System for determining angle of osteotomy

Abstract

The present invention relates to a system for determining the angle of osteotomy. The system comprises a plurality of liners, a pressure measurement apparatus and a processing module. Each liner comprises a liner body having an upper surface and a lower surface. A longitudinal distance between a slope region of each upper surface and a planar region of the upper surface gradually increases from a position near the geometric symmetry central axis of the liner to both sides of the liner, so as to define the degree of a tilt angle. The pressure measurement apparatus is used for measuring a pressure applied by each of two extremity sides of a bone joint, so as to determine a pressure difference value. The processing module is configured to determine an angle of osteotomy for the extremity sides on the basis of the tilt angles of the liners that balance the tension of the two extremity sides. The present invention restores the tension condition in a real working state of a joint before osteotomy and takes into account the balance state of the tension of soft tissue as a consideration for the angle of osteotomy, thereby effectively solving the problem of unbalanced tension between soft tissue at the inner and the outer sides of knee joints after total knee arthroplasty, and keeping the original mechanical performance of knee joints of patients after surgery.

Description

System for determining osteotomy angles Technical Field

[0001] The present invention relates to the field of medical instruments, and in particular to an osteotomy auxiliary system used in knee replacement surgery. Background Art

[0002] Knee replacement is the best treatment for end-stage osteoarthritis. It uses stainless steel and polymer materials to replace the damaged joint surface, relieving pain and restoring function. Knee replacement surgery typically addresses two key surgical objectives: first, reestablishing lower limb force alignment; second, restoring relative tension between the medial and lateral soft tissues of the knee joint.

[0003] The knee joint's lower limb force alignment is the line connecting the centers of the hip, knee, and ankle joints. A normal lower limb force alignment is a straight line. When the knee center lies outside the line connecting the hip and ankle centers, it's called genu varum; when it lies inside the line connecting the hip and ankle joints, it's called genu valgum. Studies by renowned experts both domestically and internationally have found that when the lower limb force alignment deviates by more than 3° after knee replacement surgery, 24% of patients will require a revision knee replacement within 8 years, resulting in greater trauma and potentially unreliable clinical outcomes. In clinical practice, surgeons typically use simple stainless steel distraction tools, relying on their own experience and specific anatomical landmarks to help correct lower limb force alignment, perform osteotomies, and ultimately implant a knee prosthesis. A clinical literature review revealed that less than 67% of lower limb force alignment deviations after knee replacement are within 3°. Therefore, existing clinical methods cannot guarantee accurate and consistent knee prosthesis placement. To address this, osteotomies using computer-guided, robotic-assisted techniques have been developed to improve the accuracy of lower limb force alignment.

[0004] However, while osteotomy using computer navigation, robotic surgery, and other assisted technologies can improve the accuracy of lower limb force alignment, they fail to consider the balance of soft tissue tension within the medial and lateral knee joint. As a weight-bearing joint, the knee joint is surrounded by soft tissue ligaments and a joint capsule. These soft tissue ligaments and capsule possess very high tension, ensuring knee stability. During knee replacement surgery to reconstruct lower limb force alignment, force alignment correction is often accompanied by changes in soft tissue tension. Osteotomy is performed based on the corrected lower limb force alignment, and further assessment of soft tissue tension is required after osteotomy. However, due to the lack of objective tension assessment tools, surgeons can only subjectively assess the magnitude and distribution of soft tissue tension within the medial and lateral knee joint using simple rectangular molds or stainless steel distraction tools, or by finger feel, to facilitate soft tissue balancing procedures, such as soft tissue release. On the one hand, relying solely on the surgeon's subjective assessment of soft tissue tension within the medial and lateral knee joint for soft tissue release can result in over- or under-release. On the other hand, soft tissue release has several drawbacks, such as the potential for damage to the patient's soft tissue. Even if there is no injury, the released soft tissue usually cannot maintain its original mechanical properties, which will lead to significant changes in the patient's gait after surgery, and changes in the patient's proprioception and muscle mobilization.

[0005] Summary of the Invention

[0006] The technical solution proposed in the present invention aims to solve the problem of unbalanced tension of the inner and outer soft tissues of the knee joint after knee replacement surgery in the prior art.

[0007] In one aspect of the present invention, a system for determining an osteotomy angle is provided, the system comprising: a plurality of pads, each pad comprising a pad body, the pad body comprising: an upper surface having an upper surface inclined area and an upper surface plane area, wherein the upper surface inclined area and the upper surface plane area are respectively located on both sides of the upper surface, and the longitudinal distance between the upper surface inclined area and the upper surface plane area gradually increases from near the geometric symmetry center line of the pad toward both sides of the pad to define an inclination angle, and a lower surface for mounting to a pressure measuring device; the pressure measuring device is used to combine with one of the plurality of pads, When the first side part of the two side parts of the bone end of the bone joint presses against one area of ​​the upper surface inclined area and the upper surface plane area of ​​the pad and the second side part presses against the other area of ​​the upper surface inclined area and the upper surface plane area of ​​the pad, the pressure applied by each side part is measured to determine the pressure difference; and a processing module, the processing module is communicatively coupled with the pressure measuring device and is configured to: determine whether the first side part and the second side part reach tension balance based on the pressure difference; determine the osteotomy angle of the bone end based on the inclination angle of the pad that makes the first side part and the second side part reach tension balance.

[0008] In at least one embodiment of one aspect of the present invention, the bone end is a femoral condyle, the femoral condyle includes the distal femur and the posterior femoral condyle, the first side portion of the two side portions of the bone end includes the inner side of the distal femur or the inner side of the posterior femoral condyle, and the second side portion of the two side portions of the bone end includes the outer side of the distal femur or the outer side of the posterior femoral condyle, and the pressure measuring device is used to be installed between the tibial plateau and the pad.

[0009] In at least one embodiment of one aspect of the present invention, the pressure measuring device is used in combination with one of the multiple pads to measure a first pressure applied by a first side portion and a second pressure applied by a second side portion on both sides of the bone end at each of a plurality of flexion angles of the knee joint, wherein the upper surface inclined area of ​​the pad is located below the medial side of the femoral condyle of a knee joint with genu varum or below the lateral side of the femoral condyle of a knee joint with genu valgum, and the processing module is further configured to calculate a corresponding pressure difference based on the first pressure and the second pressure measured by the pressure measuring device at each of a plurality of flexion angles of the knee joint.

[0010] In at least one embodiment of one aspect of the present invention, the processing module is further configured to: compare the absolute value of each of the multiple pressure difference values ​​with a predetermined pressure difference threshold; and based on the comparison result, determine whether the first side portion and the second side portion reach tension balance.

[0011] In at least one embodiment of one aspect of the present invention, the processing module is further configured to: when more than one absolute value of each of the multiple pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold, determine the inclination angle of the new pad to be used to be greater than the inclination angle of the pad currently in use, so as to subsequently use the new pad to re-measure the pressure.

[0012] In at least one embodiment of one aspect of the present invention, the processing module is further configured to: when the absolute value of only one specific pressure difference value among the multiple pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold, determine the inclination angle of the new cushion to be used based on the specific pressure difference value, the flexion angle corresponding to the specific pressure difference value, and a comparison table, so as to subsequently re-measure the pressure using the new cushion, wherein the comparison table reflects the correspondence between multiple pressure difference values ​​and the inclination angle of the cushion at different flexion angles.

[0013] In at least one embodiment of one aspect of the present invention, determining the inclination angle of the new pad to be used based on the specific pressure difference, the flexion angle corresponding to the specific pressure difference, and the comparison table further includes: determining a pressure difference compensation value based on the thickness difference between the patient's own femoral condyle and the femoral condyle prosthesis to be installed on the patient and the specific pressure difference; determining a compensated pressure difference based on the pressure difference compensation value; and determining the inclination angle of the new pad to be used based on the compensated pressure difference, the flexion angle corresponding to the compensated pressure difference, and the comparison table, so as to re-measure the pressure using the new pad subsequently.

[0014] In at least one embodiment of one aspect of the present invention, the comparison table is set based on experience or experiments.

[0015] In at least one embodiment of one aspect of the present invention, determining whether the first side portion and the second side portion have reached tension balance based on the comparison result includes: in response to the absolute value of each of the multiple pressure difference values ​​being less than the predetermined pressure difference threshold, determining that the first side portion and the second side portion have reached tension balance.

[0016] In at least one embodiment of one aspect of the present invention, the processing module is further configured to determine the osteotomy angle of the bone end based on the varus and valgus angles of the initial femoral osteotomy and the inclination angle of the pad that achieves tension balance between the first side part and the second side part.

[0017] In at least one embodiment of one aspect of the present invention, the system further comprises a display module, which is communicatively coupled to the processing module and is configured to: display at least one of the following: the pressure data measured by the pressure measuring device, the pressure difference, the inclination angle of the pad that enables the first side portion and the second side portion to achieve tension balance, and the determined osteotomy angle.

[0018] In at least one embodiment of one aspect of the present invention, the inclination angle of the cushion is the angle between the line between the first point in the upper surface inclined area and the second point in the upper surface plane area relative to the plane in which the upper surface plane area is located, wherein the first point is symmetrical with the second point relative to the geometric symmetry midline of the upper surface of the cushion.

[0019] In at least one embodiment of one aspect of the present invention, the lower surface of the cushion body is positionally mounted on the top surface of the pressure measuring device via a hole-column matching structure.

[0020] In at least one embodiment of one aspect of the present invention, the lower surface of the cushion body has a first lower surface area and a second lower surface area respectively opposite to the upper surface plane area and the upper surface inclined area, wherein the first lower surface area and the second lower surface area respectively have at least one contact portion for contacting the corresponding pressure testing portion on the pressure measuring device.

[0021] The technical solution proposed by the present invention can evaluate the internal and external soft tissue tension of the knee joint in the entire flexion movement process in real time during knee replacement. Compared with the traditional method of actively expanding the soft tissue with a expander after osteotomy and subjectively evaluating the tension, the present invention can restore the actual tension conditions of the joint under the working state to the greatest extent before osteotomy, and incorporate the soft tissue tension balance state into the osteotomy angle consideration factor, so that the patient's original knee joint mechanical properties can be retained to the greatest extent after surgery, and the patient's postoperative comfort can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to further illustrate the above and other advantages and features of various embodiments of the present invention, a more specific description of various embodiments of the present invention will be presented with reference to the accompanying drawings. It should be understood that these drawings only depict typical embodiments of the present invention and are therefore not to be considered as limiting the scope of protection claimed in the present invention.

[0023] FIG1 shows a schematic diagram of a system for determining an osteotomy angle according to an embodiment of the present invention.

[0024] FIG2 is a schematic diagram showing a pad and a pressure measurement device installed on a left knee joint according to an embodiment of the present invention.

[0025] FIG3 is a schematic structural diagram of the upper surface of a cushion according to an embodiment of the present invention.

[0026] FIG. 4 illustrates a side view of a cushion according to an embodiment of the present invention.

[0027] FIG5 is a schematic structural diagram of the lower surface of a cushion according to an embodiment of the present invention.

[0028] FIG6 shows a schematic structural diagram of an existing pressure measuring device.

[0029] FIG7 is a schematic structural diagram of the upper surface of a second type of cushion according to an embodiment of the present invention.

[0030] FIG. 8 shows a side view of a second type of cushion according to an embodiment of the present invention.

[0031] FIG9 shows a schematic structural diagram of the lower surface of a second type cushion according to an embodiment of the present invention.

[0032] FIG. 10 illustrates a method for determining the varus and valgus angle of a femoral osteotomy according to an embodiment of the present invention.

[0033] FIG. 11 illustrates a method for determining the inclination angle of a new pad according to an embodiment of the present invention.

[0034] Reference numerals: 100 System for determining osteotomy angle 10 Pad 11 Upper surface of pad 111 Upper surface inclined area 113 Upper surface flat area 13 Lower surface of pad 132 Limiting column 134 Inclined side contact portion 136 Flat side contact portion 20 Pressure measuring device 21 Limiting hole 30 Processing module 40 Display module 51 Tibial plateau 52 Medial side of femoral condyle 54 Lateral side of femoral condyle DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific embodiments and accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0036] This application uses specific terms to describe the embodiments of the application. For example, "one embodiment," "other embodiments," and / or "some embodiments" refer to a feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "one embodiment," "other embodiments," or "some embodiments" mentioned twice or multiple times in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application may be appropriately combined.

[0037] It should be noted that in order to simplify the description of the present disclosure and thus facilitate understanding of one or more embodiments, the present disclosure may sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the present application requires more features than those mentioned in the claims.

[0038] As used herein, expressions referring to "inwardly" refer to closer to the midline of the body, while expressions referring to "outwardly" refer to away from the midline of the body.

[0039] As used herein, descriptions of numerical ranges are intended to encompass any value within the range, including the lower limit but excluding the upper limit. For example, "[30, 50]," "between 30N and 50N," are intended to encompass any value between 30 and 50, including 30 but excluding 50.

[0040] As used herein, the term "tension balance compensation angle" refers to the inclination angle of a pad when the pressure exerted by the two sides of the bone end of the joint, as measured by a pressure measuring device in combination with the pad, reaches equilibrium (i.e., when the tension in the soft tissue surrounding the two sides of the bone end of the joint reaches equilibrium). For example, the inclination angle of the pad is determined when the pressure exerted by the inner and outer sides of the femoral condyle, as measured by the pressure measuring device in combination with the pad, reaches equilibrium (i.e., when the tension in the soft tissue surrounding the femoral condyle reaches equilibrium) at each of multiple flexion angles of the knee joint.

[0041] As used herein, the term "thickness of a gasket" refers to the distance between a planar area of ​​an upper surface and an opposing area of ​​a lower surface of the gasket.

[0042] In this article, the term "longitudinal distance between the upper surface inclined area and the upper surface plane area" refers to the distance between any first point in the upper surface inclined area of ​​the pad and the corresponding second point in the upper surface plane area in the thickness direction of the pad, where the first point is symmetrical to the second point relative to the geometric symmetry midline of the upper surface of the pad.

[0043] In this article, the term "inclination angle of the pad" refers to the angle between the line between any first point in the inclined area of ​​the upper surface of the pad and the corresponding second point in the plane area of ​​the upper surface relative to the plane in which the plane area of ​​the upper surface is located, where the first point is symmetrical to the second point relative to the geometric symmetry midline of the upper surface of the pad.

[0044] In this article, the term "knee flexion angle" refers to the angle between the tibia and the extension line of the femur, with the knee joint as the origin of the femur. Generally, when the knee joint is fully extended, the tibia roughly coincides with the extension line of the femur.

[0045] In this article, the term "tibial osteotomy angle" includes the angle of the tibial osteotomy plane relative to the coronal plane when osteotomy is performed on the proximal tibia (this angle may also be called the "anteroposterior tilt angle of the tibial osteotomy") and the angle of the tibial osteotomy plane relative to the sagittal plane (this angle may also be called the "tibial osteotomy varus angle").

[0046] In this article, the term "femoral osteotomy angle" includes the angle of the femoral osteotomy plane relative to the coronal plane when the femoral condyle is osteotomized (this angle may also be called the "femoral osteotomy anteroposterior tilt angle") and the angle of the femoral osteotomy plane relative to the sagittal plane (this angle may also be called the "femoral osteotomy varus angle").

[0047] As used herein, the term "femoral condyle thickness" refers to the thickness of the patient's native femoral condyle to be harvested, and the term "femoral condyle prosthesis thickness" refers to the thickness of the femoral condyle prosthesis to be installed in the patient. It should be understood that some patients may have osteophytes or wear on their femoral condyles, and therefore, the thickness of the patient's native femoral condyle to be harvested at the osteophytes or wear sites may differ from that of the femoral condyle prosthesis to be installed in the patient.

[0048] As used herein, the term "femoral condyle" includes both the distal femur and the posterior femoral condyle.

[0049] 1 , which shows a schematic diagram of a system 100 for determining an osteotomy angle according to an embodiment of the present invention.

[0050] As shown in FIG1 , a system 100 for determining osteotomy angles (hereinafter referred to as system 100) may include a plurality of pads 10, a pressure measurement device 20, a processing module 30, and a display module 40. Each of the plurality of pads 10 may have a specific thickness and a specific inclination angle. The thickness and inclination angle of the pads 10 will be described in detail below with reference to FIG3-5 .

[0051] During operation, the pad 10 and the pressure measuring device 20 can be installed at the patient's bone joint (such as the knee joint) to measure the pressure at the bone end of the bone joint. Figure 2 shows a schematic diagram of the pad 10 and the pressure measuring device 20 installed at the left knee joint according to an embodiment of the present invention. As shown in Figure 2, the pressure measuring device 20 can be placed on the tibial plateau 51 after osteotomy, and the pad 10 can be installed above the pressure measuring device 20. Referring to Figure 2, when the pad 10 and the pressure measuring device 20 are installed on the tibial plateau 51 of the knee joint, the medial side 52 of the femoral condyle and the lateral side 54 of the femoral condyle can contact and press against the two side areas of the upper surface of the pad 10 (for example, the upper surface plane area 113 and the upper surface inclined area 111 described below in conjunction with Figures 3-5). At this time, the pressure measuring device 20 can measure the pressure applied by the medial side 52 of the femoral condyle and the lateral side 54 of the femoral condyle. The pressure applied by the inner and outer sides of the femoral condyle measured by the pressure measuring device 20 can be used to measure the soft tissue tension on the inner and outer sides of the knee joint. For example, the pressure applied by the inner side 52 of the femoral condyle measured by the pressure measuring device 20 can be used to measure the soft tissue tension on the inner side of the knee joint, and the pressure applied by the outer side 54 of the femoral condyle measured by the pressure measuring device 20 can be used to measure the soft tissue tension on the outer side of the knee joint. In Figure 2, a scenario of pressure measurement when the knee joint is in a flexed position is illustrated. During the actual pressure measurement operation, the operator (e.g., a doctor) can flex the patient's calf so that the knee joint is in a flexed position at different angles. The pressure measuring device 20 can measure the pressure applied by the inner and outer sides of the femoral condyle (e.g., the distal femur or the posterior femoral condyle, depending on the flexion angle of the knee joint) when the knee joint is in different flexion angles, thereby measuring the soft tissue tension on the inner and outer sides of the knee joint during the entire flexion movement.

[0052] The cushion member 10 will be described in detail below with reference to Figures 3 to 5. Figure 3 shows a schematic diagram of the structure of the upper surface of the cushion member 10 according to an embodiment of the present invention. Figure 4 shows a side view of the cushion member 10 according to an embodiment of the present invention. Figure 5 shows a schematic diagram of the structure of the lower surface of the cushion member 10 according to an embodiment of the present invention.

[0053] 3 , a cushion 10 has an upper surface 11. Upper surface 11 may include an upper surface inclined region 111 and an upper surface planar region 113, located on either side of upper surface 11. Referring to FIG3 and FIG4 , the longitudinal distance between upper surface inclined region 111 and upper surface planar region 113 may gradually increase from near the geometrically symmetrical centerline M of cushion 10 toward either side of cushion 10, thereby defining the inclination angle of cushion 10. The longitudinal distance between upper surface inclined region 111 and upper surface planar region 113 is the distance, in the thickness direction I of cushion 10, between any first point (e.g., point A) in upper surface inclined region 111 and a corresponding second point (e.g., point B) in upper surface planar region 113. The first point (e.g., point A) may be symmetrical to the second point (e.g., point B) relative to the geometrically symmetrical centerline M of cushion 10's upper surface 11. The inclination angle of the cushion 10 can be defined as the angle α formed by a line connecting any first point (e.g., point A) in the upper surface inclined region 111 and a corresponding second point (e.g., point B) in the upper surface planar region 113 relative to the plane of the upper surface planar region 113, where the first point (e.g., point A) is symmetrical to the second point (e.g., point B) relative to the geometric symmetry midline M of the upper surface 11 of the cushion 10. Different cushions 10 can be configured to have different inclination angles α, for example, 1°, 7°, any angle between 1° and 7°, or other suitable angles.

[0054] 4 and 5 , the cushion 10 further comprises a lower surface 13, which may comprise two positioning posts 132 for engaging with corresponding positioning holes 21 on the pressure measuring device 20 to facilitate mounting the cushion 10 on the pressure measuring device 20. Referring to FIG6 , FIG6 illustrates a schematic structural diagram of an existing pressure measuring device 20. The pressure measuring device 20 may be the knee joint soft tissue pressure measuring device described in the invention patent application with publication number CN111419253A or another suitable pressure measuring device. As shown in FIG6 , the pressure measuring device 20 may comprise two positioning holes 21, each for inserting the two positioning posts 132 on the lower surface 13 of the cushion 10.

[0055] 4 , the thickness T of the pad 10 herein may be defined as the distance between the upper surface planar region 113 and an opposing region of the lower surface 13. Different pads 10 may be configured to have different thicknesses T.

[0056] Referring to FIG. 5 , the lower surface 13 of the gasket 10 may further include three inclined side contact portions 134 and three flat side contact portions 136, respectively located in the first and second lower surface regions 131 and 133 of the gasket 10. These contact portions can respectively contact corresponding pressure testing portions on the pressure measuring device 20. The first lower surface region 131 of the gasket 10 may correspond to the inclined upper surface region 111 of the gasket 10, thereby allowing the pressure measuring device 20 to measure the pressure applied to the inclined upper surface region 111 of the gasket 10 through the pressure testing portion. The second lower surface region 133 of the gasket 10 may correspond to the flat upper surface region 113 of the gasket 10, thereby allowing the pressure measuring device 20 to measure the pressure applied to the flat upper surface region 113 of the gasket 10 through the pressure testing portion. It should be understood that the number and arrangement of the inclined side contact portions 134 and flat side contact portions 136 on the lower surface 13 of the gasket 10 described above are illustrative and are not intended to limit the present invention. Those skilled in the art may set the sloped side contact portion 134 and the flat side contact portion 136 of the lower surface 13 of the cushion 10 according to needs (eg, measurement requirements of a pressure measuring device).

[0057] The pad 10 described above in conjunction with Figures 3-5 can be referred to as a first type pad. This first type pad is designed based on the physiological valgus structural characteristics of the left leg tibial plateau, and is designed so that when the pad 10 is installed on the patient's left leg tibial plateau, the upper surface bevel area 111 of the pad 10 is located on the outside of the patient's left leg. It should be understood that the pad 10 designed based on the physiological valgus structural characteristics of the left leg tibial plateau can also be applied to the right leg tibial plateau, which has physiological varus structural characteristics. When the pad 10 is installed on the patient's right leg tibial plateau, the upper surface bevel area 111 of the pad 10 is located on the inside of the patient's right leg, and the upper surface flat area 113 of the pad 10 is located on the outside of the patient's right leg.

[0058] In addition, a second type of pad 10' can also be designed, and the second type of pad 10' can be suitable for the left leg tibial plateau with physiological inversion structural characteristics. The second type of pad 10' can be constructed similarly. For example, the second type of pad 10' can be constructed to have a mirror image structure of the pad 10 described above in conjunction with Figures 3 to 5. Figures 7 to 9 show the second type of pad 10'. Figure 7 shows a schematic structural diagram of the upper surface of the second type of pad 10' according to an embodiment of the present invention. Figure 8 shows a side view of the second type of pad 10' according to an embodiment of the present invention. Figure 9 shows a schematic structural diagram of the lower surface of the second type of pad 10' according to an embodiment of the present invention.

[0059] As shown in FIG7 , the second type gasket 10' has an upper surface 11', and the upper surface 11' may have an upper surface inclined surface area 111' and an upper surface flat surface area 113', which are respectively located on both sides of the upper surface 11'. The upper surface inclined surface area 111' and the upper surface flat surface area 113' may be configured to limit the inclination angle of the second type gasket 10'. Referring to FIG9 , the lower surface 13' of the second type gasket 10' may have three inclined side contact portions 134' and three flat side contact portions 136', which are respectively located in the first lower surface area 131' and the second lower surface area 133' of the second type gasket 10', and these contact portions can respectively contact the corresponding pressure test portions on the pressure measuring device 20.

[0060] Likewise, it should be understood that the second type of pad 10 ′ designed based on the physiological inversion structural characteristics of the left leg tibial plateau can also be applied to the right leg tibial plateau having the physiological valgus structural characteristics.

[0061] Referring back to FIG1 , the processing module 30 can be communicatively coupled to the pressure measuring device 20 to receive pressure data from the pressure measuring device 20. Based on the pressure data from the pressure measuring device 20, the processing module 30 can determine the inclination angle of the pad that achieves tension balance between the medial and lateral sides of the femoral condyle (which can be simply referred to as the "tension balance compensation angle"), and determine the varus and valgus angle of the femoral osteotomy based on the tension balance compensation angle. In some embodiments, the processing module 30 can be a separate component from the pressure measuring device 20, or can be integrated into the pressure measuring device 20. As shown in FIG1 , the processing module 30 can also be communicatively coupled to the display module 40 to transmit the received pressure data, its determination result on "whether tension balance is achieved between the medial and lateral sides of the femoral condyle", the inclination angle of the new pad 10 to be used, the tension balance compensation angle determined, the varus and valgus angle of the femoral osteotomy determined, and / or other suggestions to assist the operator (e.g., a doctor) in subsequent operations, etc., to the display module 40 for display. Additionally, the display module 40 may be communicatively coupled to the pressure testing module 20 to receive pressure data directly from the pressure measurement device 20 .

[0062] The system 100 for determining the osteotomy angle described above can be used to evaluate the internal and external tension of the knee joint during the entire flexion movement in real time during knee replacement surgery and determine the appropriate osteotomy angle based on the balance of the internal and external tension, so as to assist the operator in performing precise osteotomy, thereby reducing the changes in the patient's original knee joint mechanical properties caused by osteotomy.

[0063] FIG10 illustrates a method 600 for determining the varus and valgus angle of a femoral osteotomy according to an embodiment of the present invention. In some embodiments, the method 600 can be performed using the system 100 for determining osteotomy angles described above. The following describes the method 600 for determining the varus and valgus angle of a femoral osteotomy using a left leg having physiological valgus anatomy as an example (thus, the first type of spacer 10 in the system 100 will be utilized, rather than the second type of spacer 10′).

[0064] At step 601, a pad and a pressure measuring device are installed. In some embodiments, before an operator (e.g., a physician) installs the pad 10 and the pressure measuring device 20 in the system 100 for determining an osteotomy angle, a conventional mechanical tool or computer-assisted technique may be used to determine the tibial osteotomy angle and thickness, and then a tibial osteotomy is performed based on the tibial osteotomy angle and thickness. The upper surface of the tibia after osteotomy is referred to as the tibial plateau, on which the pad 10 and the pressure measuring device 20 may be placed. After the tibial osteotomy, the operator may select a pad 10 having an appropriate thickness and initial inclination angle and install the pad 10 on the pressure measuring device 20. The thickness of the pad 10 may be determined based on the tibial osteotomy thickness. For example, the thickness of the pad 10 may be selected such that, after the pad 10 is installed on the pressure measuring device 20, the height between the upper surface planar area 113 of the pad 10 and the bottom surface of the pressure measuring device 20 is equal to the tibial osteotomy thickness. The initial inclination angle of the pad 10 can be selected based on preoperative planning, operator experience, or randomly selected. Subsequently, the operator can place the assembled pad 10 and pressure-measuring device 20 on the tibial plateau 51, as shown in FIG2 . When the pad 10 and pressure-measuring device 20 are installed on the tibial plateau 51, the bottom surface of the pressure-measuring device 20 can contact the tibial plateau 51, and the upper surface bevel region 111 of the pad 10 can be located below the lateral femoral condyle 54 of the patient's left leg, while the upper surface flat region 113 can be located below the medial femoral condyle 52 of the patient's left leg. It should be understood that FIG2 illustrates the installation of the pad 10 on a left leg with physiological valgus anatomy. Therefore, the upper surface bevel region 111 of the pad 10 is located below the lateral femoral condyle 54 of the patient's left leg, while the upper surface flat region 113 is located below the medial femoral condyle 52 of the patient's left leg. However, when the pad 10 is mounted on a right leg with a physiological varus structure, the upper surface bevel region 111 of the pad 10 is located below the medial side of the femoral condyle of the patient's right leg, and the upper surface flat region 113 is located below the lateral side of the femoral condyle of the patient's right leg. Furthermore, when the second type pad 10' is mounted on a left leg with a physiological varus structure, the upper surface bevel region 111' of the pad 10' is located below the medial side of the femoral condyle of the patient's left leg, and the upper surface flat region 113' is located below the lateral side of the femoral condyle of the patient's left leg. When the second type pad 10' is mounted on a right leg with a physiological valgus structure, the upper surface bevel region 111' of the pad 10' is located below the lateral side of the femoral condyle of the patient's right leg, and the upper surface flat region 113' is located below the medial side of the femoral condyle of the patient's right leg.

[0065] Next, method 600 may proceed to step 603 .

[0066] At step 603, the medial and lateral femoral condyle pressures are measured at multiple flexion angles. In some embodiments, after the pad 10 and the pressure measuring device 20 are installed on the tibial plateau 51, the operator can lift the patient's calf to fully extend the knee joint, and slowly flex the patient's calf from the extended position to change the flexion angle of the knee joint from the extended position to the maximum flexion angle value, for example, approximately 120°. During the flexion of the patient's knee joint, the medial side of the patient's femoral condyle (e.g., the distal femur or the posterior femoral condyle) can contact and press against the upper surface planar area 113 of the pad 10 below it at some flexion angles, and further apply pressure P1 to the corresponding pressure testing portion of the pressure measuring device 20 located below the pad 10 via the planar side contact portion 136 of the lower surface 13 of the pad 10. Similarly, during flexion of the patient's knee joint, the lateral side of the patient's femoral condyle (e.g., the distal femur or posterior femoral condyle) may contact and press against the inclined surface area 111 of the upper surface of the cushion 10 below it at certain flexion angles. Furthermore, the inclined surface contact portion 134 of the lower surface 13 of the cushion 10 may apply pressure P2 to the corresponding pressure testing portion of the pressure measuring device 20 located below the cushion 10. At this point, the pressure measuring device 20 may collect medial femoral condyle pressure P1 and lateral femoral condyle pressure P2 at multiple flexion angles (e.g., approximately 0°, 30°, 60°, 90°, 120°, etc.). Next, method 600 may proceed to step 605.

[0067] At step 605, pressure differentials are determined for multiple flexion angles. In some embodiments, the processing module 30 in the system 100 may receive pressure data (including P1 and P2) from the pressure measurement device 20 and, based on the received pressure data, calculate a corresponding pressure differential between P1 and P2 at each of the multiple flexion angles (e.g., by calculating P1-P2 or P2-P1), thereby determining the multiple pressure differentials. Each of the multiple pressure differentials corresponds to a corresponding flexion angle from the multiple flexion angles. In other embodiments, the pressure measurement device 20 itself may calculate a corresponding pressure differential between P1 and P2 at each of the multiple flexion angles based on the measured pressure data (e.g., by calculating P1-P2 or P2-P1), thereby determining the multiple pressure differentials. The pressure measurement device 20 may transmit the measured pressure data and / or the determined multiple pressure differentials to the processing module 30 for subsequent use. In some embodiments, the processing module 30 may transmit the received pressure data and the plurality of pressure difference values ​​to the display module 40 for display by the display module 40. Next, the method 600 may proceed to step 607.

[0068] At step 607, it is determined whether the inner and outer sides of the femoral condyle have reached tension balance during knee flexion. In some embodiments, the processing module 30 may compare the absolute value of each of the multiple pressure difference values ​​with a predetermined pressure difference threshold. In some embodiments, the predetermined pressure difference threshold may be any value between 30N-70N, for example, 30N, 40N, 67.5N, and the like. When it is determined that the absolute value of each of the multiple pressure difference values ​​is less than the predetermined pressure difference threshold, the processing module 30 may determine that the inner and outer sides of the femoral condyle have reached tension balance. At this point, the method 600 may proceed to step 609. When it is determined that the absolute value of at least one of the multiple pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold, the processing module 30 may determine that the inner and outer sides of the femoral condyle have not reached tension balance. At this point, the method 600 may proceed to step 602.

[0069] In some embodiments, the processing module 30 may transmit the determination result of whether the medial and lateral femoral condyles have reached tension balance to the display module 40 for display by the display module 40. For example, the display module 40 may display "medial and lateral tension balance" or "medial and lateral tension imbalance".

[0070] At step 609, the femoral osteotomy varus angle is determined. When the absolute value of each of the multiple pressure difference values ​​is determined to be less than a predetermined pressure difference threshold, the processing module 30 may determine that tension balance is achieved between the medial and lateral sides of the femoral condyle, and determine the femoral osteotomy varus angle based on the inclination angle of the pad 10 used to achieve tension balance between the medial and lateral sides of the femoral condyle (i.e., the "tension balance compensation angle"). In some embodiments, the processing module 30 may compensate the initial femoral osteotomy varus angle with the tension balance compensation angle (e.g., by subtracting the tension balance compensation angle from the initial femoral osteotomy varus angle or adding the tension balance compensation angle) to determine a compensated femoral osteotomy varus angle as the femoral osteotomy varus angle. If the patient's knee joint is in genu varum, the processing module 30 may determine the compensated femoral osteotomy varus angle by adding the tension balance compensation angle to the initial femoral osteotomy varus angle. If the patient's knee joint is in genu valgum, the processing module 30 may determine the compensated femoral osteotomy varus angle by subtracting the tension balance compensation angle from the initial femoral osteotomy varus angle. In other words, when the patient's knee joint is in genu varum, the processing module 30 can determine that the compensated varus and valgus angles of the femoral osteotomy are equal to the initial varus and valgus angles of the femoral osteotomy + the tension balance compensation angle. When the patient's knee joint is in genu valgum, the processing module 30 can determine that the compensated varus and valgus angles of the femoral osteotomy are equal to the initial varus and valgus angles of the femoral osteotomy - the tension balance compensation angle. In one embodiment, when at step 601, a pad 10 with a 3° inclination angle and a pressure measuring device 20 are installed on the tibial plateau 51 of the left leg having physiological valgus structural characteristics, at step 603, the pressure measuring device 20 performs pressure measurement in combination with the pad 10 with a 3° inclination angle, and at step 607, when the processing module 30 determines that the inner and outer sides of the femoral condyle have reached tension balance, the processing module 30 can determine that the compensated varus and valgus angles of the femoral osteotomy are equal to the initial varus and valgus angles of the femoral osteotomy - 3°. In some embodiments, the initial femoral osteotomy varus and varus angle can be determined using conventional mechanical tools or computer-assisted techniques. For example, the femoral inclination angle determined according to the method described in the invention patent application publication number CN110974493A can be used as the initial femoral osteotomy angle, which includes the initial femoral osteotomy varus and varus angle. In some embodiments, the processing module 30 can transmit the determined femoral osteotomy varus and varus angle to the display module 40 for display to the operator. Next, the method 600 can proceed to step 606.

[0071] At step 602, the inclination angle of the new cushion 10 is determined. When the absolute value of at least one of the multiple pressure differential values ​​is greater than or equal to a predetermined pressure differential threshold, processing module 30 may determine that tension equilibrium has not been achieved between the medial and lateral sides of the femoral condyle. At this point, processing module 30 may further determine the inclination angle of the new cushion 10. The inclination angle of the new cushion 10 may be determined based on method 700 described below.

[0072] At step 604, a new pad is replaced. In some embodiments, after the inclination angle of the new pad 10 is determined, the operator may replace the pad 10 previously installed on the pressure measurement device 20 with the new pad 10. Next, the method 600 may return to step 603 to re-measure the medial femoral condyle pressure and the lateral femoral condyle pressure at multiple flexion angles using the new pad 10 installed on the tibial plateau 51 and the pressure measurement device 20.

[0073] At step 606 , the method 600 for determining the varus and valgus angles of a femoral osteotomy ends.

[0074] 11 illustrates a method 700 for determining the inclination angle of a new spacer 10 according to an embodiment of the present invention. In some embodiments, the method 700 can be performed using the system 100 for determining osteotomy angles described above.

[0075] At step 701, a determination is made as to whether the absolute value of only one specific pressure difference value among the plurality of pressure difference values ​​is greater than or equal to a predetermined pressure difference threshold. In some embodiments, when it is determined at step 607 in method 600 that the absolute value of at least one pressure difference value among the plurality of pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold, processing module 30 may determine that tension equilibrium has not been achieved between the medial and lateral sides of the femoral condyle, and processing module 30 may further determine whether the absolute value of only one specific pressure difference value among the plurality of pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold. When it is determined that the absolute value of only one specific pressure difference value among the plurality of pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold, method 700 may proceed to step 703. When it is determined that the absolute values ​​of more than one pressure difference value among the plurality of pressure difference values ​​are greater than or equal to the predetermined pressure difference threshold, method 700 may proceed to step 702.

[0076] At step 703, the thickness difference between the patient's own femoral condyle and the femoral condyle prosthesis to be installed to the patient is determined. In some embodiments, the patient's own femoral condyle may not completely match the femoral condyle prosthesis to be installed to the patient (for example, the patient's own femoral condyle may have osteophytes or wear). CT (Computed Tomography) or magnetic resonance imaging can be performed before knee replacement surgery to reconstruct the patient's own femoral condyle model, and the femoral condyle model can be simulated and compared with the femoral condyle prosthesis to be installed to determine the thickness difference between the patient's own femoral condyle and the femoral condyle prosthesis to be installed to the patient. This thickness difference can be determined as the thickness of the patient's own femoral condyle minus the thickness of the femoral condyle prosthesis to be installed to the patient. Next, method 700 can proceed to step 705.

[0077] At step 705, a compensated pressure differential value is determined. In some embodiments, the processing module 30 may determine a pressure differential compensation value based on the specific pressure differential value determined at step 701 to be greater than or equal to the predetermined pressure differential threshold and the thickness difference value determined at step 703, and determine the compensated pressure differential value based on the pressure differential compensation value. For example, the processing module 30 may determine the compensated pressure differential value by adding the determined pressure differential compensation value to the specific pressure differential value. In some embodiments, the processing module 30 may generally determine the pressure differential compensation value by referring to Table 1 below.

[0078] Table 1

[0079] Note: The pressure difference in Table 1 is the difference between the medial femoral condyle pressure and the lateral femoral condyle pressure. A positive pressure difference indicates that the medial femoral condyle pressure is greater than the lateral femoral condyle pressure, which can indicate that the knee joint is in genu varum. A negative pressure difference indicates that the medial femoral condyle pressure is less than the lateral femoral condyle pressure, which can indicate that the knee joint is in genu valgum.

[0080] According to Table 1, when the specific pressure difference is between 30N and 50N and the thickness difference is 1mm (i.e., the patient's own femoral condyle is 1mm thicker than the femoral condyle prosthesis to be installed in the patient), the processing module 30 may determine the pressure difference compensation value to be -20N. When the specific pressure difference is between 30N and 50N and the thickness difference is 2mm (i.e., the patient's own femoral condyle is 2mm thicker than the femoral condyle prosthesis to be installed in the patient), the processing module 30 may determine the pressure difference compensation value to be 2*(-20N)=-40N. When the specific pressure difference is between 30N and 50N and the thickness difference is -1mm (i.e., the patient's own femoral condyle is 1mm thinner than the femoral condyle prosthesis to be installed in the patient), the processing module 30 may determine the pressure difference compensation value to be 20N. When the specific pressure difference is between 30 N and 50 N and the thickness difference is -2 mm (i.e., the thickness of the patient's own femoral condyle is 2 mm thinner than the thickness of the femoral condyle prosthesis to be installed in the patient), the processing module 30 may determine the pressure difference compensation value to be 2*(20 N) = 40 N. When the specific pressure difference is between -30 N and -50 N and the thickness difference is 1 mm (i.e., the thickness of the patient's own femoral condyle is 1 mm thicker than the thickness of the femoral condyle prosthesis to be installed in the patient), the processing module 30 may determine the pressure difference compensation value to be 20 N. When the specific pressure difference is between -30 N and -50 N and the thickness difference is 2 mm (i.e., the thickness of the patient's own femoral condyle is 2 mm thicker than the thickness of the femoral condyle prosthesis to be installed in the patient), the processing module 30 may determine the pressure difference compensation value to be 2*(20 N) = 40 N. When the specific pressure difference is between -30 N and -50 N and the thickness difference is -1 mm (i.e., the thickness of the patient's own femoral condyle is 1 mm thinner than the thickness of the femoral condyle prosthesis to be installed in the patient), the processing module 30 may determine the pressure difference compensation value to be -20 N. When the specific pressure difference is between 30 N and 50 N and the thickness difference is -2 mm (i.e., the thickness of the patient's own femoral condyle is 2 mm thinner than the thickness of the femoral condyle prosthesis to be installed in the patient), the processing module 30 may determine the pressure difference compensation value to be 2*(-20 N) = -40 N.

[0081] Table 1 above is exemplarily set when the predetermined pressure difference threshold is 30 N. It should be understood that those skilled in the art may set Table 1 according to actual conditions and based on their experience or experiments.

[0082] Next, method 700 may proceed to step 707 .

[0083] At step 707, the inclination angle of the new cushion 10 is determined. In some embodiments, the processing module 30 may determine the inclination angle of the new cushion 10 based on the compensated pressure difference value determined at step 705 and the flexion angle corresponding to the compensated pressure difference value. In other embodiments, the above steps 703 and 705 may be omitted, and the processing module 30 may determine the inclination angle of the new cushion 10 based on the specific pressure difference value determined at step 701 and the flexion angle corresponding to the specific pressure difference value. The processing module 30 may directly determine the inclination angle of the new cushion 10 by querying Table 2 below. Table 2 may reflect the correspondence between multiple pressure difference values ​​and the inclination angle of the cushion at different flexion angles.

[0084] Table 2

[0085] Note: The pressure differential in Table 2 is the difference between the medial femoral condyle pressure and the lateral femoral condyle pressure. A positive pressure differential indicates that the medial femoral condyle pressure is greater than the lateral femoral condyle pressure, indicating a genu varum. A negative pressure differential indicates that the medial femoral condyle pressure is less than the lateral femoral condyle pressure, indicating a genu valgum. A positive inclination angle indicates that the varus / valgus angle of the femoral resection can be determined by adding the inclination angle to the initial varus / valgus angle. A negative inclination angle indicates that the varus / valgus angle of the femoral resection can be determined by subtracting the absolute value of the inclination angle from the initial varus / valgus angle.

[0086] When the compensated pressure differential or specific pressure differential is between 30N and 50N and the corresponding flexion angle is 30 degrees, the inclination angle obtained by querying Table 2 is 1°. In this case, the processing module 30 can determine that the inclination angle of the new cushion 10 is 1°. When the compensated pressure differential or specific pressure differential is between 50N and 80N and the corresponding flexion angle is 30 degrees, the inclination angle obtained by querying Table 2 is 1° / 2°. In this case, the processing module 30 can determine that the inclination angle of the new cushion 10 is 1° or 2°. When the compensated pressure differential or specific pressure differential is between -80N and -120N and the corresponding flexion angle is 0 degrees, the inclination angle obtained by querying Table 2 is -3° / -4°. In this case, the processing module 30 can determine that the inclination angle of the new cushion 10 is 3° or 4°.

[0087] Table 2 above is exemplarily set when the predetermined pressure difference threshold is 30 N. It should be understood that those skilled in the art may set Table 2 according to actual conditions and based on their experience or experiments.

[0088] In some embodiments, the processing module 30 may transmit the determined inclination angle of the new cushion 10 to the display module 30 for display by the display module 30 .

[0089] Next, method 700 may proceed to step 709 .

[0090] At step 702, the inclination angle of the new cushion 10 is determined. When it is determined that the absolute value of more than one pressure difference value among the multiple pressure difference values ​​is greater than or equal to a predetermined pressure difference threshold, the processing module 30 may determine the inclination angle of the new cushion 10 to be greater than the inclination angle of the currently used cushion 10. For example, when the absolute value of each of the multiple pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold, and the inclination angle of the currently used cushion 10 is 5°, the processing module 30 or the operator may determine the inclination angle of the new cushion 10 to be greater than 5°, such as 6°, 7°, or another greater angle. The determined greater inclination angle may be based on the inclination angle of the currently used cushion 10 plus an angle value. In some embodiments, the added angle value may be a fixed value (e.g., 1°, 2°, or another angle value). In other embodiments, the added angle value may be adjusted based on the deviation between the absolute value of the pressure difference value and the predetermined pressure difference threshold. For example, the greater the deviation between the absolute value of the pressure difference value and the predetermined pressure difference threshold, the greater the added angle value. The processing module 30 may transmit the determined inclination angle of the new cushion 10 to the display module 30 for display by the display module 30. Next, the method 700 may proceed to step 709.

[0091] At step 709 , the method 700 for determining the rake angle of the new pad 10 ends.

[0092] One or more modules in each embodiment of the present disclosure may be implemented by hardware. For example, they may be implemented using at least one of application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, micro-processors, and electrical units for performing other functions.

[0093] Some parts of the various embodiments of the present disclosure may be provided as a computer program product, which may include a computer-readable medium having computer program instructions stored thereon, and the computer program instructions may be used to program a computer (or other electronic device) to be executed by one or more processors to perform a process according to certain embodiments. The computer-readable medium may include, but is not limited to, a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic card or an optical card, a flash memory, or other types of computer-readable media suitable for storing electronic instructions. In addition, the embodiment may also be downloaded as a computer program product, wherein the program can be transferred from a remote computer to a requesting computer. In some embodiments, a non-transient computer-readable storage medium has data representing an instruction sequence stored thereon, which, when executed by a processor, causes the processor to perform certain operations, for example, one or more steps in the method 600 and method 700 described above in conjunction with Figures 10 and 11.

[0094] Although the present invention has been described in terms of the preferred embodiments of the present disclosure, it is not intended to be limited thereto, but rather to be limited only by the scope set forth in the appended claims. It will be understood by those skilled in the art that various modifications and changes may be made to the embodiments described herein without departing from the broader spirit and scope of the present invention as set forth in the appended claims.

Claims

1. A system for determining an osteotomy angle, characterized in that: The system comprises: A plurality of cushions, each cushion comprising a cushion body having: The upper surface has an upper surface inclined area and an upper surface plane area, wherein the upper surface inclined area and the upper surface plane area are respectively located on both sides of the upper surface, and the longitudinal distance between the upper surface inclined area and the upper surface plane area gradually increases from close to the geometric symmetry center line of the cushion to both sides of the cushion to define an inclination angle, and a lower surface for mounting to a pressure measuring device; a pressure measuring device for combining with one of the plurality of cushions to measure the pressures applied by the two side parts when a first side part of the two side parts of the bone end of the bone joint presses against one of the upper surface inclined area and the upper surface plane area of ​​the cushion and a second side part presses against the other of the upper surface inclined area and the upper surface plane area of ​​the cushion, so as to determine a pressure difference; and a processing module communicatively coupled to the pressure measurement device and configured to: Based on the pressure difference, determining whether the first side portion and the second side portion reach tension balance; The osteotomy angle of the bone end is determined based on the inclination angle of the pad that allows the first side portion and the second side portion to achieve tension balance.

2. The system according to claim 1, characterized in that The bone end is a femoral condyle, the femoral condyle includes a distal femur and a posterior femoral condyle, a first side portion of the two side portions of the bone end includes an inner side of the distal femur or an inner side of the posterior femoral condyle, and a second side portion of the two side portions of the bone end includes an outer side of the distal femur or an outer side of the posterior femoral condyle, The pressure measuring device is used to be installed between the tibial plateau and the pad.

3. The system according to claim 2, characterized in that The pressure measuring device is used to combine with one of the plurality of cushions to measure a first pressure applied by a first side portion and a second pressure applied by a second side portion of the two side portions of the bone end at each of a plurality of flexion angles of the knee joint, wherein the upper surface inclined area of ​​the cushion is located below the inner side of the femoral condyle of the knee joint with genu varum or below the outer side of the femoral condyle of the knee joint with genu valgum, The processing module is further configured to: Based on the first pressure and the second pressure measured by the pressure measuring device when the knee joint is at each of a plurality of flexion angles, a corresponding pressure difference is calculated.

4. The system according to claim 3, characterized in that The processing module is further configured to: comparing the absolute value of each of the plurality of pressure difference values ​​with a predetermined pressure difference threshold; and Based on the comparison result, it is determined whether the first side portion and the second side portion reach tension balance.

5. The system according to claim 4, characterized in that The processing module is further configured to: When more than one absolute value of each of the multiple pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold, the inclination angle of the new cushion to be used is determined to be greater than the inclination angle of the cushion currently in use, so that the pressure can be re-measured using the new cushion subsequently.

6. The system according to claim 4, characterized in that The processing module is further configured to: When the absolute value of only one specific pressure difference value among the multiple pressure difference values ​​is greater than or equal to the predetermined pressure difference threshold, the inclination angle of the new cushion to be used is determined based on the specific pressure difference value, the flexion angle corresponding to the specific pressure difference value, and a comparison table, so as to subsequently re-measure the pressure using the new cushion, wherein the comparison table reflects the correspondence between multiple pressure difference values ​​and the inclination angle of the cushion at different flexion angles.

7. The system according to claim 6, characterized in that Based on the specific pressure difference, the flexion angle corresponding to the specific pressure difference, and the comparison table, determining the inclination angle of the new cushion to be used further includes: determining a pressure difference compensation value based on a thickness difference between the patient's own femoral condyle and a femoral condyle prosthesis to be installed in the patient and the specific pressure difference; determining a compensated pressure difference value based on the pressure difference compensation value; and Based on the compensated pressure difference, the flexion angle corresponding to the compensated pressure difference, and the comparison table, the inclination angle of the new cushion to be used is determined so that the new cushion can be used later. Re-measure the pressure.

8. The system according to claim 6, characterized in that The comparison table is set based on experience or experiments.

9. The system according to claim 4, characterized in that Determining whether the first side portion and the second side portion reach tension balance based on the comparison result includes: In response to the absolute value of each of the plurality of pressure difference values ​​being smaller than the predetermined pressure difference threshold, it is determined that the first side portion and the second side portion reach tension balance.

10. The system according to any one of claims 1 to 9, characterized in that: The processing module is further configured to: The osteotomy angle of the bone end is determined based on the varus and valgus angle of the initial femoral osteotomy and the inclination angle of the pad that enables the first side portion and the second side portion to achieve tension balance.

11. The system according to claim 10, characterized in that The system also includes a display module, the display module being communicatively coupled to the processing module and configured to: At least one of the following items is displayed: the pressure data measured by the pressure measuring device, the pressure difference, the inclination angle of the pad that enables the first side portion and the second side portion to achieve tension balance, and the determined osteotomy angle.

12. The system according to any one of claims 1 to 9, characterized in that: The inclination angle of the cushion is the angle between the line between the first point in the upper surface inclined area and the second point in the upper surface plane area relative to the plane where the upper surface plane area is located, wherein the first point is symmetrical to the second point relative to the geometric symmetry midline of the upper surface of the cushion.

13. The system according to any one of claims 1 to 9, characterized in that: The lower surface of the cushion body is installed with the top surface of the pressure measuring device through a hole-column matching structure.

14. The system according to any one of claims 1 to 9, characterized in that: The lower surface of the cushion body has a first lower surface area and a second lower surface area respectively opposite to the upper surface plane area and the upper surface inclined area, wherein the first lower surface area and the second lower surface area respectively have at least one contact portion for contacting the corresponding pressure testing portion on the pressure measuring device.

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