CN113995560A - Lower limb length measuring device and method for hip joint replacement - Google Patents

Lower limb length measuring device and method for hip joint replacement Download PDF

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CN113995560A
CN113995560A CN202111195883.2A CN202111195883A CN113995560A CN 113995560 A CN113995560 A CN 113995560A CN 202111195883 A CN202111195883 A CN 202111195883A CN 113995560 A CN113995560 A CN 113995560A
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arc
ankle
lower limb
shaped
measuring device
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王铖
李想
崔翔
白阳
赵祎
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Fourth Medical Center General Hospital of Chinese PLA
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Fourth Medical Center General Hospital of Chinese PLA
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/46—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor
    • A61F2/4603—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor for insertion or extraction of endoprosthetic joints or of accessories thereof
    • A61F2/4607—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor for insertion or extraction of endoprosthetic joints or of accessories thereof of hip femoral endoprostheses
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/107—Measuring physical dimensions, e.g. size of the entire body or parts thereof
    • A61B5/1072—Measuring physical dimensions, e.g. size of the entire body or parts thereof measuring distances on the body, e.g. measuring length, height or thickness
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/46—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor
    • A61F2/4657—Measuring instruments used for implanting artificial joints
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/46—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor
    • A61F2/4657—Measuring instruments used for implanting artificial joints
    • A61F2002/4658—Measuring instruments used for implanting artificial joints for measuring dimensions, e.g. length

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Abstract

The invention discloses a lower limb length measuring device and method for hip joint replacement, relating to the technical field of medical instruments, and the technical scheme is as follows: the ankle joint comprises two arc-shaped shells, wherein ankle grooves are formed in the two arc-shaped shells; the outer side wall of each arc-shaped shell is provided with a measuring device, two width adjusting belts are arranged between the two arc-shaped shells, and two ends of each width adjusting belt are respectively connected with the end parts of the two arc-shaped shells; the measuring device comprises 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, and the display control panel, the timer and the three-axis acceleration sensor are fixedly connected with the outer side wall of the arc-shaped shell; the control processor is located in the arc-shaped shell. The measuring device and the measuring method enable medical staff to measure the length of the lower limb of the patient easily and conveniently, and are high in measurement controllability and measurement precision.

Description

Lower limb length measuring device and method for hip joint replacement
Technical Field
The invention relates to the technical field of medical instruments, in particular to a lower limb length measuring device and method for hip joint replacement.
Background
Total Hip Arthroplasty (THA) is a common clinical treatment for hip disease with significant clinical efficacy, but is prone to complications of unequal length of the two Lower Limbs (LLD) after surgery. The occurrence of LLD may cause the patient to have the phenomena of scoliosis, pelvic tilt, ischial nerve paralysis, lumbago and backache, prosthesis looseness, lameness and the like, and is not beneficial to the postoperative rehabilitation of the patient. Therefore, the LLD phenomenon in total hip replacement surgery is highly regarded in clinic.
In the prior art, in order to prevent the occurrence of the LLD phenomenon, the physician adopts the intra-operative techniques such as a PCA limb length measuring device, a Kirschner wire positioning method, a suture positioning method and the like. These measurement methods have advantages and disadvantages, for example, although the suture method in operation is simple and low in cost, the result may be erroneous due to the elasticity of the skin of the patient, the position of the affected limb, and the like; although the Kirschner wire positioning method can effectively control the extension of the limbs of the patient after the operation and has simple operation, the precision is not high.
Therefore, a need exists for a lower limb length measuring device and method for total hip replacement surgery, which is simple in operation, highly controllable and highly accurate.
Disclosure of Invention
The invention aims to provide a lower limb length measuring device and method for hip joint replacement, which enable medical staff to measure the length of the lower limb of a patient simply and conveniently, have high measurement controllability and high measurement precision.
The technical purpose of the invention is realized by the following technical scheme: a lower limb length measuring device for hip joint replacement comprises two arc shells, wherein ankle grooves are formed in the two arc shells; the outer side wall of the arc-shaped shell is provided with a measuring device, two width adjusting belts are arranged between the arc-shaped shells, and two ends of each width adjusting belt are respectively connected with the end parts of the two arc-shaped shells.
By adopting the technical scheme, the measuring device is arranged on the outer side wall of the arc-shaped shell, so that the length of the lower limb of the patient can be accurately obtained; two width adjusting belts are arranged between the arc-shaped shells, so that the lower limbs with different thicknesses can be suitable; through set up the ankle recess on the arc casing, not only have spacing effect, can also the accurate length of measuring low limbs.
The invention is further configured to: the measuring device comprises 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 fixedly connected with the outer side wall of the arc-shaped shell; the control processor is located in the arc-shaped shell.
By adopting the technical scheme, an operator can correct the space coordinate system through the display control panel and display the length of the lower limb of the patient; the timer is arranged on the outer side wall of the arc-shaped shell, so that the position information of each moment can be accurately recorded; through set up control processor in the arc casing, can handle the operation with the information of every point, finally reachs patient's low limbs length.
The invention is further configured to: the three-axis acceleration sensor is positioned at the ankle groove.
Through adopting above-mentioned technical scheme, put triaxial acceleration sensor in ankle groove, can accurately calculate the length of patient's low limbs.
The invention is further configured to: and a soft gasket is arranged on the inner side wall of the arc-shaped shell.
Through adopting above-mentioned technical scheme, set up soft liner at the inside wall of arc casing, can improve patient's comfort level among the measurement process.
A method of measuring the length of a lower limb for hip replacement comprising the steps of:
1) tightly binding the two arc-shaped shells at the ankle, and fixing the two arc-shaped shells through a width adjusting belt connected with the end parts of the arc-shaped shells, wherein the ankle is positioned in the ankle groove;
2) the correction button in the display interface of the display control panel is clicked by utilizing the display control panel arranged on the outer side wall of the arc-shaped shell to obtain the correction buttonThe corrected space rectangular coordinate system, and after the correction button is clicked, the initial position of the ankle is an O point; then, a triaxial acceleration sensor of an ankle groove arranged on the arc-shaped shell is utilized to record the acceleration ac in the directions of x, y and z of a space rectangular coordinate systemx，acy，acz；
3) When the ankle is rotated, the measured value of the three-axis acceleration sensor begins to change, a timer is utilized to start timing, a group of acceleration values are recorded every 0.01s, and the following data are measured: (ac)x1，acy1，acz1)；(acx2，acy2，acz2)；(acx3，acy3，acz3)；(acx4，acy4，acz4)……(acxi，acyi，aczi)；
4) Calculating the average speed between every two moments by a calculation program in the implantation control processor according to the data measured in the step 3), wherein the calculation formula is as follows:
Figure BDA0003302931450000031
Figure BDA0003302931450000032
Figure BDA0003302931450000033
5) according to the step 4), the displacements in the three directions of x, y and z are obtained by superposition, and the calculation formula is as follows:
Figure BDA0003302931450000034
Figure BDA0003302931450000041
Figure BDA0003302931450000042
6) the timer counts every 2s, and the control processor reads a set of spatial coordinates (x, y, z), and then:
A(x1，y1，z1)，B(x2，y2，z2)，C(x3，y3，z3)；
7) according to step 6), a vector is derived
Figure BDA0003302931450000043
And
Figure BDA0003302931450000044
Figure BDA0003302931450000045
Figure BDA0003302931450000046
8) judging whether the three points A, B and C are on the same straight line:
if it is
Figure BDA0003302931450000047
The control processor reads the next set of data D (x)4，y4，z4) And obtaining the vector by adopting the method of the step 7)
Figure BDA0003302931450000048
And
Figure BDA0003302931450000049
and judge
Figure BDA00033029314500000410
And
Figure BDA00033029314500000411
whether the two vectors are on the same straight line, if
Figure BDA00033029314500000412
And
Figure BDA00033029314500000413
on the same straight line, repeating the step 7) and the step 8);
9) according to step 8), when
Figure BDA00033029314500000414
Then, the sphere center coordinates defining a sphere are O' (a, b, c), by the following three equations:
Figure BDA00033029314500000415
Figure BDA00033029314500000416
Figure BDA00033029314500000417
result in O' (a)0，b0，c0)；
10) According to the step 9), the radius of the sphere is calculated three times according to the distance from the center of the sphere to the three points A, B and C, and the calculation formula is as follows:
Figure BDA00033029314500000418
Figure BDA00033029314500000419
Figure BDA0003302931450000051
then to the calculated R1，R2And R3Averaging
Figure BDA0003302931450000052
Then:
Figure BDA0003302931450000053
and calculated
Figure BDA0003302931450000054
And displaying through the display control panel.
By adopting the technical scheme, the two arc-shaped shells are tightly bound at the ankle, and the ankle is positioned in the ankle groove, so that the measured data of each group at the ankle can be ensured, and the length of the lower limb can be accurately obtained; a space rectangular coordinate system can be obtained by correcting through the display control panel, so that the position information is specified; acceleration values in the x, y and z directions are obtained every 0.01s, so that the average speed between every two moments can be accurately obtained, and the position of each 2s ankle can be accurately obtained; judging whether the obtained three points are not on the same straight line by a method of whether the vectors are parallel or not, and ensuring that the obtained three position points can form a spherical surface; the distance from the sphere center to each point can be obtained by calculating the coordinates of the sphere center; the calculation accuracy can be improved by averaging the distances from the center of sphere to each point.
In conclusion, the invention has the following beneficial effects:
1. the outer side wall of the arc-shaped shell is provided with the measuring device, so that the length of the lower limb of the patient can be accurately obtained;
2. two width adjusting belts are arranged between the arc-shaped shells, so that the lower limbs with different thicknesses can be suitable;
3. the ankle groove is formed in the arc-shaped shell, so that the limiting effect is achieved, and the length of the lower limb can be accurately measured;
4. a space rectangular coordinate system can be obtained by correcting through the display control panel, so that the position information is specified;
5. acceleration values in the x, y and z directions are obtained every 0.01s, so that the average speed between every two moments can be accurately obtained, and the position of each 2s ankle can be accurately obtained;
6. judging whether the obtained three points are not on the same straight line by a method of whether the vectors are parallel or not, and ensuring that the obtained three position points can form a spherical surface;
7. the distance from the sphere center to each point can be obtained by calculating the coordinates of the sphere center;
8. the calculation accuracy can be improved by averaging the distances from the center of sphere to each point.
Drawings
FIG. 1 is a plan view of a lower limb length measuring apparatus for hip replacement according to embodiment 1 of the present invention;
FIG. 2 is a left side view of a lower limb length measuring device for hip replacement according to embodiment 1 of the present invention;
FIG. 3 is a cross-sectional view of section A-A of FIG. 1;
FIG. 4 is a view showing a state in which a lower limb length measuring device for hip replacement according to embodiment 1 of the present invention is used;
fig. 5 is a schematic diagram in embodiment 2 of the present invention;
fig. 6 is a flowchart of the steps in embodiment 2 of the present invention.
In the figure: 1. an arc-shaped shell; 2. a soft pad; 3. a three-axis acceleration sensor; 4. an ankle groove; 5. a width adjustment belt; 6. a display control panel; 7. a control processor; 8. a timer.
Detailed Description
The invention is described in further detail below with reference to figures 1-6.
Example 1: a lower limb length measuring device for hip replacement, as shown in fig. 1 to 4, comprises two arc-shaped shells 1, wherein the two arc-shaped shells 1 are provided with ankle grooves 4; the lateral wall of arc casing 1 is equipped with measuring device, is equipped with two width control area 5 between two arc casings 1, and the both ends of two width control area 5 respectively with the end connection of two arc casings 1.
In this embodiment, when the medical staff needs to use this lower limb length measuring device to measure, pass patient's lower limbs between two arc shells 1 to put the ankle in ankle recess 4, pull width regulation area 5 again, make two arc shells 1 tightly laminate with the lower limb, then rotate patient's lower limb again, obtain the length of lower limb through measuring device.
The measuring device comprises 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 fixedly connected with the outer side wall of the arc-shaped shell 1; the control processor 7 is positioned in the arc-shaped shell 1.
In the embodiment, the specific implementation manner of measuring the length of the lower limb mentioned above is that the three-axis acceleration sensor 3 measures accelerations of the ankle position in three directions during the rotation of the lower limb, the timer 8 enables the control processor 7 to record data every 0.01s, the control processor 7 calculates the average speed at each moment, finally calculates the position coordinates obtained every 2s, calculates the three obtained coordinates which are not on the same straight line to obtain the spherical position, finally obtains the radius of the sphere, calculates the final length of the lower limb by the average value through the control processor 7, and finally the control processor 7 transmits information to the display control panel 6, and the medical staff reads the length of the lower limb through the display control panel 6, so that the accurate measurement of the length of the lower limb of the patient is realized.
The triaxial acceleration sensor 3 is located at the ankle groove 4.
In this embodiment, the three-axis acceleration is located at the ankle groove 4, so that the acceleration information of the end of the limb can be accurately recorded, and the length of the lower limb can be accurately measured.
The inner side wall of the arc-shaped shell 1 is provided with a soft gasket 2.
In this embodiment, the soft pad 2 can improve the comfort of the patient.
Example 2: a method of measuring the length of a lower limb for hip replacement, as shown in figures 5 and 6, comprising the steps of:
1) tightly binding the two arc-shaped shells 1 at the ankle, and fixing the two arc-shaped shells 1 through a width adjusting belt 5 connected with the end parts of the arc-shaped shells 1, wherein the ankle is positioned in the ankle groove 4;
2) by utilizing the display control panel 6 arranged on the outer side wall of the arc-shaped shell 1, a corrected space rectangular coordinate system is obtained by clicking a correction button in a display interface of the display control panel 6, and after the correction button is clicked, the initial position of the ankle is an O point; then, the acceleration ac in the directions of x, y and z of a space rectangular coordinate system is recorded by using a three-axis acceleration sensor 3 of an ankle groove 4 arranged on the arc-shaped shell 1x，acy，acz；
3) When the ankle is turned, the measured value of the three-axis acceleration sensor 3 starts to change, the timer 8 is used for starting to count time, a group of acceleration values are recorded every 0.01s, and the following data are measured: (ac)x1，acy1，acz1)；(acx2，acy2，acz2)；(acx3，acy3，acz3)；(acx4，acy4，acz4)……(acxi，acyi，aczi)；
4) Calculating the average speed between every two moments by a calculation program in the implantation control processor 7 according to the data measured in step 3), wherein the calculation formula is as follows:
Figure BDA0003302931450000091
Figure BDA0003302931450000092
Figure BDA0003302931450000093
5) according to the step 4), the displacements in the three directions of x, y and z are obtained by superposition, and the calculation formula is as follows:
Figure BDA0003302931450000094
Figure BDA0003302931450000095
Figure BDA0003302931450000096
6) the timer 8 counts every 2s, and the control processor 7 reads a set of spatial coordinates (x, y, z), which is then:
A(x1，y1，z1)，B(x2，y2，z2)，C(x3，y3，z3)；
7) according to step 6), a vector is derived
Figure BDA0003302931450000097
And
Figure BDA0003302931450000098
Figure BDA0003302931450000099
Figure BDA00033029314500000910
8) judging whether the three points A, B and C are on the same straight line:
if it is
Figure BDA00033029314500000911
The control processor 7 readsTake down a set of data D (x)4，y4，z4) And obtaining the vector by adopting the method of the step 7)
Figure BDA00033029314500000912
And
Figure BDA00033029314500000913
and judge
Figure BDA00033029314500000914
And
Figure BDA00033029314500000915
whether the two vectors are on the same straight line, if
Figure BDA00033029314500000916
And
Figure BDA00033029314500000917
on the same straight line, repeating the step 7) and the step 8);
9) according to step 8), when
Figure BDA00033029314500000918
Then, the sphere center coordinates defining a sphere are O' (a, b, c), by the following three equations:
Figure BDA0003302931450000101
Figure BDA0003302931450000102
Figure BDA0003302931450000103
result in O' (a)0，b0，c0)；
10) According to the step 9), the radius of the sphere is calculated three times according to the distance from the center of the sphere to the three points A, B and C, and the calculation formula is as follows:
Figure BDA0003302931450000104
Figure BDA0003302931450000105
Figure BDA0003302931450000106
then to the calculated R1，R2And R3Averaging
Figure BDA0003302931450000107
Then:
Figure BDA0003302931450000108
and calculated
Figure BDA0003302931450000109
Displayed by the display control panel 6.
In the embodiment, the two arc-shaped shells 1 are tightly bound at the ankle, and the ankle is positioned in the ankle groove 4, so that each group of measured data can be ensured to be data of the ankle, and the length of the lower limb can be accurately obtained; a space rectangular coordinate system can be obtained by correcting through the display control panel 6, so that the position information is specified, and the relative position of each point can be obtained; acceleration values in the x, y and z directions are obtained every 0.01s, so that the average speed between every two moments can be accurately calculated, a group of position information is obtained every 2s, and the position of the ankle of every 2s can be accurately obtained; judging whether the obtained three points are not on the same straight line by a method of whether the vectors are parallel or not, and ensuring that the obtained three position points can form a spherical surface; the distance from the center of sphere to each point can be obtained by calculating the coordinates of the center of sphere, and two decimal places are reserved for the three calculated distance values by the control processor 7 when the distance is calculated; the calculation accuracy can be improved by averaging the distances from the center of sphere to each point.
The working principle is as follows: the outer side wall of the arc-shaped shell 1 is provided with the measuring device, so that the length of the lower limb of a patient can be accurately obtained; two width adjusting belts 5 are arranged between the arc-shaped shells 1, so that the lower limbs with different thicknesses can be suitable; the ankle groove 4 is formed in the arc-shaped shell 1, so that the limiting effect is achieved, and the length of the lower limb can be accurately measured; the two arc-shaped shells 1 are tightly bound at the ankle, and the ankle is positioned in the ankle groove 4, so that the measured data of each group at the ankle can be ensured, and the length of the lower limb can be accurately obtained; a space rectangular coordinate system can be obtained by correcting through the display control panel 6, so that the position information is specified; acceleration values in the x, y and z directions are obtained every 0.01s, so that the average speed between every two moments can be accurately obtained, and the position of each 2s ankle can be accurately obtained; judging whether the obtained three points are not on the same straight line by a method of whether the vectors are parallel or not, and ensuring that the obtained three position points can form a spherical surface; the distance from the sphere center to each point can be obtained by calculating the coordinates of the sphere center; the calculation accuracy can be improved by averaging the distances from the center of sphere to each point.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims (5)

1. A lower limb length measuring device for hip joint replacement is characterized in that: the ankle joint comprises two arc-shaped shells (1), wherein ankle grooves (4) are formed in the two arc-shaped shells (1); the outer side wall of the arc-shaped shell (1) is provided with a measuring device, two width adjusting belts (5) are arranged between the arc-shaped shell (1), and two ends of each width adjusting belt (5) are respectively connected with the end parts of the two arc-shaped shells (1).
2. The device for measuring the length of a lower limb for hip replacement according to claim 1, wherein: the measuring device comprises 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 fixedly connected with the outer side wall of the arc-shaped shell (1); the control processor (7) is positioned in the arc-shaped shell (1).
3. The device for measuring the length of a lower limb for hip replacement according to claim 2, wherein: the three-axis acceleration sensor (3) is positioned at the ankle groove (4).
4. The device for measuring the length of a lower limb for hip replacement according to claim 1, wherein: the inner side wall of the arc-shaped shell (1) is provided with a soft gasket (2).
5. A lower limb length measuring method for hip joint replacement is characterized in that: the method comprises the following steps:
1) tightly binding the two arc-shaped shells (1) at the ankle, and fixing the two arc-shaped shells (1) through a width adjusting belt (5) connected with the end parts of the arc-shaped shells (1), wherein the ankle is positioned in the ankle groove (4);
2) by utilizing a display control panel (6) arranged on the outer side wall of the arc-shaped shell (1), a corrected space rectangular coordinate system is obtained by clicking a correction button in a display interface of the display control panel (6), and after the correction button is clicked, the initial position of the ankle is 0 point; then, a triaxial acceleration sensor (3) of an ankle groove (4) arranged on the arc-shaped shell (1) is utilized to record the acceleration ac in the x, y and z directions of a space rectangular coordinate systemx，acy，acz；
3) Of a rotary-ankle, three-axis acceleration sensor (3)The measured values start to change, the time is started by using a timer (8), and a group of acceleration values are recorded every 0.01s, and the following data are measured: (ac)x1，acy1，acz1)；(acx2，acy2，acz2)；(acx3，acy3，acz3)；(acx4，acy4，acz4)……(acxi，acyi，aczi)；
4) Calculating the average speed between every two moments by a calculation program in an implantation control processor (7) according to the data measured in the step 3), wherein the calculation formula is as follows:
Figure FDA0003302931440000021
Figure FDA0003302931440000022
Figure FDA0003302931440000023
5) according to the step 4), the displacements in the three directions of x, y and z are obtained by superposition, and the calculation formula is as follows:
Figure FDA0003302931440000024
Figure FDA0003302931440000025
Figure FDA0003302931440000026
6) the timer (8) counts every 2s, and the control processor (7) reads a set of spatial coordinates (x, y, z) such that:
A(x1，y1，z1)，B(x2，y2，z2)，C(x3，y3，z3)；
7) according to step 6), a vector is derived
Figure FDA0003302931440000027
And
Figure FDA0003302931440000028
Figure FDA0003302931440000029
Figure FDA00033029314400000210
8) judging whether the three points A, B and C are on the same straight line:
if it is
Figure FDA0003302931440000031
The control processor (7) reads the next set of data D (x)4，y4，z4) And obtaining the vector by adopting the method of the step 7)
Figure FDA0003302931440000032
And
Figure FDA0003302931440000033
and judge
Figure FDA0003302931440000034
And
Figure FDA0003302931440000035
whether the two vectors are on the same straight line, if
Figure FDA0003302931440000036
And
Figure FDA0003302931440000037
on the same straight line, repeating the step 7) and the step 8);
9) according to step 8), when
Figure FDA0003302931440000038
Then, the sphere center coordinates defining a sphere are O' (a, b, c), by the following three equations:
Figure FDA0003302931440000039
Figure FDA00033029314400000310
Figure FDA00033029314400000311
result in O' (a)0，b0，c0)；
10) According to the step 9), the radius of the sphere is calculated three times according to the distance from the center of the sphere to the three points A, B and C, and the calculation formula is as follows:
Figure FDA00033029314400000312
Figure FDA00033029314400000313
Figure FDA00033029314400000314
then to the calculated R1，R2And R3Averaging
Figure FDA00033029314400000315
Then:
Figure FDA00033029314400000316
and calculated
Figure FDA00033029314400000317
Displayed through a display control panel (6).
CN202111195883.2A 2021-10-14 2021-10-14 Lower limb length measuring device and method for hip joint replacement Pending CN113995560A (en)

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