A lower limb length measuring device and method for hip joint replacement

Abstract

The present invention discloses a lower limb length measuring device and method for hip joint replacement, which relates to the technical field of medical devices. The key points of its technical solution are as follows: It includes two arc-shaped shells, and both arc-shaped shells are provided with ankle grooves; a measuring device is provided on the outer side wall of the arc-shaped shell, and two width adjusting belts are provided between the two arc-shaped shells. The two ends of the two width adjusting belts are respectively connected to the ends of the two arc-shaped shells; the measuring device includes a display control panel, a control processor, a three-axis acceleration sensor, and a timer; the display control panel, the control processor, the three-axis acceleration sensor, and the timer are electrically connected. The display control panel, the timer, and the three-axis acceleration sensor are all fixedly connected to the outer side wall of the arc-shaped shell; the control processor is located inside the arc-shaped shell. This measuring device and measuring method enable medical staff to perform simple and convenient measuring operations when measuring the lower limb length of patients, and have high measurement controllability and high measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and more specifically, it relates to a device and method for measuring the length of the lower limb for hip replacement. Background Art

[0002] Total hip arthroplasty (THA) is a commonly used method in clinical practice for treating hip diseases, and the clinical effect is remarkable. However, complications such as limb length discrepancy (LLD) of the lower limbs are likely to occur after the operation. The occurrence of LLD may cause phenomena such as scoliosis, pelvic tilt, sciatic nerve palsy, low back pain, prosthesis loosening, and limping in patients, which is not conducive to the postoperative rehabilitation of patients. Therefore, clinical practice attaches great importance to the LLD phenomenon during total hip arthroplasty.

[0003] In the prior art, in order to prevent the occurrence of the LLD phenomenon, intraoperative techniques adopted by doctors include PCA limb length measuring device, Kirschner wire positioning method, suture positioning method, etc. These measurement methods have their own advantages and disadvantages. For example, although the intraoperative suture method is simple to operate and low in cost, the results may be inaccurate due to factors such as the skin elasticity of the patient and the change in the placement position of the affected limb; although the Kirschner wire positioning method can effectively control the limb lengthening of the patient after the operation and is simple to operate, its accuracy is not high.

[0004] Therefore, there is an urgent need for a device and method for measuring the length of the lower limb during total hip arthroplasty that are simple to operate, have strong controllability, and high accuracy. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for measuring the length of the lower limb for hip replacement. The measuring device and method enable medical staff to perform simple and convenient measurement operations when measuring the length of the patient's lower limb, and have high measurement controllability and high measurement accuracy.

[0006] The above technical purpose of the present invention is achieved through the following technical solutions: A device for measuring the length of the lower limb for hip replacement includes two arc-shaped shells, and both of the two arc-shaped shells are provided with ankle grooves; a measuring device is provided on the outer side wall of the arc-shaped shell, and two width adjustment belts are provided between the two arc-shaped shells, and both ends of the two width adjustment belts are respectively connected to the ends of the two arc-shaped shells.

[0007] By adopting the above technical solutions, installing a measuring device on the outer side wall of the arc-shaped shell can accurately obtain the length of the patient's lower limb; installing two width adjustment belts between the arc-shaped shells can be applicable to lower limbs of different thicknesses; by providing ankle grooves on the arc-shaped shells, it not only has a limiting effect but also can accurately measure the length of the lower limb.

[0008] The present invention is further configured such that: the measuring device includes a display control panel, a control processor, a three-axis acceleration sensor, and a timer; the display control panel, the timer, and the three-axis acceleration sensor are all fixedly connected to the outer side wall of the arc-shaped housing; the control processor is located inside the arc-shaped housing.

[0009] By adopting the above technical solution, the operator can perform spatial coordinate system calibration through the display control panel and display the length of the patient's lower limb; by providing a timer on the outer side wall of the arc-shaped housing, the position information at each moment can be accurately recorded; by providing a control processor inside the arc-shaped housing, the information at each point can be processed and calculated, and finally the length of the patient's lower limb can be obtained.

[0010] The present invention is further configured such that: the three-axis acceleration sensor is located at the ankle groove.

[0011] By adopting the above technical solution, by placing the three-axis acceleration sensor at the ankle groove, the length of the patient's lower limb can be accurately calculated.

[0012] The present invention is further configured such that: a soft cushion is provided on the inner side wall of the arc-shaped housing.

[0013] By adopting the above technical solution, by providing a soft cushion on the inner side wall of the arc-shaped housing, the comfort of the patient during the measurement process can be improved.

[0014] A method for measuring the length of the lower limb for hip replacement includes the following steps:

[0015] 1) Tightly tie two arc-shaped housings around the ankles, and fix the two arc-shaped housings through a width adjustment band connected to the end of the arc-shaped housing, wherein the ankles are located within the ankle grooves;

[0016] 2) Using the display control panel installed on the outer side wall of the arc-shaped housing, by clicking the calibration button in the display interface of the display control panel, a calibrated spatial rectangular coordinate system is obtained, and after clicking the calibration button, the initial position of the ankle is point O; then, using the three-axis acceleration sensor installed in the ankle groove of the arc-shaped housing, record the accelerations ac x ac y ac z in the x, y, and z directions of the spatial rectangular coordinate system;

[0017] 3) Rotate the ankle, the measured values of the three-axis acceleration sensor start to change, use the timer to start timing, and record a set of acceleration values every 0.01 s, and obtain the following data: (ac x1 ac y1 ac z1 ); (ac x2 ac y2 acz2 ); (ac x3 , ac y3 , ac z3 ); (ac x4 , ac y4 , ac z4 )... (ac xi , ac yi , ac zi );

[0018] 4) Based on the data measured in step 3), calculate the average speed between every two moments through the calculation program implanted in the control processor. The calculation formula is as follows:

[0019]

[0020]

[0021]

[0022] 5) According to step 4), superimpose to obtain the displacements in the x, y, and z directions. The calculation formula is as follows:

[0023]

[0024]

[0025]

[0026] 6) The timer counts every 2 s, and the control processor reads a set of spatial coordinates (x, y, z), then we get:

[0027] A(x1, y1, z1), B(x2, y2, z2), C(x3, y3, z3);

[0028] 7) According to step 6), obtain the vectors and

[0029]

[0030]

[0031] 8) Determine whether the three points A, B, and C are on the same straight line:

[0032] If then the control processor reads the next set of data D(x4, y4, z4), and uses the method in step 7) to obtain the vectors and and determine and whether the two vectors are on the same straight line. If and are on the same straight line, then repeat steps 7) and 8);

[0033] 9) According to step 8), when the center coordinates of a sphere are defined as O′(a, b, c) through the following three equations:

[0034]

[0035]

[0036]

[0037] obtain O′(a0, b0, c0);

[0038] 10) According to step 9), calculate the radius of the sphere three times respectively according to the distances from the center of the sphere to the three points A, B, and C. The calculation formulas are as follows:

[0039]

[0040]

[0041]

[0042] Then take the average value of the calculated R1, R2, and R3 Then:

[0043]

[0044] and the calculated is displayed through the display control panel.

[0045] By adopting the above technical solutions, the two arc-shaped shells are tightly tied to the ankle, and the ankle should be located in the ankle groove, so as to ensure that each set of measured data is the data at the ankle, and thus the length of the lower limb can be accurately obtained; through calibration by the display control panel, a space rectangular coordinate system can be obtained, so as to concretize the position information; the acceleration values in the x, y, and z directions are obtained every 0.01 s, so that the average speed between each moment can be accurately calculated, and thus the position of the ankle every 2 s can be accurately obtained; by judging whether the vectors are parallel, it can be determined whether the three obtained points are not on a straight line, ensuring that the three obtained position points can form a spherical surface; by calculating the center coordinates of the sphere, the distance from the center of the sphere to each point can be obtained; by taking the average value of the distances from the center of the sphere to each point respectively, the calculation accuracy can be improved.

[0046] In summary, the present invention has the following beneficial effects:

[0047] 1. Install a measuring device on the outer side wall of the arc-shaped housing, which can accurately obtain the lower limb length of the patient;

[0048] 2. Install two width adjustment bands between the arc-shaped housings, so that it can be applicable to lower limbs of different thicknesses;

[0049] 3. By setting an ankle groove on the arc-shaped housing, it not only has a limiting effect, but also can accurately measure the lower limb length;

[0050] 4. Through calibration by the display control panel, a spatial rectangular coordinate system can be obtained, so as to concretize the position information;

[0051] 5. Obtain the acceleration values in the x, y, and z directions every 0.01 s, so that the average velocity between each moment can be accurately calculated, and thus the position of the ankle every 2 s can be accurately obtained;

[0052] 6. By the method of judging whether the vectors are parallel, it is determined whether the three obtained points are not on a straight line, ensuring that the three obtained position points can form a spherical surface;

[0053] 7. By calculating the spherical center coordinates, the distance from the spherical center to each point can be obtained;

[0054] 8. By averaging the distances from the spherical center to each point respectively, the calculation accuracy can be improved. Description of the Drawings

[0055] Figure 1 is the top view of a lower limb length measuring device for hip joint replacement in Embodiment 1 of the present invention;

[0056] Figure 2 is the left view of a lower limb length measuring device for hip joint replacement in Embodiment 1 of the present invention;

[0057] Figure 3 is Figure 1 the sectional view of the A-A section in

[0058] Figure 4 is the usage state diagram of a lower limb length measuring device for hip joint replacement in Embodiment 1 of the present invention;

[0059] Figure 5 is the schematic diagram in Embodiment 2 of the present invention;

[0060] Figure 6 is the step flow chart in Embodiment 2 of the present invention.

[0061] In the figure: 1. Arc-shaped housing; 2. Soft padding; 3. Triaxial acceleration sensor; 4. Ankle groove; 5. Width adjustment strap; 6. Display control panel; 7. Control processor; 8. Timer. Detailed implementation

[0062] The following further elaborates on the present invention in conjunction with the attached Figures 1-6 drawings.

[0063] Embodiment 1: A lower limb length measuring device for hip replacement, as Figures 1 to 4 shown, includes two arc-shaped housings 1, and both of the two arc-shaped housings 1 are provided with ankle grooves 4; a measuring device is provided on the outer side wall of the arc-shaped housing 1, and two width adjustment straps 5 are provided between the two arc-shaped housings 1, and both ends of the two width adjustment straps 5 are respectively connected to the ends of the two arc-shaped housings 1.

[0064] In this embodiment, when medical staff needs to use this lower limb length measuring device for measurement, pass the patient's lower limb through between the two arc-shaped housings 1, and place the ankle in the ankle groove 4, then pull the width adjustment strap 5 to make the two arc-shaped housings 1 tightly fit the lower limb, and then rotate the patient's lower limb, and the length of the lower limb can be obtained through the measuring device.

[0065] The measuring device includes a display control panel 6, a control processor 7, a triaxial acceleration sensor 3, and a timer 8; the display control panel 6, the timer 8, and the triaxial acceleration sensor 3 are all fixedly connected to the outer side wall of the arc-shaped housing 1; the control processor 7 is located inside the arc-shaped housing 1.

[0066] In this embodiment, the specific implementation method of measuring the length of the lower limb mentioned above is that the triaxial acceleration sensor 3 measures the accelerations in three directions at the ankle position during the rotation of the lower limb, the timer 8 makes the control processor 7 record the data every 0.01 s, the control processor 7 calculates the average speed at each moment, finally calculates the position coordinates obtained every 2 s, calculates the spherical position from the three non-collinear coordinates obtained, finally obtains the radius of the sphere, and then calculates the average value through the control processor 7 to obtain the final length of the lower limb, and finally the control processor 7 transmits the information to the display control panel 6, and the medical staff reads the length of the lower limb through the display control panel 6, thus achieving accurate measurement of the length of the patient's lower limb.

[0067] The triaxial acceleration sensor 3 is located at the ankle groove 4.

[0068] In this embodiment, the triaxial acceleration is located at the position of the ankle groove 4, which can accurately record the acceleration information at the end of the lower limb, so as to accurately measure the length of the lower limb.

[0069] The inner side wall of the arc-shaped housing 1 is provided with a soft padding 2.

[0070] In this embodiment, the soft pad 2 can improve the comfort of the patient.

[0071] Embodiment 2: A method for measuring the length of the lower limb for hip replacement, as Figure 5 and Figure 6 shown, includes the following steps:

[0072] 1) Tightly tie the two arc-shaped shells 1 around the ankle, and fix the two arc-shaped shells 1 through the width adjustment belt 5 connected to the end of the arc-shaped shell 1, wherein the ankle is located in the ankle groove 4;

[0073] 2) Using the display control panel 6 installed on the outer side wall of the arc-shaped shell 1, by clicking the calibration button in the display interface of the display control panel 6, obtain the calibrated space rectangular coordinate system, and after clicking the calibration button, the initial position of the ankle is the O point; then use the three-axis acceleration sensor 3 of the ankle groove 4 installed on the arc-shaped shell 1 to record the accelerations ac x , ac y , ac z ;

[0074] 3) Rotate the ankle, and the measured values of the three-axis acceleration sensor 3 start to change. Use the timer 8 to start timing, and record a set of acceleration values every 0.01 s, and obtain the following data: (ac x1 , ac y1 , ac z1 ); (ac x2 , ac y2 , ac z2 ); (ac x3 , ac y3 , ac z3 ); (ac x4 , ac y4 , ac z4 )... (ac xi , ac yi , ac zi );

[0075] 4) According to the data measured in step 3), calculate the average speed between every two moments through the calculation program implanted in the control processor 7, and the calculation formula is as follows:

[0076]

[0077]

[0078]

[0079] 5) According to step 4), the displacements in the x, y, and z directions are superimposed, and the calculation formulas are as follows:

[0080]

[0081]

[0082]

[0083] 6) The timer 8 times every 2 s, and the control processor 7 reads a set of spatial coordinates (x, y, z), then:

[0084] A(x1, y1, z1), B(x2, y2, z2), C(x3, y3, z3);

[0085] 7) According to step 6), the vectors and

[0086]

[0087]

[0088] 8) Determine whether the three points A, B, and C are on the same straight line:

[0089] If then the control processor 7 reads the next set of data D(x4, y4, z4), and uses the method in step 7) to obtain the vectors and and determine and whether the two vectors are on the same straight line. If and are on the same straight line, then repeat steps 7) and 8);

[0090] 9) According to step 8), when is satisfied, define the center coordinates of a sphere as O′(a, b, c), and through the following three equations:

[0091]

[0092]

[0093]

[0094] Obtain O′(a0, b0, c0);

[0095] 10) According to step 9), calculate the radius of the sphere three times based on the distances from the center of the sphere to the three points A, B, and C respectively. The calculation formulas are as follows:

[0096]

[0097]

[0098]

[0099] Then, calculate the average value of the calculated R1, R2, and R3. Then:

[0100]

[0101] And the calculated Is displayed through the display control panel 6.

[0102] In this embodiment, the two arc-shaped shells 1 are tightly tied to the ankle, and the ankle should be located within the ankle groove 4, so as to ensure that each set of measured data is the data of the ankle, thereby accurately obtaining the length of the lower limb; through calibration by the display control panel 6, a spatial rectangular coordinate system can be obtained, thereby concretizing the position information and obtaining the relative position of each point; the acceleration values in the x, y, and z directions are obtained every 0.01 s, so that the average velocity between each moment can be accurately calculated. A set of position information is taken every 2 s, and the position of the ankle every 2 s can be accurately obtained; by using the method of determining whether vectors are parallel to determine whether the three obtained points are not on the same straight line, ensuring that the three obtained position points can form a spherical surface; by calculating the coordinates of the center of the sphere, the distance from the center of the sphere to each point can be obtained. When calculating the distance, the control processor 7 needs to retain two decimal places for the three calculated distance values; by averaging the distances from the center of the sphere to each point respectively, the calculation accuracy can be improved.

[0103] Working principle: A measuring device is installed on the outer sidewall of the arc-shaped housing 1, which can accurately obtain the lower limb length of the patient; two width adjustment bands 5 are installed between the arc-shaped housings 1, so that it can be applicable to lower limbs of different thicknesses; by setting the ankle groove 4 on the arc-shaped housing 1, it not only has a limiting effect, but also can accurately measure the lower limb length; the two arc-shaped housings 1 are tightly tied to the ankle, and the ankle should be located in the ankle groove 4, so that it can ensure that each set of measured data is the data at the ankle, and thus the lower limb length can be accurately obtained; through calibration by the display control panel 6, a spatial rectangular coordinate system can be obtained, so as to concretize the position information; the acceleration values in the x, y, and z directions are obtained every 0.01 s, so that the average velocity between each moment can be accurately calculated, and thus the position of the ankle every 2 s can be accurately obtained; by judging whether the vectors are parallel, it is determined whether the three obtained points are not on the same straight line, ensuring that the three obtained position points can form a spherical surface; by calculating the spherical center coordinates, the distance from the spherical center to each point can be obtained; by averaging the distances from the spherical center to each point respectively, the calculation accuracy can be improved.

[0104] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A method for measuring the length of the lower limb for hip joint replacement, characterized in that: Use a lower limb length measuring device for hip replacement, including two arc-shaped shells (1), and ankle grooves (4) are provided on both of the two arc-shaped shells (1); a measuring device is provided on the outer side wall of the arc-shaped shell (1), and two width adjusting belts (5) are provided between the two arc-shaped shells (1), and both ends of the two width adjusting belts (5) are respectively connected to the ends of the two arc-shaped shells (1); The measuring device includes a display control panel (6), a control processor (7), a three-axis acceleration sensor (3) and a timer (8); the display control panel (6), the timer (8) and the three-axis acceleration sensor (3) are all fixedly connected to the outer side wall of the arc-shaped shell (1); the control processor (7) is located inside the arc-shaped shell (1); The three-axis acceleration sensor (3) is located at the ankle groove (4); A soft cushion (2) is provided on the inner side wall of the arc-shaped shell (1); The measuring method includes the following steps: 1) Tightly tie the two arc-shaped shells (1) to the ankles, and fix the two arc-shaped shells (1) through the width adjusting belts (5) connected to the ends of the arc-shaped shells (1), wherein the ankles are located inside the ankle grooves (4); 2) By using the display control panel (6) installed on the outer wall of the arc-shaped housing (1), click the calibration button in the display interface of the display control panel (6) to obtain the calibrated spatial rectangular coordinate system. After clicking the calibration button, the initial position of the ankle is point O. Then, use the triaxial acceleration sensor (3) installed in the ankle groove (4) of the arc-shaped housing (1) to record the accelerations ac x , ac y , ac z ; 3) Rotate the ankle, the measured values of the three-axis acceleration sensor (3) start to change, use the timer (8) to start timing, and record a set of acceleration values every 0.01 s, and obtain the following data: (ac x1 , ac y1 , ac z1 ); (ac x2 , ac y2 , ac z2 ); (ac x3 , ac y3 , ac z3 ); (ac x4 , ac y4 , ac z4 )... (ac xi , ac yi , ac zi ); 4) According to the data measured in step 3), calculate the average speed between every two moments through the calculation program implanted in the control processor (7), and the calculation formula is as follows: 5) According to step 4), superimpose to obtain the displacements in the x, y, and z directions, and the calculation formula is as follows: 6) The timer (8) times every 2 s, and the control processor (7) reads a set of spatial coordinates (x, y, z), then we get: A(x1, y1, z1), B(x2, y2, z2), C(x3, y3, z3); 7) According to step 6), the vectors and 8) Judge whether the three points A, B, and C are on the same straight line: If then control the processor (7) to read the next set of data D(x4, y4, z4), and obtain the vectors using the method in step 7) and and determine and whether the two vectors are on the same straight line. If and are on the same straight line, then repeat step 7) and step 8); 9) According to step 8), when the center coordinates of a sphere are defined as O'(a, b, c) through the following three equations: Obtain O′(a0, b0, c0); 10) According to step 9), calculate the radius of the sphere three times respectively according to the distances from the center of the sphere to the three points A, B, and C, and the calculation formula is as follows: Then calculate the average value of the calculated R1, R2, and R3 Then: and the calculated is displayed through the display control panel (6).

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