Motion axis positioner for total knee replacement

Abstract

The present invention provides a motion axis locator for artificial knee replacement, which includes two spoon arms and a connecting body. The two spoon arms can be placed between the proximal tibia and the distal femur, and the proximal tibia and the distal femur are restrained by ligaments, so that the medial condyle and the lateral condyle of the femur are respectively clamped against the two spoon arms on the tibial platform with corresponding curvatures. The connecting body naturally locates a reference axis according to the position of the two spoon arms when clamped. The reference axis is nearly parallel to the motion axis of the medial condyle and the lateral condyle relative to the tibial platform. The joint surface between the proximal tibia and the distal femur is trimmed according to the reference axis, thereby forming the present invention.

Description

Technical Field

[0001] The invention relates to an instrument for artificial knee replacement, in particular to a motion axis positioner for artificial knee replacement. Background Art

[0002] Among the many joints in the human skeleton, the knee joints in the lower limbs bear heavy weight and are subject to frequent friction, so the knee joints will inevitably wear out after years of use, and pain will follow. When the wear is severe, it will lead to inconvenience in movement and trouble in life. At this time, it must be improved through surgical replacement of artificial joints.

[0003] The current total knee replacement surgery (TKA) is to first trim the proximal tibia and distal femur, and then implant the artificial joint and pad. Since the proximal tibia and distal femur cannot be restored after surgical trimming, in order to make the artificial joint have good adaptability to the patient's native bones after surgery, how to trim the proximal tibia and distal femur in the right way is one of the important topics of knee replacement surgery.

[0004] Regarding the trimming of the proximal tibia and distal femur, an existing technology is the so-called mechanical alignment (MA). The so-called mechanical axis uses the line from the center of rotation of the femoral head through the center of the proximal tibia to the midpoint of the medial and lateral malleolus as the reference axis, which can generally be obtained through X-ray fluoroscopy. The proximal tibia and distal femur can be cut into vertical joint surfaces along the mechanical axis, and then the artificial joint and pad are implanted to complete the artificial joint replacement. However, clinically, it is found that, compared with the proportion in the population census, less than 2% of the lower limbs meet the setting of the mechanical axis. Many patients often have the so-called "varying degrees of knee varum" or "knee valgum" deformity. At this time, the articular surfaces of the patient's original proximal tibia and distal femur are no longer perpendicular to the mechanical axis. If the articular surface perpendicular to the mechanical axis is obtained through surgery through the aforementioned mechanical axis calibration for artificial joint replacement, although the articular surface after surgery can be restored to be perpendicular to the mechanical axis, the collateral ligament on the narrow side before correction must be stretched during the operation to correct the so-called "knee varum" or "knee valgum" deformity. However, the collateral ligament becomes loose due to being stretched, which leads to instability of the knee joint and the sequelae of walking weakness and pain.

[0005] Another existing method of trimming the proximal tibia and distal femur is the so-called kinematic alignment (KA). The so-called kinematic axis is the reference axis of the medial / lateral condyle of the femur (Medial / Lateral condyle femur) flipping relative to the tibial plateau (Tibial Plateau) when the lower limb is bent. The difference from the aforementioned mechanical axis calibration knee replacement surgery is that if the knee replacement surgery is performed according to the kinematic axis calibration, the articular surface of the proximal tibia and distal femur after correction will almost overlap with the articular surface before trimming, that is, the original angle of the tibia and femur is still maintained after the surgery, and the collateral ligaments on both sides of the knee joint do not need to be pulled apart during the operation. Therefore, compared with the mechanical axis calibration knee replacement surgery, it will not cause the collateral ligament to loosen and cause the sequelae of knee joint weakness and pain when walking.

[0006] The "motion axis" is a virtual imaginary axis that cannot be measured by the naked eye. One way to find the motion axis in the prior art is to measure the upper and lower positions of the patient's femur and tibia through images, and then calculate and model through the dynamic process of lower limb swinging, and then establish a personal surgical tool (Personal Specific Instrument, PSI), and finally use the personalized surgical tool to perform knee replacement surgery with motion axis alignment. However, if you want to obtain the personalized surgical tool for knee replacement surgery, the current practice is to measure the image and calculate the modeling, and then send the relevant data of the modeling to Singapore for certification. After certification, it will be made by a mold factory in Belgium. This certification and production process takes two weeks to one month to complete, and the production cost is very high, resulting in time-consuming, labor-intensive and costly knee replacement surgery with motion axis alignment.

[0007] Another example is the invention patent case No. US08900242B2 of the United States, which is a stylus assembly, which mainly utilizes one end (17, 18) to abut against the unworn posterior femoral condyle (56) to provide a positioning reference surface, and then performs proximal tibia resection based on the reference surface. The stylus assembly of this invention patent is still a tool design based on the principle of mechanical axis alignment. This case utilizes multiple needle pen assemblies, and the end of each needle pen assembly is designed with different thicknesses (such as 1 to 3 mm) to correspond to the loosening of the medial collateral ligament due to wear of different joint surfaces, and is used to spread the condyle of the knee joint and restore the medial collateral ligament to its normal tightness. It is not actually used to locate the movement axis. In clinical operations, it is found that if the aforementioned end is against the lateral femoral condyle on the unworn side and uses it as a positioning reference surface for resection of the proximal tibia, it is easy to cause insufficient resection of the worn medial tibial condyle. On the contrary, if the aforementioned end is against the medial femoral condyle on the worn side, it is easy to cause too much resection of the unworn lateral tibial condyle. Therefore, it is necessary to make repeated corrections during the resection process to achieve a balance, thus causing inconvenience and trouble in knee joint surface trimming. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a motion axis positioner for artificial knee replacement to assist the surgeon in positioning the motion axis before trimming the articular surfaces of the proximal tibia and the distal femur.

[0009] An embodiment of the present invention provides a motion axis locator for artificial knee replacement, which includes two spoon arms and a connecting body. The two spoon arms are symmetrically arranged on the same side of the connecting body, and the two spoon arms of the guide cutting piece are respectively curved to correspond to the curvature of the medial condyle and lateral condyle of the human femur on the sagittal spherical surface. The two spoon arms can be inserted between the proximal tibia and the distal femur along the sagittal axis, and the proximal tibia and the distal femur are restrained by ligaments so that the medial condyle and the lateral condyle are respectively clamped against the two spoon arms on the tibial platform with corresponding curvatures. The connecting body naturally positions a reference axis according to the position of the two spoon arms when clamped. The reference axis is nearly parallel to the motion axis of the medial condyle and the lateral condyle relative to the tibial platform, and the joint surface between the proximal tibia and the distal femur is trimmed according to the reference axis.

[0010] In another embodiment of the present invention, the connecting system is elongated and extends in a straight line. The two spoon arms include a fixed spoon arm and a movable spoon arm. The fixed spoon arm is integrally formed at one end of the connecting body. The movable spoon arm is arranged on the connecting body and can slide along the length direction of the connecting body. The movable spoon arm is fixed to the connecting body after adjusting the distance between the movable spoon arm and the fixed spoon arm.

[0011] In another embodiment of the present invention, the movable spoon arm has an end portion with a slide groove, the inner contour of the slide groove corresponds to the cross-sectional contour of the connecting body, and the end portion is sleeved with the connecting body through the slide groove and can slide along the length direction.

[0012] In another embodiment of the present invention, the connecting body has a guide groove on a side different from the two spoon arms, the guide groove is opened along the length direction of the connecting body, the end has a convex portion in the slide groove corresponding to the guide groove, and the end is provided with a clamping piece on a side different from the convex portion. When the end is sleeved on the connecting body with the slide groove and the convex portion is in the guide groove, the clamping piece is actuated to clamp the connecting body with the convex portion to position it.

[0013] In another embodiment of the present invention, the clamping member is a bolt, and a screw hole is provided at the end corresponding to the clamping member. The clamping member is screwed into the screw hole and can be screwed to abut against the connecting body and clamp the end of the bolt to the connecting body with the protrusion.

[0014] In another embodiment of the present invention, the connecting body has a handle, which extends perpendicularly to the linear extension direction of the connecting body, and the handle and the two spoon arms extend from the connecting body in opposite directions, and the handle is located between the two spoon arms; the curvature radius of each spoon arm is 17mm to 29mm.

[0015] In another embodiment of the present invention, it further includes a guide cutting piece, the guide cutting piece has a relatively upper sleeve and a relatively lower fixing portion, and the guide cutting piece has a long slit between the sleeve and the fixing portion. When the connecting body is naturally positioned with the reference axis as described above, the handle is sleeved on the sleeve with a corresponding thickness, and is fixed to the proximal tibia at the position by the fixing portion. The long slit is parallel to the reference axis in the length direction, and the cutting tool extends into the long slit and trims the tibial platform along the reference axis.

[0016] In another embodiment of the present invention, the guide cutting piece has an installation groove between the sleeve and the fixing part, and the installation groove is open on one side of the guide cutting piece. The guide cutting piece has a block with a long slit, and the block is assembled in the installation groove and positioned from the open side of the installation groove.

[0017] In another embodiment of the present invention, the long slit is inclined from high to low in the width direction of the block, relative to the side of the connecting body with the handle toward the side with the two spoon arms.

[0018] In another embodiment of the present invention, the fixing portion has a plurality of through holes, and a bone screw used for surgery can be inserted through one of the through holes to lock the fixing portion at a proper position of the proximal tibia.

[0019] Thus, the motion axis locator for artificial knee replacement surgery of the present invention is a surgical auxiliary instrument with a simple structure and easy operation. Before the articular surfaces of the proximal tibia and the distal femur are trimmed, the reference axis of the motion axis can be located and compared by it, and then the articular surfaces of the proximal tibia and the distal femur can be trimmed. Clinical experiments have confirmed that the results of the articular surface trimming of the proximal tibia and the distal femur are as accurate as those using personalized surgical tools, and the operation is simple and easy, so as to achieve the purpose of saving time and money consumed in calculation model verification and mold opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a three-dimensional composite diagram of a motion axis positioner according to an embodiment of the present invention;

[0021] Figure 2 is an exploded configuration diagram of a motion axis positioner according to an embodiment of the present invention;

[0022] Figure 3 yes Figure 1 A side cross-sectional view taken along section line 3-3;

[0023] Figure 4 is a side view schematic diagram of a motion axis positioner according to an embodiment of the present invention being placed into a knee joint along a sagittal axis with two spoon arms;

[0024] Figure 5 is a front view schematic diagram of a motion axis positioner according to an embodiment of the present invention, with two spoon arms placed into a knee joint along a sagittal axis;

[0025] Figure 6 yes Figure 5 A front view schematic diagram of a handle with a cutting guide installed;

[0026] Figure 7 yes Figure 6 A schematic diagram of a guide cutting piece being fixed to the proximal tibia by a bone screw;

[0027] Figure 8 This is a schematic diagram of the proximal tibia after revised resection of the tibial plateau. It can be seen in the figure that the tibial plateau is parallel to the axis of motion after resection.

[0028] Description of Reference Numerals

[0029] 100: Motion axis positioner 10: Spoon arm

[0030] 11: Side wall 20: Spoon arm

[0031] 21: Side wall 22: End

[0032] 221: screw hole 23: slide groove

[0033] 24: Projection 25: Clamping piece

[0034] 30: Connector 31: Guide groove

[0035] 32: handle 40: guide cutting piece

[0036] 41: sleeve 42: fixed part

[0037] 421: Perforation 43: Long slit

[0038] 44: Mounting slot 45: Block

[0039] 50: Bone screw K: Motion axis

[0040] F: Distal Femur IC: Medial Condyle

[0041] L: Ligament OC: Lateral condyle

[0042] P: Tibial plateau T: Proximal tibia

[0043] X: Reference axis Y: Sagittal axis

[0044] R: radius of curvature t: thickness. DETAILED DESCRIPTION

[0045] In order to facilitate the description of the central idea of ​​the present invention in the above invention content column, a specific embodiment is used for expression. Various objects in the embodiment are depicted according to the proportion, size, deformation or displacement suitable for description, rather than being drawn according to the proportion of the actual component, which is explained first.

[0046] See also Figures 1 to 8 As shown, the present invention provides a motion axis locator 100 for artificial knee replacement, which, as the name implies, is used to locate the motion axis during artificial knee replacement. The definition of the motion axis has been clearly described in the background art and will not be repeated here. The motion axis locator 100 mainly includes spoon arms 10, 20 and a connecting body 30, and in a preferred embodiment also includes a guide cutting member 40, wherein:

[0047] The spoon arms 10, 20 are symmetrical in shape and are respectively curved and similar to the shape of a spoon. The curved shape of the spoon arms 10, 20 corresponds to the curvature of the medial and lateral condyles of the femur of the human body on the sagittal spherical surface. In this embodiment, each spoon arm 10, 20 is flat and has a smooth surface, and each spoon arm 10, 20 has a side wall 11 and a side wall 21 on both sides of the middle part. The side walls 11 of the spoon arm 10 are symmetrically arranged, and the side walls 21 of the spoon arm 20 are also symmetrically arranged, and the top edges of each side wall 11, 21 are flat. The connecting body 30 is provided with the spoon arms 10, 20 on the same side. In this embodiment, the connecting body 30 is long and extends along a straight line, and is a long rectangular block. The connecting body 30 is flat on both sides of the width direction along the extension direction of the straight line.

[0048] The spoon arm 10 is a fixed spoon arm in this embodiment, and the other spoon arm 20 is a movable spoon arm in this embodiment. The spoon arm 10 is integrally formed at one end of the connecting body 30; the spoon arm 20 is arranged on the connecting body 30 and can slide along the length direction of the connecting body 30. After adjusting the distance between the spoon arm 20 and the spoon arm 10, the spoon arm 20 can be fixed to the connecting body 30. Preferably, the spoon arm 20 has an end 22, and a slide groove 23 is arranged in the end 22. The inner contour of the slide groove 23 corresponds to the cross-sectional contour of the connecting body 30. The end 22 of the spoon arm 20 is sleeved on the connecting body 30 through the slide groove 23, so that the spoon arm 20 can slide along the length direction of the connecting body 30. The curvature radius R of the spoon arm 20 is 17 mm to 29 mm to adapt to the different curvatures of the medial and lateral femoral condyles on the sagittal spherical surface. When the knee joint performs extension-flexion movement, it naturally reflects the movement axis of the different medial and lateral femoral condyles when they rotate like a sphere. The curvature radius R of the spoon arms 10 and 20 in this embodiment is 25 mm. In addition, the spoon arms 10 and 20 in this embodiment correspond to the curvature of the medial and lateral femoral condyles on the sagittal spherical surface, and their thickness t is 1 mm.

[0049] As mentioned above, the connecting body 30 of the present embodiment has a guide groove 31 on a side different from the spoon arms 10 and 20. The guide groove 31 is also opened along the length direction of the connecting body 30, that is, the guide groove 31 runs through both ends of the connecting body 30. The end 22 of the spoon arm 20 has a protrusion 24 in the slide groove 23, and the protrusion 24 is provided corresponding to the guide groove 31; the end 22 is also provided with a tightening member 25 on a side different from the protrusion 24. When the end 22 is sleeved on the connecting body 30 with the slide groove 23 and the protrusion 24 is located in the guide groove 31, the operator can clamp the tightening member 25 and the protrusion 24 in the guide groove 31 on the connecting body 30 for positioning by actuating the tightening member 25. The end portion 22 has a protrusion 24 that cooperates with the guide groove 31 of the connecting body 30, which is only one embodiment of the present invention. In different embodiments, the protrusion 24 can also be provided on the connecting body 30, and the guide groove 31 can be provided on the end portion 22, which can also play a limiting role when the end portion 22 slides on the connecting body 30.

[0050] Preferably, the tightening member 25 in this embodiment is a bolt, and the end portion 22 is provided with a screw hole 221 corresponding to the tightening member 25. The tightening member 25 is screwed into the screw hole 221 and can be screwed until it abuts against the connecting body 30. When the tightening member 25 is screwed to a certain depth in the screw hole 221, the tightening member 25 links the protrusion 24 to clamp the end portion 22 on the connecting body 30, so as to fix the spoon arm 20 on the connecting body 30. In addition, the present embodiment has a handle 32 on the connecting body 30. The handle 32 extends perpendicularly to the straight extension direction of the connecting body 30 (i.e., the handle 32 and the connecting body 30 are connected in a T-shape), and the handle 32 and the spoon arms 10, 20 extend from the connecting body 30 in opposite directions. The handle 32 of the present embodiment extends from a side of the connecting body 30 having the guide groove 31. The handle 32 is located between the spoon arms 10, 20, and the handle 32 can be held by the operator.

[0051] In actual operation of the motion axis locator 100 of the above embodiment, taking the left foot as an example, when the skin and flesh tissue at the patient's knee joint is cut open and the joint of the proximal tibia T and the distal femur F is visible, the spoon arms 10 and 20 are placed between the proximal tibia T and the distal femur F along the sagittal axis Y (such as Figure 4 As shown in FIG. 1 ), at this time, since the proximal tibia T and the distal femur F are restrained by the ligaments L (including the lateral collateral ligament and the cruciate ligament), the proximal tibia T and the distal femur F will maintain a pulling force in the opposite direction, and the spoon arms 10 and 20 can maintain contact between the tibial plateau P and the medial condyle IC and the lateral condyle OC of the femur, and the medial condyle IC and the lateral condyle OC are clamped against the spoon arms 10 and 20 on the tibial plateau P with corresponding curvatures (as shown in FIG. Figure 5 As shown in FIG. 1 , and as the spoon arms 10 and 20 are parallel or have a height difference in the horizontal direction, the connecting body 30 will naturally locate a reference axis X according to the position of the spoon arms 10 and 20 when they are clamped. This reference axis X is the relative pivotal motion axis K of the medial condyle IC and the lateral condyle OC on the tibial plateau P (see FIG. 1 ). Figure 8 ) are close to parallel, then the articular surface between the proximal tibia T and the distal femur F can be trimmed according to the reference axis X.

[0052] In order to cooperate with the motion axis positioner 100 of the above embodiment to perform artificial knee replacement, after the connection body 30 locates the reference axis X, the present invention further includes a guide cutting member 40 in a preferred embodiment to assist in trimming the tibial plateau P. The guide cutting member 40 has a sleeve 41 and a fixing portion 42, the sleeve 41 is relatively above the guide cutting member 40, and the fixing portion 42 is relatively below the guide cutting member 40, and the guide cutting member 40 has a long slit 43 between the sleeve 41 and the fixing portion 42.

[0053] Preferably, the guide cutting member 40 has a mounting groove 44 between the sleeve 41 and the fixing portion 42. The mounting groove 44 is open on one side of the guide cutting member 40. The guide cutting member 40 has a block 45 with a long slit 43. The block 45 is assembled in the mounting groove 44 from the open side of the mounting groove 44, and the block 45 is positioned in the mounting groove 44.

[0054] As described above, the fixing portion 42 has a plurality of through holes 421, each of which can be used for a surgical bone screw 50 to be inserted, so as to lock the fixing portion 42 in a proper position on the proximal tibia T. Furthermore, the long slit 43 is formed on the block 45, and is inclined from high to low relative to the side of the connecting body 30 with the handle 32 toward the side with the spoon arms 10, 20 (such as Figure 3 As shown), and because the block 45 can be separated and reassembled on the guide cutting piece 40, the long slit 43 of the block 45 can be designed with different inclinations, and the block 45 with long slits 43 of different inclinations can be selected according to actual conditions and assembled on the guide cutting piece 40, so as to facilitate the smooth progress of artificial joint replacement surgery.

[0055] The actual operation of the motion axis locator 100 described above is that when the connecting body 30 has been naturally positioned at the reference axis X according to the position of the spoon arms 10 and 20 when clamped, the handle 32 extends outward corresponding to the position of the connecting body 30. At this time, the sleeve 41 of the guide cutting member 40 can be sleeved with the handle 32 with a corresponding thickness (such as Figure 6 As shown), the guide cutting member 40 is moved along the handle 32 toward the proximal tibia T, and then the bone screw 50 is inserted into and locked in the proximal tibia T by selecting a suitable through hole 421 (as shown). Figure 7 As shown in the figure, the fixing portion 42 of the guide cutting member 40 can be fixed on the proximal tibia T at its position, and the long slit 43 on the block 45 is parallel to the reference axis X in the length direction, so that the cutting tool (not shown) can be inserted into the long slit 43 and the tibial plateau P can be removed along the reference axis X, so that the articular surface between the proximal tibia T and the distal femur F can be trimmed. At this time, after the proximal tibia T is corrected and the tibial plateau is removed, a section parallel to the motion axis K (i.e., the reference axis X) can be obtained.

[0056] From the above description, it is not difficult to find that the characteristic of the present invention is that the motion axis locator 100 for artificial knee replacement of the present invention can be composed of only spoon arms 10, 20 and a connecting body 30, which is actually a surgical auxiliary device with a simple structure and easy operation. Before the articular surfaces of the proximal tibia and the distal femur are trimmed, the spoon arms 10, 20 can be clamped against the tibial plateau P by the medial condyle IC and the lateral condyle OC with corresponding curvatures respectively, so that a reference axis X for the motion axis can be located, and then the articular surfaces of the proximal tibia T and the distal femur F can be trimmed. It has been confirmed by clinical experiments that the result of trimming the articular surfaces of the proximal tibia and the distal femur using personalized surgical tools as described in the prior art is as accurate, and there is no problem of having to make repeated corrections during the resection process to achieve balance. Even if the surgeon is not experienced, the motion axis locator 100 of the present invention can be used to simply locate the reference axis X for the motion axis, thereby saving the time and money spent on calculation model verification and mold opening.

[0057] The above embodiments are only used to illustrate the present invention, and are not used to limit the scope of the present invention. Any modifications or changes that do not violate the spirit of the present invention are within the scope of the present invention.

Claims

1. A motion axis locator for artificial knee replacement, characterized in that: The invention comprises two spoon arms and a connecting body, wherein the two spoon arms are arranged on the same side of the connecting body, and the two spoon arms are symmetrical in shape and are respectively curved to correspond to the curvature of the medial condyle and the lateral condyle of the human femur on the sagittal spherical surface, the two spoon arms are placed between the proximal tibia and the distal femur along the sagittal axis, and the proximal tibia and the distal femur are restrained by ligaments, the medial condyle and the lateral condyle clamp the two spoon arms on the tibial platform with corresponding curvatures, and the connecting body naturally positions a reference axis according to the position of the two spoon arms when clamped, and the reference axis is The medial condyle and the lateral condyle are parallel to the axis of relative pivoting of the tibial platform, and the articular surface between the proximal tibia and the distal femur is trimmed according to the reference axis; wherein the connecting body is elongated and extends in a straight line, and the two spoon arms include a fixed spoon arm and a movable spoon arm, and the fixed spoon arm is integrally formed at one end of the connecting body; the movable spoon arm is arranged on the connecting body and can slide along the length direction of the connecting body, and the movable spoon arm is fixed to the connecting body after adjusting the distance between the movable spoon arm and the fixed spoon arm; the connecting body has a handle; The motion axis locator also includes a guide cutting piece, which has a relatively upper sleeve and a relatively lower fixing portion, and the guide cutting piece has a long slit between the sleeve and the fixing portion. When the connecting body locates the reference axis, the handle is sleeved on the sleeve with a corresponding thickness and is fixed to the proximal tibia at the location by the fixing portion. The long slit is parallel to the reference axis in the length direction, and the cutting tool extends into the long slit and trims the tibial plateau along the reference axis.

2. The motion axis positioner for artificial knee replacement according to claim 1, characterized in that: The movable spoon arm has an end portion with a slide groove, the inner contour of the slide groove corresponds to the cross-sectional contour of the connecting body, and the end portion is sleeved on the connecting body through the slide groove and can slide along the length direction.

3. The motion axis positioner for artificial knee replacement according to claim 2, characterized in that: The connecting body has a guide groove on a side different from the two spoon arms, and the guide groove is opened along the length direction of the connecting body. The end has a convex portion in the slide groove corresponding to the guide groove, and the end is provided with a clamping piece on a side different from the convex portion. When the end is sleeved on the connecting body by the slide groove and the convex portion is in the guide groove, the clamping piece is actuated to clamp the connecting body with the convex portion to position it.

4. The motion axis positioner for artificial knee replacement according to claim 3, characterized in that: The clamping piece is a bolt, and a screw hole is arranged at the end corresponding to the clamping piece. The clamping piece is screwed in the screw hole and can be screwed to abut against the connecting body to clamp the end on the connecting body with the protrusion.

5. The motion axis positioner for artificial knee replacement according to claim 2, characterized in that: The handle is vertically extended relative to the linear extension direction of the connecting body, and the handle and the two spoon arms are extended from the connecting body in opposite directions. The handle is arranged between the two spoon arms; the curvature radius of each of the curved spoon arms is 17mm to 29mm.

6. The motion axis positioner for artificial knee replacement according to claim 1, characterized in that: The guide cutting piece has an installation groove between the sleeve and the fixing part, and the installation groove is open at one side of the guide cutting piece. The guide cutting piece has a block with the long slit, and the block is assembled in the installation groove from the open side of the installation groove and positioned.

7. The motion axis positioner for artificial knee replacement according to claim 6, characterized in that: The long slit is inclined from high to low in the width direction of the block, relative to the side of the connecting body having the handle portion toward the side having the two spoon arms.

8. The motion axis positioner for artificial knee replacement according to claim 1, characterized in that: The fixing part has a plurality of through holes for the bone screws used for surgery to pass through.

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