A method for acquiring dynamic spine and pelvic parameters based on motion capture system

Abstract

The present invention relates to a method for obtaining dynamic spinal column and pelvic parameters based on a motion capture system, the method comprising the following steps: setting a reflective ball at a body surface position corresponding to a subject's bones; the subject taking an X-ray on the basis of step one; calculating the initial spinal column and pelvic parameters and the relative relationship between the reflective ball and the human bones according to the X-ray; adding a skeletal model to the motion capture system based on step three, and adding a virtual ball to the motion capture system; the subject makes any movement in the motion capture scene, and performs dynamic calculation of spinal column and pelvic parameters. Compared with the prior art, the present invention obtains dynamic spinal column and pelvic data through a motion capture system, thereby calculating medical spinal column and pelvic parameters, and the subject can obtain dynamic spinal column and pelvic parameters by any movement in the motion capture scene, which helps doctors to more effectively analyze the patient's spinal condition and formulate better treatment plans.

Description

Technical Field

[0001] The invention relates to the fields of medicine and motion capture, and in particular to a method for acquiring dynamic spinal column and pelvic parameters based on a motion capture system. Background Art

[0002] Spinal pelvic parameters are an important parameter for judging the health of the human spine. Doctors can get the health of the spine by analyzing the spinal pelvic parameters, and arrange follow-up treatment plans for different situations, aiming to restore spinal balance and improve the quality of life of patients. However, with the progress of population aging, the incidence of adult spinal deformity has increased year by year, and the spine has experienced a vicious degenerative cycle, resulting in spinal coronal sagittal imbalance, low back pain, difficulty standing upright, lameness and other symptoms, which seriously affect health status.

[0003] Until now, spinal and pelvic parameters have been calculated based on X-rays. The disadvantage is that there is only one frame of static data, which makes it difficult to fully and objectively reflect the dynamic changes of the patient's spine. 15%-30% of patients still cannot obtain the expected treatment effect even if they reach the spinal and pelvic parameters designed before surgery. Therefore, the transition from static evaluation of spinal function to dynamic evaluation is particularly important.

[0004] Therefore, since traditional static spinal and pelvic parameters cannot objectively analyze the patient's spinal condition, it is necessary to propose a dynamic evaluation method for spinal and pelvic parameters. Summary of the invention

[0005] In order to solve the problem that traditional X-rays can only obtain static spinal and pelvic parameters but are difficult to objectively reflect the patient's spinal condition, the present invention provides a dynamic spinal and pelvic parameter calculation method based on a motion capture system. The motion capture system is used to construct a human skeleton model to dynamically and continuously obtain spinal and pelvic parameters.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for acquiring dynamic spinal column and pelvic parameters based on a motion capture system, the method comprising the following steps:

[0008] Step 1: Set a reflective ball at the body surface position corresponding to the subject's bones;

[0009] Step 2: The subject takes an X-ray based on the step 1;

[0010] Step 3: Calculate the initial spinal pelvic parameters and the relative relationship between the reflective ball and the human bones based on the X-ray film;

[0011] Step 4: Add a skeleton model to the motion capture system based on step 3, and add a virtual ball to the motion capture system;

[0012] Step 6: The subject makes any movement in the motion capture scene, and the spinal column and pelvic parameters are dynamically calculated.

[0013] Furthermore, the positions where the reflective balls are arranged on the body surface correspond to: the seventh cervical vertebra, the third thoracic vertebra, the fifth thoracic vertebra, the seventh thoracic vertebra, the ninth thoracic vertebra, the twelfth thoracic vertebra, the second lumbar vertebra, the third lumbar vertebra, the fifth lumbar vertebra spinous process, the head, below the navel, the bilateral anterior superior iliac spines, the posterior superior iliac spines, the bilateral acromion of the upper limbs, the midpoint of the upper arm, the medial and lateral condyles of the elbow, the midpoint of the forearm, the ulnar and radial sides of the wrist, the backs of both hands, the bilateral greater trochanters of the femurs of the lower limbs, the medial and lateral condyles of the knees, the midpoint of the anterior edge of the tibia, the lateral malleolus and the dorsum of both feet.

[0014] Furthermore, the X-ray filming includes coronal plane X-rays and sagittal plane X-rays.

[0015] Furthermore, the reflective balls are balls that passively reflect infrared light.

[0016] Furthermore, the cameras of the motion capture system include multiple high-speed infrared cameras.

[0017] Furthermore, the virtual balls added in step 4 include virtual balls S1 and S5 for representing the coccygeal vertebrae, and the adding method is:

[0018] P s1 =P L5 +P L5-s1

[0019] P s5 =point(L s1-s5 )

[0020] Among them, P s1 is the position of the virtual ball S1 relative to the human body, P L5 is the position of the reflective ball corresponding to the fifth waist cone relative to the human body, P L5-s1 It is the position of the virtual ball S1 obtained through the X-ray film relative to the reflective ball corresponding to the fifth waist cone.

[0021] Furthermore, the step of dynamically calculating the spinal column and pelvic parameters includes:

[0022] Use the X-ray obtained in step 3 to adjust the position of the bones in the motion capture system;

[0023] Fitting the human spine curve;

[0024] Calculate the positions of virtual balls S1 and S5;

[0025] Calculate spinal and pelvic parameters.

[0026] Furthermore, the position of the virtual balls S1 and S5 is calculated as follows:

[0027]

[0028]

[0029] in, is the position of the virtual ball S1 relative to the world, R wh is the body's rotation relative to the world, T wh is the position of the body relative to the world, is the position of the virtual ball S5 relative to the world.

[0030] Furthermore, the spinal column and pelvic parameters include: sagittal vertical offset, thoracic kyphosis angle, lumbar lordosis angle, pelvic tilt angle and pelvic incidence angle.

[0031] Furthermore, the calculation method of the sagittal vertical offset is:

[0032]

[0033] Where d is the sagittal vertical offset, is the Y-axis coordinate of the seventh cervical cone in the human body coordinate system, is the Y-axis coordinate of the virtual ball S1 in the human body coordinate system;

[0034] The calculation method of the thoracic kyphosis angle is:

[0035] TK=arctan(y'(T4))±arctan(y'(T12))

[0036] Wherein, TK is the thoracic kyphosis angle, y'(T4) is the slope of the fourth thoracic vertebra on the spinal curve, arctan(y'(T4)) is the angle between the extension line of the fourth thoracic vertebra endplate and the horizontal direction; y'(T12) is the slope of the twelfth thoracic vertebra on the spinal curve, arctan(y'(T12)) is the angle between the extension line of the twelfth thoracic vertebra endplate and the horizontal direction, ± indicates that the plus and minus signs will change with the change of human body posture;

[0037] The calculation method of the lumbar lordosis angle is:

[0038] LL=arctan(y'(L1))±θ s1

[0039] Where LL is the lumbar lordosis angle, y'(L1) is the slope of the first lumbar cone on the spinal curve, arctan(y'(L1)) is the angle between the extension line of the first lumbar cone end plate and the horizontal direction, θ s1 It represents the angle between the coccygeal endplate and the horizontal direction;

[0040] The calculation method of the pelvic tilt angle is:

[0041]

[0042] Where PT is the pelvic tilt angle, is the point where the left femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the right femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the virtual ball S1 is mapped to the YZ plane in the human body coordinate system. is the angle between two vectors;

[0043] The calculation method of the pelvic incident angle is:

[0044]

[0045] Where PI is the pelvic incidence angle, is the point where the left femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the right femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the virtual ball S1 is mapped to the YZ plane in the human body coordinate system. is the point where the virtual ball S1 is mapped to the YZ plane in the human body coordinate system. is the angle between the two vectors.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The parameter acquisition method provided by the present invention constructs a human skeleton model in a motion capture system and accurately restores the shape of the human spine. Dynamic spinal and pelvic data are obtained through the motion capture system, thereby calculating medical spinal and pelvic parameters. The subject can obtain dynamic spinal and pelvic parameters by arbitrarily moving in the motion capture scene, which helps doctors to more effectively analyze the patient's spinal condition and formulate a better treatment plan. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flow chart of a method for calculating dynamic pelvic parameters based on a motion capture system of the present invention;

[0049] Figure 2 A schematic diagram of the human spine;

[0050] Figure 3 Schematic diagram of a skeleton model established based on a motion capture system in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0052] like Figure 1 As shown, the embodiment of the present invention provides a method for calculating dynamic pelvic parameters based on a motion capture system, and the specific steps are as follows:

[0053] Step 1. Attach reflective balls to specific locations on the subject's body surface, corresponding to the seventh cervical vertebra, the third thoracic vertebra, the fifth thoracic vertebra, the seventh thoracic vertebra, the ninth thoracic vertebra, the twelfth thoracic vertebra, the second lumbar vertebra, the third lumbar vertebra, the fifth lumbar vertebra spinous process, the head (4), 1 cm below the navel, the bilateral anterior superior iliac spine, the posterior superior iliac spine, the bilateral acromion of the upper limbs, the midpoint of the upper arm, the medial and lateral condyles of the elbow, the midpoint of the forearm, the ulnar radial side of the wrist, and the back of the hand (2), the bilateral greater trochanter of the femur, the medial and lateral condyles of the knee, the midpoint of the anterior edge of the tibia, the lateral malleolus, and the dorsum of the foot (2) on the lower limbs; a total of 50 reflective balls;

[0054] Step 2: After the reflective balls have been attached in step 1, ask the subjects to take X-rays with the reflective balls on their body surface, one in the coronal and one in the sagittal planes;

[0055] Step 3: Calculate the initial spinal pelvic parameters based on the X-ray film, and calculate the position of the vertebral center of the spine relative to the reflective ball;

[0056] Step 4: The subject stands still in the field of the motion capture system, and a skeleton model is added to the motion capture software;

[0057] Step 5: Using the result obtained in step 3, add virtual balls S1 and S5 representing the coccygeal vertebrae. The method of adding virtual balls S1 and S5 is as follows:

[0058] P s1 =P L5 +P L5-s1

[0059] P s5 =point(L s1-s5 )

[0060] Among them, P s1 is the position of the virtual ball S1 relative to the human body, P L5 is the position of the reflective ball corresponding to the fifth waist cone relative to the human body, P L5-s1 It is the position of the virtual ball S1 obtained through the X-ray film relative to the reflective ball corresponding to the fifth waist cone.

[0061] Step 6: Using the results from step 3, adjust the position of the bones in the motion capture software to fit the X-ray film;

[0062] Step 7: According to the position of the vertebrae of the spine, fit a spinal curve in the sagittal plane;

[0063] Step 8. Using the results of steps 3, 4 and 5, calculate the positions of virtual balls S1 and S5. The method for calculating the positions of S1 and S5 is:

[0064]

[0065]

[0066] in is the position of the virtual ball S1 relative to the world, R wh is the body's rotation relative to the world, T wh is the position of the body relative to the world, is the position of the virtual ball S5 relative to the world.

[0067] Step 9: Calculate the spinal column and pelvic parameters according to the spinal column curve in step 7 and the virtual ball in step 8. The method for calculating the spinal column and pelvic parameters is as follows:

[0068] The method for calculating the sagittal vertical offset is:

[0069]

[0070] Where d is the sagittal vertical offset, It is the Y-axis coordinate of the seventh cervical cone in the human body coordinate system. It is the Y-axis coordinate of the virtual ball S1 in the human body coordinate system.

[0071] The calculation method for thoracic kyphosis angle is:

[0072] TK=arctan(y'(T4))±arctan(y'(T12))

[0073] Where TK is the thoracic kyphosis angle, y'(T4) is the slope of the fourth thoracic vertebra on the spinal curve, and arctan(y'(T4)) is the angle between the extension line of the fourth thoracic vertebra endplate and the horizontal direction. y'(T12) is the slope of the twelfth thoracic cone on the spinal curve, and arctan(y'(T12)) is the angle between the extension line of the twelfth thoracic cone endplate and the horizontal direction. ± indicates that the plus and minus signs will change with the change of human posture.

[0074] The calculation method for lumbar lordosis angle is:

[0075] LL=arctan(y'(L1))±θ s1

[0076] Where LL is the lumbar lordosis angle, y'(L1) is the slope of the first lumbar cone on the spinal curve, and arctan(y'(L1)) is the angle between the extension line of the first lumbar cone end plate and the horizontal direction. θ s1 It represents the angle between the coccygeal endplate and the horizontal direction.

[0077] The calculation method for calculating the pelvic tilt angle is:

[0078]

[0079] PT is the pelvic tilt angle, is the point where the left femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the right femoral head is mapped to the YZ plane in the human body coordinate system, is the angle between the two vectors.

[0080] The calculation method for calculating the pelvic incidence angle is:

[0081]

[0082] where PI is the pelvic incidence angle, It is the point where the right femoral head is mapped to the YZ plane in the human coordinate system.

[0083] Finally, the subject makes any movement in the motion capture scene and returns to step six to achieve dynamic calculation of the spine and pelvis parameters.

[0084] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for acquiring dynamic spinal and pelvic parameters based on a motion capture system, characterized in that: The method comprises the following steps: Step 1: Set a reflective ball at the body surface position corresponding to the subject's bones; Step 2: The subject takes an X-ray based on the step 1; Step 3: Calculate the initial spinal pelvic parameters and the relative relationship between the reflective ball and the human bones based on the X-ray film; Step 4: Add a skeleton model to the motion capture system based on step 3, and add a virtual ball to the motion capture system; The added virtual balls include virtual balls S1 and S5 for representing the coccygeal vertebrae, and the adding method is: P s1 =P L5 +P L5-s1 P s5 =point(L s1-s5 ) Among them, P s1 is the position of the virtual ball S1 relative to the human body, P L5 is the position of the reflective ball corresponding to the fifth lumbar vertebra relative to the human body, P L5-s1 is the position of the virtual ball S1 obtained through the X-ray film relative to the reflective ball corresponding to the fifth lumbar vertebra; Step 5: The subject makes any movement in the motion capture scene to perform dynamic calculation of the spinal column and pelvic parameters. The dynamic calculation steps include: using the X-ray film obtained in step 3 to adjust the bone position in the motion capture system; fitting the human spine curve; calculating the positions of the virtual balls S1 and S5; and calculating the spinal column and pelvic parameters. The spinal column and pelvic parameters include: The sagittal vertical offset is calculated as: Where d is the sagittal vertical offset, is the Y-axis coordinate of the seventh cervical vertebra in the human body coordinate system, is the Y-axis coordinate of the virtual ball S1 in the human body coordinate system; The thoracic kyphosis angle is calculated as follows: TK=arctan(y'(T4))±arctan(y'(T12)) Wherein, TK is the thoracic kyphosis angle, y'(T4) is the slope of the fourth thoracic vertebra on the spinal curve, arctan(y'(T4)) is the angle between the extension line of the fourth thoracic vertebra endplate and the horizontal direction; y'(T12) is the slope of the twelfth thoracic vertebra on the spinal curve, arctan(y'(T12)) is the angle between the extension line of the twelfth thoracic vertebra endplate and the horizontal direction, ± indicates that the plus and minus signs will change with the change of human body posture; The lumbar lordosis angle is calculated as follows: LL=arctan(y'(L1))±θ s1 Where LL is the lumbar lordosis angle, y'(L1) is the slope of the first lumbar vertebra on the spinal curve, arctan(y'(L1)) is the angle between the extension line of the first lumbar endplate and the horizontal direction, θ s1 It represents the angle between the coccygeal endplate and the horizontal direction; The pelvic tilt angle is calculated as: Where PT is the pelvic tilt angle, is the point where the left femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the right femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the virtual ball S1 is mapped to the YZ plane in the human body coordinate system. is the angle between two vectors; The pelvic incidence angle is calculated as: Where PI is the pelvic incidence angle, is the point where the left femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the right femoral head is mapped to the YZ plane in the human body coordinate system, is the point where the virtual ball S1 is mapped to the YZ plane in the human body coordinate system. is the point where the virtual ball S5 is mapped to the YZ plane in the human body coordinate system. is the angle between the two vectors.

2. The method for acquiring dynamic spinal column and pelvic parameters based on a motion capture system according to claim 1, characterized in that: The positions where the reflective balls are set on the body surface correspond to: the seventh cervical vertebra, the third thoracic vertebra, the fifth thoracic vertebra, the seventh thoracic vertebra, the ninth thoracic vertebra, the twelfth thoracic vertebra, the second lumbar vertebra, the third lumbar vertebra, the fifth lumbar vertebra spinous process, the head, below the navel, the bilateral anterior superior iliac spines, the posterior superior iliac spines, the bilateral acromions of the upper limbs, the midpoint of the upper arm, the medial and lateral condyles of the elbows, the midpoint of the forearms, the ulnar and radial sides of the wrists, the backs of both hands, the bilateral greater trochanters of the femurs of the lower limbs, the medial and lateral condyles of the knees, the midpoint of the anterior edge of the tibia, the lateral malleolus and the dorsum of both feet.

3. The method for acquiring dynamic spinal column and pelvic parameters based on a motion capture system according to claim 1, characterized in that: The X-ray filming includes coronal plane X-ray film and sagittal plane X-ray film.

4. The method for acquiring dynamic spinal column and pelvic parameters based on a motion capture system according to claim 1, characterized in that: The reflective balls are balls that passively reflect infrared light.

5. The method for acquiring dynamic spinal column and pelvic parameters based on a motion capture system according to claim 4, characterized in that: The cameras of the motion capture system include a plurality of high-speed infrared cameras.

6. The method for acquiring dynamic spinal column and pelvic parameters based on a motion capture system according to claim 1, characterized in that: The calculation method of the positions of the virtual balls S1 and S5 is: in, is the position of the virtual ball S1 relative to the world, R wh is the body's rotation relative to the world, T wh is the position of the body relative to the world, is the position of the virtual ball S5 relative to the world.

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