A total knee arthroplasty prosthesis positioning and gap balancing simulation training method

Abstract

This application relates to a simulation training method for total knee arthroplasty prosthesis positioning and gap balancing, belonging to the field of simulation training technology. To provide a standardized and repeatable workflow for individualized planning of total knee arthroplasty surgery, this application provides a simulation training method for total knee arthroplasty prosthesis positioning and gap balancing. This method includes determining the amount of osteotomy on the posteromedial femoral condyle based on the thickness of the femoral prosthesis's posterior condyle; determining the rotational alignment parameters of the femoral prosthesis based on a femoral trochlea model to obtain a patellar trajectory that meets the requirements; determining the placement of the tibial prosthesis on the tibia with the knee joint model in a flexed state; and determining the placement of the femoral prosthesis on the femur with the knee joint model in an extended state. This method enables individualized planning of total knee arthroplasty surgery, precise prosthesis positioning, flexion-extension gap balancing, and standardized training of the surgical procedure, improving surgical accuracy and postoperative outcomes.

Description

Technical Field

[0001] This invention relates to a simulation training method for positioning and gap balancing of total knee arthroplasty prostheses, belonging to the field of simulation training technology. Background Technology

[0002] Total knee arthroplasty is an effective treatment for end-stage knee osteoarthritis, with the primary goals of relieving pain, restoring joint function, and improving patients' quality of life. In recent years, robot-assisted technology has been increasingly widely used in total knee arthroplasty. Through preoperative three-dimensional planning and precise intraoperative robotic arm execution, it improves the accuracy and repeatability of prosthesis placement, significantly reducing outliers in force lines and prosthesis position.

[0003] For example, the data processing method, device, processor and electronic device for total knee replacement disclosed in patent authorization announcement number CN115462865B, announcement date 20230310, solves the problem that the accuracy of establishing the lower limb force line is relatively low when the lower limb force line is established by opening the medulla oblongata with the help of corresponding tools in the related technology.

[0004] In knee replacement surgery and related research, FA (Functional Alignment), MA (Mechanical Alignment), aMA (Adjusted Mechanical Alignment), and KA (Kinematic Alignment) are important concepts describing the alignment of the knee joint. Functional alignment (FA) emphasizes the alignment of the knee joint during functional activities (such as walking and climbing stairs), focusing on the stability and efficiency of the knee joint in dynamic processes. FA strategies, in particular, rely on dynamic feedback provided by robotic systems, aiming to achieve knee joint balance throughout its range of motion by fine-tuning the prosthesis position to adapt to the patient's unique anatomy and ligament tension. Specific quantitative indicators of FA may vary from study to study, but the core is to ensure that the knee joint maintains optimal biomechanical distribution during functional activities to reduce wear and pain.

[0005] Existing femoral joint (FA) strategies, when adjusting femoral and tibial prostheses in a coordinated manner, only provide the corresponding boundaries for prosthesis placement, lacking a standardized and repeatable adjustment process and sequence. This affects the anatomical reconstruction and soft tissue balance of the knee joint, as well as the accurate recovery of PCO (Posterior Condylar Offset) and JLH (Joint Line Height), thus impacting postoperative knee joint flexion stability and kinematic function.

[0006] To overcome the aforementioned shortcomings, this application provides a simulation training method for prosthesis positioning and gap balance in total knee arthroplasty. The aim is to establish a linked adjustment method centered on PCO and the femoral trochlea, providing a standardized and repeatable workflow. This enables individualized planning, precise prosthesis positioning, flexion-extension gap balance, and standardized training of the surgical procedure for total knee arthroplasty, improving surgical precision and postoperative outcomes. Ultimately, this enhances the accuracy of PCO and JLH recovery, achieves flexion-extension gap balance, improves postoperative knee flexion stability, enhances kinematic function, and increases patient satisfaction. Summary of the Invention

[0007] To overcome the limitations of existing technologies, such as the lack of a standardized and repeatable workflow in the coordinated adjustment of femoral and tibial prostheses, which affects the anatomical reconstruction and soft tissue balance of the knee joint, as well as the accurate restoration of PCO and JLH, thus impacting the flexion stability and kinematic function of the knee joint, this application provides a simulation training method for prosthesis positioning and gap balancing in total knee arthroplasty. The aim is to establish a coordinated adjustment method centered on PCO and the femoral trochlea, providing a standardized and repeatable workflow to achieve individualized planning, precise prosthesis positioning, flexion-extension gap balancing, and standardized training of the surgical procedure for total knee arthroplasty, thereby improving surgical precision and postoperative outcomes.

[0008] This application provides a method for simulating the positioning and gap balance of a total knee arthroplasty prosthesis, including: A three-dimensional model of the knee joint was created on a robot-assisted system based on the preoperative CT scan results. The three-dimensional model included the femoral model, the tibia model, and the femoral trochlea model. Based on the three-dimensional model of the knee joint, a matching physical model of the knee joint is selected, and the type and size of the prosthesis to be implanted are selected. The physical model includes the femur, tibia and femoral trochlea, and the prosthesis includes femoral prosthesis and tibial prosthesis. The amount of osteotomy on the posteromedial femoral condyle is determined based on the thickness of the posterior condyle of the femoral prosthesis. Based on the femoral trochlea model, the rotational alignment parameters of the femoral prosthesis were determined, and the femoral trochlea was simulated to return to the preoperative level on a robot-assisted system in order to obtain the required patellar trajectory. With the knee joint model in a flexed state, the medial flexion gap and lateral flexion gap are collected. Based on the collection results, the osteotomy depth and osteotomy varus / valgus angle of the tibia are adjusted to obtain a rectangular flexion gap. The difference between the medial flexion gap and the lateral flexion gap in the rectangular flexion gap is kept within a preset range to determine the installation position of the tibial prosthesis on the tibia. With the knee joint model in extension, the medial extension gap and lateral extension gap are collected. Combined with the determined tibial prosthesis installation position, the varus / valgus angle and osteotomy amount of the distal femur are finally adjusted to obtain a rectangular extension gap, and the extension gap is matched with the flexion gap to determine the installation position of the femoral prosthesis on the femur.

[0009] In some embodiments, determining the rotational alignment parameters of the femoral prosthesis based on the femoral trochlea model specifically includes: Based on the three-dimensional graphics, two-dimensional cross-sections, and simulated prosthesis position of the knee joint provided by the robot-assisted system, the internal and external rotation angles of the femoral model are determined. The internal and external rotation angles of the femoral prosthesis are adjusted with reference to the position of the femoral trochlear model until they coincide with the internal and external rotation angles of the femoral model. Obtain the internal and external rotation angles for osteotomy on a physical model; The position of the reconstructed femoral trochlea after osteotomy should coincide with the position of the femoral trochlea model.

[0010] In some embodiments, the preset range is greater than or equal to 0 mm and less than or equal to 1 mm.

[0011] In this embodiment, the above-described operation anchors the amount of osteotomy on the posteromedial femoral condyle within a narrow range, making the PCO relatively constant. To achieve a rectangular flexion gap, the osteotomy depth and varus / valgus angles of the tibial plateau are mainly adjusted. By limiting the rectangular flexion gap to an acceptable range with a relatively small numerical limit, the amount of osteotomy on the tibial plateau is also kept within a relatively constant and small range. This effectively avoids excessive removal of proximal tibial bone in pursuit of flexion gap balance, reduces the risk of excessive joint line elevation, and achieves precise restoration of the joint line, resulting in better mid-term function and stability of the patient's knee joint post-surgery.

[0012] In this embodiment, a linkage adjustment method centered on PCO and femoral trochlea is established through simulation training of total knee arthroplasty prosthesis positioning and gap balancing. This provides a standardized and repeatable workflow, allowing surgeons to complete osteotomy, prosthesis positioning, and gap balancing according to uniform and repeatable steps, reducing reliance on experience and improving surgical consistency. Preoperative planning of femoral / tibial osteotomy volume, rotational alignment, and flexion-extension gap matching reduces operational errors and improves prosthesis placement accuracy. Rectangular flexion and extension gaps are pre-adjusted and obtained in the simulation to achieve symmetrical matching of flexion-extension gaps, reducing the risk of postoperative instability, pain, and loosening. The accuracy of femoral trochlea, joint line height (JLH), and posterior femoral condyle offset (PCO) recovery is improved, which helps to reconstruct the lower limb biomechanical axis and improve postoperative motor function. Novice surgeons can practice repeatedly, reducing operational errors, shortening operation time, and improving overall surgical safety. Personalized simulation based on the patient's CT 3D model enables a one-person-one-plan approach, improving postoperative function and patient satisfaction.

[0013] In this embodiment, the simulation training method for prosthesis positioning and gap balancing in total knee arthroplasty can realize individualized planning, precise prosthesis positioning, flexion-extension gap balancing, and standardized training of surgical procedures for total knee arthroplasty, thereby improving surgical accuracy and postoperative outcomes. It also helps to improve the accuracy of PCO and JLH recovery in patients, achieve flexion-extension gap balancing, improve the flexion stability of the knee joint after surgery, and improve patients' kinematic function and satisfaction. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating a simulation training method for total knee arthroplasty prosthesis positioning and gap balancing in one embodiment of this application.

[0015] Figure 2 This is a schematic diagram of the knee joint in one embodiment of this application.

[0016] Figure 3 This is a schematic diagram of the femur structure in one embodiment of this application.

[0017] Figure 4 This is a schematic diagram of the tibia in one embodiment of this application.

[0018] Figure 5 This is a schematic diagram of a knee joint model in an extended state according to one embodiment of this application.

[0019] Figure 6 This is a schematic diagram of a knee joint model in a flexed state according to one embodiment of this application.

[0020] Figure 7 This is a schematic diagram of the structure of an existing physical model of a knee joint. Detailed Implementation

[0021] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] When using the terms “including,” “having,” and “comprising” as described herein, another component may be added unless explicitly qualifying terms such as “only,” “consisting of,” etc. are used. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0024] It should be understood that although the terms “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0025] It should also be understood that, in interpreting an element, although not explicitly described, the element is interpreted as including a range of error, which should be within the acceptable deviation range of a particular value as determined by a person skilled in the art. For example, "approximately," "about," or "substantially" can mean within one or more standard deviations, without limitation herein.

[0026] Furthermore, the accompanying drawings are not drawn to a 1:1 scale, and the relative dimensions of the components are shown in the drawings only as examples and not necessarily to actual scale.

[0027] In recent years, robot-assisted technology has been increasingly widely used in total knee arthroplasty, improving the accuracy and repeatability of prosthesis placement through preoperative 3D planning and precise intraoperative robotic arm execution. A robot-assisted system is an osteotomy aid that uses 3D modeling based on preoperative CT images to simulate the expected prosthesis placement position in real time within the robotic surgical operating system. It also determines the medial and lateral flexion-extension gap of the joint by placing the prosthesis at the expected position and the osteotomy plan. Once a satisfactory gap and osteotomy plan are obtained, the osteotomy operation can begin. Robots include, but are not limited to, the HURWA robot and the Mako robot.

[0028] Multiple studies have confirmed that, compared with conventional total knee arthroplasty, robot-assisted surgery can significantly reduce outliers in force line and prosthesis position, and achieve more precise prosthesis rotational positioning, thus improving surgical accuracy. In particular, the FA (Automatic Joint Assembly) strategy relies heavily on dynamic feedback provided by the robotic system, aiming to achieve knee joint balance throughout its entire range of motion by fine-tuning the prosthesis position to adapt to the patient's unique anatomy and ligament tension.

[0029] The implanted knee prosthesis consists of three parts: the femoral prosthesis, the tibial prosthesis, and a polyethylene liner. The femoral prosthesis is placed at the distal end of the femur, the tibial prosthesis at the proximal end of the tibia, and the polyethylene liner is integrated with the tibial prosthesis through a specific locking mechanism. The specific design of the polyethylene liner within each prosthesis conforms to the shape of the femoral prosthesis, thereby enabling knee flexion and extension movements.

[0030] In knee replacement surgery and related research, FA (Functional Alignment), MA (Mechanical Alignment), aMA (Adjusted Mechanical Alignment), and KA (Kinematic Alignment) are important concepts describing the alignment of the knee joint. Functional alignment (FA) emphasizes the alignment of the knee joint during functional activities (such as walking and climbing stairs), focusing on the stability and efficiency of the knee joint in dynamic processes. FA strategies, in particular, rely on dynamic feedback provided by robotic systems, aiming to achieve knee joint balance throughout its range of motion by fine-tuning the prosthesis position to adapt to the patient's unique anatomy and ligament tension. Specific quantitative indicators of FA may vary from study to study, but the core is to ensure that the knee joint maintains optimal biomechanical distribution during functional activities to reduce wear and pain.

[0031] Existing femoral joint (FA) strategies, when adjusting femoral and tibial prostheses in a coordinated manner, only provide the corresponding boundaries for prosthesis placement. When surgeons or surgical systems simultaneously adjust multiple degrees of freedom such as femoral rotation, distal femoral osteotomy, and tibial osteotomy, there is a lack of clear priority order and constraint rules. In other words, there is a lack of a standardized and repeatable adjustment process and sequence. This may result in the sacrifice of accurate reconstruction of femoral trochlear morphology and PCO while achieving satisfactory flexion-extension gap, thereby affecting patellofemoral joint function and long-term stability, impacting anatomical reconstruction and soft tissue balance of the knee joint, as well as the accurate recovery of PCO (Posterior Condylar Offset) and JLH (Joint Line Height), ultimately affecting postoperative knee flexion stability and kinematic function.

[0032] Soft tissue imbalances can lead to joint instability, misalignment, prosthesis loosening, excessive polyethylene wear, poor postoperative function, impaired knee proprioception, and reduced prosthesis survival rates. Soft tissue balance can be achieved through proper osteotomy, appropriate joint line height, suitable soft tissue release, and selection of a suitable prosthesis.

[0033] PCO refers to the vertical distance from the distal femoral posterior condyle axis to the line connecting the anterior and posterior femoral condyles, reflecting the degree of posterior displacement of the femur relative to the anterior side; JLH refers to the vertical distance between the tibial plateau and the femoral condyle, representing the height of the knee joint space. These two are important anatomical parameters in total knee arthroplasty (TKA) and have a potential impact on postoperative knee biomechanics and function.

[0034] PCO primarily affects the knee joint's rotation radius and impingement timing. Theoretically, a larger PCO can delay the impingement between the posterior edge of the tibial plateau and the posterior femoral cortex, potentially increasing the maximum flexion angle. Furthermore, changes in PCO affect the flexion gap, thus impacting flexion stability. Inappropriate PCO settings can lead to mid-flexion instability or impaired knee extension strength.

[0035] Changes in the posterior condyle height (JLH) are directly related to the flexion-extension balance and soft tissue tension of the knee joint. Elevation of the joint line may reduce the posterior condyle offset (PCO), negatively affecting the flexion angle and extension force, and leading to mid-shaft flexion instability. Maintaining an appropriate JLH is crucial for ensuring flexion-extension balance and patellofemoral joint mechanics. Both excessively high and excessively low joint lines may cause postoperative functional impairment.

[0036] PCO and JLH are interconnected and together form the three-dimensional alignment basis for knee replacement. PCO indirectly affects the joint line height by changing the position of the posterior femoral condyle relative to the tibial plateau, and vice versa. When planning surgery, both need to be considered to avoid biomechanical imbalance. For example, excessive increase in PCO may lead to joint line elevation, causing posterior impingement or stability problems.

[0037] The simulation training and positioning methods provided in this application, with their core steps and logic, can serve as advanced strategies for optimizing the operation of existing robot-assisted surgical platforms (such as the Mako and HURWA robot systems). The scope of protection of this application lies in the sequence of method steps and the control logic based on that sequence, and is not limited to any specific robot hardware brand or prosthesis model. The method of this invention can be integrated into the software planning module of a corresponding robot system to guide system operations and / or prompt surgeons to perform procedures.

[0038] This invention provides a simulation training method for total knee arthroplasty prosthesis positioning and gap balance, such as... Figures 1 to 7 As shown, the aim is to establish a linkage adjustment method centered on PCO and femoral trochlea, providing a standardized and repeatable workflow to achieve individualized planning, precise prosthesis positioning, flexion-extension gap balancing, and standardized training of surgical procedures for total knee replacement surgery. This will improve surgical precision and postoperative outcomes, thereby enhancing the accuracy of PCO and JLH recovery, achieving flexion-extension gap balancing, improving postoperative knee flexion stability, enhancing kinematic function, and increasing patient satisfaction.

[0039] This application provides a method for simulating the positioning and gap balance of a total knee arthroplasty prosthesis, including: Step 1: Based on the preoperative CT scan results, a three-dimensional model of the knee joint is created on the robot-assisted system. The three-dimensional model includes the femoral model, tibia model, and femoral trochlea model. Step 2: Select a matching physical model of the knee joint based on the three-dimensional model of the knee joint, and select the type and size of the prosthesis to be implanted. The physical model includes the femur, tibia and femoral trochlea, and the prosthesis includes femoral prosthesis and tibial prosthesis. Step 3: Determine the amount of osteotomy of the posteromedial femoral condyle based on the thickness of the posterior condyle of the femoral prosthesis; Step 4: Based on the femoral trochlea model, determine the rotation alignment parameters of the femoral prosthesis, and simulate the femoral trochlea to return to the preoperative level on a robot-assisted system to obtain a patellar trajectory that meets the requirements. Step 5: With the knee joint model in a flexed state, collect the medial flexion gap and the lateral flexion gap, and adjust the osteotomy depth and osteotomy varus / valgus angle of the tibia according to the collection results to obtain a rectangular flexion gap. Make sure that the difference between the medial flexion gap and the lateral flexion gap in the rectangular flexion gap is within the preset range, and determine the installation position of the tibial prosthesis on the tibia. Step 6: With the knee joint model in an extended position, collect the medial extension gap and the lateral extension gap. Combined with the determined tibial prosthesis installation position, make final adjustments to the varus / valgus angle and osteotomy amount of the distal femur to obtain a rectangular extension gap, and make the extension gap match the flexion gap to determine the installation position of the femoral prosthesis on the femur.

[0040] In step one of this application's embodiments, the patient's existing diseased knee joint data can be obtained through CT scan results, thereby providing basic support for the patient's personalized surgical plan. Then, a three-dimensional model is performed using a robotic system and the patient's existing diseased knee joint data, thereby reproducing the femoral trochlea morphology in the patient's normal state in the model.

[0041] In this embodiment, regarding prosthesis selection in step two, the method provided in this application is applicable to robotic systems from different manufacturers and with different prostheses, regardless of whether it is an open platform (which can use prostheses from multiple manufacturers) or a closed platform (which can only use prostheses from a specific manufacturer). For example, the Stryker Triathlon series of posterior cruciate ligament-preserving (CR) knee prostheses. The specific prosthesis series used is determined by the surgeon, and the prosthesis model within that series is selected based on the preoperative visualization presented to the patient in the robotic system. The robotic system can be used to clarify the surgical prosthesis model preoperatively.

[0042] The prosthesis size and bone size are correlated. For different patients with different bone sizes, the prosthesis size will vary accordingly and will be determined preoperatively based on the patient's individual anatomy. The remaining amount of osteotomy will be determined based on the real-time gap information provided by the robotic system and the patient's preoperative trochlear morphology, aiming to achieve a balanced flexion-extension gap.

[0043] In step three of this application's embodiment, the posteromedial femoral condyle refers to the ankle bone located posterior and medially to the femur, with the patient as a reference. For example... Figure 3 As shown in the diagram, the yellow line indicates the location for the posteromedial femoral condyle osteotomy. The amount of osteotomy can be set as a target value based on the thickness of the posterior condyle of the prosthesis used in the surgery; for example, 9mm could be set for the Stryker Triathlon prosthesis. By setting a target value for the amount of osteotomy of the posteromedial femoral condyle and using this value as an initial anchor point, a benchmark is provided for all subsequent adjustments, thus establishing a stable posterior femoral reference for simulated surgical procedures. During the procedure, if soft tissue balance is difficult to achieve, fine-tuning is allowed within a narrow range of 8.5mm to 9.5mm to ensure the relative stability of the PCO (postoperative condyle osteotomy).

[0044] In one example, when the patient uses the Triathlon series prosthesis, the posterior condyle thickness of the femoral prosthesis is 8.9 mm. Therefore, 9 mm can be used as the anchor value for the posteromedial femoral condyle osteotomy. The osteotomy positions of other bony structures can be adjusted accordingly using the methods described earlier. Specifically, the adjusted posteromedial femoral condyle osteotomy can be used as a reference to plan the subsequent anterior femoral condyle osteotomy, adjusting the flexion or extension angle of the femoral prosthesis to avoid notching in the anterior femoral cortex.

[0045] In this embodiment, by anchoring the amount of posteromedial femoral condyle osteotomy within a narrow range, the change in PCO is controlled, making the recovery of the patient's PCO precise and predictable. This helps the patient achieve the expected recovery effect after knee surgery, thereby maintaining normal knee "backward rolling" movement, having good flexion stability, obtaining a satisfactory postoperative flexion angle, and ensuring the treatment effect.

[0046] In this embodiment, the amount of osteotomy on the posteromedial femoral condyle is used as the initial and relatively constant geometric anchor point to constrain the recovery range of PCO. This allows the task of adjusting the initial flexion gap balance to be mainly assigned to the osteotomy adjustment on the tibial side, thereby avoiding sacrificing the rotational alignment of the femoral prosthesis (especially physiological rotational reconstruction based on the trochlear model) in order to balance the gap.

[0047] Compared to existing methods that allow surgeons to freely adjust their alignment strategies (such as FA) based solely on their habits or preferences, the simulation training method for total knee arthroplasty prosthesis positioning and gap balance provided in this application can reduce the probability of poor flexion stability and limited flexion range of motion caused by poor PCO recovery, and reduce the probability of joint line displacement, patellofemoral joint function, and knee extensor muscle strength caused by excessive PCO recovery.

[0048] In this embodiment, the osteotomy direction of the posteromedial femoral condyle can be adjusted for prosthesis flexion or extension based on the patient's anterior cortical condition to avoid notching. The internal and external rotation adjustment of the osteotomy is determined using the morphology of a preoperative femoral trochlear model to obtain a suitable patellar trajectory.

[0049] In step four of this embodiment, the rotation alignment of the femoral prosthesis refers to the internal or external rotation angle of the femoral prosthesis. The rotation alignment of the femoral prosthesis is determined based on the patient's original trochlear morphology and is determined according to the patient's specific anatomical characteristics. It is unique and highly adaptable. Compared to traditional reference axes such as the posterior condylar axis (PCA) and the transepicondylar axis (TEA), it can reduce the difficulty of identifying rotation alignment and improve surgical outcomes and efficiency. The internal and external rotation of the femoral prosthesis is relative to the PCA or the TEA. The explicit numerical relationship between the PCA and TEA (e.g., 3° ​​for PCA corresponds to 0° for TEA) is provided by the robotic system.

[0050] In some embodiments, step four, based on the femoral trochlear model, specifically includes determining the rotation alignment parameters of the femoral prosthesis: according to the three-dimensional graphics, two-dimensional cross-sections, and simulated prosthesis position of the knee joint provided by the robot-assisted system, determining the internal and external rotation angles of the femoral model; adjusting the internal and external rotation angles of the femoral prosthesis with reference to the position of the femoral trochlear model until they coincide with the internal and external rotation angles of the femoral model; obtaining the internal and external rotation angles for osteotomy on the physical model; aligning the position of the femoral trochlear with the position of the femoral trochlear model; and ensuring that the reconstructed position of the femoral trochlear after osteotomy coincides with the position of the femoral trochlear model.

[0051] In step four of this application embodiment, obtaining a patellar trajectory that meets the requirements enables the position and movement trajectory of the femoral prosthesis to be consistent with the position and movement trajectory of the patient's original normal femur simulated by the three-dimensional model. This helps to restore the patient's physiological femoral trochlear function, reconstruct the normal patellofemoral joint movement trajectory, reduce the incidence of postoperative anterior knee pain, and optimize postoperative function.

[0052] In step five of this embodiment, after completing the preliminary planning of the posteromedial femoral condyle osteotomy and rotation, with the knee joint physical model in a flexed state, the medial and lateral flexion gap data of the knee joint are collected by a robotic system. Based on the medial and lateral soft tissue gap data of the three-dimensional knee joint model, osteotomy planning is performed before the installation of the tibial prosthesis, including the osteotomy depth and varus / valgus angles of the tibial plateau.

[0053] In one example, the specific steps of collecting the medial and lateral flexion gaps when the knee joint physical model is in flexion in step five of this application embodiment include: Complete distal femoral and proximal tibial bone resection; Position the knee joint in a flexed position (85°-95°) so that the tibial cutting plane is parallel to the posterior femoral cutting plane; The system acquires and obtains the medial and lateral flexion gap values ​​of the knee joint in real time, completing the quantitative acquisition of the flexion gap. This step specifically includes: the robotic system acquires and displays the medial and lateral flexion gap values ​​in real time, records the difference and symmetry of the gaps on both sides; while keeping the knee flexion angle stable, the acquisition is repeated 2-3 times and the average value is taken to complete the accurate acquisition of the medial and lateral flexion gaps.

[0054] In the osteotomy procedure of knee replacement surgery, the joint space can be dynamically controlled by increasing the varus angle, increasing the valgus angle, increasing the osteotomy depth, and decreasing the osteotomy depth. For example... Figure 4 As shown in the figure, the left side is the lateral side and the right side is the medial side; the yellow line represents eversion osteotomy, and the red line represents inversion osteotomy. The adjustment of the osteotomy amount and angle is determined based on the anatomical landmarks selected during the robot system modeling process as reference points.

[0055] In this embodiment, when the medial flexion gap is small, the medial tibial osteotomy depth or the tibial eversion angle is increased; when the lateral flexion gap is small, the lateral tibial osteotomy depth or the tibial varus angle is increased, until the medial flexion gap and the lateral flexion gap are basically symmetrical; after repeated acquisition and adjustment, the final tibial osteotomy parameters are determined after obtaining a balanced flexion gap.

[0056] Specifically, to increase the varus angle, the varus angle of the femoral or tibial osteotomy guide can be adjusted to create an osteotomy surface that is higher on the inside and lower on the outside, thereby increasing the medial space of the knee joint. This procedure is suitable for cases with medial joint contracture and medial space narrowing as assessed preoperatively, and can effectively restore the normal anatomical space of the medial compartment.

[0057] To increase the valgus angle, the osteotomy guide can be tilted laterally to adjust the osteotomy angle to be higher on the outside and lower on the inside, thereby increasing the lateral space of the knee joint. This procedure is mainly used for patients with severe lateral compartment wear and narrow lateral space. By performing valgus osteotomy, the pressure on the medial and lateral joints is balanced, avoiding postoperative stress concentration on the lateral side.

[0058] To increase the osteotomy depth, while maintaining the same osteotomy angle, appropriately increasing the osteotomy depth can simultaneously increase the medial and lateral joint space of the knee joint. This procedure must be strictly based on preoperative imaging measurements and is typically used in cases of overall joint contracture and insufficient flexion-extension space to ensure that joint mobility is not restricted after prosthesis implantation.

[0059] To reduce the depth of osteotomy, the depth can be controlled to the lower limit of the pre-planned safe range, while simultaneously reducing the medial and lateral joint space of the knee. This procedure is suitable for patients with poor bone quality and insufficient bone volume, maintaining joint stability and reducing the risk of prosthesis loosening by preserving more autologous bone.

[0060] In this embodiment, the prosthesis also includes a polyethylene pad, which is locked to the tibial prosthesis during implantation. In step six, after the installation position of the tibial prosthesis is determined, the position of the polyethylene pad is also determined.

[0061] In step six of this embodiment, the osteotomy depth and varus / valgus angles of the tibia are adjusted to obtain a rectangular flexion gap (indicating that the flexion gap is in a balanced state). The difference between the medial and lateral flexion gaps within the rectangular flexion gap is ensured to be within a preset range, allowing for further adjustment. The preset range is greater than or equal to 0 mm and less than or equal to 1 mm, which is an acceptable range for the difference between the medial and lateral gaps and the flexion-extension gap for most surgeons. For patients with severe deformities, the surgeon may, based on their subjective preference, obtain an unbalanced gap with a difference.

[0062] In this embodiment, the task of balancing the flexion gap is mainly assigned to the tibial side, avoiding excessive alteration of femoral rotation (rotational positioning of the femoral prosthesis relative to the transcondylar eminence (TEA)) to balance the flexion gap, thereby protecting the established physiological trochlear trajectory; reducing the difference between the femoral trochlear trajectory of the femoral prosthesis and the patient's original femoral trochlear trajectory before surgery, reducing the probability of problems such as differences between the patellar trajectory and the preoperative state, and reducing the probability of postoperative anterior knee pain and other complications induced by poor patellar trajectory.

[0063] In one example, the specific steps of collecting the medial and lateral extension gap when the knee joint is in extension in step five of this embodiment include: Complete distal femoral and proximal tibial osteotomy to ensure unobstructed knee extension; Keep the knee joint in an extended position (0°-10° flexion), maintain neutral rotation of the lower limb, and avoid inversion, eversion, and rotational stress; The system acquires and obtains the values ​​of the medial and lateral knee extension gaps in real time, completing the quantitative acquisition of the extension gaps. This step specifically includes: the robotic system acquires and displays the medial and lateral knee extension gap values ​​in real time, recording the difference between the two sides; while maintaining the knee joint in an extended position, the acquisition is repeated 2–3 times, and the average value is taken to complete the accurate acquisition of the medial and lateral knee extension gaps.

[0064] In this embodiment, the valgus and valgus angles of the distal femoral osteotomy are adjusted based on the symmetry of the medial and lateral extension gaps: when the medial gap is small and the tension is large, the valgus angle of the distal femoral end is increased; when the lateral gap is small and the tension is large, the valgus angle of the distal femoral end is decreased. The amount of distal femoral osteotomy is adjusted according to the size of the medial and lateral extension gaps: when both gaps are small, the amount of distal femoral osteotomy is increased adaptively; when the gaps are uneven, the amount of osteotomy is adjusted based on the side with the smaller gap to achieve balance in the extension gaps. Finally, the extension gaps are measured again for verification until the medial and lateral extension gaps are basically symmetrical, thus completing the final determination of the distal femoral osteotomy parameters.

[0065] In this embodiment of the application, in step six, the extension gap and flexion gap are matched to obtain balanced and equal flexion-extension gaps, so that they meet the desired target gap value. Proximal and distal are relative to the trunk, while medial and lateral are relative to the knee joint.

[0066] In this embodiment, the above-described operation anchors the amount of osteotomy on the posteromedial femoral condyle within a narrow range, making the PCO relatively constant. To obtain a rectangular flexion gap, this is mainly achieved by adjusting the osteotomy depth and varus / valgus angle of the tibial plateau. By limiting the rectangular flexion gap to an acceptable range, and with a relatively small acceptable range, the amount of osteotomy on the tibia will also remain within a relatively constant and small range. This effectively avoids excessive removal of proximal tibial bone in pursuit of flexion gap balance, reduces the risk of excessive joint line elevation, and achieves precise restoration of the joint line, resulting in better mid-term function and stability of the patient's knee joint post-surgery.

[0067] In this embodiment, a linkage adjustment method centered on PCO and femoral trochlea is established through simulation training of total knee arthroplasty prosthesis positioning and gap balancing. This provides a standardized and repeatable workflow and sequence, allowing surgeons to complete osteotomy, prosthesis positioning, and gap balancing according to uniform and repeatable steps, reducing reliance on experience and improving surgical consistency. Preoperative planning of femoral / tibial osteotomy volume, rotational alignment, and flexion-extension gap matching reduces operational errors and improves prosthesis placement accuracy. Rectangular flexion and extension gaps are pre-adjusted and obtained in the simulation to achieve symmetrical matching of flexion-extension gaps, reducing the risk of postoperative instability, pain, and loosening. The accuracy of femoral trochlea, joint line height (JLH), and posterior femoral condyle offset (PCO) recovery is improved, which helps to reconstruct the lower limb biomechanical axis and improve postoperative motor function. Novice surgeons can practice repeatedly, reducing operational errors, shortening operation time, and improving overall surgical safety. Personalized simulation based on the patient's CT 3D model enables a one-person-one-plan approach, improving postoperative function and patient satisfaction.

[0068] In this embodiment, the simulation training method for prosthesis positioning and gap balancing in total knee arthroplasty can realize individualized planning, precise prosthesis positioning, flexion-extension gap balancing, and standardized training of surgical procedures for total knee arthroplasty, thereby improving surgical accuracy and postoperative outcomes. It also helps to improve the accuracy of PCO and JLH recovery in patients, achieve flexion-extension gap balancing, improve the flexion stability of the knee joint after surgery, and improve patients' kinematic function and satisfaction.

[0069] In this embodiment, an accurate workflow can also reduce subjectivity and variability in surgical decisions. Standardized methods can also reduce subjectivity and variability in surgical decisions. By fully utilizing the precision of the robotic system in planning and execution, surgeons with different levels of experience can obtain more consistent and predictable excellent surgical results, reduce doctors' reliance on operational experience, and improve surgical treatment outcomes.

[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for simulating the positioning and gap balancing of a total knee arthroplasty prosthesis, characterized in that, include: A three-dimensional model of the knee joint was created on a robot-assisted system based on the preoperative CT scan results. The three-dimensional model included the femoral model, the tibia model, and the femoral trochlea model. Based on the three-dimensional model of the knee joint, a matching physical model of the knee joint is selected, and the type and size of the prosthesis to be implanted are selected. The physical model includes the femur, tibia and femoral trochlea, and the prosthesis includes femoral prosthesis and tibial prosthesis. The amount of osteotomy on the posteromedial femoral condyle is determined based on the thickness of the posterior condyle of the femoral prosthesis. Based on the femoral trochlea model, the rotational alignment parameters of the femoral prosthesis were determined, and the femoral trochlea was simulated to return to the preoperative level on a robot-assisted system in order to obtain the required patellar trajectory. With the knee joint model in a flexed state, the medial flexion gap and lateral flexion gap are collected. Based on the collection results, the osteotomy depth and osteotomy varus / valgus angle of the tibia are adjusted to obtain a rectangular flexion gap. The difference between the medial flexion gap and the lateral flexion gap in the rectangular flexion gap is kept within a preset range to determine the installation position of the tibial prosthesis on the tibia. With the knee joint model in extension, the medial extension gap and lateral extension gap are collected. Combined with the determined tibial prosthesis installation position, the varus / valgus angle and osteotomy amount of the distal femur are finally adjusted to obtain a rectangular extension gap, and the extension gap is matched with the flexion gap to determine the installation position of the femoral prosthesis on the femur.

2. The method for simulation training of total knee arthroplasty prosthesis positioning and gap balance according to claim 1, characterized in that, The determination of the rotational alignment parameters of the femoral prosthesis based on the femoral trochlea model specifically includes: Based on the three-dimensional graphics, two-dimensional cross-sections, and simulated prosthesis position of the knee joint provided by the robot-assisted system, the internal and external rotation angles of the femoral model are determined. The internal and external rotation angles of the femoral prosthesis are adjusted with reference to the position of the femoral trochlear model until they coincide with the internal and external rotation angles of the femoral model. Obtain the internal and external rotation angles for osteotomy on a physical model; The position of the reconstructed femoral trochlea after osteotomy should coincide with the position of the femoral trochlea model.

3. The method for simulation training of total knee arthroplasty prosthesis positioning and gap balance according to claim 1, characterized in that, The preset range is greater than or equal to 0 mm and less than or equal to 1 mm.

Images