Evaluation method for patellofemoral joint stress in stair walking

Abstract

The invention relates to the field of evaluation methods of sports biomechanics, in particular to an evaluation method of patellofemoral joint stress in stair walking, which comprises the following steps: S1, acquiring an action video of a human body in a movement process in stair walking; s2, acquiring three-dimensional plantar pressure data of a human body in a movement process when the human body walks on stairs; s3, constructing a calculation model; and S4, obtaining a final patellofemoral joint stress value. According to the method for obtaining the patellofemoral joint stress in the stair walking movement process of the human body through video capturing, plantar pressure testing and calculation model building, indirect calculation and evaluation can be conducted on the patellofemoral joint stress of the human body, the stress relation between the patella inside the knee joint and the thighbone can be better explained, and the accuracy of the patellofemoral joint stress is improved. And theoretical basis guidance is provided for preventing stair walking falling.

Description

Technical Field

[0001] The invention relates to the field of evaluation methods for sports biomechanics, and in particular to an evaluation method for patellofemoral joint stress during stair walking. Background Art

[0002] As the aging process in my country intensifies, the proportion of the elderly population increases. Elderly people are prone to falling when walking up stairs, which can cause damage to the elderly's musculoskeletal system, loss of independent living ability, and even threaten their life safety. The force on the lower limb musculoskeletal bone system is another major factor affecting the high risk of falling when walking up stairs in the elderly. Previous studies have determined the dominant role and power source pattern of the knee joint in stair walking. The joint composed of the patella and femur inside the knee joint is called the patellofemoral joint. The pressure generated by the contact between the patella and femur inside the knee joint is the patellofemoral joint force, and the patellofemoral joint force per unit area of ​​the contact between the two is called the patellofemoral joint stress. Compared with the knee joint torque, the patellofemoral joint stress can better explain the relationship between the patella and femur forces inside the knee joint. Compared with walking on flat ground, the higher patellofemoral joint force and patellofemoral joint stress when walking on stairs are the main factors leading to patellofemoral joint cartilage wear, pain and degenerative lesions. Degenerative lesions of the joint are an important factor leading to an increased risk of falls in the elderly. Patellofemoral joint stress is a more sensitive indicator for evaluating the patellofemoral joint stress of the lower limbs.

[0003] Existing technologies mostly use ground reaction force, muscle strength, and joint torque to evaluate the stress of the lower limb musculoskeletal system. However, in a state of motion, the influence of the internal forces between human bones on the stress of the human musculoskeletal system has to be considered. However, no research method has been reported on the use of biomechanical indicators related to the internal forces between bones to evaluate the stress of the lower limb musculoskeletal system. Summary of the invention

[0004] The purpose of the present invention is to address the problem that there is a lack of methods for evaluating patellofemoral joint stress in the background technology, and to propose a method for evaluating patellofemoral joint stress during stair walking.

[0005] The technical solution of the present invention is a method for evaluating patellofemoral joint stress during stair walking, comprising the following steps:

[0006] S1, obtaining a motion video of a human body walking on stairs;

[0007] S2, obtaining three-dimensional plantar pressure data of a person walking on stairs;

[0008] S3, building a computational model;

[0009] S4. Obtain the final patellofemoral joint stress value.

[0010] Preferably, in S1, reflective marking points are attached to the head, left and right upper arms, left and right forearms, trunk, pelvis, left and right thighs, left and right calves, and left and right feet of the human body; the human body walks up or down the stairs one step at a time; an infrared three-dimensional motion capture system is used to capture the action video of the human body walking on the stairs to obtain kinematic data of the human body's movements.

[0011] Preferably, according to the Visual3D software model, 41 reflective marking points with a diameter of 14 mm are pasted on the head, left and right upper arms, left and right forearms, trunk, pelvis, left and right thighs, left and right calves, and left and right feet of the human body; the action video is named, intercepted, and deleted and supplemented by ViconNexus software to obtain the spatial position coordinate data of all reflective marking points.

[0012] Preferably, in S2, a three-dimensional force platform is placed in a groove of a stair step, and the three-dimensional force platform is used to collect mechanical data of a human body in the front-to-back direction, left-to-right direction, and up-down direction during stair walking.

[0013] Preferably, the three-dimensional force platform has an acquisition frequency of 1000 Hz.

[0014] Preferably, the kinematic data and mechanical data are imported into Visual3D software to perform human bone structure modeling, data filtering and data standardization.

[0015] Preferably, S3 specifically includes the following steps:

[0016] S31. Calculate the effective muscle force arm of the quadriceps femoris as follows:

[0017]

[0018] Where LA is the effective muscle moment arm of the quadriceps femoris, θ is the knee joint angle in the sagittal plane, and LA is a piecewise function of θ;

[0019] S32. Calculate the quadriceps muscle strength. The calculation formula is as follows:

[0020] F Q (θ i )=M EXT (θ i )*[LA(θ i )*0.01]

[0021] In the formula, F Q (θ i ) is the instantaneous quadriceps muscle force in the i-th frame, θ i is the instantaneous knee flexion and extension angle of the i-th frame, where M EXT (θ i ) is the instantaneous net knee moment in the sagittal plane of the i-th frame, LA(θi ) is the instantaneous effective muscle force arm of the quadriceps femoris in the i-th frame;

[0022] S33. Calculate the patellofemoral joint force using the following formula:

[0023] F PF =2F Q sin(β / 2)β=30.46+0.53

[0024] In the formula, F PF is the patellofemoral joint force, β is the angle between the quadriceps muscle force line and the patellar ligament tension line;

[0025] S34. Calculate the contact area between the patellofemoral area and the femur. The calculation formula is as follows:

[0026]

[0027] In the formula, S PFCA (θ i ) is the instantaneous contact area between the patellofemoral and femur in the i-th frame, θ i is the instantaneous sagittal plane knee angle of the i-th frame;

[0028] S35. Calculate the patellofemoral joint stress using the following formula:

[0029] P PFJS (θ i )=F PF (θ i ) / S PFCA (θ i )

[0030] Where P PFJS (θ i ) is the instantaneous patellofemoral joint stress at the i-th frame, F PF (θ i ) is the instantaneous patellofemoral joint force at the i-th frame, S PFCA (θ i ) is the instantaneous contact area between the patellofemoral and femur in the i-th frame.

[0031] Compared with the prior art, the present invention has the following beneficial technical effects: by video capture and plantar pressure testing, a method for establishing a calculation model to obtain the patellofemoral joint stress of a human body during stair walking can be used to indirectly calculate and evaluate the patellofemoral joint stress of a human body. Compared with indicators such as knee joint torque and plantar pressure, patellofemoral joint stress is a more sensitive indicator for evaluating the force of the patellofemoral joint of the lower limbs, which can better explain the relationship between the force of the patella and femur inside the knee joint, and further explore the factors affecting the wear, pain and degenerative lesions of the patellofemoral joint cartilage of the human body, especially the elderly, and provide theoretical basis guidance for preventing falls when walking on stairs in the elderly. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a process diagram of the reflective marking point pasting and stair walking test of the present invention;

[0033] Figure 2 It is a curve diagram showing the change of the mechanical index test results of the present invention along with the time of the dominant leg support phase;

[0034] Figure 3 A comparison diagram of the sagittal plane knee joint angle test results of young people and the elderly of the present invention;

[0035] Figure 4 A comparison diagram of the test results of the knee extension moment of the sagittal plane of the young and the elderly in the present invention;

[0036] Figure 5 A comparison chart of the quadriceps femoris strength test results of young people and the elderly of the present invention;

[0037] Figure 6 A comparison chart of patellofemoral joint force test results of young people and the elderly of the present invention;

[0038] Figure 7 This is a comparison chart of the patellofemoral joint stress test results of young people and the elderly according to the present invention. DETAILED DESCRIPTION

[0039] Embodiment 1

[0040] The present invention provides a method for evaluating patellofemoral joint stress during stair walking, comprising the following steps:

[0041] S1, obtaining a motion video of a human body walking on stairs;

[0042] S2, obtaining three-dimensional plantar pressure data of a person walking on stairs;

[0043] S3, building a computational model;

[0044] S4. Obtain the final patellofemoral joint stress value.

[0045] Embodiment 2

[0046] like Figure 1 As shown, the present invention proposes a method for evaluating patellofemoral joint stress during stair walking. Compared with the first embodiment, this embodiment introduces in detail the method for obtaining action videos.

[0047] In S1, reflective marking points are attached to the head, left and right upper arms, left and right forearms, trunk, pelvis, left and right thighs, left and right calves, and left and right feet of a human body; the human body walks up or down the stairs one step at a time; an infrared three-dimensional motion capture system is used to capture the action video of the human body walking on the stairs, and the reflective marking points in the action video are named, intercepted, and deleted to obtain the spatial position coordinate data of all the reflective marking points; the spatial position coordinate data are calculated to obtain the kinematic data of the human body's movements.

[0048] According to the Visual3D software model, 41 reflective marking points with a diameter of 14 mm are pasted on the head, left and right upper arms, left and right forearms, torso, pelvis, left and right thighs, left and right calves, and left and right feet of the human body; the action video is named, intercepted, and deleted and supplemented by ViconNexus software to obtain the spatial position coordinate data of all the reflective marking points.

[0049] Embodiment 3

[0050] The present invention proposes a method for evaluating patellofemoral joint stress during stair walking. Compared with the first or second embodiment, this embodiment introduces in detail the method for obtaining three-dimensional plantar pressure data.

[0051] In S2, a three-dimensional force platform is placed in the groove of the stair step. The three-dimensional force platform is used to collect mechanical data in the front-to-back direction, left-to-right direction, and up-down direction of the human body during stair walking. The infrared three-dimensional motion capture system has a collection frequency of 100Hz; the three-dimensional force platform has a collection frequency of 1000Hz.

[0052] The kinematic data and mechanical data were imported into Visual3D software for modeling, data filtering, and data standardization of the human bone structure. The kinematic data and mechanical data were filtered using Butterworth fourth-order digital low-pass data filtering, with cutoff frequencies of 6 Hz and 50 Hz, respectively. The data standardization method was to standardize the kinematic data by time and the mechanical data by weight.

[0053] Embodiment 4

[0054] The present invention proposes a method for evaluating patellofemoral joint stress during stair walking. Compared with the first embodiment, the second embodiment or the third embodiment, the present embodiment introduces in detail the specific steps of constructing a calculation model.

[0055] S31. Calculate the effective muscle force arm of the quadriceps femoris as follows:

[0056]

[0057] Where LA is the effective muscle moment arm of the quadriceps femoris, θ is the knee joint angle in the sagittal plane, and LA is a piecewise function of θ;

[0058] S32. Calculate the quadriceps muscle strength. The calculation formula is as follows:

[0059] F Q (θ i )=M EXT (θ i )*[LA(θ i )*0.01]

[0060] In the formula, F Q (θ i ) is the instantaneous quadriceps muscle force in the i-th frame, θ i is the instantaneous knee flexion and extension angle of the i-th frame, where M EXT (θ i ) is the instantaneous net knee moment in the sagittal plane of the i-th frame, LA(θ i ) is the instantaneous effective muscle force arm of the quadriceps femoris in the i-th frame;

[0061] S33. Calculate the patellofemoral joint force using the following formula:

[0062] F PF =2F Q sin(β / 2)β=30.46+0.53

[0063] In the formula, F PF is the patellofemoral joint force, β is the angle between the quadriceps muscle force line and the patellar ligament tension line;

[0064] S34. Calculate the contact area between the patellofemoral area and the femur. The calculation formula is as follows:

[0065]

[0066] In the formula, S PFCA (θ i ) is the instantaneous contact area between the patellofemoral and femur in the i-th frame, θ i is the instantaneous sagittal plane knee angle of the i-th frame;

[0067] S35. Calculate the patellofemoral joint stress using the following formula:

[0068] P PFJS (θ i )=F PF (θ i ) / S PFCA (θ i )

[0069] Where P PFJS (θ i ) is the instantaneous patellofemoral joint stress at the i-th frame, F PF (θ i ) is the instantaneous patellofemoral joint force at the i-th frame, SPFCA (θ i ) is the instantaneous contact area between the patellofemoral and femur in the i-th frame.

[0070] In summary, when the present invention is implemented, 18 young female and elderly female subjects are randomly selected from schools and communities respectively, and divided into a youth group and an elderly group. The selection criteria are: the youth group is between 20 and 30 years old, and the elderly group is between 65 and 75 years old; they can walk up stairs independently; they have no history of falls in the past year; and the subjects who need to be excluded are patients with cardiovascular and cerebrovascular diseases, respiratory diseases, musculoskeletal system diseases, visual dysfunction, vestibular dysfunction, etc., which affect their posture control ability.

[0071] Then, the subjects wore uniform test clothes and test shoes, and measured the body morphological parameters and tested the dominant leg. According to the Visual3D software model, 41 reflective marking points with a diameter of 14 mm were pasted on the subjects' heads, left and right upper arms, left and right forearms, trunks, pelvises, left and right thighs, left and right calves, and left and right feet. The human body wore uniform test clothes and test shoes during the movement process of stair walking. The dominant foot took a step first during the stair walking, and the dominant foot was completely stepped on the three-dimensional force platform as a successful test. Each person completed a total of 3 successful tests. The infrared three-dimensional motion capture system was used to capture the action video of the human body walking on the stairs. The action video was named, intercepted, and deleted and supplemented by the reflective marking points, and the spatial position coordinate data of all the reflective marking points were obtained; the spatial position coordinate data was calculated to obtain the kinematic data of the human body's movements. The three-dimensional force platform was placed in the groove of the stair step, and the internal dimensions of the stair step groove were the same as the external dimensions of the three-dimensional force platform; the three-dimensional force platform can collect the mechanical data of the front-to-back direction, left-right direction, and up-down direction of the human body walking on the stairs. The action video is named, intercepted, and deleted using Vicon Nexus software to obtain the spatial position coordinate data of all reflective marker points.

[0072] Then, the kinematic data and mechanical data were imported into Visual3D software for modeling, data filtering, and data standardization of human bone structure. The kinematic data and mechanical data were filtered by Butterworth fourth-order digital low-pass data, with cutoff frequencies of 6 Hz and 50 Hz, respectively. The data standardization method was that the kinematic data was standardized by time and the mechanical data was standardized by weight. Furthermore, SPSS19.0 was used to test the normal distribution and homogeneity of the test results, and two-way ANOVA was used to analyze the patellofemoral joint stress between and within groups. If there was an interaction effect, Tukey was used for post hoc test.

[0073] The present invention divides the dominant leg support phase into a first double support stage, a dominant leg single support stage, and a second double support stage. The first double support stage starts when the dominant foot touches the ground at the third step of the simulated stairs and ends when the non-dominant foot leaves the ground at the fourth step; the dominant leg single support stage starts when the non-dominant foot leaves the ground at the fourth step of the simulated stairs and ends when the non-dominant foot touches the ground at the second step; the second double support stage starts when the non-dominant foot touches the ground at the second step of the simulated stairs and ends when the dominant foot leaves the ground at the third step.

[0074] like Figure 2 As shown in the evaluation results of the present invention, the curve graph change trends of the knee angle, sagittal knee moment, quadriceps muscle force, patellofemoral joint force and patellofemoral joint stress of the elderly group and the young group in the single support phase cycle tend to be consistent, and both groups of subjects have two peaks in the single support phase cycle time. The knee angle of the dominant leg continues to increase throughout the single support phase cycle; the sagittal knee moment, quadriceps muscle force, patellofemoral joint force and patellofemoral joint stress are in an increasing trend throughout the first double support stage, and then continue to increase in the dominant leg single support stage to reach the first peak, then decrease and increase again, and finally reach the second peak in the initial stage of the second double support, and then decrease again.

[0075] like Figure 3-Figure 7 As shown, * indicates that there is a significant difference between the two groups; ** indicates that there is a very significant difference between the two groups. The present invention compares the two peak values ​​of the patellofemoral joint mechanical indicators in the single support phase cycle of the subjects. The knee joint angles corresponding to the first peak moment of the patellofemoral joint stress in the youth group and the elderly group are 36.64±7.45° and 31.88±7.13°, respectively, with no statistical difference; compared with the youth group, the elderly group has a smaller first peak value of the sagittal knee moment, the first peak value of the quadriceps muscle force, the first peak value of the patellofemoral joint force and the first peak value of the patellofemoral joint stress.

[0076] The knee joint angles corresponding to the second peak of patellofemoral joint stress in the young group and the elderly group were 62.72±6.25° and 54.75±5.70°, respectively, which were very significantly different. Compared with the young group, the elderly group had a smaller second peak of sagittal knee moment, second peak of quadriceps muscle force, second peak of patellofemoral joint force, and second peak of patellofemoral joint stress.

[0077] In the youth group, there was no significant difference between the second peak sagittal plane knee moment and the first peak sagittal plane knee moment; compared with the first peak, the second peak moment corresponding to the knee angle, the second peak quadriceps muscle force, the second peak patellofemoral joint force, and the second peak patellofemoral joint stress were significantly larger.

[0078] In the elderly group, compared with the first peak, the second peak moment of the second peak corresponding to the knee angle, the second peak of the sagittal knee moment, the second peak of the quadriceps muscle force, the second peak of the patellofemoral joint force, and the second peak of the patellofemoral joint stress were significantly larger.

[0079] The evaluation results of the present invention show that in the initial stage of the second double support stage, when the left foot touches the ground, the support force of the human body mainly comes from the right leg, and at this time the right leg has a larger sagittal plane knee angle, requiring a larger sagittal plane knee extension moment and quadriceps muscle strength to maintain the stability of the body, therefore, a larger patellofemoral joint stress will also be generated at this time. It is worth noting that the elderly walking down stairs in the initial stage of the second double support stage will produce a larger second peak of patellofemoral joint stress, which will cause a greater burden on their patellofemoral joints. Therefore, it is recommended that the elderly use crutches or stair railings as a second support to reduce patellofemoral joint stress at this moment.

[0080] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for evaluating patellofemoral joint stress during stair walking, characterized in that: The following steps are involved: S1, obtaining a motion video of a human body walking on stairs; S2, obtaining three-dimensional plantar pressure data of a person walking on stairs; S3, build a computational model; S4. Obtain the final patellofemoral joint stress value.

2. The method for evaluating patellofemoral joint stress during stair walking according to claim 1, characterized in that: In S1, reflective marking points are attached to the head, left and right upper arms, left and right forearms, trunk, pelvis, left and right thighs, left and right calves, and left and right feet of a human body; the human body walks up or down the stairs one step at a time; an infrared three-dimensional motion capture system is used to capture the action video of the human body walking on the stairs to obtain the kinematic data of the human body's movements.

3. The method for evaluating patellofemoral joint stress during stair walking according to claim 2, characterized in that: According to the Visual3D software model, 41 reflective marking points with a diameter of 14 mm were pasted on the head, left and right upper arms, left and right forearms, torso, pelvis, left and right thighs, left and right calves, and left and right feet of the human body; the action video was named, intercepted, and deleted and supplemented by Vicon Nexus software to obtain the spatial position coordinate data of all reflective marking points.

4. The method for evaluating patellofemoral joint stress during stair walking according to claim 2, characterized in that: In S2, a three-dimensional force platform is placed in a groove of a stair step, and the three-dimensional force platform is used to collect mechanical data in the front-to-back direction, left-to-right direction, and up-down direction of a human body during stair walking.

5. The method for evaluating patellofemoral joint stress during stair walking according to claim 4, characterized in that: The acquisition frequency of the three-dimensional force platform is 1000Hz.

6. The method for evaluating patellofemoral joint stress during stair walking according to claim 4, characterized in that: The kinematic data and mechanical data are imported into Visual3D software for modeling, data filtering and data standardization of human bone structure.

7. The method for evaluating patellofemoral joint stress during stair walking according to claim 1, characterized in that: S3 specifically includes the following steps: S31. Calculate the effective muscle force arm of the quadriceps femoris as follows: Where LA is the effective muscle moment arm of the quadriceps femoris, θ is the knee joint angle in the sagittal plane, and LA is a piecewise function of θ; S32. Calculate the quadriceps muscle strength. The calculation formula is as follows: F Q (θ i )=M EXT (θ i )*[LA(θ i )*0.01] In the formula, F Q (θ i ) is the instantaneous quadriceps muscle force in the i-th frame, θ i is the instantaneous knee flexion and extension angle of the i-th frame, where M EXT (θ i ) is the instantaneous net knee moment in the sagittal plane of the i-th frame, LA(θ i ) is the instantaneous effective muscle force arm of the quadriceps femoris in the i-th frame; S33. Calculate the patellofemoral joint force using the following formula: F PF =2F Q sin(β / 2) β=30.46+0.53 In the formula, F PF is the patellofemoral joint force, β is the angle between the quadriceps muscle force line and the patellar ligament tension line; S34. Calculate the contact area between the patellofemoral area and the femur. The calculation formula is as follows: In the formula, S PFCA (θ i ) is the instantaneous contact area between the patellofemoral and femur in the i-th frame, θ i is the instantaneous sagittal plane knee angle of the i-th frame; S35. Calculate the patellofemoral joint stress using the following formula: P PFJS (i i )=F PF (i i ) / S PFCA (i i ) Where P PFJS (θ i ) is the instantaneous patellofemoral joint stress at the i-th frame, F PF (θ i ) is the instantaneous patellofemoral joint force at the i-th frame, S PFCA (θ i ) is the instantaneous contact area between the patellofemoral and femur in the i-th frame.

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