2) and (d4) of the edge portions are preferably 2.5 to 6.5 mm.

[0040] Next, a method for forming descending cut surfaces and arc cut surfaces in DTO performed using the bone surgical instrument 10 of this embodiment will be described. First, a guide wire is inserted from the medial side of the tibia toward the hinge point located at the lateral proximal part, and a hinge pin is inserted in the anterior-posterior direction of the tibia (perpendicular to the tibial axis) at the hinge point.

[0041] Next, the bone surgical instrument 10 is placed on the tibia. Specifically, the hinge pin inserted into the tibia at the hinge point is passed through the through-hole 20 to position the through-hole 20 on the hinge point, and after confirming that the through-slit 40 is located distal to the tuberosity, the fixation pin is inserted into the tibia in the anterior-posterior direction via the fixation hole 70, thereby fixing the fixation part 60 to the tibia.

[0042] Next, a bone saw is inserted into the tibia from the medial side and osteotomy is performed on the posterior tuberosity parallel to the tibial axis, forming a descending cut surface DC between the guide wire and the guide.

[0043] Next, bone cutting is performed using the bone surgical instrument 10. That is, a bone cutting blade is inserted into the through slit 40 located distal to the tuberosity, and bone cutting is performed while moving the bone cutting blade in the circumferential direction within the through slit 40. This forms an arc-cut surface AC whose angle (valley angle) with the descending cut surface DC is an obtuse angle.

[0044] According to the bone surgical instrument 10 of this embodiment, in a cross-sectional view including the central axis 25 of the through hole 20 formed in the support portion 50, the through slit 40 formed in the guide portion 30 is inclined with respect to the central axis 25 so that the distance between the central axis 25 of the through hole 20 and the through slit 40 decreases toward the first surface 10A, and therefore, by moving the bone cutting blade according to the guidance of the through slit 40 to perform bone cutting, it is possible to form an arc-cut surface AC whose angle (valley angle) with the descending-cut surface DC is an obtuse angle. This alleviates stress concentration on the bone near the ridgeline (valley ridgeline) where the formed arc-cut surface AC and the descending-cut surface DC come into contact, thereby suppressing the occurrence of fractures near the ridgeline. [Explanation of symbols]

[0045] 10 Bone surgery instruments 10A 1st side (rear side) 10B 2nd side (front) 20 through holes 25 Central axis of through hole 30 Guide section 40 Through slit 50 Support section 60 Fixed part 70 fixing hole AC Arc Cut Surface DC descending cut surface P1 Hinge pin P2 fixing pin

Claims

1. A bone surgical instrument for guiding a bone cutting blade in an arc shape, The bone support includes a flat support portion, an arc-shaped guide portion connected to one end of the support portion, and a fixing portion fixed to the bone, the support portion has a first surface that contacts the surface of the bone and a second surface opposite to the first surface, and a through hole that is positioned on a specific point of the bone; a through slit is formed in the guide portion, the through slit penetrating between the first surface and the second surface and opening in an arc shape in the first surface and the second surface; the central axis of the through hole is perpendicular to the first surface and the second surface; In a cross-sectional view including the central axis of the through hole, the through slit is inclined with respect to the central axis of the through hole so that a distance from the central axis of the through hole becomes shorter toward the first surface side.

2. 2. The bone surgical instrument according to claim 1, wherein the inclination angle (θ) of the through slit is 2° or more in a cross section including the central axis of the through hole.

3. 3. The bone surgical instrument according to claim 1, wherein the through-hole is formed in the other end of the support rod.

4. 3. The bone surgical instrument according to claim 1, wherein the fixing portion is provided on the opposite side of the guide portion from the support portion.

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