JP7691783B2 - Total knee replacement measurement device - Google Patents

Description

The present invention relates to a measurement device used in total knee arthroplasty.

In total knee arthroplasty (TKA), the proximal tibia and distal femur are resected, and the tibial and femoral components of the artificial knee are attached to the resected proximal tibia and distal femur, respectively. Various devices are used in total knee arthroplasty.

For example, Patent Document 1 discloses a measuring device (referred to as a "surgical instrument" in Patent Document 1) used in total knee arthroplasty. More specifically, in total knee arthroplasty, the proximal end of the proximal tibia is resected, and the distal, anterior and posterior ends of the distal femur are resected. In addition, an anterior inclined surface is formed between the distal end resection surface and the anterior end resection surface, and a posterior inclined surface is formed between the distal end resection surface and the posterior end resection surface. A typical femoral component has a U-shaped shape in side view, covering the distal end resection surface, anterior inclined surface, anterior end resection surface, posterior inclined surface and posterior end resection surface of the distal femur, and the tibial component has a plate-shaped support portion (usually a laminate of a resin plate and a metal plate having a pair of concave curved surfaces that receive the medial and lateral condyles) that is placed on the proximal end resection surface of the proximal tibia and supports the femoral component, and a stem and keel (which are formed integrally with the metal plate of the support portion) that extend downward from the support portion and are embedded in the tibia.

The measuring device disclosed in Patent Document 1 measures the distance between the proximal end resection surface of the proximal tibia and the distal end resection surface of the distal femur in the extended position, and the distance between the proximal end resection surface of the proximal tibia and the posterior end resection surface of the distal femur in the perpendicular flexed position, before the tibial component and the femoral component are attached.

Specifically, the measurement device disclosed in Patent Document 1 includes a base placed in front of the knee joint, a locking plate fixed to the base via an arm, and a support plate facing the locking plate. The locking plate is brought into contact with the proximal end resection surface of the proximal tibia, and the support plate is brought into contact with the distal end resection surface of the distal femur in an extended position or the posterior end resection surface in a perpendicular flexed position.

The support plate is attached to the base so that it can move in a direction perpendicular to the locking plate. The measuring device includes a ratchet mechanism that switches between allowing only movement of the support plate away from the locking plate and allowing movement in both directions. By holding the support plate in the appropriate position by the ratchet mechanism, it is possible to measure the distance between the resection surfaces (the distance between the proximal end resection surface of the proximal tibia and the distal end resection surface of the distal femur in the extension position, and the distance between the proximal end resection surface of the proximal tibia and the posterior end resection surface of the distal femur in the right angle flexion position) with appropriate tension applied to soft tissues such as ligaments.

Patent No. 4095919

One method for adjusting the soft tissue balance in the extension and right-angle flexion positions of the knee joint is to adjust the resection position of the posterior end of the distal femur after resection of the distal end of the distal femur. Specifically, first, the distance between the distal end resection surface of the distal femur and the proximal end resection surface of the proximal tibia in the extension position under appropriate soft tissue tension is measured, and then the distance between the posterior end of the distal femur and the proximal end resection surface of the proximal tibia is measured under appropriate soft tissue tension in the right-angle flexion position. The resection position of the posterior end of the distal femur is then determined based on the distances measured in the extension and right-angle flexion positions. The procedure involves resecting the distal end of the distal femur in advance, but compared to before resection or after placement of the femoral component, the tension of the soft tissue attached to the patella in the right-angle flexion position changes due to the space created after resection, which may cause the distance between the posterior end of the distal femur and the proximal end resection surface of the proximal tibia to fluctuate.

Therefore, the present invention aims to provide a measurement device for total knee arthroplasty that can more accurately measure the distance between the resected surface of the proximal end of the proximal tibia and the posterior end of the distal femur in a right-angle flexion position, even when the distal end of the distal femur has been resected but not the posterior end, thereby minimizing the effect of the distal end being resected.

In order to solve the above-mentioned problems, the present invention provides a measurement device for use in total knee arthroplasty, comprising: a base disposed in front of the knee joint; a tibial paddle fixed to the base and having a first contact surface that is brought into contact with the proximal end resection surface of the proximal tibia; a femoral paddle attached to the base so as to be movable in a direction perpendicular to the first contact surface and having a second contact surface that is brought into contact with the rear end of the distal femur in a right-angle flexion position; and a tibial paddle that allows movement of the femoral paddle only in a direction away from the tibial paddle or allows movement in both directions. a femoral attachment having a third contact surface that is attachable to and detachable from the femoral paddle and that is brought into contact with the distal end resection surface of the distal part of the femur in a right-angle flexion position; and a distance display unit that displays the distance between the first contact surface and the second contact surface, wherein the femoral attachment includes a reproduction portion having a shape corresponding to a portion that covers the distal end resection surface of the distal part of the femur in the femoral component of an artificial knee joint, and the reproduction portion has the third contact surface.

According to the above configuration, the distance between the first contact surface of the tibial paddle and the second contact surface of the femoral paddle is displayed by the distance display unit, so that the distance between the proximal end resection surface of the proximal tibia and the rear end of the distal femur can be measured by contacting the first contact surface with the proximal end resection surface of the proximal tibia and the rear end of the distal femur in a right-angle flexion position and the second contact surface with the rear end of the distal femur. Moreover, by holding the femoral paddle in an appropriate position by the ratchet mechanism, the distance between the proximal end resection surface of the proximal tibia and the rear end of the distal femur can be measured with appropriate tension applied to soft tissues such as ligaments.

When resecting the proximal tibia and the distal femur, the patella and other parts (the patella and the soft tissues attached thereto, such as the patellar tendon and the quadriceps tendon) must be retracted to the inside or outside of the knee joint. After resecting the distal end of the distal femur, if the patella and other parts are returned to their original positions with the distal end resection surface exposed in a right-angle flexion position, the soft tissues attached to the patella will be loosened. In contrast, in the above configuration, the femoral attachment that can be detached from the femoral paddle includes a reproduction part having a shape that partially corresponds to the femoral component to be installed. Therefore, if the third contact surface of the reproduction part of the femoral attachment is brought into contact with the distal end resection surface of the distal femur while the femoral attachment is attached to the femoral paddle, the soft tissues attached to the patella can be appropriately tensioned when the patella and other parts are returned to their original positions. That is, the distance between the resected surface of the proximal end of the proximal tibia and the posterior end of the distal femur can be measured under the same conditions as after the future attachment of the femoral component. In other words, the distance between the resected surface of the proximal end of the proximal tibia and the posterior end of the distal femur in the right-angle flexion position can be measured more accurately by suppressing the effect of the resection of the distal end even in a state in which the distal end of the distal femur has been resected but not the posterior end.

Furthermore, when the femoral attachment is removed from the femoral paddle, by bringing the first contact surface into contact with the proximal end resection surface of the proximal tibia in the extended position and bringing the second contact surface into contact with the distal end resection surface of the distal femur, the distance between the proximal end resection surface of the proximal tibia and the distal end resection surface of the distal femur can be measured.

The femoral attachment may be attached to the femoral paddle so as to be movable in the anterior-posterior direction of the knee joint. With this configuration, the relative positions of the proximal tibia and the distal femur in the anterior-posterior direction of the knee joint can be adjusted by moving the femoral attachment with the third contact surface of the femoral attachment in contact with the distal end resection surface of the distal femur in the perpendicular flexion position. This allows the relative positions of the proximal tibia and the distal femur in the anterior-posterior direction of the knee joint to be aligned with the ideal relative positions after installation of the artificial knee joint when measuring the distance between the proximal end resection surface of the proximal tibia and the rear end of the distal femur.

The femoral paddle may be divided into a first femoral paddle and a second femoral paddle arranged in the medial-lateral direction of the knee joint, and the first femoral paddle and the second femoral paddle may be attached to the base so as to be movable in a direction perpendicular to the first contact surface independently of each other, and the distance display unit may display the distance between the first contact surface and the second contact surface for each of the first femoral paddle and the second femoral paddle. With this configuration, when the positions of the rear ends of the medial condyle and the lateral condyle of the distal femur are different in a right-angle flexion position, it is possible to measure both the distance from the proximal end resection surface of the proximal tibia to the rear end of the medial condyle and the distance from the proximal end resection surface of the proximal tibia to the rear end of the lateral condyle. In addition, when the positions of the distal resection surfaces of the medial and lateral condyles of the distal femur are different in the extended position, it is possible to measure both the distance from the proximal resection surface of the proximal tibia to the distal resection surface of the medial condyle and the distance from the proximal resection surface of the proximal tibia to the distal resection surface of the lateral condyle.

Alternatively, the femoral paddle may be swung around a swing axis extending in the front-rear direction of the knee joint, and the distance display unit may display the distance between the first contact surface and the second contact surface on a perpendicular line passing through the swing center of the femoral paddle that is perpendicular to the first contact surface. With this configuration, when the positions of the posterior ends of the medial condyle and the lateral condyle of the distal femur are different in the right-angle flexion position, the femoral paddle can be brought into contact with both the posterior end of the medial condyle and the posterior end of the lateral condyle. Also, when the positions of the distal ends of the medial condyle and the lateral condyle of the distal femur are different in the extension position before resection of the distal end of the distal femur, the femoral paddle can be brought into contact with both the distal end of the medial condyle and the distal end of the lateral condyle. Furthermore, when the space between the proximal tibia and the distal femur is widened after resection of the distal or posterior end of the distal femur to provide appropriate tension to the soft tissue, the femoral paddle can be brought into surface contact with the distal end resection surface even if the distal end resection surface or posterior end resection surface of the distal femur is inclined relative to the proximal end resection surface of the proximal tibia.

The tibial paddle includes a first paddle portion having the first contact surface and a first arm portion extending from the first paddle portion toward the base, the femoral paddle includes a second paddle portion having the second contact surface, a first base portion located above the base, and a second arm portion extending from the second paddle portion toward the first base, and the femoral attachment includes a second base portion located above the base and a third arm portion extending from the reproduction portion toward the second base portion, and when one of the inward and outward directions of the knee joint is defined as a first direction and the other as a second direction, the first arm portion may be closer to the first direction than the center of the first paddle portion, the second arm portion may be closer to the first direction than the center of the second paddle portion, and the third arm portion may be closer to the first direction than the center of the reproduction portion. With this configuration, space can be secured to the sides of the first to third arm portions, and during distance measurement, the patella and other bones that have been retracted to the inside or outside of the knee joint when resecting the proximal tibia and distal femur can be returned to this space.

The measuring device for total knee arthroplasty may further include a femoral sizer that is detachable from the femoral paddle for measuring the size of the distal femur in the right-angle flexion position and for determining the resection positions of the anterior and posterior ends of the distal femur. With this configuration, the size of the distal femur can be measured and the mounting position of the femoral component can be determined while maintaining the relative positions of the proximal tibia and the distal femur in an appropriate position that reproduces the physiological state in which appropriate tension is applied to the soft tissue.

According to the present invention, it is possible to measure the distance between the proximal end resection surface of the proximal tibia and the rear end of the distal femur in a right-angle flexion position. Note that the measuring device disclosed in Patent Document 1 can also measure the distance between the proximal end resection surface of the proximal tibia and the rear end of the distal femur in a right-angle flexion position if the measuring device is used after the proximal tibia is resected and before the distal femur is resected, but the measuring device of the present invention can perform more accurate measurements than the measuring device disclosed in Patent Document 1.

1 is a perspective view of a measurement device for total knee arthroplasty according to a first embodiment of the present invention, with a femoral attachment removed; FIG. FIG. 1 is a perspective view of the base and tibial paddle. FIG. 1 is a perspective view of a femoral paddle. FIG. 2 is a plan view of a measurement device for total knee arthroplasty. 5 is a cross-sectional view taken along line VV in FIG. 4. FIG. 13 shows the measurement device for total knee arthroplasty in use in an extended position. FIG. 13 is a diagram showing the measurement device for total knee arthroplasty in use in a right-angle flexion position. FIG. 1 is a perspective view of a total knee arthroplasty measurement device when the femoral attachment is installed. FIG. 13 shows the measurement device for total knee arthroplasty equipped with a femoral attachment in use in a right angle flexion position. FIG. 1 is a perspective view of a measurement device for total knee arthroplasty when equipped with a femoral sizer. FIG. 2A is a perspective view of a femoral cutting guide as viewed from the front side, and FIG. 2B is a perspective view of the femoral cutting guide as viewed from the back side. FIG. 13 shows a measurement device for total knee arthroplasty equipped with a femoral sizer in use in a right-angle flexion position. FIG. 11 is a perspective view of a measurement device for total knee arthroplasty according to a second embodiment of the present invention. FIG. 11 is a perspective view of the measurement device for total knee arthroplasty when the femoral attachment is removed in the second embodiment. FIG. 11 is a cross-sectional view of the measurement device for total knee arthroplasty when the femoral attachment is removed in the second embodiment. FIG. 11 is a perspective view of a measurement device for total knee arthroplasty according to a third embodiment of the present invention. FIG. 11 is a cross-sectional view of the measurement device for total knee arthroplasty when the femoral attachment is removed in the third embodiment.

First Embodiment
1 shows a measurement device 1 for total knee arthroplasty according to a first embodiment of the present invention. This measurement device 1 is used for total knee arthroplasty.

Specifically, the measurement device 1 includes a base 2 placed in front of the knee joint, a tibial paddle 4 fixed to the base 2, and a femoral paddle 5 facing the tibial paddle 4. The measurement device 1 also includes a femoral attachment 7 shown in Fig. 8 and a femoral sizer 8 shown in Fig. 10.

6 and 7, the tibial paddle 4 and the femoral paddle 5 are inserted between the proximal tibia 91 and the distal femur 95. Hereinafter, for ease of explanation, as shown in Figures 1 to 5, the axial direction of the tibia will be referred to as the up-down direction, the inward-outward direction of the knee joint as the left-right direction (the lower right side of Figure 1 is the left side, and the upper left side of Figure 1 is the right side), and the anterior-posterior direction of the knee joint perpendicular to the axial direction of the tibia will be referred to simply as the anteroposterior direction.

When the measuring device 1 is used, the proximal end of the proximal tibia 91 and the distal end of the distal femur 95 are resected beforehand. The measuring device 1 measures the distance between the distal end resection surface 96 of the distal femur 95 and the proximal end resection surface 92 of the proximal tibia 91 in the extended position as shown in FIG. 6, and measures the distance between the posterior end 97 of the distal femur 95 and the proximal end resection surface 92 of the proximal tibia 91 in the right-angle flexed position as shown in FIG. 7. It is also possible to use the measuring device 1 after the resection of the proximal end of the proximal tibia 91 and before the resection of the distal femur 95. Alternatively, it is also possible to use the measuring device 1 after the resection of the posterior end 97 of the distal femur 95 to measure the distance between the posterior end resection surface of the distal femur 95 and the proximal end resection surface 92 of the proximal tibia 91 in the right-angle flexed position.

The tibial paddle 4 has a first contact surface 40 that is brought into contact with the proximal end resection surface 92 of the proximal tibia 91. The up-down direction is also a direction perpendicular to the first contact surface 40. The femoral paddle 5 has a second contact surface 50 that is brought into contact with the distal end resection surface 96 of the distal femur 95 in the extension position and with the posterior end 97 of the distal femur 95 in the right-angle flexion position.

2, the base 2 is generally plate-shaped and perpendicular to the anterior-posterior direction, and has a first main surface 2a facing rearward, a second main surface 2b facing forward, a pair of side surfaces facing left and right, and a pair of end surfaces facing upward and downward. The tibial paddle 4 extends rearward from an upper portion of the first main surface 2a of the base 2.

The base 2 is provided with a pair of through holes 22, 23 that penetrate the base 2 in the up-down direction at positions spaced apart in the left-right direction. In addition, the second main surface 2b of the base 2 is provided with a pair of grooves 24, 25 that extend in the up-down direction from the upper end surface to the lower end surface at positions spaced apart in the left-right direction.

Furthermore, a pair of support pieces 21 protrude in opposite directions from both sides of the base 2. Each support piece 21 has a flat upper surface perpendicular to the up-down direction, with the upper surface of the right support piece 21 continuing to the right side surface of the groove 24, and the upper surface of the left support piece 21 continuing to the left side surface of the groove 25.

The tibial paddle 4 includes a first paddle portion 41 having a first contact surface 40, and a first arm portion 42 extending from the first paddle portion 41 toward the base 2. The first arm portion 42 is parallel to the anterior-posterior direction and is connected to an upper portion of the first main surface 2a of the base 2. On the other hand, the first arm portion 42 is shifted to the right of the center of the first paddle portion 41.

The femoral paddle 5 is attached to the base 2 so as to be movable in the up-down direction. The femoral paddle 5 includes a second paddle portion 51 having a second contact surface 50, a first base portion 53 located above the base 2, and a second arm portion 52 extending from the second paddle portion 51 toward the first base portion 53. The second arm portion 52 is parallel to the anterior-posterior direction and is shifted to the right of the center of the second paddle portion 51, similar to the first arm portion 42 of the tibial paddle 4. In other words, the second arm portion 52 is located directly above the first arm portion 42.

In this embodiment, the femoral paddle 5 is divided into a first femoral paddle 5A and a second femoral paddle 5B arranged in the left-right direction as shown in Fig. 4. Therefore, the second contact surface 50 is also divided into contact surfaces 50A and 50B, the second paddle portion 51 is also divided into paddle portions 51A and 51B, the second arm portion 52 is also divided into arm portions 52A and 52B, and the first base portion 53 is also divided into base portions 53A and 53B. However, the femoral paddle 5 may be a combination of the first femoral paddle 5A and the second femoral paddle 5B.

The first femoral paddle 5A and the second femoral paddle 5B are attached to the base 2 so that they can move up and down independently of each other. More specifically, a rod 54A having a circular cross section extends downward from the base 53A of the first femoral paddle 5A, and the rod 54A is inserted into the through hole 22 of the base 2, allowing the first femoral paddle 5A to slide relative to the base 2. Similarly, a rod 54B having a circular cross section extends downward from the base 53B of the second femoral paddle 5B, and the rod 54B is inserted into the through hole 23 of the base 2, allowing the second femoral paddle 5B to slide relative to the base 2.

As shown in Figure 3, the left side of the rod 54A of the first femoral paddle 5A has a tooth surface 54a with repeated concaves and convexes in the up-down direction. On the other hand, as shown in Figure 2, the base 2 rotatably holds an operating shaft 31 extending in the front-rear direction to the left of the through hole 22. The operating shaft 31 is operated by a user such as a doctor.

As shown in Fig. 5, the operating shaft 31 is provided with a pinion 33 that meshes with the tooth surface 54a. Therefore, when the operating shaft 31 is operated, the first femoral paddle 5A moves in the vertical direction by an amount corresponding to the amount of operation (amount of rotation).

Similarly, as shown in Fig. 3, the left side of the rod 54B of the second femoral paddle 5B is formed with a tooth surface 54b that has repeated concaves and convexes in the vertical direction. On the other hand, as shown in Fig. 2, the base 2 rotatably holds an operating shaft 32 that extends in the front-rear direction to the left of the through hole 23. The operating shaft 32 is operated by a user such as a doctor.

As shown in Figure 5, the operating shaft 32 is provided with a pinion 34 that meshes with the tooth surface 54b. Therefore, when the operating shaft 32 is operated, the second femoral paddle 5B moves up and down by an amount corresponding to the amount of operation (amount of rotation).

Furthermore, the measuring device 1 includes a ratchet mechanism 6 that switches between allowing only movement of the femoral paddle 5 away from the tibial paddle 4 (i.e., upward) or allowing movement in both directions (i.e., upward and downward), and a distance display unit 11 that displays the distance between the first contact surface 40 and the second contact surface 50.

As described above, since the femoral paddle 5 is divided into the first femoral paddle 5A and the second femoral paddle 5B, the ratchet mechanism 6 includes a first ratchet mechanism 6A for the first femoral paddle 5A and a second ratchet mechanism 6B for the second femoral paddle 5B. Similarly, the distance display unit 11 also includes a first distance display unit 11A for the first femoral paddle 5A and a second distance display unit 11B for the second femoral paddle 5B. In other words, the distance display unit 11 displays the distance between the first contact surface 40 and the second contact surface 50 (contact surface 50A or contact surface 50B) for each of the first femoral paddle 5A and the second femoral paddle 5B.

The first ratchet mechanism 6A is composed of a pillar 55A provided on the first femoral paddle 5A, a ratchet lever 61 (see FIG. 2) attached to the base 2 so as to be able to swing, and a spring 63 that biases the ratchet lever 61. However, the configuration of the first ratchet mechanism 6A is not limited to this and can be modified as appropriate.

3, the pillar 55A is located in front of the rod 54A and extends downward from the base 53A of the first femoral paddle 5A. The pillar 55A has a rectangular cross section and fits into the groove 24 provided in the second main surface 2b of the base 2. A tooth surface 55a with repeated concaves and convexes in the vertical direction is formed on the right side surface of the pillar 55A.

The ratchet lever 61 is disposed above the right support piece 21 and is attached to the base 2 via a pin extending in the front-rear direction near the groove 24. The ratchet lever 61 includes an operating part extending to the right from the pin, and a hook part extending upward from the pin and engaging with the tooth surface 55a at its tip.

The above-mentioned spring 63 is disposed between the operating part of the ratchet lever 61 and the support piece 21, and biases the ratchet lever 61 in a direction that maintains the engagement between the hook part and the tooth surface 55a. With this structure, when the operating part is not operated, only the upward movement of the first femoral paddle 5A is possible, and when the operating part is operated to release the engagement between the hook part and the tooth surface 55a, the first femoral paddle 5A can move upward and downward.

Similarly, the second ratchet mechanism 6B is composed of a pillar 55B provided on the second femoral paddle 5B, a ratchet lever 62 (see FIG. 2) attached to the base 2 so as to be able to swing, and a spring 64 that biases the ratchet lever 61. However, the configuration of the second ratchet mechanism 6B is not limited to this and can be modified as appropriate.

As shown in Figure 3, the pillar 55B is located in front of the rod 54B and extends downward from the base 53B of the second femoral paddle 5B. The pillar 55B has a rectangular cross section and fits into the groove 25 provided in the second main surface 2b of the base 2. A tooth surface 55b with repeated concaves and convexes in the vertical direction is formed on the left side surface of the pillar 55B.

The ratchet lever 62 is disposed above the left support piece 21 and is attached to the base 2 via a pin extending in the front-rear direction near the groove 25. The ratchet lever 62 includes an operating part extending leftward from the pin and a hook part extending upward from the pin and engaging with the tooth surface 55b at its tip.

The above-mentioned spring 64 is disposed between the operating part of the ratchet lever 62 and the support piece 21, and biases the ratchet lever 62 in a direction that maintains the engagement between the hook part and the tooth surface 55b. With this structure, when the operating part is not operated, only the upward movement of the second femoral paddle 5B is possible, and when the operating part is operated to release the engagement between the hook part and the tooth surface 55b, the second femoral paddle 5B can move upward and downward.

As shown in Figure 3, a scale 14 indicating the distance from the first contact surface 40 to the contact surface 50A is formed on the front surface of the pillar 55A provided on the first femoral paddle 5A. Meanwhile, a mark 12 indicating the current position of the contact surface 50A is formed on the second main surface 2b of the base 2 as shown in Figure 2. These scales 14 and marks 12 constitute a first distance display unit 11A that displays the distance between the first contact surface 40 and the contact surface 50A.

Similarly, a scale 15 indicating the distance from the first contact surface 40 to the contact surface 50B is formed on the front surface of the pillar 55B of the second femoral paddle 5B. Meanwhile, a mark 13 indicating the current position of the contact surface 50B is formed on the second main surface 2b of the base 2. These scales 15 and marks 13 constitute a second distance display unit 11B that displays the distance between the first contact surface 40 and the contact surface 50B.

6, in the extended position, the first contact surface 40 is brought into contact with the proximal resection surface 92 of the proximal tibia 91 and the second contact surface 50 is brought into contact with the distal resection surface 96 of the distal femur 95, so that the distance between the proximal resection surface 92 of the proximal tibia 91 and the distal resection surface 96 of the distal femur 95 can be measured. In this embodiment, the femoral paddle 5 is divided into the first femoral paddle 5A and the second femoral paddle 5B. Therefore, when the positions of the distal resection surface 96 differ between the medial condyle and the lateral condyle of the distal femur 95, both the distance from the proximal resection surface 92 of the proximal tibia 91 to the distal resection surface 96 of the medial condyle and the distance from the proximal resection surface 92 of the proximal tibia 91 to the distal resection surface 96 of the lateral condyle can be measured.

Moreover, by holding the femoral paddle 5 in the appropriate position by the ratchet mechanism 6, the distance between the proximal end resection surface 92 of the proximal tibia 91 and the distal end resection surface 96 of the distal femur 95 can be measured while applying appropriate tension to soft tissues such as ligaments.

7, in the right-angle flexion position, the first contact surface 40 is brought into contact with the proximal end resection surface 92 of the proximal tibia 91 and the second contact surface 50 is brought into contact with the rear end 97 of the distal femur 95, so that the distance between the proximal end resection surface 92 of the proximal tibia 91 and the rear end 97 of the distal femur 95 can be measured. In this embodiment, the femoral paddle 5 is divided into the first femoral paddle 5A and the second femoral paddle 5B. Therefore, when the positions of the rear ends 97 of the medial and lateral condyles of the distal femur 95 are different, both the distance from the proximal end resection surface 92 of the proximal tibia 91 to the rear end 97 of the medial condyle and the distance from the proximal end resection surface 92 of the proximal tibia 91 to the rear end 97 of the lateral condyle can be measured.

Moreover, by holding the femoral paddle 5 in the appropriate position by the ratchet mechanism 6, the distance between the proximal end resection surface 92 of the proximal tibia 91 and the posterior end 97 of the distal femur 95 can be measured while applying appropriate tension to soft tissues such as ligaments.

Next, the femoral attachment 7 will be described with reference to Figure 8. The femoral attachment 7 is used to measure the distance between the proximal end resection surface 92 of the proximal tibia 91 and the posterior end 97 of the distal femur 95 in a right-angle flexion position, as shown in Figure 9.

The femoral attachment 7 includes a reproduction portion 71 having a shape corresponding to the portion covering the distal end resection surface 96 of the distal femur 95 in the femoral component of the artificial knee joint (i.e., a shape that physiologically restores the resection portion of the distal femur 95), a second base portion 73 located above the base 2, and a third arm portion 72 extending from the reproduction portion 71 toward the second base portion 73. The reproduction portion 71 has a third contact surface 70 that is brought into contact with the distal end resection surface 96 of the distal femur 95 in the right-angle flexion position.

More specifically, the reproduction portion 71 includes a medial condyle portion and a lateral condyle portion spaced apart from each other in the left-right direction, and a connecting portion connecting the medial condyle portion and the lateral condyle portion. In this embodiment, the posterior surfaces of the medial condyle portion, the lateral condyle portion, and the connecting portion are located on the same plane, and form the third contact surface 70.

The third arm portion 72 is parallel to the front-rear direction and is shifted to the right of the center of the reproduction portion 71. In this embodiment, the third arm portion 72 is located directly above the arm portion 52A of the first femoral paddle 5A. The second base portion 73 is located directly above the base portion 53A of the first femoral paddle 5A.

The femoral attachment 7 is configured to be detachable from the femoral paddle 5. In this embodiment, the femoral attachment 7 is detachable from the first femoral paddle 5A. In this embodiment, the femoral attachment 7 is attached to the first femoral paddle 5A so that it can move in the front-to-back direction.

Specifically, a groove 56 having a trapezoidal cross section extending in the anterior-posterior direction is provided on the upper surface of the base 53A of the first femoral paddle 5A. Meanwhile, a rail portion 74 extending in the anterior-posterior direction is provided on the second base 73 of the femoral attachment 7, which fits into the groove 56. The rail portion 74 fits into the groove 56, allowing the femoral attachment 7 to slide relative to the first femoral paddle 5A.

The second base 73 is provided with a screw hole that passes through the second base 73 in the vertical direction, and a set screw 76 is screwed into the screw hole. By rotating the set screw 76 and pressing the tip of the set screw 76 against the bottom of the groove 56, the relative position of the femoral attachment 7 with respect to the first femoral paddle 5A can be fixed.

Furthermore, a scale 75 is formed on the upper surface of the second base 73, which indicates the relative position of the femoral attachment 7 with respect to the first femoral paddle 5A. Meanwhile, a pillar 57 is provided on the base 53A of the first femoral paddle 5A, protruding upward from the left end of the base 53A, as shown in FIG. 3. The upper surface of the pillar 57 is located on the same plane as the upper surface of the second base 73 of the femoral attachment 7 when the femoral attachment 7 is attached to the first femoral paddle 5A. A mark 58 is formed on the upper surface of the pillar 57, which indicates the current position of the femoral attachment 7.

When resecting the proximal tibia 91 and the distal femur 95, it is necessary to move the patella and other parts (the patella and the soft tissues attached thereto, such as the patellar tendon and the quadriceps tendon) to the inside or outside of the knee joint. If the patella and other parts are returned to their original positions after resecting the distal end of the distal femur 95 with the distal end resection surface 96 exposed in the right-angle flexion position, the soft tissues attached to the patella will become loose.

In contrast, in this embodiment, the femoral attachment 7 detachable from the femoral paddle 5 includes a reproduction portion 71 having a shape that partially corresponds to the femoral component to be installed. Therefore, as shown in FIG. 9, if the third contact surface 70 of the reproduction portion 71 of the femoral attachment 7 is brought into contact with the distal end resection surface 96 of the distal femoral portion 95 while the femoral attachment 7 is attached to the femoral paddle 5, appropriate tension can be applied to the soft tissue attached to the patella when the patella, etc. is returned to its original position. In other words, the distance between the proximal end resection surface 92 of the proximal tibia 91 and the rear end 97 of the distal femoral portion 95 can be measured under the same circumstances as after the future femoral component is attached. In other words, the distance between the proximal end resection surface 92 of the proximal tibia 91 and the posterior end 97 of the distal femur 95 in the right-angle flexion position can be measured more accurately by minimizing the effect of the resection of the distal end, even when the distal end of the distal femur 95 has been resected but the posterior end 97 has not been resected.

Moreover, in this embodiment, the first arm portion 42 of the tibial paddle 4 is shifted to the right of the center of the first paddle portion 41, the second arm portion 52 of the femoral paddle 5 is shifted to the right of the center of the second paddle portion 51, and the third arm portion 72 of the femoral attachment 7 is shifted to the right of the center of the reproduction portion 71. This makes it possible to secure space to the sides of the first to third arm portions 42, 52, and 72, and during distance measurement, the patella and other parts that have been retracted to the inside or outside of the knee joint when the proximal tibia portion 91 and the distal femur portion 95 are resected can be returned to this space.

Furthermore, in this embodiment, since the femoral attachment is movable in the anterior-posterior direction, the relative positions of the proximal tibia 91 and the distal femur 95 in the anterior-posterior direction of the knee joint can be adjusted by moving the femoral attachment 7 with the third contact surface 70 of the femoral attachment 7 in contact with the distal end resection surface 96 of the distal femur 95 in the 90-degree flexion position. This allows the relative positions of the proximal tibia 91 and the distal femur 95 in the anterior-posterior direction of the knee joint to be aligned with the ideal relative positions after the artificial knee joint is installed when measuring the distance between the proximal end resection surface 92 of the proximal tibia 91 and the posterior end 97 of the distal femur 95.

Next, the femoral sizer 8 will be described with reference to Figure 10. The femoral sizer 8 is for measuring the size of the distal femur 95 in the right-angle flexion position as shown in Figure 12. The femoral sizer 8 is also for determining the resection position of the anterior end and the posterior end 97 of the distal femur 95.

When resecting the anterior and posterior ends 97 of the distal femur 95, a femoral cutting guide 88, for example, as shown in Figures 11(a) and (b) is used. This femoral cutting guide 88 has a number of slits 88b-88e for guiding the resection saw. The femoral cutting guide 88 also has a pair of positioning pins 88a.

The femoral sizer 8 includes a measuring and positioning unit 81 having a contact surface that is brought into contact with the distal end resection surface 96 of the distal femoral portion 95 in a right-angle flexion position, a third base portion 83 located above the base 2, and a fourth arm portion 82 extending from the measuring and positioning unit 81 toward the third base portion 83. The measuring and positioning unit 81 is provided with a pair of through holes 81a having the same pitch as the positioning pins 88a of the femoral cutting guide 88. Through these through holes 81a, positioning holes are machined in the distal end resection surface 96. Instead of forming positioning holes, pins, screws, or nails may be driven into the distal end resection surface 96. In this case, the femoral cutting guide 88 is provided with positioning holes.

The fourth arm portion 82 is parallel to the front-to-rear direction and is shifted to the right of the center of the measurement/positioning portion 81. In this embodiment, the fourth arm portion 82 is located directly above the arm portion 52A of the first femoral paddle 5A. The third base portion 83 is located directly above the base portion 53A of the first femoral paddle 5A.

The femoral sizer 8 is configured to be detachable from the femoral paddle 5. In this embodiment, the femoral sizer 8 is detachable from the first femoral paddle 5A. In this embodiment, the femoral sizer 8 is attached to the first femoral paddle 5A so that it can move in the front-to-back direction.

Specifically, the third base 83 of the femoral sizer 8 is provided with a rail portion 84 extending in the anterior-posterior direction that fits into a groove 56 provided on the upper surface of the base 53A of the first femoral paddle 5A. The rail portion 84 fits into the groove 56, allowing the femoral sizer 8 to slide relative to the first femoral paddle 5A.

The third base 83 is provided with a screw hole that passes through the third base 83 in the vertical direction, and a set screw 86 is screwed into this screw hole. By rotating the set screw 86 and pressing the tip of the set screw 86 against the bottom of the groove 56, the relative position of the femoral sizer 8 with respect to the first femoral paddle 5A can be fixed.

Furthermore, a scale 85 indicating the relative position of the femoral sizer 8 with respect to the first femoral paddle 5A is formed on the upper surface of the third base 83. On the other hand, when the femoral sizer 8 is attached to the first femoral paddle 5A, the upper surface of a post 57 provided on the base 53A of the first femoral paddle 5A is positioned on the same plane as the upper surface of the third base 83 of the femoral sizer 8, and a mark 58 (see FIG. 3) formed on the upper surface of the post 57 indicates the current position of the femoral sizer 8.

By using such a femoral sizer 8, it is possible to measure the size of the distal femur 95 and determine the attachment position of the femoral component while maintaining the relative positions of the proximal tibia 91 and the distal femur 95 in an appropriate position that reproduces the physiological state in which appropriate tension is applied to the soft tissue. However, the measurement device 1 does not have to include the femoral sizer 8.

Second Embodiment
13 to 15 show a measurement device 1A for total knee arthroplasty according to a second embodiment of the present invention (FIGS. 14 and 15 are views showing a state in which the femoral attachment 7 has been removed). In this embodiment and a third embodiment described later, the same components as those in the first embodiment are given the same reference numerals, and duplicated explanations will be omitted.

Similar to the measuring device 1 of the first embodiment, the measuring device 1A includes a base 2, a tibial paddle 4, a femoral paddle 5, a ratchet mechanism 6, and a femoral attachment 7. The measuring device 1A may also include a femoral sizer 8 shown in FIG.

In this embodiment, instead of being divided into a first femoral paddle 5A and a second femoral paddle 5B, the femoral paddle 5 can be swung around a swing axis extending in the front-rear direction. Therefore, when the positions of the rear ends of the medial and lateral condyles of the distal femur 95 are different in the perpendicular bending position, the femoral paddle 5 can be brought into contact with both the rear end of the medial condyle and the rear end of the lateral condyle. Furthermore, when the space between the proximal tibia 91 and the distal femur 95 is widened in the perpendicular bending position after the resection of the rear end 97 of the distal femur 95 to provide appropriate tension to the soft tissue, even if the rear end resection surface of the distal femur 95 is inclined relative to the proximal end resection surface 92 of the proximal tibia 91, the femoral paddle 5 can be brought into surface contact with the rear end resection surface.

In addition, when the femoral attachment 7 is removed from the femoral paddle 5, if the positions of the distal ends of the medial and lateral condyles of the distal femur 95 are different in the extended position before the resection of the distal end of the distal femur 95, the femoral paddle 5 can be brought into contact with both the distal end of the medial condyle and the distal end of the lateral condyle. Furthermore, when the space between the proximal tibia 91 and the distal femur 95 is widened after the resection of the distal end of the distal femur 95 to provide appropriate tension to the soft tissue, the femoral paddle 5 can be brought into surface contact with the distal end resection surface 96 even if the distal end resection surface 96 of the distal femur 95 is inclined relative to the proximal end resection surface 92 of the proximal tibia 91.

Specifically, in this embodiment, the femoral paddle 5 is attached to the base 2 via the lifting member 44 so that it can move up and down. The femoral paddle 5 is also held by the lifting member 44 so that it can swing.

More specifically, in this embodiment, the base 2 is a generally rectangular parallelepiped that is long in the vertical direction. The first arm 42 of the tibial paddle 4 extends to the right of the base 2, and the first arm 42 is provided with a hanging part 43 that hangs down along the right side surface of the base 2. This hanging part 43 is connected to the base 2.

The base 2 is provided with a through hole 27 that passes through the base 2 in the vertical direction. A groove 28 that extends in the vertical direction from the upper end surface to the lower end surface is provided in the second main surface 2b of the base 2. Furthermore, a support piece 26 protrudes leftward from the left side surface of the base 2. The support piece 26 has a flat upper surface that is perpendicular to the vertical direction, and the upper surface of the support piece 26 is connected to the left side surface of the groove 28.

The lifting member 44 includes a head 46 located above the base 2 and a rod 45 with a circular cross section that extends downward from the head 46. The rod 45 is inserted into the through hole 27 of the base 2, allowing the lifting member 44 to slide relative to the base 2.

The head 46 is provided with a channel that crosses the head 46 in the left-right direction. In other words, the head 46 includes a pair of opposing walls that face each other across the channel in the front-rear direction.

The first base 53 of the femoral paddle 5 extends from a position above the head 46 to a position beyond the first arm 42 of the tibial paddle 4. A rectangular slot extending in the left-right direction is provided in the left-right portion of the first base 53, into which the rear opposing walls of the head 46 are inserted. The first base 53 is also connected to a pair of opposing walls of the head 46 via a shaft 47 extending in the front-rear direction, allowing the femoral paddle 5 to swing around the central axis of the shaft 47 as the swing axis.

A tooth surface 45a with repeated concave and convex shapes in the vertical direction is formed on the left side of the rod 45. On the other hand, an operating shaft 35 extending in the front-rear direction to the left of the through hole 27 is rotatably held in the base 2. The operating shaft 35 is operated by a user such as a doctor.

The operating shaft 35 is provided with a pinion 36 that meshes with the tooth surface 45a. Therefore, when the operating shaft 35 is operated, the lifting member 44 and the femoral paddle 5 move up and down by an amount corresponding to the amount of operation (amount of rotation).

In this embodiment, the ratchet mechanism 6 is composed of a pillar 67 provided on the lifting member 44, a ratchet lever 65 swingably attached to the base 2, and a spring 66 that biases the ratchet lever 65. However, the configuration of the ratchet mechanism 6 is not limited to this and can be changed as appropriate.

The pillar 67 is located in front of the rod 45 and extends downward from the head 46 of the lifting member 44. The pillar 67 has a rectangular cross section and fits into a groove 28 provided in the second main surface 2b of the base 2. A tooth surface 67a that has repeated concaves and convexes in the vertical direction is formed on the left side surface of the pillar 67.

The ratchet lever 65 is disposed above the support piece 26 and is attached to the base 2 via a pin extending in the front-rear direction near the groove 28. The ratchet lever 65 includes an operating portion extending leftward from the pin and a hook portion extending upward from the pin and engaging with the tooth surface 67a at its tip.

The spring 66 is disposed between the operating part of the ratchet lever 65 and the support piece 26, and biases the ratchet lever 65 in a direction that maintains the engagement between the hook part and the tooth surface 67a. With this structure, when the operating part is not operated, only the upward movement of the lifting member 44 and the femoral paddle 5 is possible, and when the operating part is operated to release the engagement between the hook part and the tooth surface 67a, the lifting member 44 and the femoral paddle 5 can move upward and downward.

As described in the first embodiment, the rail portion 74 of the femoral attachment 7 fits into the groove 56 provided in the first base portion 53 of the femoral paddle 5, allowing the femoral attachment 7 to slide relative to the femoral paddle 5. The femoral attachment 7 swings in response to the swinging of the femoral paddle 5.

Furthermore, the measurement device 1A includes a distance display unit 16 and an angle display unit 19. The distance display unit 11 displays the distance between the first contact surface 40 and the second contact surface 50 on a perpendicular line to the first contact surface 40 and passing through the swing center of the femoral paddle 5.

As shown in Figure 14, a scale 18 indicating the distance from the first contact surface 40 to the second contact surface 50 is formed on the front surface of a pillar 67 provided on the lifting member 44. Meanwhile, a mark 17 indicating the current position of the second contact surface 50 is formed on the second main surface 2b of the base 2. These scales 18 and marks 17 constitute the distance display unit 16.

The angle display unit 19 displays the angle between the first contact surface 40 and the second contact surface 50 (hereinafter referred to as the "inter-paddle angle"). A scale plate 69 is provided on the opposing wall behind the head 46 of the lifting member 44, and a scale 69a relating to the inter-paddle angle is formed on this scale plate 69. Meanwhile, a needle 59 indicating the current angle of the second contact surface 50 is provided on the first base 53 of the femoral paddle 5. These scales 69a and needle 59 constitute the angle display unit 19.

In this embodiment, as in the first embodiment, the distance between the proximal end resection surface 92 of the proximal tibia 91 and the posterior end 97 of the distal femur 95 can be measured under the same circumstances as after the future attachment of the femoral component. Moreover, in this embodiment, the angle display unit 19 displays the inter-paddle angle, so that when the positions of the distal end or distal end resection surface 96 differ between the medial and lateral condyles of the distal femur 95, the step between them and the inclination of the distal end resection surface 96 can be evaluated by angle.

Third Embodiment
16 and 17 show a measurement device 1B for total knee arthroplasty according to the third embodiment of the present invention (FIG. 17 shows a state in which the femoral attachment 7 is removed). The difference between the measurement device 1B of this embodiment and the measurement device 1A of the second embodiment is that, while the groove 56 of the measurement device 1A swings following the femoral paddle, the measurement device 1B keeps the groove 56 parallel to the first contact surface 40 even when the femoral paddle 5 swings. Therefore, the femoral attachment 7 held in the groove 56 is kept parallel to the proximal end resection surface 92 of the proximal tibia 91. The measurement device 1B may include a femoral sizer 8 shown in FIG. 10, as described in the second embodiment.

Specifically, the length in the left-right direction of the first base 53 of the femoral paddle 5 is set shorter than that of the second embodiment, and a pendulum 56a is disposed to the right of the first base 53. A groove 56 is provided in the pendulum 56a.

The pendulum 56a is connected to the first base 53 via a shaft 56d extending in the front-rear direction. A link member 56b is disposed above the first base 53. The link member 56b is connected to the pendulum 56a via a shaft 56e extending in the front-rear direction, and is connected to the head 46 of the lifting member 44 via a shaft 56c extending in the front-rear direction.

In this embodiment, as in the first embodiment, the distance between the proximal end resection surface 92 of the proximal tibia 91 and the posterior end 97 of the distal femur 95 can be measured under the same circumstances as after the future attachment of the femoral component. Moreover, in this embodiment, the same effects as in the second embodiment can be obtained.

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

For example, contrary to the above embodiment, the first arm portion 42 may be shifted to the left of the center of the first paddle portion 41. In this case, the second arm portion 52 is also shifted to the left of the center of the second paddle portion 51, and the third arm portion 72 is also shifted to the left of the center of the reproduction portion 71. Alternatively, depending on the surgical procedure of the total knee arthroplasty, the center of the first arm portion 42 may coincide with the center of the first paddle portion 41 in the left-right direction.

In addition, the femoral paddle 5 may not be divided into two and may not be able to swing around a swing axis extending in the front-to-back direction of the knee joint.

1, 1A, 1B Total knee arthroplasty measurement device 11 Distance display unit 2 Base 4 Tibia paddle 40 First contact surface 41 First paddle portion 42 First arm portion 5 Femoral paddle 5A First femoral paddle 5B Second femoral paddle 50 Second contact surface 51 Second paddle portion 52 Second arm portion 53 First base portion 6 Ratchet mechanism 7 Femoral attachment 70 Third contact surface 71 Reproduction portion 72 Third arm portion 73 Second base portion 8 Femoral sizer 91 Proximal tibia portion 92 Proximal end resection surface 95 Distal femoral portion 96 Distal end resection surface 97 Posterior end

Claims (6)

A measuring device for use in total knee arthroplasty, comprising:
A base disposed in front of the knee joint;
a tibial paddle fixed to the base and having a first contact surface adapted to contact the proximal end resection surface of the proximal tibia;
a femoral paddle having a second contact surface attached to the base so as to be movable in a direction perpendicular to the first contact surface and contacting the rear end of the distal femur in a right-angle flexion position;
a ratchet mechanism that can be switched between allowing only movement of the femoral paddle away from the tibial paddle and allowing movement in both directions;
a femoral attachment having a third contact surface that is detachable from the femoral paddle and that is brought into contact with a distal end resection surface of a distal portion of the femur in a right angle flexion position;
a distance display unit that displays a distance between the first contact surface and the second contact surface,
A measurement device for total knee arthroplasty, wherein the femoral attachment includes a reproduction portion shaped to correspond to the portion covering the distal end resection surface of the distal femur in the femoral component of the artificial knee joint, and this reproduction portion has the third contact surface. The measurement device for total knee arthroplasty according to claim 1, wherein the femoral attachment is attached to the femoral paddle so as to be movable in the anterior-posterior direction of the knee joint. The femoral paddle is divided into a first femoral paddle and a second femoral paddle arranged in the medial and lateral directions of the knee joint,
the first femoral paddle and the second femoral paddle are attached to the base so as to be movable independently of each other in a direction perpendicular to the first contact surface;
3. The measurement device for total knee arthroplasty according to claim 1, wherein the distance display unit displays the distance between the first contact surface and the second contact surface for each of the first femoral paddle and the second femoral paddle. The femoral paddle is capable of swinging about a swing axis extending in the front-rear direction of the knee joint,
3. The measurement device for total knee arthroplasty according to claim 1, wherein the distance display unit displays the distance between the first contact surface and the second contact surface on a perpendicular line to the first contact surface and passing through the swing center of the femoral paddle. The tibial paddle includes a first paddle portion having the first contact surface and a first arm portion extending from the first paddle portion toward the base,
the femoral paddle includes a second paddle portion having the second contact surface, a first base portion located above the base, and a second arm portion extending from the second paddle portion toward the first base portion;
the femoral attachment includes a second base portion located above the base, and a third arm portion extending from the reproduction portion toward the second base portion,
When one of the inward and outward directions of the knee joint is defined as the first direction and the other as the second direction,
the first arm portion is shifted toward the first direction from a center of the first paddle portion,
the second arm portion is shifted toward the first direction from a center of the second paddle portion,
3. The measurement device for total knee arthroplasty according to claim 1 , wherein the third arm portion is shifted toward the first direction from a center of the reproduction portion. 3. The measurement device for total knee arthroplasty according to claim 1 or 2, further comprising a femoral sizer that is detachable from the femoral paddle for measuring the size of the distal femur in a right angle flexion position and for determining the resection position of the anterior end and the posterior end of the distal femur.

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