Alignment block and cutting guide

Abstract

An alignment block according to one embodiment is for guiding, when the distal end of a femur is resected, a resection surface in an appropriate angular direction. The alignment block comprises a support body that has a first contact surface which contacts one of the medial and lateral condyles of the femur, and a mobile body that has a second contact surface which contacts the other of the medial and lateral condyles of the femur. A cutting block for guiding a bone saw can be removably attached to the support body. The mobile body is supported by the support body so as to be movable in a direction normal to the first contact surface. The alignment block further comprises biasing means for biasing the mobile body in the direction in which the first contact surface faces.

Description

Alignment Blocks and Cutting Guides

[0001] The present application relates to an alignment block for guiding a resection plane in an appropriate angular direction when resecting the distal end of a 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 femoral component of the artificial knee joint are attached to the resected surfaces of the tibia and the femur, respectively. Various surgical instruments are used in total knee arthroplasty.

[0003] For example, Patent Document 1 discloses an alignment block 100 (referred to as a "valgus alignment guide" in Patent Document 1) that is used together with a rod 200 (referred to as an "F rod" in Patent Document 1) and a cutting block (referred to as a "slit member" in Patent Document 1) when resecting the distal end of the femur, as shown in Figure 17. The rod 200 is inserted into the femur to be set 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 body 120 (referred to as the "main body" in Patent Document 1) attached to the rod holder 110, and a pair of movable bodies 130 (referred to as the "support body" in Patent Document 1) attached to the support body 120 that abut against the medial and lateral condyles of the femur, respectively.

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

[0006] The cutting block (not shown) described above can be attached to and detached from the tip of the support 120. Furthermore, as shown in FIG. 18 , a plurality of teeth 121 are formed on both sides of the tip of the support 120, aligned in the direction of the center line of the support 120. Meanwhile, as shown in FIG. 19 , each movable body 130 incorporates an advancing / retracting member 140 having teeth 141 engageable with the teeth 121, and a button 150 for operating the advancing / retracting member 140. The advancing / retracting member 140 is biased in the advancing direction by a spring 160, and the biasing force of the spring 160 maintains the engagement between the teeth 121 and the teeth 141. When the button 150 is pressed to retract the advancing / retracting member 140, the engagement between the teeth 121 and the teeth 141 is released, and the movable body 130 becomes movable in the direction of the center line of the support 120.

[0007] Japanese Patent No. 6434277

[0008] In the alignment block 100 of Patent Document 1, when the alignment block 100 is placed at the distal end of the femur, one or both of the movable bodies 130 can be operated to bring both contact surfaces 131 into contact with the medial and lateral condyles of the femur. Therefore, the alignment block 100 can also be used as a means for referencing the shapes of the medial and lateral condyles (as a reference for measurement and positioning).

[0009] When the alignment block 100 is installed at the distal end of the femur, the valgus angle, which is the angle of the perpendicular of the contact surface 131 relative to a specific direction (the axial direction of the rod 200 in the case of the alignment block 100), and the internal / external rotation angle around the specific direction can be adjusted by changing the orientation of the alignment block 100 relative to the femur. In this case, with a structure such as 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 every time the orientation of the alignment block 100 relative to the femur is changed, and therefore it is not possible to adjust the valgus angle or the internal / external rotation angle while maintaining a state in which the shapes of the medial and lateral condyles are referenced.

[0010] Therefore, the present application aims to provide an alignment block that can adjust the valgus angle and internal / external rotation angle while maintaining a reference to the shape of the medial and lateral condyles, and a cutting guide that includes such an alignment block.

[0011] The present application provides an alignment block for guiding a resection plane in an appropriate angular direction when resecting the distal end of a femur from one side, the alignment block comprising: a support having a first abutment surface abutting one of the medial and lateral condyles of the femur and to which a cutting block for guiding a bone saw can be detachably attached; a movable body supported on the support so as to be movable in a direction perpendicular to the first abutment surface and having a second abutment surface abutting the other of the medial and lateral condyles of the femur; and a biasing means for biasing the movable body in the direction in which the first abutment surface faces.

[0012] From another aspect, the present application provides a cutting guide comprising: a rod installed along the femoral evaluation axis; the above-mentioned alignment block, which further comprises a rod holder for holding the rod, and the support is swingably attached to the rod holder so that the valgus angle, which is the angle between the axial direction of the rod and the perpendicular direction of the first abutment surface, can be changed; and a cutting block for guiding a bone saw, which is detachably attached to the support of the alignment block.

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

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

[0015] FIG. 1 is a perspective view of an alignment block according to the first embodiment. FIG. 2 is an exploded perspective view of the alignment block. FIG. 3 is a front view of the alignment block. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a perspective view of a cutting guide including the alignment block. FIG. 6A is a front view showing the cutting guide in use. FIG. 6B is a side view showing the cutting guide in use. FIG. 7 is a perspective view of an alignment block according to a modified example. FIG. 8 is a perspective view of an alignment block according to another modified example. FIG. 9A is a perspective view of a cutting block according to a modified example. FIG. 9B is an exploded perspective view of the cutting block. FIG. 10 is a perspective view of an alignment block according to yet another modified example. FIG. 11 is a front view of the alignment block shown in FIG. 10. FIG. 12 is an exploded perspective view of a cutting guide according to a modified example. FIG. 13 is a side view showing the cutting guide shown in FIG. 12 in use. FIG. 14 is an exploded perspective view of a cutting guide according to another modified example. FIG. 15 is a side view showing the cutting guide shown in FIG. 14 in use. Fig. 16 is a perspective view of a cutting guide including an alignment block according to the second embodiment. Fig. 17 is a front view of a conventional alignment block. Fig. 18 is a perspective view of a conventional alignment block. Fig. 19 is a cross-sectional view of a moving body of a conventional alignment block.

[0016] 1 shows an alignment block 1A according to a first embodiment. This alignment block 1A is used to guide the resection plane in an appropriate angular direction when resecting the distal end of a femur 9 (see FIGS. 6A and 6B ). Although the femur 9 shown in FIGS. 6A and 6B is a left femur, the alignment block 1A can also be used for a right femur.

[0017] As shown in FIG. 5 , the alignment block 1A, together with a rod 7 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 7 is a linear intramedullary rod 7A inserted into the femur 9, and the femoral evaluation axis is the femoral anatomical axis. Here, the femoral anatomical axis is an evaluation axis for lower limb alignment that passes through the center of the femoral shaft. In this application, an axis set based on bone shape for evaluating lower limb alignment 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 center of the knee joint) can also be used as the femoral evaluation axis. In this application, the term "femoral evaluation axis" refers to either the femoral anatomical axis or the femoral functional axis.

[0018] 1 and 2 , the alignment block 1A includes a rod holder 2 that holds a rod 7, a support 3 having a first abutment surface 30 that abuts against one of the medial condyle 91 and the lateral condyle 92 of the femur 9 shown in FIGS. 6A and 6B , and a movable body 4 having a second abutment surface 40 that abuts against the other of the medial condyle 91 and the lateral condyle 92 of the femur 9. The first abutment surface 30 and the second abutment surface 40 are flat surfaces that are parallel to each other. In FIGS. 6A and 6B , the first abutment surface 30 abuts against the medial condyle 91, and the second abutment surface 40 abuts against the lateral condyle 92. However, when the alignment block 1A is used upside down or in its original orientation on the femur of the right foot, the first abutment surface 30 abuts against the lateral condyle 92, and the second abutment surface 40 abuts against the medial condyle 91.

[0019] For ease of explanation, the perpendicular direction of the first abutment surface 30 will be referred to as the up-down direction (the direction in which the first abutment surface 30 faces will be referred to as the up-down direction, and the opposite direction will be referred to as the down-down direction), the alignment direction of the first abutment surface 30 and the second abutment surface 40 will be referred to as the left-right direction (the first abutment surface 30 side will be referred to as the left, and the second abutment surface 40 side will be referred to as the right-right direction), and the direction perpendicular to the up-down direction and the left-right direction will be referred to as the front-to-back direction (the front side (surgeon's side) when using the alignment block 1A will be referred to as the front, and the back side will be referred to as the back).

[0020] In this embodiment, the rod holder 2 is slidable along the rod 7. Specifically, the rod holder 2 includes a cylindrical body 21 extending in the vertical direction, and the rod 7 is inserted into the cylindrical body 21. In this embodiment, the cylindrical body 21 is in the shape of a square prism, but the cylindrical body 21 may also be in the shape of a hexagonal prism, a cylinder, or the like.

[0021] The support body 3 is attached to the rod holder 2 so as to be swingable so that the eversion angle, which is the angle of the perpendicular of the first abutment surface 30 with respect to the axial direction of the rod 7, is variable. More specifically, the support body 3 includes a frame body 31 having a pair of long sides extending in the left-right direction and a pair of short sides extending in the front-rear direction, and the upper part of the cylindrical body 21 of the rod holder 2 fits into the frame body 31.

[0022] A hole 26 is provided in the upper part of the cylindrical body 21 of the rod holder 2, penetrating the upper part in the front-to-rear direction, while a hole 36 is also provided in the center of each long side of the frame body 31, penetrating both long sides in the front-to-rear direction. Pins 27 are inserted into the holes 36, 26 from both sides, so that the support body 3 is attached to the rod holder 2 so as to be able to swing. In other words, the support body 3 swings around the pin 27 relative to the rod 7 held by the rod holder 2.

[0023] A paddle 32 is integrally provided on the left short side of the frame 31 of the support body 3 so as to protrude upward from the short side. The paddle 32 is a flat plate in the vertical direction, in other words, a plate parallel to the front-rear and left-right directions with no irregularities or inclinations, and the upper surface of this paddle 32 constitutes the first contact surface 30 described above.

[0024] A support pillar 34 extends downward from the short side on the right side of the frame body 31 of the support body 3, and an arm 35 extends obliquely upward to the right from the lower end of the support pillar 34, more precisely in the circumferential direction centered on the pin 27. A plurality of V-shaped grooves 35a are formed on the underside of the arm 35 and aligned in the circumferential direction centered on the pin 27. For example, the V-shaped grooves 35a are formed at a pitch of 1 degree.

[0025] Meanwhile, a fixing mechanism 51 that restrains the swinging of the support body 3 is attached to the right side surface of the lower part of the cylindrical body 21 of the rod holder 2. The fixing mechanism 51 includes an operation piece 52 that is substantially L-shaped in front view. A pair of support pieces 22 that hold a part of the operation piece 52 therebetween are provided on the right side surface of the lower part of the cylindrical body 21, and the support pieces 22 and a part of the operation piece 52 are connected by a pin 23. Therefore, the operation piece 52 can swing around the pin 23.

[0026] The operating piece 52 has an operating portion that extends vertically and an engaging portion that extends rightward from the upper end of the operating portion along the arm 35. A leftward protrusion is provided on the upper end of the operating portion, and the pin 23 described above passes through this protrusion.

[0027] A tooth 53 with a triangular cross section that engages with one of the V-grooves 35a is formed at the tip of the engaging portion of the operating piece 52. A compression coil spring 25 that urges the lower end of the operating portion to the right is disposed between the lower end of the cylindrical body 21 and the lower end of the operating portion. A spring receiver 24 having a hole into which the compression coil spring 25 is inserted is provided on the right side surface of the lower end of the cylindrical body 21.

[0028] In other words, in the fixing mechanism 51, the tooth 53 is kept engaged with one of the V-grooves 35a by the force of the compression coil spring 25, and by pressing the operating portion of the operating piece 52 against the force of the compression coil spring 25, the engagement between the tooth 53 and the V-groove 35a is released, making it possible to swing the support body 3 relative to the rod holder 2.

[0029] As shown in Figure 3, the front and rear surfaces of the arm 35 are provided with scales 15 relating to the above-mentioned valgus angle for each V-groove 35a (the scales 15 formed on the rear surface of the arm 35 are not shown). The above-mentioned teeth 53 also serve to indicate the current valgus angle. In other words, the scales 15 and teeth 53 constitute a valgus angle display unit 14 that displays the valgus angle. The scales 15 are set to a number of lengths, and the longest scale 15 indicates that the valgus angle is zero degrees, i.e., that the rod holder 2 and the frame body 31 of the support body 3 are perpendicular to each other.

[0030] A cutting block 8 shown in Fig. 5 is detachably attached to the support body 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 is bent 90 degrees rearward from the underside of the head 81, a crosspiece 85 that extends left and right at the tip of the neck 84, and a pair of shafts 86 that extend rearward from both ends of the crosspiece 85. The head 81 also has a pair of positioning holes 83 above the slit 82 that are spaced apart left and right.

[0031] 2, a pair of through holes 37 are provided in the frame 31 of the support body 3, penetrating both ends of both long sides and both short sides in the front-to-rear direction. The shaft 86 of the cutting block 8 is inserted into this through hole 37, so that the cutting block 8 is detachably attached to the support body 3. Furthermore, with the shaft 86 guided by the through hole 37, the cutting block 8 is slidable in the front-to-rear direction relative to the support body 3.

[0032] The movable body 4 described above is supported by the support body 3 so as to be movable in the up and down direction. As described above, the support body 3 is attached to the rod holder 2 so as to be able to swing, and therefore, by adjusting the eversion angle, the movement direction of the movable body 4 relative to the axial direction of the rod 7 can be adjusted. In this embodiment, the movable body 4 is supported by the support body 3 via a link mechanism 6.

[0033] Specifically, the movable body 4 includes a main body 41 that is plate-shaped and extends in the vertical direction and is flat in the left-right direction, in other words, a plate-shaped body that is parallel to the front-rear and up-down directions and has no irregularities or slopes, a pair of support columns 42 that extend upward from both ends of the main body 41 in the front-rear direction, and a paddle 43 supported by the support columns 42. The paddle 43 is plate-shaped and flat in the vertical direction, in other words, a plate-shaped body that is parallel to the front-rear and up-down directions and has no irregularities or slopes, and the upper surface of this paddle 43 constitutes the second abutment surface 40 described above.

[0034] Main body 41 is provided with a pair of holes 41a that penetrate main body 41 in the front-to-rear direction at positions spaced apart from one another in the vertical direction. Support body 3 also includes a hanging portion 33 that hangs downward from the left short side of frame 31. Hanging portion 33 is provided with a pair of holes 33a that penetrate hanging portion 33 in the front-to-rear direction at positions spaced apart from one another in the vertical direction.

[0035] Link mechanism 6 includes two pairs of link bars 61 that bridge hanging portion 33 and main body 41 of movable body 4 in front of and behind support columns 34 of rod holder 2 and support body 3, and pins 62 that connect both ends of each pair of link bars 61. The left-side pin 62 is rotatably inserted into hole 33a of hanging portion 33, and both ends of pin 62 protruding on both sides from hanging portion 33 fit with the left ends of each pair of link bars 61. Similarly, the right-side pin 62 is rotatably inserted into hole 41a of main body 41 of movable body 4, and both ends of pin 62 protruding on both sides from main body 41 fit with the right ends of each pair of link bars 61.

[0036] Between the support body 3 and the movable body 4, there is disposed a biasing means 5 that biases the movable body 4 in the direction in which the first contact surface 30 faces, i.e., upward. In this embodiment, the biasing means 5 is a compression coil spring whose axial direction is the up-and-down direction.

[0037] More specifically, a spring receiver 31a is provided on the right short side of the frame 31 of the support body 3, protruding rightward from the center of the short side. The spring receiver 31a is inserted between a pair of supports 42 of the movable body 4. As shown in FIG. 4 , the spring receiver 31a is provided with a hole 31b that opens upward, and the lower part of the compression coil spring serving as the biasing means 5 is inserted into this hole 31b. The spring receiver 31a also functions as a stopper for the movable body 4 by abutting against the upper surface of the main body 41 of the movable body 4.

[0038] A rib 44 is provided at the lower end of the main body 41 of the movable body 4, extending leftward from the lower end to the support column 34 of the support body 3. As shown in FIG. 3 , marks 13 indicating the current position of the second contact surface 40 are formed on the front and rear surfaces of the rib 44 (the marks 13 formed on the rear surface of the rib 44 are not shown). Meanwhile, scales 12 indicating the level difference between the first contact surface 30 and the second contact surface 40 are formed on the front and rear surfaces of the support column 34 of the support body 3 (the scales 12 formed on the rear surface of the support column 34 are not shown). These scales 12 and marks 13 constitute a level difference indicator 11 that displays the level difference. For example, the intervals between the scales 12 are 1 mm. The scales 12 are set to a plurality of lengths, and the longest scale 12 in the center indicates that the level difference between the first contact surface 30 and the second contact surface 40 is zero, i.e., that the first contact surface 30 and the second contact surface 40 are positioned on the same plane.

[0039] 6A and 6B, a method of using the cutting guide 10A including the alignment block 1A will be described. In preparation for using the cutting guide 10A, a hole for inserting the rod 7 is drilled in the femur 9 along the anatomical axis of the femur.

[0040] First, the rod 7 and cutting block 8 are set on the alignment block 1A. Next, the valgus angle is set to the angle determined in the preoperative plan. In this embodiment, since the femoral evaluation axis is the femoral anatomical axis as described above, it is also possible to set the valgus angle to, for example, the preoperatively measured angle between the femoral anatomical axis and the femoral functional axis.

[0041] Thereafter, while inserting the rod 7 into the femur 9, the alignment block 1A is placed at the distal end of the femur 9. In the alignment block 1A of this embodiment, the movable body 4 is biased upward by the biasing means 5. Therefore, even if the orientation of the alignment block 1A relative to the femur 9 is changed when placing the alignment block 1A at the distal end of the femur 9, the second contact surface 40 automatically follows the movement of the first contact surface 30, thereby maintaining both the first contact surface 30 and the second contact surface 40 in contact with the medial condyle 91 and the lateral condyle 92 of the femur 9. Therefore, while maintaining a state in which the shapes of the medial condyle 91 and the lateral condyle 92 are referenced, it is possible to adjust the valgus angle, which is the angle of the perpendicular of the first contact surface 30 with respect to a specific direction (in this embodiment, the axial direction of the rod 7), and the internal / external rotation angle around the specific direction.

[0042] That is, with the cutting guide 10A including the alignment block 1A, 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 the lateral condyle 92 (together with other indicators). In addition, since the alignment block 1A includes the level difference display unit 11, the surgeon can grasp the level difference between the medial condyle 91 and the lateral condyle 92 simply by looking at the level difference display unit 11.

[0043] Furthermore, since the alignment block 1A includes a valgus angle display unit 14 and a fixing mechanism 51, the surgeon can adjust the valgus angle while understanding the valgus angle, and the adjusted valgus angle can be maintained by the fixing mechanism 51.

[0044] After adjusting the valgus angle and internal / external rotation angles, a positioning pin is driven into the femur 9 through the positioning hole 83 in the cutting block 8. Thereafter, the cutting block 8 is first pulled forward from the positioning pin and alignment block 1A, then the alignment block 1A is pulled downward together with the rod 7, and finally the cutting block 8 is set back onto the positioning pin. In this state, a bone saw is inserted into the slit 82 in the cutting block 8 to resect the distal end of the femur 9.

[0045] <Modifications> As in the alignment block 1B of a modification shown in Fig. 7, the movable body 4 may be supported on the support body 3 via a linear motion mechanism 6A. In this modification, the spring receiver 31a is made wider and extended downward, and a pair of through holes 63 is provided in the spring receiver 31a, penetrating the spring receiver 31a in the vertical direction. On the other hand, in the movable body 4, the main body 41 is made smaller in the vertical direction, and a pair of shafts 46 is used instead of the pair of support columns 42. The shafts 46 are guided by the through holes 63, allowing the movable body 4 to slide in the vertical direction relative to the support body 3. In other words, the through holes 63 constitute a linear motion mechanism 6A.

[0046] Instead of the arm 35 and the fixing mechanism 51, a configuration like that of another modified alignment block 1C shown in Figure 8 may be employed. In this modified example, a pair of approximately disk-shaped clamping pieces 38 facing each other in the front-to-rear direction are provided on the right side of the lower part of the support column 34, and a relatively thick dial 57 concentric with the clamping pieces 38 is clamped between the clamping pieces 38. The dial 57 is rotatably attached to the clamping pieces 38. The dial 57 is also connected to the rod holder 2 via a link mechanism 54.

[0047] A convex portion 28 that protrudes to the right is provided on the right side surface of the lower portion of the cylindrical body 21 of the rod holder 2. The link mechanism 54 includes a pair of link bars 55 that extend in the left-right direction in front of and behind the convex portion 28 and the clamping pieces 38, a pin 56a that passes through the convex portion 28 to connect the left ends of the link bars 55, and a pin 56b that passes through the dial 57 and the clamping pieces 38 to connect the right ends of the link bars 55. An arc-shaped slit 38a is provided in the lower portion of each clamping piece 38 to avoid interference with the pin 56b.

[0048] An arc-shaped opening 38b is provided in the upper right region of each clamping piece 38, with the center being the rotation center of the dial 57. A plurality of V-shaped grooves 38c are formed on the outer peripheral edge of the opening 38b and aligned in the circumferential direction.

[0049] Meanwhile, the dial 57 holds a push button 58 that protrudes radially outward from the outer circumferential surface of the dial 57. The push button 58 is biased radially outward by a spring (not shown) and can be pressed against the biasing force of the spring. The push button 58 also has a pair of teeth 58a with a generally triangular cross section that protrude into the openings 38b of both clamping pieces 38. Each tooth 58a engages with one of the V-grooves 38c. In other words, the push button 58 also serves as a fixing mechanism that restrains the swinging of the support body 3.

[0050] 8, pressing the push button 58 and rotating the dial 57 causes the support body 3 to swing relative to the rod holder 2. This provides the advantages of improved operability, such as ease of holding, one-handed operation, simplified adjustment due to the increased operating pitch, and a clear operating method.

[0051] 9A and 9B , a cutting block 8A may be employed in which a unit including a neck 84, a crosspiece 85, and a shaft 86 can be separated from a head 81. In this cutting block 8A, a connecting piece 88 protrudes from the underside of the head 81, and an insertion hole 84a is provided in the neck 84 into which the connecting piece 88 is inserted. A screw-type handle 89 is attached to the neck 84 to secure the connecting piece 88 inserted into the insertion hole 84a.

[0052] In the cutting block 8, the bone cutting thickness from the first contact surface 30 to the slit 82 cannot be adjusted, but in the cutting block 8A, the bone cutting thickness from the first contact surface 30 to the slit 82 can be adjusted.

[0053] Alternatively, as in the case of an alignment block 1D of yet another modified example shown in FIG. 10, the alignment block 1D may have a function that allows adjustment of the bone resection thickness from the first contact surface 30 to the slit 82.

[0054] Specifically, in alignment block 1D, hanging portion 33 is divided into upper hanging portion 33A that is integrally formed with frame body 31 and lower hanging portion 33B that has hole 33a (see Figure 2) into which pin 62 of link mechanism 6 is inserted.

[0055] Furthermore, in alignment block 1D, paddle 32 is a plate-like member independent of frame 31, and paddle 32 and lower hanging portion 33B are connected by a pair of shafts 32a that pass through upper hanging portion 33A. Upper hanging portion 33A is provided with boss 33b at a position corresponding to one of shafts 32a, and screw 32b for fixing shaft 32a is attached to boss 33b.

[0056] 11 , in alignment block 1D, second hanging portion 39 hangs downward from the left short side of frame 31 along hanging portion 33. Scales 17a indicating the amount of movement of first contact surface 30 from its upper limit position are formed on the front and rear surfaces of second hanging portion 39 (scale 17a formed on the rear surface of second hanging portion 39 is not shown). Meanwhile, marks 17b indicating the current position of first contact surface 30 are formed on the front and rear surfaces of lower hanging portion 33B (mark 17b formed on the rear surface of lower hanging portion 33B is not shown). These scales 17a and marks 17b constitute movement amount indicator 17 that displays the amount of movement of first contact surface 30 from its upper limit position.

[0057] Furthermore, scales 18a indicating the amount of movement of the second contact surface 40 from the upper limit position of the first contact surface 30 are formed on the front and rear surfaces of the support columns 34 of the support body 3 (the scales 18a formed on the rear surfaces of the support columns 34 are not shown). Meanwhile, marks 18b indicating the current position of the second contact surface 40 are formed on the front and rear surfaces of the main body 41 of the movable body 4 (the mark 18b formed on the rear surface of the main body 41 is not shown). These scales 18a and marks 18b constitute a movement amount display unit 18 that displays the amount of movement of the second contact surface 40 from the upper limit position of the first contact surface 30. The scales 18a have multiple lengths, and the longest scale 18a indicates that the second contact surface 40 is at the upper limit position of the first contact surface 30.

[0058] The level difference between the first abutment surface 30 and the second abutment surface 40 can be determined from the amount of movement of the first abutment surface 30 from its upper limit position displayed on the movement amount display unit 17 and the amount of movement of the second abutment surface 40 from its upper limit position displayed on the movement amount display unit 18. When the cutting block 8 to be combined is determined, the distance from the center of the shaft 86 of the cutting block 8 to the slit 82 may be considered constant (subtracted from the distance from the center of the through hole 37 of the alignment block 1D to the first abutment surface 30 or the distance from the center of the through hole 37 to the second abutment surface 40), so that the scale 17a and the scale 18a may directly display the value of the bone resection thickness. That is, the scale 17a and the mark 17b may constitute one side of the bone resection thickness display unit, and the scale 18a and the mark 18b may constitute the other side of the bone resection thickness display unit.

[0059] 12 and 13 , the rod 7 may be an extramedullary rod 7B that is placed subcutaneously along the anatomical axis of the femur, and a cutting guide 10B including the extramedullary rod 7B may be used. The extramedullary rod 7B includes an abutment portion that abuts against the front 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 that is interposed between the abutment portion and the insertion portion and that avoids the front protuberance of the femur 9.

[0060] 14 and 15, the rod 7 may be an extramedullary rod 7C that is placed outside the body, and a cutting guide 10C including the extramedullary rod 7C may be used. In this case, if the tip of the extramedullary rod 7C is placed on the diaphysis, the extramedullary rod 7C is placed along the anatomical axis of the femur, and if it is placed on the femoral head, the extramedullary rod 7C is placed along the functional axis of the femur.

[0061] In addition, for both cutting guides 10B and 10C, any of modified alignment blocks 1B, 1C, and 1D may be used in place of alignment block 1A, and cutting block 8A shown in Figures 9A and 9B may be used in place of cutting block 8.

[0062] 16 shows a cutting guide 10D including an alignment block 1E according to a second embodiment. In this embodiment, the cutting guide 10D is used in conjunction with a surgical navigation system including a camera and a monitor. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and redundant description will be omitted.

[0063] The alignment block 1E is the alignment block 1A of the first embodiment without the rod holder 2 and the arm 35 of the support body 3. In other words, the cutting guide 10D does not include the rod 7 that is placed along the femoral evaluation axis.

[0064] In addition to the alignment block 1E and the cutting block 8, the cutting guide 10D includes a marker 8a that allows the surgical navigation system to recognize the position and orientation of the cutting block 8 in three-dimensional space.

[0065] 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. When the antenna portions 8d are photographed by the camera of the surgical navigation system, the position and orientation of the cutting block 8 in three-dimensional space are recognized and displayed on the monitor of the surgical navigation system.

[0066] In this embodiment, as in the first embodiment, the movable body 4 is biased upward by the biasing means 5. Therefore, even if the orientation of the alignment block 1E relative to the femur 9 is changed when the alignment block 1E is installed at the distal end of the femur 9, the second contact surface 40 automatically follows the alignment of the first contact surface 30, thereby maintaining both the first contact surface 30 and the second contact surface 40 in contact with the medial condyle 91 and the lateral condyle 92 of the femur 9. Therefore, while maintaining a state in which the shapes of the medial condyle 91 and the lateral condyle 92 are referenced, it is possible to adjust the valgus angle, which is the angle of the perpendicular direction of the first contact surface 30 with respect 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 / external rotation angle around the specific direction.

[0067] Furthermore, with the cutting guide 10D including the alignment block 1E of this embodiment, as in the first 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 (together with other indicators).

[0068] 9A and 9B may be used instead of the cutting block 8. Furthermore, similar to the alignment block 1B shown in FIG. 7, the movable body 4 may be supported on the support body 3 via a linear motion mechanism 6A.

[0069] 5, the cutting guide 10A may be used in conjunction with a surgical navigation system by employing a marker 8a instead of the rod 7. In other words, the alignment block 1A (or 1B, 1C, or 1D) including the rod holder 2 can be used with or without a surgical navigation system.

[0070] Other Embodiments The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention.

[0071] For example, the biasing means 5 that biases the moving body 4 upward does not necessarily have to be a spring, but may be one that uses a motor or air pressure. However, if the biasing means 5 is a spring, the structure of the biasing means 5 can be simplified.

[0072] In addition, instead of the cutting block 8, 8A having a slit 82 through which the bone saw is inserted, a cutting block having a wall surface that comes into surface contact with the bone saw, or a cutting block including multiple pairs of rollers that clamp the bone saw may be used.

[0073] Furthermore, although not shown, in the first embodiment and its modified examples, the rod holder 2 does not necessarily need to be able to slide with the rod 7, and the rod 7 may be provided integrally with the rod holder 2. However, if the rod holder 2 is able to slide with the rod 7, the rod 7 and the alignment block can be operated separately.

[0074] In addition, in the first embodiment, either or both of the level difference display unit 11 and the valgus angle display unit 14 may be omitted, and in the second embodiment, the level difference display unit 11 may be omitted.

[0075] <Summary> In a first aspect, the present application provides an alignment block for guiding a resection plane in an appropriate angular direction when resecting the distal end of a femur from one side, the alignment block comprising: a support having a first abutment surface abutting one of the medial condyle and the lateral condyle of the femur and to which a cutting block for guiding a bone saw can be detachably attached; a movable body supported on the support so as to be movable in a direction perpendicular to the first abutment surface and having a second abutment surface abutting the other of the medial condyle and the lateral condyle of the femur; and biasing means for biasing the movable body in the direction in which the first abutment surface faces.

[0076] According to the above configuration, since the movable body is biased by the biasing means in the direction in which the first contact surface faces, even if the orientation of the alignment block relative to the femur is changed when the alignment block is installed at the distal end of the femur, the second contact surface automatically follows the movement of the movable body, thereby maintaining both the first and second contact surfaces in contact with the medial and lateral condyles of the femur. Therefore, while maintaining the reference state to the shapes of the medial and lateral condyles, it is possible to adjust the valgus angle, which is the angle of the perpendicular line of the first contact surface relative to a specific direction, and the angle of internal and external rotation around the specific direction.

[0077] In a second aspect, the alignment block of the first aspect may further include a level difference display unit that displays a level difference between the first and second contact surfaces. With this configuration, the surgeon can grasp the level difference between the medial and lateral condyles simply by looking at the level difference display unit.

[0078] As a third aspect, in the first or second aspect, the biasing means may be a spring. With this configuration, the structure of the biasing means can be simplified.

[0079] As a fourth aspect, in any one of the first to third aspects, for example, the moving body may be supported by the support body via a link mechanism or a linear motion mechanism.

[0080] As a fifth aspect, in any of the first to fourth aspects, the alignment block may further include a rod holder for holding a rod installed along the femoral evaluation axis, and the support may be swingably attached to the rod holder so that a valgus angle, which is the angle between the axial direction of the rod and the normal to the first abutment surface, is variable. With this configuration, the movement direction of the moving body relative to the axial direction of the rod can be adjusted by adjusting the valgus angle. For example, if the femoral evaluation axis is the femoral anatomical axis, the valgus angle can be set to a preoperative measurement angle between the femoral anatomical axis and the femoral functional axis.

[0081] As a sixth aspect, in the fifth aspect, the alignment block may further include a valgus angle display unit that displays the valgus angle. With this configuration, the surgeon can adjust the valgus angle while grasping the valgus angle.

[0082] As a seventh aspect, in the fifth or sixth aspect, the alignment block may further include a fixing mechanism that restricts the swinging of the support body. With this configuration, the adjusted state of the valgus angle can be maintained.

[0083] As an eighth aspect, in any one of the fifth to seventh aspects, the rod holder may be slidable along the rod. With this configuration, the rod and the alignment block can be operated separately.

[0084] As a ninth aspect, in any one of the fifth to seventh aspects, for example, the rod may be integrally provided with the rod holder.

[0085] As a tenth aspect, in any of the fifth to ninth aspects, the alignment block may further include a dial rotatably attached to the support and connected to the rod holder via a link mechanism. This configuration provides the advantages of improved operability, such as ease of holding, one-handed operation, simplified adjustment due to a wide operating pitch, and a clear operating method.

[0086] In an eleventh aspect, the present application provides, from another aspect, a cutting guide including a rod installed along a femoral evaluation axis, the alignment block of any one of the fifth to tenth aspects, and a cutting block for guiding a bone saw, which is detachably attached to a support of the alignment block. With this configuration, the resection position of the distal end of the femur can be determined by referring to the shapes of the medial and lateral condyles (together with other indicators).

[0087] In a twelfth aspect, from yet another aspect, the present application provides a cutting guide for use with a surgical navigation system, the cutting guide comprising: the alignment block of any one of the first to tenth aspects; a cutting block for guiding a bone saw, the cutting block being 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. With this configuration, the resection position of the distal end of the femur can be determined by referring to the shapes of the medial and lateral condyles (together with other indices).

[0088] 1A to 1E Alignment block 10A to 10D Cutting guide 11, 16 Level difference display unit 14 Valgus angle display unit 2 Rod holder 3 Support body 30 First contact surface 4 Moving body 40 Second contact surface 5 Urging means 51 Fixing mechanism 54 Link mechanism 57 Dial 58 Push button (fixing mechanism) 6 Link mechanism 6A Linear motion mechanism 7 Rod 8, 8A Cutting block 8a Marker

Claims

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

2. The alignment block according to claim 1, further comprising a level difference display portion for displaying a level difference between said first contact surface and said second contact surface.

3. The alignment block of claim 1, wherein said biasing means is a spring.

4. The alignment block according to claim 1, wherein the movable body is supported by the support body via a link mechanism or a linear motion mechanism.

5. An alignment block as described in claim 1, further comprising a rod holder for holding a rod installed along the femoral evaluation axis, wherein the support is attached to the rod holder so as to be swingable so that the valgus angle, which is the angle of the perpendicular direction of the first contact surface relative to the axial direction of the rod, can be changed.

6. The alignment block according to claim 5, further comprising a valgus angle display portion that displays the valgus angle.

7. The alignment block according to claim 5, further comprising a fixing mechanism for restraining the swinging of said support.

8. The alignment block of claim 5, wherein said rod holder is slidable along said rod.

9. The alignment block according to claim 5, wherein the rod holder is integrally provided with the rod.

10. The alignment block of claim 5, further comprising a dial rotatably mounted on said support and connected to said rod holder via a linkage.

11. A cutting guide comprising: a rod installed along a femoral evaluation axis; an alignment block according to any one of claims 5 to 10; and a cutting block for guiding a bone saw, detachably attached to a support of the alignment block.

12. A cutting guide for use with a surgical navigation system, comprising: an alignment block according to any one of claims 1 to 10; a cutting block for guiding a bone saw, which is detachably attached to a support of said alignment block; and markers for allowing said surgical navigation system to recognize the position and orientation of said cutting block in three-dimensional space.