Method for spatial positioning of the femoral head in knee surgery

Abstract

The application discloses a femoral head space positioning method in knee joint surgery and relates to the technical field of joint replacement. The femoral head space positioning method in knee joint surgery has the advantages that the movement of the hip joint and the femoral head is eliminated from the interference on the real circle center coordinate, and the femoral head and femoral force line positioning is accurate.

Description

Technical Field

[0001] The present 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 joint disorders. By replacing the articular surfaces of the knee joint with prosthetic components, it can effectively eliminate severe knee pain and significantly improve the patient's quality of life. Factors influencing the effectiveness of joint replacement include accurate three-dimensional osteotomy, balance and stability of soft tissues such as ligaments, and the position and angle of prosthetic placement. Total knee replacement has particularly stringent requirements for 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 existing technology, the patient's femur can be positioned by using optical positioning equipment and a locator, and then the patient's femur and tibia are lifted to allow the entire lower limb to move in a circular motion with the center of the femoral head. The motion 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 during knee joint surgery to solve the above problems.

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

[0007] Acquiring sampling point data; wherein the sampling point data is coordinate data of multiple points on the femur obtained by sampling the femur with 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 is obtained based on the sampling circle center coordinate data and the corresponding point coordinate data in the subsequent movement process through a world coordinate conversion operation; 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 using the multiple virtual center coordinate data corresponding to each sampling center. Based on the coordinate array and the sampling center coordinate data, the average offset value of the virtual center and the sampling center is obtained. 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 obtaining sampling point data includes:

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

[0013] Preferably, the step of forming a group of coordinate data of any four points includes:

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

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

[0016] The coordinate array is traversed, and the offset values ​​of all virtual circle centers and sampling circle centers in the coordinate array are calculated, where the offset value is the distance value between the virtual circle center and the sampling circle center, and an average offset is calculated based on the offset value.

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

[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 concentrated in:

[0020] The method for spatial positioning of the femoral head during knee joint surgery of the present invention continuously records the point coordinate data on the femoral head movement trajectory 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 solutions of the present invention, the present invention is further described in detail with reference to the following specific embodiments.

[0022] Example 1:

[0023] The method for spatial positioning of the femoral head during 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-to-back, left-to-right, and up-and-down movement, and the coordinate data of multiple points of the femur are obtained by sampling on the femur by the positioning device. In this embodiment, the positioning device is used to locate the femoral head in three dimensions 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 from the ps-tech manufacturer can be selected, or a Polaris VegaXT model positioning device from the NDI manufacturer can 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] Here, let the radius be r, and the spherical coordinates of points A, B, C, and D be (x, y, z). Using the property that the four points are at equal distance from the center of the sphere, we can obtain 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] Expanded 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 is obtained based on the sampling circle center coordinate data and the corresponding point coordinate data in the subsequent movement process through a world coordinate conversion operation; 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 using the multiple virtual center coordinate data corresponding to each sampling center. Based on the coordinate array and the sampling center coordinate data, the average offset value of the virtual center and the sampling center is obtained. 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 circle center and the sampling circle center according to the coordinate array and the sampling circle center coordinate data includes:

[0062] The coordinate array is traversed, and the offset values ​​of all virtual circle centers and sampling circle centers in the coordinate array are calculated, where the offset value is the distance value between the virtual circle center and the sampling circle center, and an average offset is calculated based on the offset value.

[0063] The method for spatial positioning of the femoral head during knee joint surgery of the present invention continuously records the point coordinate data on the femoral head movement trajectory 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, and has the advantage of accurate positioning of the femoral head and femoral force lines.

[0064] Example 2:

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

[0066] Acquiring sampling point data; wherein the sampling point data is coordinate data of multiple points on the femur obtained by sampling the femur with 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, obtaining relative coordinate data between the sampling circle center and the point coordinates based on the sampling circle center coordinate data and the corresponding point coordinate data, and obtaining multiple virtual circle center coordinate data based on the relative coordinate data and the corresponding point coordinate data during subsequent movement;

[0069] A coordinate array is established using the multiple virtual center coordinate data corresponding to each sampling center. Based on the coordinate array and the sampling center coordinate data, the average offset value of the virtual center and the sampling center is obtained. 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 obtaining sampling point data includes:

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

[0072] Preferably, the step of forming a group of coordinate data of any four points includes:

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

[0074] The step of obtaining the average offset value between 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 aforementioned various method embodiments, for the sake of simplicity, 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 during knee joint surgery, characterized by: The following steps are involved: Acquiring sampling point data; wherein the sampling point data is coordinate data of multiple points on the femur obtained by sampling the femur with 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, performing a world coordinate conversion operation based on the sampling circle center coordinate data and the corresponding point coordinate data during the subsequent movement process to obtain relative coordinate data between the sampling circle center and the point coordinates; and obtaining multiple virtual circle center coordinate data of the corresponding sampling circle center based on the relative coordinate data and the corresponding point coordinate data during the subsequent movement process; wherein the virtual circle center is the offset point of the sampling circle center during the subsequent movement process; A coordinate array is established using the multiple virtual center coordinate data corresponding to each sampling center. Based on the coordinate array and the sampling center coordinate data, the average offset value of the virtual center and the sampling center is obtained. 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 during knee joint surgery according to claim 1, characterized in that: The step of obtaining sampling point data includes: The positioning device obtains coordinate data of multiple points on the femur by sampling at a frequency of 100-150 Hz on the femur.

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

4. The method for spatial positioning of the femoral head during knee joint surgery according to claim 3, wherein: The step of obtaining the average offset value between 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, and the offset values ​​of all virtual circle centers and sampling circle centers in the coordinate array are calculated, where the offset value is the distance value between the virtual circle center and the sampling circle center, and an average offset value is calculated based on the offset value.

5. The method for spatial positioning of the femoral head during knee joint surgery according to claim 3, wherein: The step of obtaining the average offset value between 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 the multiple virtual circle center coordinate data in the coordinate data, and the average offset value 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.

Images