A model system and method for biomechanical analysis of the lower extremity

Abstract

The present application relates to the technical fields of lower limb biomechanics analysis, and especially relates to a model system suitable for lower limb biomechanics analysis and a method thereof.The technical scheme comprises the following modules: an input module for inputting bone parameters, soft tissue parameters and injury models; a calculation module for performing calculation analysis; and an output module for outputting analysis results; wherein the input module comprises a bone parameter module for establishing a bone model based on collected lower limb CT images, and performing parameterized modeling on a lower limb three-dimensional model.The present application provides a fast and efficient analysis system for lower limb biomechanics analysis, and can quickly, accurately and directly establish a lower limb model according to CT and MRI data of a subject and required parameters, perform finite element analysis, and obtain the influence of different degrees of varus, valgus, internal rotation, external rotation, meniscus tear injury, ligament injury, cartilage injury and the like on knee joint biomechanics, which has great significance for the development of lower limb biomechanics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lower limb biomechanics analysis, and particularly relates to a model system suitable for lower limb biomechanics analysis and a method thereof. BACKGROUND

[0002] In lower limb biomechanics analysis, different parameters such as knee varus, knee valgus, internal rotation and external rotation are crucial to the biomechanics of the knee joint, and muscle force and knee joint soft tissue (meniscus, articular cartilage and ligament) also affect the calculation and analysis results of lower limb biomechanics.

[0003] At present, the biomechanics analysis of the knee joint mainly adopts the mode of personalized modeling, and three-dimensional reconstruction and finite element analysis are performed on specific lower limbs. If the influence of different people and different parameters is analyzed, more time and effort are needed to scan the lower limb magnetic resonance images and establish different models, resulting in waste of resources.

[0004] Some gait analysis systems contain lower limb muscle force and can analyze lower limb biomechanics, but the lower limb model does not contain knee joint soft tissue, and the system cannot accurately analyze the influence of valgus and varus angles on the lower limbs.

[0005] Due to the specificity of the human body, how to quickly, efficiently and accurately analyze the biomechanics of the lower limbs is a problem to be solved by those skilled in the art. SUMMARY

[0006] The present application aims to solve the problem of being unable to quickly, efficiently and accurately analyze the biomechanics of the lower limbs in the background art, and proposes a model system suitable for lower limb biomechanics analysis and a method thereof.

[0007] In one aspect, the present application discloses a model system suitable for lower limb biomechanics analysis, comprising the following modules:

[0008] An input module for inputting bone parameters, soft tissue parameters and damage models;

[0009] A calculation module for performing calculation and analysis;

[0010] An output module for outputting analysis results;

[0011] The input module comprises:

[0012] A bone parameter module for establishing a bone model based on collected lower limb CT images and performing parameterized modeling on a three-dimensional model of the lower limbs;

[0013] A soft tissue module for establishing a soft tissue model based on collected knee joint MRI images and performing parameterized modeling on a knee joint soft tissue model;

[0014] an injury model module for establishing a meniscus injury model, a ligament injury model and a cartilage injury model;

[0015] The calculation module comprises:

[0016] a muscle model module for establishing a muscle model;

[0017] a working condition load module for establishing working condition loads under different mechanical environments and boundary conditions;

[0018] an analysis module for performing mechanical analysis under different parameter loads;

[0019] The output module comprises:

[0020] a result module for outputting analysis results.

[0021] Optionally, the input module is configured to input bone parameters, soft tissue parameters and injury site parameters of a lower limb of a patient.

[0022] Optionally, the result module comprises contact stress and displacement of knee joint components, contact stress of articular cartilage, ankle joint axial force, knee joint axial force and compartment pressure under different varus angles, valgus angles, internal rotation angles and external rotation angles; wherein the knee joint components comprise one or more of medial and lateral menisci, femur, tibia and articular cartilage.

[0023] In another aspect, the application discloses a method for lower limb biomechanical analysis, which is applied to the model system for lower limb biomechanical analysis and comprises the following steps:

[0024] a. collecting CT and knee joint MRI images of a lower limb of a subject, wherein the data is used as basic input for the calculation module and the modeling module;

[0025] b. establishing a three-dimensional bone model and a three-dimensional soft tissue model based on the collected CT and MRI images, and performing smoothing and solidification on the three-dimensional bone model and the three-dimensional soft tissue model;

[0026] c. performing parameterization modeling on the three-dimensional bone model and the three-dimensional soft tissue model, and writing scripts to encapsulate the parameters as a bone parameter module and a soft tissue parameter module;

[0027] d. establishing an injury module according to different injury classifications, and writing scripts to encapsulate the injury module as an injury model module;

[0028] e. establishing working condition loads under different mechanical environments and boundary load conditions, and writing scripts to encapsulate the working condition loads as a working condition load module;

[0029] f. Input the model of the input module into the calculation module for calculation to obtain the analysis results;

[0030] g. Input the analysis results into the output module and output the result report.

[0031] Optionally, in step c, the parameters of the bone parameter module include: the distance between the anterior superior iliac spine and the posterior superior iliac spine of the hip joint, the length and width of the hip joint, the length of the femur, the diameter of the femoral trochanter, the proximal femoral diameter, the middle femoral diameter, the distal femoral diameter, the width of the internal and external condyles of the femur, the width of the tibial plateau, the proximal tibial diameter, the middle tibial diameter, the distal tibial diameter, the foot width, the foot length, the internal and external angles of the lower limb, and the internal and external rotation angles.

[0032] Optionally, in step c, the soft tissue parameter module includes knee joint parameters, wherein the knee joint parameters include: medial collateral ligament length, width, thickness, lateral collateral ligament length, width, thickness, anterior cruciate ligament length, width, thickness, posterior cruciate ligament length, width, thickness, patellar ligament length, width, thickness, quadriceps femoris length, width, thickness, medial meniscus diameter length, axis length, edge thickness, cross-sectional shape, lateral meniscus diameter length, axis length, edge thickness, cross-sectional shape, cartilage length, width, thickness, cross-sectional shape.

[0033] Optionally, step d establishes a damage module, specifically including the following steps:

[0034] A meniscus tear injury model was established based on the established three-dimensional model of the lower limb bones, including radial tear, vertical tear, longitudinal tear, flap tear, and posterior root tear in different regions.

[0035] Establish a ligament injury model, including: anterior and posterior cruciate ligament injury, medial and lateral collateral ligament injury, and patellar ligament injury in different regions;

[0036] A cartilage injury model was established, specifically including femoral cartilage injury and tibial cartilage injury in different regions.

[0037] Optionally, step f, inputting the model of the input module into the calculation module for calculation, specifically includes the following steps:

[0038] The established three-dimensional lower limb model including the knee joint soft tissue was imported into the finite element analysis software. Based on the distribution of human muscles, the corresponding muscle starting points, insertion points and approach points were established, and the muscle node positions were attached to the lower limb model.

[0039] Establish line elements to connect muscle nodes, assign corresponding stiffness, and create a lower limb muscle model;

[0040] The optimal muscle force is determined by using an optimization method, so that the lower limb model is in a balanced state under static load, the objective function is the balance of the moment around the knee joint, and the change of the moment is limited to 0-100 Nm;

[0041] Different mechanical environments and boundary load conditions are established to create a working condition load module.

[0042] A reasonable contact mode is applied for finite element analysis.

[0043] Optionally, in step g, the output module outputs a result report after script processing, wherein the result report includes the following contents: under static or dynamic environment, under different varus angles, valgus angles, internal rotation angles, external rotation angles, and different types of meniscus injury, ligament injury, and cartilage injury, the contact stress and displacement of the medial and lateral meniscus, the contact stress of the articular cartilage, the ankle joint axial force, the knee joint axial force, and the compartment pressure.

[0044] Compared with the prior art, the present application has the following beneficial technical effects:

[0045] The model system suitable for lower limb biomechanics analysis of the present application mainly aims to provide a fast and efficient analysis system for the analysis of lower limb biomechanics, which can quickly, accurately and directly establish a lower limb model according to the CT and MRI data of the subject and the required parameters, perform finite element analysis, and obtain the influence of different degrees of varus, valgus, internal rotation, external rotation, meniscus tear injury, ligament injury, and cartilage injury on the biomechanics of the knee joint, which has great significance for the development of lower limb biomechanics. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 The system block diagram of the embodiment of the present application is shown.

[0047] Figure 2 The step flowchart of the embodiment of the present application is shown.

[0048] Figure 3 The system block diagram of the input module of the embodiment of the present application is shown.

[0049] Figure 4 The system block diagram of the calculation module of the embodiment of the present application is shown.

[0050] Figure 5 The system block diagram of the output module of the embodiment of the present application is shown. DETAILED DESCRIPTION

[0051] The core of the present application is to provide a model system for lower extremity biomechanical analysis, which quickly, efficiently and accurately establishes a lower extremity model and obtains lower extremity biomechanical analysis results under different parameters and injury types by combining three-dimensional design software and finite element analysis software. The technical solutions of the present application are further described below in combination with the drawings and specific embodiments.

[0052] Embodiments

[0053] As shown in the following figure, the present application is applicable to lower extremity biomechanical analysis, and the specific implementation process is realized by the following modules: Figure 1

[0054] Input module 110: bone parameter module 1101, soft tissue parameter module 1102, injury model module 1103;

[0055] Calculation module 120: muscle model module 1201, working condition load module 1202;

[0056] Output module 130: analysis module 1303

[0057] The establishment of each module specifically includes:

[0058] Input module 110:

[0059] Bone parameter module 1101:

[0060] Step i: a three-dimensional model of the lower extremity including the hip joint, femur, knee joint, tibia and foot is established through the CT image of the subject;

[0061] Step ii: parameterized modeling is adopted to model the length and diameter of the femur and tibia, the varus and valgus angle, and the internal and external rotation angle;

[0062] Soft tissue parameter module 1102:

[0063] Step iii: a knee joint soft tissue model including meniscus, ligament and articular cartilage is established through the MRI image of the subject;

[0064] Step iv: parameterized modeling is adopted to model the shape of the meniscus, the shape of the ligament, the thickness and length of the cartilage, etc.

[0065] Injury model module 1103:

[0066] Step v: a knee joint meniscus tear injury model, a ligament injury model and a cartilage injury model are established;

[0067] Specific embodiments include:

[0068] ​Step i: By collecting the lower extremity CT data of the subject, the reconstruction of the double lower extremity model is performed in the medical three-dimensional reconstruction software, including the hip joint, femur, tibia and foot; the three-dimensionally reconstructed model is imported into the surface processing software for surface smoothing treatment of the model; then the model is imported into the three-dimensional design software for surface solidification treatment of the model.

[0069] Step ii: Parameterized modeling of the lower extremity model in the three-dimensional software. The following parameters are subjected to parameterized modeling treatment: the distance between the left and right anterior superior iliac spines of the hip joint, the distance between the left and right posterior superior iliac spines of the hip joint, the length and width of the hip joint, the length of the femur, the diameter of the femoral trochanter, the diameter of the proximal femur, the diameter of the middle femur, the diameter of the distal femur, the width of the medial and lateral femoral condyles, the width of the tibial plateau, the diameter of the proximal tibia, the diameter of the middle tibia, the diameter of the distal tibia, the foot width, the foot length, the varus and valgus angles of the lower extremity, the internal and external rotation angles.

[0070] A script is written for encapsulation treatment as the bone parameter module of the input module.

[0071] Step iii: By collecting the MRI data of the knee joint of the subject, the reconstruction of the knee joint soft tissue is performed in the medical three-dimensional reconstruction software, including the medial collateral ligament, the lateral collateral ligament, the anterior cruciate ligament, the posterior cruciate ligament, the medial meniscus, the lateral meniscus, the patellar ligament, the femoral cartilage and the tibial cartilage.

[0072] The three-dimensionally reconstructed model is imported into the surface processing software for surface smoothing treatment of the model; then the model is imported into the three-dimensional design software for surface solidification treatment of the model and matching of the position with the lower extremity model.

[0073] Step iv: Parameterized modeling of the knee joint soft tissue model in the three-dimensional software. The following parameters are subjected to parameterized modeling treatment:

[0074] The length, width and thickness of the medial collateral ligament, the length, width and thickness of the lateral collateral ligament, the length, width and thickness of the anterior cruciate ligament, the length, width and thickness of the posterior cruciate ligament, the length, width and thickness of the patellar ligament, the length, width and thickness of the quadriceps femoris, the diameter, axial length, edge thickness and cross-sectional shape of the medial meniscus, the diameter, axial length, edge thickness and cross-sectional shape of the lateral meniscus, the length, width, thickness and cross-sectional shape of the cartilage.

[0075] A script is written for encapsulation treatment as the soft tissue parameter module of the input module.

[0076] Step v: Establishment of a meniscus tear damage model, specifically including: radial tear in different regions, vertical tear, longitudinal tear, flap tear, posterior root tear, bucket handle tear, etc.

[0077] A ligament injury model was established, specifically including anterior and posterior cruciate ligament injuries, medial and lateral collateral ligament injuries, and patellar ligament injuries in different regions.

[0078] A cartilage injury model was established, specifically including femoral cartilage injury and tibial cartilage injury in different regions.

[0079] Write a script to encapsulate the damage model as the damage model module of the input module.

[0080] Computing module 120:

[0081] Muscle Model Module 1201:

[0082] Step vi: Establishment of lower limb muscle model in finite element software.

[0083] Working load module 1202:

[0084] Step vii: Establishment of different mechanical environments and boundary conditions in finite element software.

[0085] Analysis module 1203:

[0086] Step viii: Finite element analysis of the lower limb model under working loads.

[0087] Specific implementations include:

[0088] Step vi: Import the three-dimensional lower limb model including the knee joint soft tissue into the finite element analysis software. According to the distribution of muscles in human anatomy, establish the corresponding muscle starting points, insertion points, and approach points. The muscle node positions are established based on the lower limb model.

[0089] Line elements were established to connect muscle nodes and assigned corresponding stiffness to create a lower limb muscle model. The model mainly included the following muscle forces: iliopsoas, piriformis, gluteus maximus, gluteus medius, gluteus minimus, quadriceps femoris, hip adductor muscles, hamstrings, biceps femoris, semitendinosus, semimembranosus, tibialis anterior, triceps surae, sartorius, and pedis muscles.

[0090] An optimization method is used to determine the optimal muscle force so that the lower limb model is in equilibrium under static load. The objective function is the torque balance around the knee joint, and the torque is limited to 0-100 Nm. The optimization design is as follows:

[0091]

[0092]

[0093]

[0094] In formula (1), is the knee joint torque, For muscle strength, is the distance from the muscle to the center of the knee joint, is the initial muscle strength.

[0095] Write a script to encapsulate the establishment of the muscle model as the muscle model module of the calculation module.

[0096] Step vii: Applying mechanical environment, specifically including: finite element analysis of lower limb dynamics and finite element analysis of lower limb statics;

[0097] Among them, lower limb statics specifically include: static posture simulation (twice body weight load), slight flexion simulation (twice body weight vertical load, 60% body weight forward load).

[0098] Lower limb statics specifically include: 0°-90° knee flexion dynamic simulation, walking dynamic simulation (International Organization for Standardization ISO14243 gait guidelines).

[0099] Boundary conditions were applied, specifically fixing the tibia and fibula during static analysis and dynamic simulation of knee flexion; and applying ISO14243 gait boundary conditions during dynamic simulation of walking.

[0100] Write a script to encapsulate the working condition load as the working condition load module of the calculation module.

[0101] Step viii: Apply a reasonable contact method, select the appropriate working load in the working load module, and perform finite element analysis. Specific indicators include: contact stress and displacement of the medial and lateral menisci, contact stress of articular cartilage, axial force of the ankle and knee joints, and compartment pressure.

[0102] Write scripts to encapsulate the analysis indicators as the analysis module of the calculation module.

[0103] Output module 130:

[0104] Result module 1301:

[0105] Specific implementations include:

[0106] Output the finite element results of the lower limb model, specifically including: contact stress and displacement of the medial and lateral menisci, contact stress of articular cartilage, axial force and compartment pressure of the ankle and knee joints under different varus and valgus angles, different internal rotation and external rotation angles, and different types of meniscus injury, ligament injury, and cartilage injury in a static or dynamic environment. The finite element results such as stress, displacement, and axial force are used as output indicators of the result module.

[0107] Write a script to encapsulate the result module as the result module of the output module.

[0108] The invention is implemented by software, and the corresponding software program is stored in a readable storage medium.

[0109] The core of the present invention is to provide a model system for lower limb biomechanics analysis. By combining three-dimensional design and finite element analysis, a lower limb model can be established quickly, efficiently and accurately to obtain lower limb biomechanics analysis results under different parameters.

[0110] The model system of the present invention is suitable for lower limb biomechanical analysis. Model parameters are input in the input module to directly establish a corresponding lower limb model, and different meniscus injury forms, ligament injuries, and cartilage injuries can be selected; a muscle model is established in the calculation module, and different working conditions are selected for finite element analysis; and contact stress, displacement, and joint axial force results are viewed in the output module.

[0111] In addition to the above-mentioned knee joint-related meniscus injury model, ligament injury model and cartilage injury model, the present invention can also establish lower limb-related fracture models, osteotomy models, etc., which are all within the scope of application of the present invention.

[0112] The main purpose of the model system suitable for lower limb biomechanics analysis of the present invention is to provide a fast and efficient analysis system for the analysis of lower limb biomechanics. It can quickly, accurately and directly establish a lower limb model based on the subject's CT and MRI data and required parameters, perform finite element analysis, and obtain the effects of different degrees of inversion, eversion, internal rotation, external rotation, as well as meniscus tear injuries, ligament injuries, cartilage injuries, etc. on knee joint biomechanics, which is of great significance to the development of lower limb biomechanics.

[0113] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

[0114] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant inspirations of the above embodiments, those skilled in the art may make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A model system suitable for lower limb biomechanics analysis, characterized in that: Includes the following modules: An input module, used for inputting bone parameters, soft tissue parameters and injury models; A computing module for performing computational analysis; Output module, used to output analysis results; Wherein, the input module includes: The bone parameter module is used to establish a bone model based on the collected CT images of the lower limbs and perform parametric modeling of the lower limb three-dimensional model. The parameters of the bone parameter module include: the distance between the anterior superior iliac spine and the posterior superior iliac spine of the hip joint, the length and width of the hip joint, the length of the femur, the diameter of the femoral trochanter, the proximal femoral diameter, the middle femoral diameter, the distal femoral diameter, the width of the internal and external femoral condyles, the width of the tibial plateau, the proximal tibial diameter, the middle tibial diameter, the distal tibial diameter, the foot width, the foot length, the internal and external angles of the lower limb, and the internal and external rotation angles; The soft tissue module is used to establish a soft tissue model and perform parametric modeling of the knee joint soft tissue model based on the acquired knee joint MRI images; Injury model module, used to establish meniscus, ligament injury models and cartilage injury models; The calculation module includes: Muscle model module, used to build muscle models; Working load module, used to establish working loads for different mechanical environments and boundary conditions; Analysis module, which performs mechanical analysis under different parameter loads; The output module includes: Result module: used to output analysis results; Inputting the model of the input module into the calculation module for calculation specifically includes the following steps: The established three-dimensional lower limb model including the knee joint soft tissue was imported into the finite element analysis software. Based on the distribution of human muscles, the corresponding muscle starting points, insertion points and approach points were established, and the muscle node positions were attached to the lower limb model. Establish line elements to connect muscle nodes, assign corresponding stiffness, and create a lower limb muscle model; An optimization method was used to determine the optimal muscle force to keep the lower limb model in equilibrium under static load. The objective function was the torque balance around the knee joint, and the torque was limited to 0-100 Nm. Establish different mechanical environments and boundary load conditions and create working load modules; Apply reasonable contact mode and conduct finite element analysis; The result module is used to output the finite element analysis results, including the contact stress and displacement of the medial and lateral menisci at different varus, valgus, internal rotation and external rotation angles, the contact stress of the articular cartilage, the axial force and compartment pressure of the ankle and knee joints.

2. A model system suitable for lower limb biomechanics analysis according to claim 1, characterized in that: The input module is used to input bone parameters, soft tissue parameters, and injury site parameters of the patient's lower limbs.

3. A method for lower limb biomechanics analysis, applied to the model system for lower limb biomechanics analysis according to claim 2, characterized in that: The following steps are involved: a. Collect CT scans of the subjects' lower limbs and MRI images of their knee joints. These images serve as the basic input for the calculation and modeling modules. b. Based on the acquired CT and MRI images, three-dimensional models of the lower limb bones and soft tissues are constructed, and the models are smoothed and solidified; c. Perform parametric modeling on the lower limb bone model and soft tissue model respectively, and write scripts to encapsulate the parameters as the bone parameter module and soft tissue parameter module respectively; d. Establish damage modules based on different damage classifications and write scripts to encapsulate the damage modules as damage model modules; e. Establish different mechanical environments and boundary load conditions, establish working loads, and write scripts to encapsulate the working loads as working load modules; f. Input the model of the input module into the calculation module for calculation to obtain the analysis results; g. Input the analysis results into the output module and output the result report.

4. A biomechanical analysis method for lower limbs according to claim 3, characterized in that: In step c, the soft tissue parameter module includes knee joint parameters, wherein the knee joint parameters include: medial collateral ligament length, width, thickness, lateral collateral ligament length, width, thickness, anterior cruciate ligament length, width, thickness, posterior cruciate ligament length, width, thickness, patellar ligament length, width, thickness, quadriceps femoris length, width, thickness, medial meniscus diameter length, axis length, edge thickness, cross-sectional shape, lateral meniscus diameter length, axis length, edge thickness, cross-sectional shape, cartilage length, width, thickness, cross-sectional shape.

5. The biomechanical analysis method for lower limbs according to claim 3, characterized in that: Step d: Establishing a damage module, specifically including the following steps: A meniscus tear injury model was established based on the established three-dimensional model of the lower limb bones, including radial tear, vertical tear, longitudinal tear, flap tear, and posterior root tear in different regions. Establish a ligament injury model, including: anterior and posterior cruciate ligament injury, medial and lateral collateral ligament injury, and patellar ligament injury in different regions; A cartilage injury model was established, specifically including femoral cartilage injury and tibial cartilage injury in different regions.

6. The biomechanical analysis method for lower limbs according to claim 3, characterized in that: In step g, the output module writes a result report after script processing, wherein the result report includes the following contents: In static or dynamic environments, under different inversion and eversion angles, different internal rotation and external rotation angles, and different types of meniscus injury, ligament injury, and cartilage injury, the contact stress and displacement of the medial and lateral menisci, the contact stress of the articular cartilage, the axial force and compartment pressure of the ankle and knee joints are analyzed.

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