Femoral head space positioning method in knee joint operation

Abstract

The invention discloses a femoral head space positioning method in a knee joint operation, and relates to the technical field of joint replacement. According to the femoral head space positioning method in the knee joint operation, point coordinate data on a femoral head moving track are continuously recorded, corresponding sampling circle center coordinates and virtual circle center coordinates are calculated, and the average deviation value of the virtual circle center coordinates and the sampling circle center coordinates is calculated; a sampling circle center coordinate with the highest precision is obtained through average deviation value comparison to serve as a real circle center coordinate, interference of movement of the hip joint and the femoral head on the real circle center coordinate is eliminated, and the method has the advantage of being accurate in femoral head and femoral head force line positioning.

Description

Technical Field

[0001] The invention relates to the technical field of joint replacement, and in particular to a method for spatial positioning of a femoral head in knee joint surgery. Background Art

[0002] Total Knee Arthroplasty (TKA) is a new technology for treating knee diseases. By replacing the articular surface of the knee joint with prosthetic components, it can effectively eliminate severe knee pain and greatly improve the quality of life of the surgical subjects. Factors that affect the effect of joint replacement include accurate osteotomy in three-dimensional space, balance and stability of soft tissues such as ligaments, and the position and angle of prosthesis placement. Total knee replacement is particularly strict with these factors.

[0003] In knee replacement surgery, in order to determine the femoral force line of the lower limb, it is necessary to find the center position of the femoral head and the line connecting the distal end of the femur as the femoral force line. In the prior art, the patient's femur can be positioned by using an optical positioning device and a locator, and then the patient's femur and tibia are lifted to allow the entire lower limb to move in a circle with the femoral head as the center. The movement trajectory is recorded as a point on the surface of a sphere to calculate the center position of the femoral head.

[0004] The center position of the femoral head measured by the above method is under ideal conditions (that is, the patient's hip joint and femoral head are both in a static state). However, during the actual operation, when the doctor lifts the patient's thigh, the hip joint will also move, causing the center of the circle corresponding to the collected points on the surface of the sphere to also shift, which in turn causes a slight error between the calculated center of the circle and the actual center of the circle. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a method for spatial positioning of the femoral head in knee joint surgery to solve the above problems.

[0006] To achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: a method for spatial positioning of the femoral head in knee joint surgery, comprising the following steps:

[0007] Acquiring sampling point data; wherein the sampling point data is the coordinate data of multiple points of the femur obtained by sampling on the femur through the positioning device after fixing the positioning device on the femur and moving the patient's leg so that the femoral head moves around the hip joint;

[0008] Taking any four of the point coordinate data as a group, using Cramer's law, obtain a number of sampling circle center coordinate data;

[0009] For each sampling circle center, a plurality of virtual circle center coordinate data of the corresponding sampling circle center are obtained through world coordinate conversion operation according to the sampling circle center coordinate data and the corresponding point coordinate data in the subsequent movement process; wherein the virtual circle center is the offset point of the sampling circle center in the subsequent movement process;

[0010] A coordinate array is established with the multiple virtual center coordinate data corresponding to each sampling center, and the average offset value of the virtual center and the sampling center is obtained based on the coordinate array and the sampling center coordinate data. The average offset values ​​of all sampling centers are compared, and the sampling center coordinate data corresponding to the smallest average offset value is used as the real center coordinate data.

[0011] Preferably, the step of acquiring sampling point data comprises:

[0012] The positioning device obtains coordinate data of multiple points on the femur by sampling at a frequency of 100-150 Hz.

[0013] Preferably, the step of taking the point coordinate data of any four points as a group comprises:

[0014] Four point coordinate data in a set of point coordinate data are acquired at time intervals of 5 ms to 16 ms.

[0015] Preferably, the step of obtaining the average offset value of the virtual circle center and the sampling circle center according to the coordinate array and the sampling circle center coordinate data comprises:

[0016] The coordinate array is traversed to calculate the offset values ​​of all virtual circle centers and sampling circle centers in the coordinate array, wherein the offset value is the distance value between the virtual circle center and the sampling circle center, and the average offset is calculated according to the offset value.

[0017] Preferably, the step of obtaining the average offset value of the virtual circle center and the sampling circle center according to the coordinate array and the sampling circle center coordinate data comprises:

[0018] The average virtual circle center coordinate data is calculated based on multiple virtual circle center coordinate data in the coordinate data, and the average offset is calculated based on the average virtual circle center coordinate data and the corresponding sampling coordinate data. The average offset value is the distance value between the central virtual circle center and the sampling circle center.

[0019] The beneficial effects of the present invention are mainly embodied in:

[0020] The method for spatial positioning of the femoral head in knee joint surgery of the present invention continuously records the point coordinate data on the movement trajectory of the femoral head and calculates the corresponding sampling center coordinates and virtual center coordinates, calculates the average offset value of the virtual center coordinates and the sampling center coordinates, and obtains the most accurate sampling center coordinates as the true center coordinates through average offset value comparison to eliminate the interference of the movement of the hip joint and femoral head on the true center coordinates, which has the advantage of accurate positioning of the femoral head and femoral force lines. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail with reference to the following specific embodiments.

[0022] Embodiment 1:

[0023] The method for spatial positioning of the femoral head in knee surgery includes the following steps:

[0024] Acquire sampling point data; wherein, the sampling point data is after fixing the positioning device on the femur, moving the patient's leg to make the femoral head move around the hip joint, wherein the movement of the femoral head around the hip joint includes front and back, left and right, and up and down movement, and the positioning device is used to sample on the femur to obtain multiple point coordinate data of the femur. In this embodiment, the positioning device is used to locate the femoral head in three-dimensional space and obtain coordinate data. The positioning device is a prior art and will not be elaborated on in detail. For example, a PST Base model positioning device produced by ps-tech manufacturer may be selected, or a Polaris VegaXT model positioning device produced by NDI manufacturer may be selected.

[0025] Among them, point coordinate data can be recorded as A (x1, y1, z1), B (x2, y2, z2), C (x3, y3, z3), D (x4, y4, z4)...;

[0026] Taking any four of the point coordinate data as a group, using Cramer's law, obtain a number of sampling circle center coordinate data;

[0027] Among them, let the radius be r, and the spherical coordinates of the four points A, B, C, and D be (x, y, z). Using the property that the distances from the four points to the center of the sphere are equal, we can get the following four equations:

[0028] (x-x1) 2 +(y-y1) 2 +(z-z1) 2 =r 2 ;

[0029] (x-x2) 2 +(y-y2) 2 +(z-z2) 2 =r2 ;

[0030] (x-x3) 2 +(y-y3) 2 +(z-z3) 2 =r 2 ;

[0031] (x-x3) 2 +(y-y3) 2 +(z-z3) 2 =r 2 ;

[0032] Expand to:

[0033] x 2 +y 2 +z 2 -2(x1x+y1y+z1z)+x1 2 +y1 2 +z1 2 =r 2 ; ①

[0034] x 2 +y 2 +z 2 -2(x2x+y2y+z2z)+x2 2 +y2 2 +z2 2 =r 2 ; ②

[0035] x 2 +y 2 +z 2 -2(x3x+y3y+z3z)+x3 2 +y3 2 +z3 2 =r 2 ; ③

[0036] x 2 +y 2 +z 2 -2(x4x+y4y+z4z)+x4 2 +y4 2 +z4 2 =r 2 ; ④

[0037] Perform ①-②, ③-④, ②-③ respectively to obtain:

[0038]

[0039] The corresponding coefficient determinant can be set as:

[0040]

[0041]

[0042] Then a=(x1-x2), b=(y1-y2), c=(z1-z2)

[0043] a1=(x3-x4), b1=(y3-y4), c1=(z3-z4);

[0044] a2=(x2-x3), b2=(y2-y3), c2=(z2-z3);

[0045] The constant term determinant is:

[0046] P

[0047] Q

[0048] R

[0049] but

[0050]

[0051] Existing

[0052]

[0053]

[0054] From Cramer's rule in linear algebra, we know that:

[0055] x = Dx / D;

[0056] y=Dy / D;

[0057] z=Dz / D;

[0058] In this way, the solution of the system of three linear equations can be obtained, and the solution obtained is the coordinates of the center of the sphere where the four points in space are located.

[0059] For each sampling circle center, a plurality of virtual circle center coordinate data of the corresponding sampling circle center are obtained through world coordinate conversion operation according to the sampling circle center coordinate data and the corresponding point coordinate data in the subsequent movement process; wherein the virtual circle center is the offset point of the sampling circle center in the subsequent movement process;

[0060] A coordinate array is established with the multiple virtual center coordinate data corresponding to each sampling center, and the average offset value of the virtual center and the sampling center is obtained based on the coordinate array and the sampling center coordinate data. The average offset values ​​of all sampling centers are compared, and the sampling center coordinate data corresponding to the smallest average offset value is used as the real center coordinate data.

[0061] In this embodiment, the step of obtaining the average offset value between the virtual center and the sampling center according to the coordinate array and the sampling center coordinate data includes:

[0062] The coordinate array is traversed to calculate the offset values ​​of all virtual circle centers and sampling circle centers in the coordinate array, wherein the offset value is the distance value between the virtual circle center and the sampling circle center, and the average offset is calculated according to the offset value.

[0063] The method for spatial positioning of the femoral head in knee joint surgery of the present invention continuously records the point coordinate data on the movement trajectory of the femoral head and calculates the corresponding sampling center coordinates and virtual center coordinates, calculates the average offset value of the virtual center coordinates and the sampling center coordinates, and obtains the most accurate sampling center coordinates as the true center coordinates through average offset value comparison to eliminate the interference of the movement of the hip joint and femoral head on the true center coordinates, which has the advantage of accurate positioning of the femoral head and femoral force lines.

[0064] Embodiment 2:

[0065] On the basis of the above embodiments, in order to further implement the present invention better, the following configuration is particularly adopted, and the spatial positioning method of the femoral head in knee joint surgery comprises the following steps:

[0066] Acquiring sampling point data; wherein the sampling point data is the coordinate data of multiple points of the femur obtained by sampling on the femur through the positioning device after fixing the positioning device on the femur and moving the patient's leg so that the femoral head moves around the hip joint;

[0067] Taking any four of the point coordinate data as a group, using Cramer's law, obtain a number of sampling circle center coordinate data;

[0068] For each sampling circle center, according to the sampling circle center coordinate data and the corresponding point coordinate data, the relative coordinate data of the sampling circle center and the point coordinates are obtained, and according to the relative coordinate data and the corresponding point coordinate data in the subsequent movement process, a plurality of virtual circle center coordinate data are obtained;

[0069] A coordinate array is established with the multiple virtual center coordinate data corresponding to each sampling center, and the average offset value of the virtual center and the sampling center is obtained based on the coordinate array and the sampling center coordinate data. The average offset values ​​of all sampling centers are compared, and the sampling center coordinate data corresponding to the smallest average offset value is used as the real center coordinate data.

[0070] Preferably, the step of acquiring sampling point data comprises:

[0071] The positioning device obtains coordinate data of multiple points on the femur by sampling at a frequency of 100-150 Hz.

[0072] Preferably, the step of taking the point coordinate data of any four points as a group comprises:

[0073] Four point coordinate data in a set of point coordinate data are acquired at time intervals of 5 ms to 16 ms.

[0074] The step of obtaining the average offset value of the virtual circle center and the sampling circle center according to the coordinate array and the sampling circle center coordinate data comprises:

[0075] The average virtual circle center coordinate data is calculated based on multiple virtual circle center coordinate data in the coordinate data, and the average offset is calculated based on the average virtual circle center coordinate data and the corresponding sampling coordinate data. The average offset value is the distance value between the central virtual circle center and the sampling circle center.

[0076] It should be noted that, for the above-mentioned various method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and units involved are not necessarily required by this application.

Claims

1. A method for spatial positioning of the femoral head in knee joint surgery, characterized in that: The following steps are involved: Acquiring sampling point data; wherein the sampling point data is the coordinate data of multiple points of the femur obtained by sampling on the femur through the positioning device after fixing the positioning device on the femur and moving the patient's leg so that the femoral head moves around the hip joint; Taking any four of the point coordinate data as a group, using Cramer's law, obtain a number of sampling circle center coordinate data; For each sampling circle center, a plurality of virtual circle center coordinate data of the corresponding sampling circle center are obtained through world coordinate conversion operation according to the sampling circle center coordinate data and the corresponding point coordinate data in the subsequent movement process; wherein the virtual circle center is the offset point of the sampling circle center in the subsequent movement process; A coordinate array is established with the multiple virtual center coordinate data corresponding to each sampling center, and the average offset value of the virtual center and the sampling center is obtained based on the coordinate array and the sampling center coordinate data. The average offset values ​​of all sampling centers are compared, and the sampling center coordinate data corresponding to the smallest average offset value is used as the real center coordinate data.

2. The method for spatial positioning of the femoral head in knee joint surgery according to claim 1, characterized in that: The step of obtaining sampling point data comprises: The positioning device obtains coordinate data of multiple points on the femur by sampling at a frequency of 100-150 Hz.

3. The method for spatial positioning of the femoral head in knee joint surgery according to claim 2, characterized in that: The step of taking the point coordinate data of any four points as a group comprises: Four point coordinate data in a set of point coordinate data are acquired at time intervals of 5 ms to 16 ms.

4. The method for spatial positioning of the femoral head in knee joint surgery according to claim 3, characterized in that: The step of obtaining the average offset value of the virtual circle center and the sampling circle center according to the coordinate array and the sampling circle center coordinate data comprises: The coordinate array is traversed to calculate the offset values ​​of all virtual circle centers and sampling circle centers in the coordinate array, wherein the offset value is the distance value between the virtual circle center and the sampling circle center, and the average offset is calculated according to the offset value.

5. The method for spatial positioning of the femoral head in knee joint surgery according to claim 3, characterized in that: The step of obtaining the average offset value of the virtual circle center and the sampling circle center according to the coordinate array and the sampling circle center coordinate data comprises: The average virtual circle center coordinate data is calculated based on multiple virtual circle center coordinate data in the coordinate data, and the average offset is calculated based on the average virtual circle center coordinate data and the corresponding sampling coordinate data. The average offset value is the distance value between the central virtual circle center and the sampling circle center.

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