Alignment block and cutting guide

Abstract

An alignment block according to one embodiment is for guiding a cut surface into an appropriate angular direction during cutting of the distal end of a femur and includes: a support body to which a cutting block that guides a bone saw is detachably attachable; a first movable body having a first contact surface that comes into contact with one of the medial and lateral condyles of the femur; and a second movable body having a second contact surface that comes into contact with the other of the medial and lateral condyles of the femur. The first movable body and the second movable body are supported by the support body so as to be movable in a direction perpendicular to the first contact surface and the second contact surface. The alignment block further includes a first biasing means for biasing the first movable body in the facing direction of the first contact surface and a second biasing means for biasing the second movable body in the facing direction of the second contact surface.

Description

Alignment Block and Cutting Guide

[0001] This application relates to an alignment block for guiding a resection surface in an appropriate angular direction when resected the distal end of the femur, and a cutting guide including the alignment block.

[0002] In total knee arthroplasty (TKA), the proximal end of the tibia and the distal end of the femur are resected, and the tibial component and the femoral component of the artificial knee joint are respectively attached to the resection surface of the tibia and the resection surface of the femur. In total knee arthroplasty, various surgical instruments are used.

[0003] For example, Patent Document 1 discloses an alignment block 100 (referred to as "valgus alignment guide" in Patent Document 1) used together with a rod 200 (referred to as "F rod" in Patent Document 1) and a cutting block (not shown) when resected the distal end of the femur as shown in FIG. 20. The rod 200 is inserted into the femur and installed along the anatomical axis of the femur, and the cutting block guides the bone saw.

[0004] Specifically, the alignment block 100 includes a rod holder 110 that holds the rod 200, a support 120 (referred to as "main body part" in Patent Document 1) attached to the rod holder 110, and a pair of moving bodies 130 (referred to as "support" in Patent Document 1) attached to the support 120 and respectively contacting the medial condyle and the lateral condyle of the femur.

[0005] The support 120 has a shape symmetric about the center line, and is swingably attached to the rod holder 110 so that the valgus angle, which is the angle of the center line with respect to the axial direction of the rod 200, can be changed. Each moving body 130 is attached to the support 120 so as to be movable in the direction in which the center line of the support 120 extends. The surface of each moving body 130 facing the femur side is the contact surface 131.

[0006] A cutting block, not shown in the figure, is detachably attached to the tip of the support 120. Furthermore, as shown in Figure 21, multiple teeth 121 are formed on both sides of the tip of the support 120, aligned in the direction in which the centerline of the support 120 extends. Meanwhile, each movable body 130 incorporates a retractable member 140 having teeth 141 that can engage with the teeth 121, and a button 150 for operating the retractable member 140, as shown in Figure 22. The retractable member 140 is biased in the forward direction by a spring 160, and the biasing force of the spring 160 maintains the engagement between the teeth 121 and 141. Pressing the button 150 retracts the retractable member 140, releasing the engagement between the teeth 121 and 141, allowing the movable body 130 to move in the direction in which the centerline of the support 120 extends.

[0007] Japanese Patent No. 6434277

[0008] In the alignment block 100 of Patent Document 1, when the alignment block 100 is placed on the distal end of the femur, the contact surfaces 131 of both sides can be brought into contact with the medial and lateral condyles of the femur by operating one or both of the movable bodies 130. For this reason, the alignment block 100 can also be used as a means to refer to the shapes of the medial and lateral condyles (as a reference for measurement and positioning).

[0009] Incidentally, when the alignment block 100 is placed on the distal end of the femur, the eversion angle, which is the angle perpendicular to the contact surface 131 with respect to a specific direction (in the case of the alignment block 100, the axial direction of the rod 200), and the internal and external rotation angles around the said specific direction are adjusted by changing the orientation of the alignment block 100 relative to the femur. In this case, with a structure like the alignment block 100 of Patent Document 1, it is necessary to operate one or both of the movable bodies 130 to re-contact both the medial and lateral condyles each time the orientation of the alignment block 100 relative to the femur is changed, so it is not possible to adjust the eversion angle or internal and external rotation angles while maintaining a state that references the shapes of the medial and lateral condyles.

[0010] Therefore, the present application aims to provide an alignment block that can adjust the eversion angle and internal / external rotation angle while maintaining a state that references the shapes of the inner and outer condyles, and a cutting guide including the alignment block.

[0011] This application provides an alignment block for guiding the cutting surface in an appropriate angular direction when resecting the distal end of a femur from one side, comprising: a support to which a cutting block that guides a bone saw can be attached and detached; a first movable body having a first contact surface that abuts against one of the medial and lateral condyles of the femur, and supported by the support so as to be movable in a direction perpendicular to the first contact surface; a first biasing means for biasing the first movable body in the direction toward the first contact surface; a second movable body having a second contact surface that abuts against the other of the medial and lateral condyles of the femur, and supported by the support so as to be movable in a direction perpendicular to the second contact surface; and a second biasing means for biasing the second movable body in the direction toward the second contact surface.

[0012] This application also provides a cutting guide comprising: a rod installed along the femoral evaluation axis; an alignment block further comprising a rod holder for holding the rod, wherein the support is pivotably attached to the rod holder such that the eversion angle, which is the angle perpendicular to the first contact surface with respect to the axial direction of the rod, can be changed; and a cutting block for guiding a bone saw, which is detachably attached to the support of the alignment block.

[0013] This application also provides, from yet another aspect, a cutting guide for use with a surgical navigation system, comprising: an alignment block (with or without a rod holder); a cutting block for guiding a bone saw, which is detachably attached to a support of the alignment block; and a marker for the surgical navigation system to recognize the position and orientation of the cutting block in three-dimensional space.

[0014] According to this application, an alignment block is provided that can adjust the eversion angle and internal / external rotation angle while maintaining a reference to the shapes of the medial and lateral condyles, and a cutting guide including the alignment block is provided.

[0015] Figure 1 is a perspective view of an alignment block according to the first embodiment. Figure 2 is an exploded perspective view of the alignment block around the rod holder. Figure 3 is an exploded perspective view of the alignment block around the first and second moving parts. Figure 4 is a front cross-sectional view of the alignment block. Figure 5 is a front view of the alignment block. Figure 6 is a perspective view of a cutting guide including the alignment block. Figure 7A is a front view showing the cutting guide in use. Figure 7B is a side view showing the cutting guide in use. Figure 8 is a perspective view of a modified alignment block. Figure 9 is a perspective view of the alignment block shown in Figure 8 from a different angle. Figure 10 is a perspective view of another modified alignment block. Figure 11 is a front view of yet another modified alignment block. Figure 12A is a perspective view of a modified cutting block. Figure 12B is an exploded perspective view of the cutting block. Figure 13 is an exploded perspective view of a modified cutting guide. Figure 14 is a side view showing the cutting guide shown in Figure 13 in use. Figure 15 is an exploded perspective view of a cutting guide of another modified example. Figure 16 is a side view showing the cutting guide shown in Figure 15 in use. Figure 17 is a perspective view of an alignment block according to a second embodiment. Figure 18 is a front view of the alignment block shown in Figure 17. Figure 19 is a perspective view of a cutting guide including an alignment block according to a third embodiment. Figure 20 is a front view of a conventional alignment block. Figure 21 is a perspective view of a conventional alignment block. Figure 22 is a cross-sectional view of the movable body of a conventional alignment block.

[0016] <First Embodiment> Figure 1 shows an alignment block 1A according to the first embodiment. This alignment block 1A is used to guide the resection surface in an appropriate angular direction when resecting the distal end of the femur 9 (see Figures 7A and 7B). The femur 9 shown in Figures 7A and 7B is the femur of the left leg, but the alignment block 1A can also be used for the femur of the right leg.

[0017] As shown in Figure 6, the alignment block 1A, together with a rod 20 installed along the femoral evaluation axis and a cutting block 8 that guides a bone saw (not shown), constitutes a cutting guide 10A. In this embodiment, the rod 20 is a linear intramedullary rod 20A inserted into the femur 9, and the femoral evaluation axis is the femoral anatomical axis. Here, the femoral anatomical axis is the evaluation axis for lower limb alignment that passes through the center of the femoral shaft. In this application, the axis set from the bone shape for lower limb alignment evaluation is referred to as the evaluation axis. In addition to the femoral anatomical axis, the femoral functional axis (an evaluation axis for lower limb alignment that connects the femoral head and the knee joint center) can also be used as the femoral evaluation axis, and in this application, the term femoral evaluation axis refers to either the femoral anatomical axis or the femoral functional axis.

[0018] Specifically, as shown in Figures 1 to 3, the alignment block 1A includes a rod holder 2 for holding the rod 20, a support 3 that is pivotably attached to the rod holder 2, and a first movable body 4 and a second movable body 5 supported by the support 3.

[0019] As shown in Figures 7A and 7B, the first movable body 4 has a first contact surface 40 that abuts against one of the medial condyle 91 and lateral condyle 92 of the femur 9, and the second movable body 5 has a second contact surface 50 that abuts against the other of the medial condyle 91 and lateral condyle 92 of the femur 9. The first contact surface 40 and the second contact surface 50 are flat surfaces parallel to each other. In Figures 7A and 7B, the first contact surface 40 abuts against the medial condyle 91 and the second contact surface 50 abuts against the lateral condyle 92. However, when the alignment block 1A is used upside down or when it is used on the femur of the right foot in its original orientation, the first contact surface 40 abuts against the lateral condyle 92 and the second contact surface 50 abuts against the medial condyle 91.

[0020] For the sake of explanation, the perpendicular direction of the first contact surface 40 and the second contact surface 50 will be referred to as the up-down direction (the direction in which the first contact surface 40 and the second contact surface 50 face is upward, and the opposite direction is downward), the direction in which the first contact surface 40 and the second contact surface 50 are aligned will be referred to as the left-right direction (the side of the first contact surface 40 is to the left, and the side of the second contact surface 50 is to the right), and the direction perpendicular to the up-down and left-right directions will be referred to as the front-back direction (the front side (operator side) when using the alignment block 1A is forward, and the back side is backward).

[0021] In this embodiment, the rod holder 2 is slidable along the rod 20. Specifically, the rod holder 2 includes a cylindrical body 21 extending in the vertical direction, and the rod 20 is inserted into the cylindrical body 21. In this embodiment, the cylindrical body 21 is rectangular prism-shaped, but the cylindrical body 21 may also be hexagonal prism-shaped, cylindrical, or the like.

[0022] The support 3 is pivotably mounted on the rod holder 2 such that the eversion angle, which is the angle perpendicular to the first contact surface 40 with respect to the axial direction of the rod 20, can be changed. More specifically, the support 3 includes a frame 31 having a pair of long sides extending in the left-right direction and a pair of short sides extending in the front-back direction, with the upper part of the cylindrical body 21 of the rod holder 2 fitting into the frame 31.

[0023] The upper part of the cylindrical body 21 of the rod holder 2 is provided with a hole 26 that penetrates the upper part in the front-to-back direction, while the center of both long sides of the frame body 31 is also provided with a hole 37 that penetrates both long sides in the front-to-back direction. By inserting pins 27 into the holes 37 and 26 from both sides, the support body 3 is pivotably attached to the rod holder 2. In other words, the support body 3 pivots around the pins 27 relative to the rod 20 held by the rod holder 2.

[0024] Support columns 32 and 33 extend downward from both short sides of the frame 31 of the support body 3, sandwiching the rod holder 2. A projection 30 is provided at the lower end of the right-hand support column 33, projecting toward the rod holder 2.

[0025] In this embodiment, the support 3 is only capable of swinging in the direction in which the second contact surface 50 rises and the first contact surface 40 falls, starting from a state in which the perpendicular direction of the first contact surface 40 and the axial direction of the rod 20 are parallel. In other words, as shown in Figure 5, the support 3 is capable of swinging counterclockwise around the pin 27 relative to the rod 20 held in the rod holder 2, starting from a state in which the perpendicular direction of the first contact surface 40 and the axial direction of the rod 20 are parallel, as viewed from the front. On the other hand, in the support 3, clockwise swinging of the pin 27 relative to the rod 20 held in the rod holder 2 is restricted, starting from a state in which the perpendicular direction of the first contact surface 40 and the axial direction of the rod 20 are parallel, as viewed from the front. In other words, the projection 30 functions as a stopper that contacts the cylindrical body 21 of the rod holder 2 when the perpendicular direction of the first contact surface 40 and the axial direction of the rod 20 are parallel. Furthermore, the right side of the lower part of the left support column 32 is inclined so as to make surface contact with the left side of the cylindrical body 21 of the rod holder 2 when the support body 3 swings.

[0026] An arm 34 extends diagonally upward to the right from the lower end of the right-side support column 33, more precisely in the circumferential direction centered on the pin 27. Multiple V-grooves 34a are formed on the lower surface of the arm 34, arranged in the circumferential direction centered on the pin 27. For example, the V-grooves 34a are formed at a 1-degree pitch.

[0027] On the other hand, a fixing mechanism 71 that restrains the swinging of the support 3 is attached to the right side of the lower part of the cylindrical body 21 of the rod holder 2. The fixing mechanism 71 includes an operating piece 72 that is roughly L-shaped in front view. A pair of support pieces 22 that clamp a part of the operating piece 72 are provided on the right side of the lower part of the cylindrical body 21, and the support pieces 22 and a part of the operating piece 72 are connected by a pin 23. As a result, the operating piece 72 can swing around the pin 23.

[0028] The operating piece 72 has an operating portion that extends vertically and an engaging portion that extends to the right along the arm 34 from the upper end of the operating portion. A leftward projection is provided at the upper end of the operating portion, and this projection passes through the pin 23 described above.

[0029] The tip of the engaging portion of the operating piece 72 has a triangular cross-section tooth 73 that engages with one of the V-grooves 34a. A compression coil spring 25 is positioned between the lower end of the cylindrical body 21 and the lower end of the operating portion, biasing the lower end of the operating portion to the right. A spring holder 24 with a hole into which the compression coil spring 25 is inserted is provided on the right side of the lower end of the cylindrical body 21.

[0030] In other words, in the fixing mechanism 71, the biasing force of the compression coil spring 25 maintains the state in which the tooth 73 is engaged with one of the V-grooves 34a. By pressing the operating part of the operating piece 72 against the biasing force of the compression coil spring 25, the engagement between the tooth 73 and the V-groove 34a is released, making it possible to swing the support 3 relative to the rod holder 2.

[0031] As shown in Figure 5, scales 15a relating to the eversion angle described above are formed on the front and rear surfaces of the arm 34 for each V-groove 34a (the scale 15a formed on the rear surface of the arm 34 is not shown). The teeth 73 described above also serve to indicate the current eversion angle. In other words, the scales 15a and teeth 73 constitute the eversion angle display unit 15 that displays the eversion angle. Multiple lengths are set for the scales 15a, and the longest scale 15a indicates that the eversion angle is zero degrees, that is, the perpendicular direction of the first contact surface 40 and the axial direction of the rod 20 are parallel.

[0032] A cutting block 8, as shown in Figure 6, is detachably attached to the support 3. In this embodiment, the cutting block 8 includes a head 81 having a slit 82 into which a bone saw is inserted, a neck 84 that bends 90 degrees from the lower surface of the head 81 toward the rear, a crossbar 85 that spreads out in the left-right direction at the tip of the neck 84, and a pair of shafts 86 that extend backward from both ends of the crossbar 85. The head 81 also has a pair of positioning holes 83 above the slit 82 that are spaced apart from each other in the left-right direction.

[0033] On the other hand, as shown in Figure 2, the frame 31 of the support 3 is provided with a pair of through holes 38 that penetrate both ends of the long sides and both short sides in the front-rear direction. The cutting block 8 is detachably attached to the support 3 by inserting the shaft 86 of the cutting block 8 into these through holes 38. Furthermore, the cutting block 8 is slidable in the front-rear direction relative to the support 3 because the shaft 86 is guided by the through holes 38.

[0034] The first movable body 4 and the second movable body 5 described above are supported on the support body 3 so as to be movable in the vertical direction. As described above, the support body 3 is pivotably attached to the rod holder 2, so the direction of movement of the first movable body 4 and the second movable body 5 with respect to the axial direction of the rod 20 can be adjusted by adjusting the eversion angle. In this embodiment, the first movable body 4 is supported on the support body 3 via a link mechanism 6A, and the second movable body 5 is supported on the support body 3 via a link mechanism 6B.

[0035] As shown in Figure 3, the first movable body 4 includes a main body portion 41 that extends vertically and is flattened horizontally, in other words, a plate-shaped body that is parallel to the front-rear and vertical directions and has no irregularities or slopes, a pair of support columns 42 that extend upward from both ends of the main body portion 41 in the front-rear direction, and a paddle 43 supported by the support columns 42. The paddle 43 is flattened vertically and is plate-shaped, in other words, a plate-shaped body that is parallel to the front-rear and horizontal directions and has no irregularities or slopes, and the upper surface of this paddle 43 constitutes the first contact surface 40 described above.

[0036] The main body portion 41 is provided with a pair of holes 41a that penetrate the main body portion 41 in the front-to-back direction at positions spaced apart vertically. On the other hand, the left support column 32 of the support body 3 is provided with a pair of holes 32a that penetrate the support column 32 in the front-to-back direction at positions spaced apart vertically.

[0037] The link mechanism 6A includes two pairs of link bars 61 that bridge the main body 41 of the first movable body 4 and the support column 32 of the support 3 at the front and rear, and a pin 62 that connects the ends of each pair of link bars 61. The left pin 62 is rotatably inserted into the hole 41a of the main body 41, and both ends of the pin 62 protruding from the main body 41 on both sides engage with the left end of each pair of link bars 61. Similarly, the right pin 62 is rotatably inserted into the hole 32a of the support column 32, and both ends of the pin 62 protruding from the support column 32 on both sides engage with the right end of each pair of link bars 61.

[0038] Similarly, the second mobile body 5 includes a main body portion 51 that extends vertically and is flattened horizontally, in other words, a plate-shaped body that is parallel to the front-rear and vertical directions and has no irregularities or slopes, a pair of support columns 52 that extend upward from both ends of the main body portion 51 in the front-rear direction, and a paddle 53 supported by the support columns 52. The paddle 53 is flattened vertically and is plate-shaped, in other words, a plate-shaped body that is parallel to the front-rear and horizontal directions and has no irregularities or slopes, and the upper surface of this paddle 53 constitutes the second contact surface 50 described above.

[0039] The main body portion 51 is provided with a pair of holes 51a that penetrate the main body portion 51 in the front-rear direction at positions spaced apart vertically. On the other hand, the right support column 33 of the support body 3 is provided with a pair of holes 33a that penetrate the support column 33 in the front-rear direction at positions spaced apart vertically.

[0040] The link mechanism 6B includes two pairs of link bars 63 that bridge the main body 51 of the second mobile body 5 and the support column 33 of the support 3 at the front and rear, and a pin 64 that connects the ends of each pair of link bars 63. The right-hand pin 64 is rotatably inserted into the hole 51a of the main body 51, and both ends of the pin 64 protruding from the main body 51 on both sides engage with the right end of each pair of link bars 63. Similarly, the left-hand pin 64 is rotatably inserted into the hole 33a of the support column 33, and both ends of the pin 64 protruding from the support column 33 on both sides engage with the left end of each pair of link bars 63.

[0041] As shown in Figure 4, a first biasing means 11 is positioned between the support 3 and the first moving body 4 to bias the first moving body 4 in the direction in which the first contact surface 40 faces, i.e., upward, and a second biasing means 12 is positioned between the support 3 and the second moving body 5 to bias the second moving body 5 in the direction in which the second contact surface 50 faces, i.e., upward. In this embodiment, both the first biasing means 11 and the second biasing means 12 are compression coil springs with their axial direction being vertical.

[0042] More specifically, a spring receiver 35 is provided on the left short side of the frame 31 of the support body 3, projecting to the left from the center of the short side. The spring receiver 35 is inserted between a pair of support columns 42 of the first movable body 4. The spring receiver 35 also has an upward-opening hole 35a into which the lower part of the compression coil spring, which is the first biasing means 11, is inserted. The spring receiver 35 also functions as a stopper for the first movable body 4 by contacting the upper surface of the main body 41 of the first movable body 4.

[0043] Similarly, a spring receiver 36 is provided on the right short side of the frame 31 of the support 3, projecting to the right from the center of the short side. The spring receiver 36 is inserted between a pair of support columns 52 of the second movable body 5. The spring receiver 36 also has an upward-opening hole 36a into which the lower part of the compression coil spring, which is the second biasing means 12, is inserted. The spring receiver 36 also functions as a stopper for the second movable body 5 by contacting the upper surface of the main body 51 of the second movable body 5.

[0044] As shown in FIG. 5, marks 13a indicating the current position of the first contact surface 40 are formed on the front and rear surfaces of the lower end of the main body 41 of the first moving body 4 (the mark 13a formed on the rear surface of the main body 41 is not shown). On the other hand, scales 13b regarding the amount of movement from the reference position (the upper limit position in this embodiment) of the first contact surface 40 are formed on the front and rear surfaces of the left support column 32 of the support 3 (the scale 13b formed on the rear surface of the support column 32 is not shown). These scales 13b and marks 13a constitute a first amount-of-movement display unit 13 for displaying the amount of movement of the first contact surface 40. For example, the interval between the scales 13b is 1 mm. A plurality of lengths are set for the scales 13b, and the uppermost scale 13b indicates that the first contact surface 40 is located at the reference position.

[0045] Similarly, marks 14a indicating the current position of the second contact surface 50 are formed on the front and rear surfaces of the lower end of the main body 51 of the second moving body 5 (the mark 14a formed on the rear surface of the main body 51 is not shown). On the other hand, scales 14b regarding the amount of movement from the reference position (the upper limit position in this embodiment) of the second contact surface 50 are formed on the front and rear surfaces of the right support column 33 of the support 3 (the scale 14b formed on the rear surface of the support column 33 is not shown). These scales 14b and marks 14a constitute a second amount-of-movement display unit 14 for displaying the amount of movement of the second contact surface 50. For example, the interval between the scales 14b is 1 mm. A plurality of lengths are set for the scales 14b, and the uppermost scale 14b indicates that the second contact surface 50 is located at the reference position.

[0046] When the cutting block 8 to be combined is defined, the scale 13b may directly display the amount of bone cutting, which is the distance from the slit 82 of the cutting block 8 to the first contact surface 40, and the scale 14b may directly display the amount of bone cutting, which is the distance from the slit 82 of the cutting block 8 to the second contact surface 50. That is, the scale 13b and the mark 13a may constitute an amount-of-bone-cutting display unit on one side, and the scale 14b and the mark 14a may constitute an amount-of-bone-cutting display unit on the other side.

[0047] Next, a method of using the cutting guide 10A including the alignment block 1A will be described with reference to FIGS. 7A and 7B. As a preparation before using the cutting guide 10A, a hole for inserting the rod 20 is provided along the femoral anatomical axis in the femur 9 by a drill.

[0048] First, the rod 20 and the cutting block 8 are set on the alignment block 1A. Then, the valgus angle is set to the angle determined in the preoperative plan. In the present embodiment, since the femoral evaluation axis is the femoral anatomical axis as described above, for example, it is also possible to set the valgus angle to the preoperative measurement angle between the femoral anatomical axis and the femoral functional axis.

[0049] Thereafter, while inserting the rod 20 into the femur 9, the alignment block 1A is placed at the distal end of the femur 9. In the alignment block 1A of the present embodiment, since the first moving body 4 is biased upward by the first biasing means 11 and the second moving body 5 is biased upward by the second biasing means 12, even if the posture of the alignment block 1A with respect to the femur 9 is changed when the alignment block 1A is placed at the distal end of the femur 9, both the first contact surface 40 and the second contact surface 50 are maintained in a state of contacting the medial condyle 91 and the lateral condyle 92 of the femur 9 by the automatic follow-up of the first contact surface 40 and the second contact surface 50. Therefore, while maintaining the state of referring to the shapes of the medial condyle 91 and the lateral condyle 92, the valgus angle, which is the angle in the direction perpendicular to the first contact surface 40 with respect to a specific direction (in the present embodiment, the axial direction of the rod 20), and the internal and external rotation angles around the specific direction can be adjusted.

[0050] That is, with the cutting guide 10A including the alignment block 1A, the resection position at the distal end of the femur 9 can be determined by referring to the shapes of the medial condyle 91 and the lateral condyle 92 (in combination with other indicators). Further, since the alignment block 1A includes the first movement amount display portion 13 and the second movement amount display portion 14, the operator can grasp the movement amounts of the first contact surface 40 and the second contact surface 50 just by looking at the first movement amount display portion 13 and the second movement amount display portion 14.

[0051] Furthermore, since the alignment block 1A includes an eversion angle indicator 15 and a fixing mechanism 71, the operator can adjust the eversion angle while keeping track of it, and the fixing mechanism 71 can maintain the adjusted eversion angle.

[0052] After adjusting the valgus angle and internal / external rotation angle, the positioning pin is driven into the femur 9 through the positioning hole 83 of the cutting block 8. Then, first, the cutting block 8 is pulled forward from the positioning pin and alignment block 1A, then the alignment block 1A is pulled downward together with the rod 20, and finally the cutting block 8 is set back into the positioning pin. In this state, the bone saw is inserted into the slit 82 of the cutting block 8 and the distal end of the femur 9 is resected.

[0053] <Modified Version> As shown in the modified alignment block 1B in Figures 8 and 9, the first movable body 4 may be supported on the support 3 via a linear motion mechanism 6C, and the second movable body 5 may be supported on the support 3 via a linear motion mechanism 6D. In this modified version, the width of the left spring receiver 35 is increased and it is extended downward, and the spring receiver 35 is provided with a pair of through holes 65 that penetrate the spring receiver 35 in the vertical direction. On the other hand, in the first movable body 4, the main body portion 41 is made smaller in the vertical direction, and a pair of shafts 44 are used instead of a pair of support columns 42. The shafts 44 are guided by the through holes 65, so that the first movable body 4 can slide vertically relative to the support 3. In other words, the through holes 65 constitute the linear motion mechanism 6C.

[0054] In this modified version, the width of the right-side spring receiver 36 is increased and it is extended downward, and the spring receiver 36 is provided with a pair of through holes 66 that penetrate it vertically. On the other hand, in the second movable body 5, the main body portion 51 is reduced in the vertical direction, and a pair of shafts 54 are used instead of a pair of support columns 52. The shafts 54 are guided by the through holes 66, allowing the second movable body 5 to slide vertically relative to the support 3. In other words, the through holes 66 constitute a linear motion mechanism 6D.

[0055] Instead of the arm 34 and fixing mechanism 71, a configuration such as the alignment block 1C of another modification shown in Figure 10 may be employed. In this modification, a pair of substantially disc-shaped clamping pieces 39 facing each other in the front-rear direction are provided on the right side of the lower part of the right support column 33, and a relatively thick dial 77 concentric with the clamping pieces 39 is clamped between these clamping pieces 39. The dial 77 is rotatably attached to the clamping pieces 39. The dial 77 is also connected to the rod holder 2 via a link mechanism 74.

[0056] A projection 28 is provided on the right side of the lower part of the cylindrical body 21 of the rod holder 2, projecting to the right. The link mechanism 74 includes a pair of link bars 75 extending in the left-right direction in front of and behind the projection 28 and the clamping piece 39, a pin 76a that passes through the projection 28 and connects the left ends of the link bars 75, and a pin 76b that passes through the dial 77 and the clamping piece 39 and connects the right ends of the link bars 75. An arc-shaped slit 39a is provided at the lower part of each clamping piece 39 to avoid interference with the pin 76b.

[0057] Furthermore, an arc-shaped opening 39b is provided in the upper right region of each clamping piece 39, centered on the rotation center of the dial 77. Multiple V-grooves 39c are formed on the outer edge of the opening 39b, arranged in the circumferential direction.

[0058] Meanwhile, the dial 77 holds a push button 78 that protrudes radially outward from the outer surface of the dial 77. The push button 78 is biased radially outward by a spring (not shown) and can be pressed against the biasing force of the spring. The push button 78 also has a pair of teeth 78a with a roughly triangular cross-section that protrude into the openings 39b of the two clamping pieces 39. Each tooth 78a engages with one of the V-grooves 39c. In other words, the push button 78 also serves as a fixing mechanism that restrains the oscillation of the support 3.

[0059] With the alignment block 1C shown in Figure 10, pressing the push button 78 and rotating the dial 77 causes the support 3 to swing relative to the rod holder 2. This results in improved operability, such as being easy to hold, allowing for one-handed operation, simplifying adjustments due to an expanded operating pitch, and having a clear operating method.

[0060] Furthermore, as shown in the alignment block 1D of yet another modification in Figure 11, the first movable body 4 may be supported on the support 3 via a linear motion mechanism 6C, and the second movable body 5 may be supported on the support 3 via a link mechanism 6E, the first movable body 4, and the linear motion mechanism 6C. Although not shown in Figure 11, in the alignment block 1D, similar to the first embodiment, the first movable body 4 is biased upward by the first biasing means 11, and the second movable body 5 is biased upward by the second biasing means 12.

[0061] The link mechanism 6E includes two pairs of link bars 67 that bridge the main body 41 of the first movable body 4 and the main body 51 of the second movable body 5 at the front and rear of the support columns 32 and 33 of the rod holder 2 and support body 3, and a pin 68 that penetrates the main body portions 41 and 51 and connects the ends of each pair of link bars 67.

[0062] In Figure 11, the first mobile body 4 is supported on the support 3 via a linear motion mechanism 6C, but the first mobile body 4 may also be supported on the support 3 via a link mechanism 6A, similar to the first embodiment. In this case, the second mobile body 5 is supported on the support 3 via a link mechanism 6E, the first mobile body 4, and the link mechanism 6A.

[0063] A cutting block 8A may be used in which the unit, including the neck 84, the crossbar 85, and the shaft 86, is separable from the head 81, as shown in Figures 12A and 12B. In this cutting block 8A, a connecting piece 88 protrudes from the lower surface of the head 81, and the neck 84 is provided with an insertion hole 84a into which the connecting piece 88 is inserted. A screw-type handle 89 is also attached to the neck 84 for fixing the connecting piece 88 inserted into the insertion hole 84a.

[0064] In cutting block 8, the amount of bone cutting from the first contact surface 40 to the slit 82 cannot be adjusted, but in cutting block 8A, the amount of bone cutting from the first contact surface 40 to the slit 82 can be adjusted.

[0065] As shown in Figures 13 and 14, the rod 20 is an extramedullary rod 20B that is placed subcutaneously along the anatomical axis of the femur, and a cutting guide 10B including the extramedullary rod 20B may be used. The extramedullary rod 20B includes a contact portion that abuts against the anterior flat portion of the femur 9, an insertion portion that is inserted into the rod holder 2 of the alignment block 1A, and an offset portion interposed between the contact portion and the insertion portion to avoid the anterior prominence of the femur 9.

[0066] Alternatively, as shown in Figures 15 and 16, the rod 20 may be an extramedullary rod 20C placed outside the body, and a cutting guide 10C including the extramedullary rod 20C may be used. In this case, if the tip of the extramedullary rod 20C is placed on the diaphysis, the extramedullary rod 20C is placed along the anatomical axis of the femur, and if it is placed on the femoral head, the extramedullary rod 20C is placed along the functional axis of the femur.

[0067] In addition, in either the cutting guide 10B or 10C, any of the modified alignment blocks 1B, 1C, or 1D may be used instead of the alignment block 1A, or the cutting block 8A shown in Figures 12A and 12B may be used instead of the cutting block 8.

[0068] <Second Embodiment> Figures 17 and 18 show the alignment block 1E according to the second embodiment. In this embodiment and the third embodiment described later, the same reference numerals are used for the same components as in the first embodiment, and redundant explanations are omitted.

[0069] In this embodiment, the indicator needle 16 is provided in the center of the long side of the front of the frame 31 of the support body 3. The indicator needle 16 contacts the intercondyles of the femur 9. However, the indicator needle 16 may also be provided on the rod holder 2.

[0070] Furthermore, in this embodiment, the reference position of the first moving body 4 and the reference position of the second moving body 5 are at the same height as the tip of the indicator needle 16. In this embodiment, the reference positions of the first moving body 4 and the second moving body 5 are at the upper limit position, but the reference positions of the first moving body 4 and the second moving body 5 may be lower than the upper limit position.

[0071] Furthermore, in this embodiment, the support 3 is pivotable in both directions: from a state where the perpendicular direction of the first contact surface 40 and the axial direction of the rod 20 are parallel, the first contact surface 40 rises and the second contact surface 50 falls, and the second contact surface 50 rises and the first contact surface 40 falls. In other words, as shown in Figure 18, the support 3 is pivotable in both clockwise and counterclockwise directions relative to the rod 20 held by the rod holder 2, from a state where the perpendicular direction of the first contact surface 40 and the axial direction of the rod 20 are parallel when viewed from the front. For this reason, the arm 34 is set to be longer than in the first embodiment, and the number of V-grooves 34a is also increased.

[0072] Furthermore, in the eversion angle indicator section 15, the central scale 15a is set to be the longest, and this scale 15a indicates that the eversion angle is zero degrees, that is, that the perpendicular direction of the first contact surface 40 and the axial direction of the rod 20 are parallel.

[0073] In this embodiment, as in the first embodiment, the first movable body 4 is biased upward by the first biasing means 11, and the second movable body 5 is biased upward by the second biasing means 12. Therefore, even if the orientation of the alignment block 1E relative to the femur 9 is changed when the alignment block 1E is placed on the distal end of the femur 9, the automatic tracking of the first contact surface 40 and the second contact surface 50 maintains that both the first contact surface 40 and the second contact surface 50 are in contact with the medial condyle 91 and lateral condyle 92 of the femur 9. Thus, while maintaining a state that references the shapes of the medial condyle 91 and lateral condyle 92, it is possible to adjust the eversion angle, which is the angle of the first contact surface 40 perpendicular to a specific direction (in this embodiment, the axial direction of the rod 20), and the internal and external rotation angles around the specific direction.

[0074] Furthermore, in this embodiment, since an indicator needle 16 is employed, the first movable body 4 and the second movable body 5 can be operated using the indicator needle 16, which contacts the intercondyles of the femur 9, as a reference. This simplifies the operation of the first movable body 4 and the second movable body 5 compared to when the indicator needle 16 is not used. In addition, the osteotomy position can be set using the intercondyles as a reference point other than the medial and lateral condyles.

[0075] Furthermore, since the support body 3 is capable of swinging in both directions, the operation of the first mobile body 4 and the second mobile body 5 can be performed with either the left or right foot while the indicator needle 16 is in contact with the condyles in front of the rod 20.

[0076] <Modifications> Similar to the alignment block 1B shown in Figures 8 and 9, the first movable body 4 may be supported on the support 3 via a linear motion mechanism 6C, or the second movable body 5 may be supported on the support 3 via a linear motion mechanism 6D. Alternatively, similar to the alignment block 1D shown in Figure 11, the first movable body 4 may be supported on the support 3 via a linear motion mechanism 6C, and the second movable body 5 may be supported on the support 3 via a link mechanism 6E, the first movable body 4, and the linear motion mechanism 6C, or the first movable body 4 may be supported on the support 3 via a link mechanism 6A, and the second movable body 5 may be supported on the support 3 via a link mechanism 6E, the first movable body 4, and the link mechanism 6A.

[0077] <Third Embodiment> Figure 19 shows a cutting guide 10D including an alignment block 1F according to the third embodiment. In this embodiment, the cutting guide 10D is used together with a surgical navigation system including a camera and a monitor.

[0078] Alignment block 1F is obtained by removing the rod holder 2 and the arm 34 of the support 3 from alignment block 1A of the first embodiment. In other words, the cutting guide 10D does not include the rod 20 that is installed along the femoral evaluation axis.

[0079] In addition to the alignment block 1F and the cutting block 8, the cutting guide 10D includes a marker 8a for the surgical navigation system to recognize the position and orientation of the cutting block 8 in three-dimensional space.

[0080] The marker 8a has a plate-shaped portion 8c that is inserted into the slit 82 of the cutting block 8, a rod-shaped portion 8b that extends forward from the plate-shaped portion 8c and then bends backward, and three antenna portions 8d attached to the rod-shaped portion 8b. The antenna portions 8d are captured by the camera of the surgical navigation system, so that the position and orientation of the cutting block 8 in three-dimensional space are recognized, and that position and orientation are displayed on the monitor of the surgical navigation system.

[0081] In this embodiment, as in the first embodiment, the first movable body 4 is biased upward by the first biasing means 11, and the second movable body 5 is biased upward by the second biasing means 12. Therefore, even if the orientation of the alignment block 1F relative to the femur 9 is changed when the alignment block 1F is placed on the distal end of the femur 9, the automatic tracking of the first contact surface 40 and the second contact surface 50 maintains that both the first contact surface 40 and the second contact surface 50 are in contact with the medial condyle 91 and lateral condyle 92 of the femur 9. Thus, while maintaining a state that references the shapes of the medial condyle 91 and lateral condyle 92, it is possible to adjust the valgus angle, which is the angle of the first contact surface 40 perpendicular to a specific direction (in this embodiment, the femoral evaluation axis (which may be the femoral anatomical axis or the femoral functional axis)), and the internal and external rotation angles around the specific direction.

[0082] Furthermore, in the cutting guide 10D including the alignment block 1F of this embodiment, the resection position of the distal end of the femur 9 can be determined by referring to the shapes of the medial condyle 91 and lateral condyle 92 (in conjunction with other indicators), similar to the first embodiment.

[0083] <Modification> Instead of cutting block 8, cutting block 8A shown in Figures 12A and 12B may be used. Also, similar to alignment block 1B shown in Figures 8 and 9, the first movable body 4 may be supported on the support 3 via a linear motion mechanism 6C, or the second movable body 5 may be supported on the support 3 via a linear motion mechanism 6D. Alternatively, similar to alignment block 1D shown in Figure 11, the first movable body 4 may be supported on the support 3 via a linear motion mechanism 6C, and the second movable body 5 may be supported on the support 3 via a link mechanism 6E, the first movable body 4, and the linear motion mechanism 6C, or the first movable body 4 may be supported on the support 3 via a link mechanism 6A, and the second movable body 5 may be supported on the support 3 via a link mechanism 6E, the first movable body 4, and the link mechanism 6A.

[0084] Furthermore, by using a marker 8a instead of the rod 20 in the cutting guide 10A shown in Figure 6, it can also be used as a cutting guide in conjunction with a surgical navigation system. In other words, any alignment block 1A (or 1B, 1C, 1D, 1E) including the rod holder 2 can be used interchangeably with and without surgical navigation.

[0085] <Other Embodiments> The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0086] For example, the first biasing means 11 that biases the first moving body 4 upward and the second biasing means 12 that biases the second moving body 5 upward do not necessarily have to be springs; they may use motors or air pressure. However, if one or both of the first biasing means 11 and the second biasing means 12 are springs, the structure of the first biasing means 11 and / or the second biasing means 12 can be simplified.

[0087] Alternatively, instead of the cutting blocks 8, 8A having a slit 82 into which the bone saw is inserted, a cutting block having a wall surface that makes surface contact with the bone saw, or a cutting block including multiple pairs of rollers that hold the bone saw in place, may be used.

[0088] Furthermore, although not shown in the figures, in the first embodiment and its modified versions, as well as in the second embodiment, the rod holder 2 does not necessarily need to be slidable with respect to the rod 20, and the rod 20 may be integrally provided with the rod holder 2. However, if the rod holder 2 is slidable with respect to the rod 20, the rod 20 and the alignment block can be operated separately.

[0089] Furthermore, in the first embodiment and its modified form, the second embodiment and the third embodiment, the first displacement display unit 13 and the second displacement display unit 14 may be omitted, and in the first embodiment and its modified form and the second embodiment, the eversion angle display unit 15 may be omitted.

[0090] <Summary> In a first aspect, the present disclosure provides an alignment block for guiding the cutting surface in an appropriate angular direction when resecting the distal end of a femur from one side, comprising: a support to which a cutting block for guiding a bone saw can be attached and detached; a first movable body having a first contact surface that contacts one of the medial and lateral condyles of the femur, and supported by the support so as to be movable in a direction perpendicular to the first contact surface; a first biasing means for biasing the first movable body in the direction toward the first contact surface; a second movable body having a second contact surface that contacts the other of the medial and lateral condyles of the femur, and supported by the support so as to be movable in a direction perpendicular to the second contact surface; and a second biasing means for biasing the second movable body in the direction toward the second contact surface.

[0091] With the above configuration, the first moving body is biased by the first biasing means in the direction toward the first contact surface, and the second moving body is biased by the second biasing means in the direction toward the second contact surface. Therefore, even if the orientation of the alignment block relative to the femur is changed when the alignment block is placed on the distal end of the femur, the automatic tracking of the first and second contact surfaces ensures that both the first and second contact surfaces remain in contact with the medial and lateral condyles of the femur. Consequently, while maintaining a state that references the shapes of the medial and lateral condyles, it is possible to adjust the eversion angle, which is the angle perpendicular to the first contact surface with respect to a specific direction, and the internal and external rotation angles around the specific direction.

[0092] In a second embodiment, the alignment block described above in the first embodiment may further include a first movement amount display unit that displays the amount of movement of the first contact surface from a reference position, and a second movement amount display unit that displays the amount of movement of the second contact surface from a reference position. With this configuration, the operator can grasp the amount of movement of the first contact surface and the amount of movement of the second contact surface simply by looking at the first movement amount display unit and the second movement amount display unit.

[0093] In a third embodiment, in the first or second embodiment, one or both of the first biasing means and the second biasing means may be springs. This configuration allows for a simplified structure of the first biasing means and / or the second biasing means.

[0094] In a fourth embodiment, in any of the first to third embodiments, for example, the first moving body and the second moving body may each be supported by the support via a link mechanism or a linear motion mechanism.

[0095] In a fifth embodiment, in any of the first to third embodiments, for example, the first moving body may be supported on the support via a linear motion mechanism, and the second moving body may be supported on the support via a link mechanism, the first moving body, and the linear motion mechanism.

[0096] In a sixth embodiment, in any of the first to third embodiments, for example, the first moving body may be supported on the support via a first link mechanism, and the second moving body may be supported on the support via a second link mechanism, the first moving body, and the first link mechanism.

[0097] In a seventh embodiment, in any of the first to sixth embodiments, the support may be provided with an indicator needle that contacts the intercondyles of the femur. With this configuration, the first and second movable bodies can be operated using the indicator needle that contacts the intercondyles as a reference, thus simplifying the operation of the first and second movable bodies compared to when there is no indicator needle. In addition, the osteotomy position can be set using the intercondyles as a reference point other than the medial and lateral condyles.

[0098] In an eighth aspect, in any of the first to seventh aspects, the alignment block further comprises a rod holder for holding a rod positioned along the femoral evaluation axis, and the support may be pivotably mounted to the rod holder such that the eversion angle, which is the angle perpendicular to the first contact surface with respect to the axial direction of the rod, can be changed. With this configuration, the direction of movement of the first and second moving bodies with respect to the axial direction of the rod can be adjusted by adjusting the eversion angle. For example, if the femoral evaluation axis is the femoral anatomical axis, the eversion angle can also be set to the preoperative measurement angle between the femoral anatomical axis and the femoral functional axis.

[0099] In a ninth aspect, in the eighth aspect, the rod holder may be provided with an indicator needle that contacts the intercondyles of the femur. With this configuration, the first and second movable bodies can be operated using the indicator needle that contacts the intercondyles as a reference, thus simplifying the operation of the first and second movable bodies compared to when there is no indicator needle. In addition, the osteotomy position can be set using the intercondyles as a reference point other than the medial and lateral condyles.

[0100] In a tenth embodiment, in any of the eighth to ninth embodiments, the alignment block may further include a valgus angle indicator that displays the valgus angle. With this configuration, the operator can adjust the valgus angle while keeping track of it.

[0101] In an eleventh embodiment, in any of the eighth to tenth embodiments, the alignment block may further include a fixing mechanism for restraining the oscillation of the support. This configuration makes it possible to maintain the state in which the eversion angle has been adjusted.

[0102] In a twelfth aspect, in any of the eighth to eleventh aspects, the rod holder may be slidable along the rod. This configuration allows the rod and the alignment block to be operated separately.

[0103] In a thirteenth embodiment, in any of the eighth to eleventh embodiments, for example, the rod may be integrally provided with the rod holder.

[0104] In a 14th embodiment, in any of the 8th to 13th embodiments, the alignment block may further include a dial that is rotatably mounted on the support and connected to the rod holder via a link mechanism. This configuration provides the advantages of improved operability, such as one-handed operation, easier adjustment due to an expanded operating pitch, and a clearer operating method.

[0105] In a fifteenth aspect, the present disclosure provides a cutting guide comprising a rod positioned along the femoral evaluation axis, an alignment block of any eighth to fourteenth aspects, and a cutting block for guiding a bone saw, which is detachably attached to the support of the alignment block. This configuration allows for the determination of the resection position of the distal end of the femur by referring to the shapes of the medial and lateral condyles (in conjunction with other indicators).

[0106] In a sixteenth aspect, the present disclosure provides a cutting guide for use with a surgical navigation system, comprising: an alignment block of any of the first to fourteenth aspects; a cutting block for guiding a bone saw, which is detachably attached to a support of the alignment block; and markers for the surgical navigation system to recognize the position and orientation of the cutting block in three-dimensional space. This configuration allows for the determination of the resection position of the distal end of the femur by referring to the shapes of the medial and lateral condyles (in conjunction with other indicators).

[0107] 1A-1F Alignment block 10A-10D Cutting guide 11 First biasing means 12 Second biasing means 13 First movement amount indicator 14 Second movement amount indicator 15 Everthrust angle indicator 16 Indicator needle 2 Rod holder 20 Rod 3 Support 4 First moving body 40 First contact surface 5 Second moving body 50 Second contact surface 6A, 6B, 6E Link mechanism 6C, 6D Linear motion mechanism 71 Fixing mechanism 74 Link mechanism 77 Dial 78 Push button (fixing mechanism) 8, 8A Cutting block 8a Marker

Claims

1. An alignment block for guiding the cutting surface in an appropriate angular direction when resecting the distal end of a femur, comprising: a support to which a cutting block that guides a bone saw can be attached and detached; a first movable body having a first contact surface that contacts one of the medial and lateral condyles of the femur, and supported by the support so as to be movable in a direction perpendicular to the first contact surface; a first biasing means for biasing the first movable body in the direction toward the first contact surface; a second movable body having a second contact surface that contacts the other of the medial and lateral condyles of the femur, and supported by the support so as to be movable in a direction perpendicular to the second contact surface; and a second biasing means for biasing the second movable body in the direction toward the second contact surface.

2. The alignment block according to claim 1, further comprising: a first movement amount display unit for displaying the amount of movement of the first contact surface from a reference position; and a second movement amount display unit for displaying the amount of movement of the second contact surface from a reference position.

3. The alignment block according to claim 1, wherein one or both of the first biasing means and the second biasing means are springs.

4. The alignment block according to claim 1, wherein each of the first moving body and the second moving body is supported on the support via a link mechanism or a linear motion mechanism.

5. The alignment block according to claim 1, wherein the first moving body is supported on the support via a linear motion mechanism, and the second moving body is supported on the support via a link mechanism, the first moving body, and the linear motion mechanism.

6. The alignment block according to claim 1, wherein the first movable body is supported on the support via a first link mechanism, and the second movable body is supported on the support via a second link mechanism, the first movable body, and the first link mechanism.

7. The alignment block according to claim 1, wherein the support is provided with an indicator needle that contacts the intercondyles of the femur.

8. The alignment block according to claim 1, further comprising a rod holder for holding a rod positioned along the femoral evaluation axis, wherein the support is pivotably mounted to the rod holder such that the eversion angle, which is the angle perpendicular to the first contact surface with respect to the axial direction of the rod, is variable.

9. The alignment block according to claim 8, wherein the rod holder is provided with an indicator needle that contacts the intercondyles of the femur.

10. The alignment block according to claim 8, further comprising an eversion angle display unit for displaying the eversion angle.

11. The alignment block according to claim 8, further comprising a fixing mechanism for restraining the oscillation of the support.

12. The alignment block according to claim 8, wherein the rod holder is slidable along the rod.

13. The alignment block according to claim 8, wherein the rod is integrally provided with the rod holder.

14. The alignment block according to claim 8, further comprising a dial rotatably mounted on the support and connected to the rod holder via a link mechanism.

15. A cutting guide comprising: a rod installed along the femoral evaluation axis; an alignment block according to any one of claims 8 to 14; and a cutting block for guiding a bone saw, which is detachably attached to the support of the alignment block.

16. A cutting guide for use with a surgical navigation system, comprising: an alignment block according to any one of claims 1 to 14; a cutting block for guiding a bone saw, which is detachably attached to a support of the alignment block; and a marker for the surgical navigation system to recognize the position and orientation of the cutting block in three-dimensional space.

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