Method and apparatus for calculating postoperative offset and length difference in hip arthroplasty

Abstract

The application provides a calculation and evaluation method and device for postoperative offset and length difference of hip arthroplasty. The method comprises the following steps: preoperatively, the femur in the CT image is aligned according to the characteristic points, and the preoperative length difference and offset are calculated; intraoperatively, the hip bone is registered to the navigation camera coordinate system, the femur on the surgical side is placed in the natural position, a marker nail is installed at the edge of the greater trochanter of the femur, an electrode sheet is attached to the lower edge of the patella of the knee joint, and the positions of the marker nail and the electrode sheet are registered to the navigation camera by using a probe; postoperatively, the femur on the surgical side is placed in the natural position, the positions of the marker nail and the electrode sheet at this time are registered to the navigation camera by using the probe, and the positioning is corrected; and the postoperative length difference and offset are calculated. The application simplifies the surgical procedure and operation for calculating the postoperative length difference and offset, saves the operation time, reduces the additional operation of the doctor in the operation, and simultaneously provides a relatively accurate calculation and evaluation method.

Description

Technical Field

[0001] This invention relates to the field of medical technology, specifically to a method and apparatus for calculating and evaluating the difference between offset and length after hip replacement surgery. Background Technology

[0002] Existing hip replacement surgery usually includes two types of methods: traditional artificial replacement and surgical robot-assisted replacement. In traditional artificial replacement surgery, the calculation and evaluation of postoperative offset and length difference need to be measured with the help of postoperative CT images, including linear measurement method, three-dimensional reconstruction measurement method, comparative analysis method, etc. There are two main methods for measuring offset and length difference after surgical robot-assisted hip replacement: (1) Install bone pins and reflective arrays in the middle of the femur on the surgical side. Before the operation, use a probe with reflective array to collect feature points on the surgical side of the patient's femur. Then, use software to perform point cloud registration and finally obtain the position information on the femur. Then, use certain features, such as adjusting the internal rotation, abduction, and flexion of the femur to 0, to determine the standard femur position and then calculate the length difference and offset; (2) Install marking nails on the lateral aspect of the greater trochanter of the femur and the lower edge of the patella of the knee joint as proximal and distal examination points, respectively. Use probes to collect points on the marking nails before and after the operation for approximate calculation and evaluation.

[0003] Furthermore, in traditional hip arthroplasty, measurements using CT images are typically performed post-surgery, preventing adjustments to the prosthesis based on the results. Even if the surgical outcome is poor, resulting in significant post-operative length discrepancies and eccentricities, there's no way to readjust the prosthesis through a second surgery. Additionally, CT scans can cause radiation damage to patients, and accurate CT image measurement and analysis require experienced radiologists or technicians. In robot-assisted hip replacement, the first method is cumbersome and time-consuming, requiring point cloud registration of femoral feature points, increasing surgical complexity. The second method suffers from inconsistencies in femoral positioning before and after surgery, introducing errors and significantly reducing the reliability of the results. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technical solutions described in the background section, and to provide a method and apparatus for calculating and evaluating the offset and length difference after hip replacement surgery. This method is based on information acquired during preoperative planning and surgery, eliminating the need for additional operations such as postoperative CT imaging analysis, and avoiding cumbersome operations such as installing a reflective array on the femur, acquiring femoral side feature points, and performing point cloud registration using software. It provides a simple and accurate method for calculating length difference and offset in robot-assisted hip replacement.

[0005] This invention is achieved through the following technical solution: In a first aspect, this invention provides a method for calculating and evaluating the difference between offset and length after hip replacement surgery, comprising the following steps: S101, before the operation, the femur in the CT image is aligned according to the feature points using preoperative planning software, and the length difference and offset before hip replacement surgery are calculated. S102, during the operation, the patient's hip bone is registered to the coordinate system of the navigation camera, the femur on the operated side is positioned in its natural position, a marker pin is installed at the edge of the greater trochanter of the femur, an electrode pad is attached to the lower edge of the patella of the knee joint, and a probe with an array is used to register the positions of the marker pin and the electrode pad to the navigation camera respectively. S103, after the operation, the femur on the operated side is positioned in its natural position, and the positions of the marker pins and electrode pads at this time are registered to the navigation camera using a probe with an array, and the positioning is corrected. S104, calculate the length difference and eccentricity after hip replacement surgery, and evaluate the surgical effect.

[0006] Furthermore, in S101, the preoperative planning software is used to align the femur in the CT image according to the feature points, and the length difference and offset before hip replacement surgery are calculated, including: Before the operation, the femur in the patient's CT image was aligned according to the feature points using preoperative planning software, that is, the femoral range of motion, internal rotation, abduction, and flexion were all 0. By obtaining the CT coordinate system under the natural alignment of the femur, and combining the coordinates of the bilateral anterior superior iliac spines and the lesser trochanter of the femur with the position of the midline, the length difference and eccentricity before hip replacement surgery are calculated.

[0007] Furthermore, the positioning correction described in S103 includes the following steps: According to the preoperative planning, the coordinates of the center point of the acetabulum in the CT coordinate system are obtained and transformed into the hip bone array coordinate system. At the same time, the coordinates of the two points, the preoperative marked pin position and the electrode position, form plane A. Because the center point of the acetabular fossa after the prosthesis replacement differs from the preoperatively planned center point of the acetabular fossa, a probe is used to collect 6 points along the rim of the acetabular cup after the prosthesis replacement. The 6 collected points are then fitted into a circle using software calculation methods to obtain the center of the circle. The fitted center point, together with the postoperative marking pin position and the electrode pad position, form plane B. Using software calculation methods, plane B is rotated around the fitted center point until it is parallel to plane A, thus obtaining the rotation matrix P; Based on rotating plane B to be parallel to plane A, the line connecting the postoperative marker pin position and the electrode position is rotated around the fitted center point to be parallel to the line connecting the preoperative marker pin position and the electrode position, thus obtaining the rotation matrix L; The positions of the postoperative marker pins were multiplied by rotation matrix P and rotation matrix L respectively to obtain the postoperative marker pin positions after positioning correction.

[0008] Furthermore, the calculation of the length difference after hip replacement surgery described in S104 includes: In the hip bone array coordinate system, calculate the distance from the preoperative and postoperative marking pin positions to the anterior superior iliac spine of the femur on the surgical side; Subtract the obtained distances to get the distance difference between a point on the same femur position and the anterior superior iliac spine of the femur on the operated side before and after the operation. Combine this with the length difference of the femur in its natural alignment state calculated by CT before the operation to get the length difference after the operation.

[0009] Furthermore, the calculation of the eccentricity after hip replacement surgery described in S104 includes: In the hip bone array coordinate system, calculate the distance from the preoperative and postoperative marking pin positions to the midline of the hip bone, respectively; Subtract the obtained distances to get the distance difference between a point on the same femur position and the midline of the hip bone before and after the operation. Combine this with the preoperative eccentricity of the femur calculated from CT scans in a naturally aligned state to obtain the postoperative eccentricity.

[0010] In a second aspect, the present invention also provides a device for calculating and evaluating the difference between offset and length after hip replacement surgery, comprising: The module for calculating preoperative length difference and offset uses preoperative planning software to align the femur in the CT image according to the feature points before surgery and calculates the preoperative length difference and offset of hip replacement surgery. The registration module registers the patient's hip bone into the coordinate system of the navigation camera during the operation, positions the femur on the operated side in its natural position, installs a marker pin on the edge of the greater trochanter of the femur, attaches an electrode pad to the lower edge of the patella of the knee joint, and uses a probe with an array to register the positions of the marker pin and the electrode pad into the navigation camera respectively. The positioning correction module positions the operated femur to its natural position post-surgery, and uses an array of probes to register the positions of the marker pins and electrode pads to the navigation camera for positioning correction. The calculation and evaluation module calculates the length difference and eccentricity after hip replacement surgery and evaluates the surgical outcome.

[0011] Thirdly, the present invention also provides a device for calculating and evaluating the difference between offset and length after hip replacement surgery. The device includes a processor, a memory, and computer program instructions stored in the memory and executable on the processor. The processor is used to execute the computer program instructions stored in the memory to implement the above-described method for calculating and evaluating the difference between offset and length after hip replacement surgery.

[0012] Fourthly, the present invention also provides a computer storage medium for calculating and evaluating the difference between offset and length after hip replacement surgery. The computer storage medium stores computer program instructions, which, when executed by a processor, implement the above-described method for calculating and evaluating the difference between offset and length after hip replacement surgery.

[0013] This invention provides a method and apparatus for calculating and evaluating the difference between offset and length after hip replacement surgery, which has the following technical advantages compared with the prior art: 1. Obtaining the calculation and assessment results of the eccentricity and length difference immediately after surgery facilitates doctors' timely evaluation of the surgical effect and determines whether on-site revision is necessary; 2. It simplifies the surgical procedure and operation for calculating and assessing postoperative length difference and eccentricity, saves surgical time, reduces the amount of extra work required by doctors during surgery, and provides a more accurate calculation and assessment method. Attached Figure Description

[0014] The features, advantages and technical effects of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0015] Figure 1 This is a schematic diagram of the calculation and evaluation method for the difference between eccentricity and length after hip replacement surgery provided in this embodiment of the invention. Figure 2 This is a schematic diagram of the device for calculating and evaluating the difference between offset and length after hip replacement surgery provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of a computing device provided in an embodiment of the present invention. Detailed Implementation

[0016] The features and exemplary embodiments of various aspects of this disclosure will now be described in detail. To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, will provide a further detailed description. It should be understood that the specific embodiments described herein are intended only to explain this disclosure and not to limit it. For those skilled in the art, this disclosure can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this disclosure by illustrating examples.

[0017] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0018] To better understand the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of the calculation and evaluation method for the difference between offset and length after hip replacement surgery provided in this embodiment of the invention.

[0020] like Figure 1 As shown, this invention provides a method for calculating and evaluating the difference between offset and length after hip replacement surgery, including the following steps: S101, before the operation, the femur in the CT image is aligned according to the feature points using preoperative planning software, and the length difference and offset before hip replacement surgery are calculated. S102, during the operation, the patient's hip bone is registered to the navigation camera coordinate system, the femur on the operated side is positioned in its natural position, a marker pin is installed at the edge of the greater trochanter of the femur, an electrode pad is attached to the lower edge of the patella of the knee joint, and a probe with an array is used to register the positions of the marker pin and the electrode pad to the navigation camera respectively. S103, after the operation, the femur on the operated side is positioned in its natural position, and the positions of the marker pins and electrode pads at this time are registered to the navigation camera using a probe with an array, and the positioning is corrected. S104, calculate the length difference and eccentricity after hip replacement surgery, and evaluate the surgical effect.

[0021] As an optional implementation, the navigation camera is a binocular camera. The coordinate system of the navigation camera is established as follows: with the left eye of the binocular camera as the coordinate center, the horizontal axis parallel to the camera surface is the X-axis, the axis perpendicular to the camera surface and outward is the Z-axis, and the Y-axis is determined according to the right-hand rule.

[0022] As an optional implementation, registering the patient's hip bone to the navigation camera coordinate system as described in S102 includes: Bone pins and reflective arrays were installed on the surgical side of the hip. The same probe with a reflective array is used to collect the registration points on the surgical side of the hip bone, and sparse point cloud registration is performed with the preoperative segmented and reconstructed bone model to register the hip bone in the navigation camera coordinate system.

[0023] As an optional implementation, in S101, the femur in the CT image is aligned according to feature points using preoperative planning software, and the length difference and eccentricity before hip replacement surgery are calculated, including: Before the operation, the femur in the patient's CT image was aligned according to the feature points using preoperative planning software, that is, the femoral range of motion, internal rotation, abduction, and flexion were all 0. By obtaining the CT coordinate system under the natural alignment of the femur, and combining the coordinates of the bilateral anterior superior iliac spines and the lesser trochanter of the femur with the position of the midline, the length difference and eccentricity before hip replacement surgery are calculated.

[0024] As an optional implementation, the positioning correction described in S103 includes the following steps: According to the preoperative planning, the coordinates of the center point of the acetabulum in the CT coordinate system are obtained and transformed into the hip bone array coordinate system. At the same time, the coordinates of the two points, the preoperative marked pin position and the electrode position, form plane A. Because the center point of the acetabular fossa after the prosthesis replacement differs from the preoperatively planned center point of the acetabular fossa, a probe is used to collect 6 points along the rim of the acetabular cup after the prosthesis replacement. The 6 collected points are then fitted into a circle using software calculation methods to obtain the center of the circle. The fitted center point, together with the postoperative marking pin position and the electrode pad position, form plane B. Using software calculation methods, plane B is rotated around the fitted center point until it is parallel to plane A, thus obtaining the rotation matrix P; Based on rotating plane B to be parallel to plane A, the line connecting the postoperative marker pin position and the electrode position is rotated around the fitted center point to be parallel to the line connecting the preoperative marker pin position and the electrode position, thus obtaining the rotation matrix L; The positions of the postoperative marker pins were multiplied by rotation matrix P and rotation matrix L respectively to obtain the postoperative marker pin positions after positioning correction.

[0025] As an optional implementation, the hip bone array includes an array support and three reflective stickers, each detachably mounted on the array support and recognizable by a navigation camera. The hip bone array coordinate system is determined by the positions of the three reflective stickers: the center point of the hip bone array is determined based on the center positions of the three reflective stickers, and this center point is taken as the origin of the hip bone array coordinate system. The plane containing the centers of the three reflective stickers is the XOY plane, the axis perpendicular to this plane and pointing outwards is the Z-axis, the extension of the line connecting the origin to any one of the reflective sticker center points is the Y-axis, and the direction of the X-axis is determined by the cross product.

[0026] As an optional implementation, the calculation of the length difference after hip replacement surgery in S104 includes: In the hip bone array coordinate system, calculate the distance from the preoperative and postoperative marking pin positions to the anterior superior iliac spine of the femur on the surgical side; Subtract the obtained distances to get the distance difference between a point on the same femur position and the anterior superior iliac spine of the femur on the operated side before and after the operation. Combine this with the length difference of the femur in its natural alignment state calculated by CT before the operation to get the length difference after the operation.

[0027] As an optional implementation, the calculation of the eccentricity after hip replacement surgery in S104 includes: In the hip bone array coordinate system, calculate the distance from the preoperative and postoperative marking pin positions to the midline of the hip bone, respectively; Subtract the obtained distances to get the distance difference between a point on the same femur position and the midline of the hip bone before and after the operation. Combine this with the preoperative eccentricity of the femur calculated from CT scans in a naturally aligned state to obtain the postoperative eccentricity.

[0028] As an alternative implementation method, the surgical outcome can be assessed in a timely manner by comparing the preoperative length difference and eccentricity with the postoperative length difference and eccentricity.

[0029] like Figure 2 As shown, the present invention also provides a device for calculating and evaluating the difference between offset and length after hip replacement surgery, comprising: The module 201 calculates the preoperative length difference and eccentricity. Before the operation, the femur in the CT image is aligned according to the feature points using preoperative planning software, and the preoperative length difference and eccentricity of the hip replacement are calculated. Registration module 202: During the operation, the patient's hip bone is registered to the coordinate system of the navigation camera, the femur on the operated side is positioned in its natural position, a marker pin is installed at the edge of the greater trochanter of the femur, an electrode pad is attached to the lower edge of the patella of the knee joint, and a probe with an array is used to register the positions of the marker pin and the electrode pad to the navigation camera respectively. Positioning correction module 203: After surgery, the femur on the operated side is positioned in its natural position. The positions of the marker pins and electrode pads at this time are registered to the navigation camera using a probe with an array, and positioning correction is performed. The calculation and evaluation module 204 calculates the length difference and eccentricity after hip replacement surgery and evaluates the surgical effect.

[0030] Figure 2 Each module / unit in the illustrated device has the ability to implement Figure 1 The functions of each step in the process and their corresponding technical effects are described in detail here for the sake of brevity.

[0031] like Figure 3 As shown, the present invention also provides a device for calculating and evaluating the difference between offset and length after hip replacement surgery. The device includes a processor 301, a memory 302, and computer program instructions stored in the memory 302 and executable on the processor 301. The processor 301 is used to execute the computer program instructions stored in the memory 302 to implement the above-described method for calculating and evaluating the difference between offset and length after hip replacement surgery.

[0032] Specifically, the processor 301 may include a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the present invention.

[0033] Memory 302 may include mass storage for data or instructions. For example, and not as a limitation, memory may include hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these.

[0034] In one instance, memory 302 may include removable or non-removable (or fixed) media, or the memory may be non-volatile solid-state memory. The memory may be internal or external to the integrated gateway disaster recovery device.

[0035] In one instance, memory 302 may be read-only memory (ROM). In one instance, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM), or flash memory, or a combination of two or more of these.

[0036] In one example, memory 302 may include read-only memory (ROM), random access memory (RAM), disk storage media device, optical storage media device, flash memory device, electrical, optical, or other physical / tangible memory storage device. Thus, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to one aspect of this disclosure.

[0037] The processor 301 reads and executes computer program instructions stored in the memory 302 to achieve... Figure 1 The methods / steps in the illustrated embodiments, and their corresponding technical effects, will not be elaborated further here for the sake of brevity.

[0038] In one embodiment, the computing device may further include a communication interface 303 and a bus 304. For example... Figure 3 As shown, the processor 301, memory 302, and communication interface 303 are connected through bus 304 and complete communication with each other.

[0039] The communication interface 303 is mainly used to realize communication between various modules, devices, units and / or equipment in this invention.

[0040] Bus 304 includes hardware, software, or both, that couples components of an online data flow metering device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Extended Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, the bus may include one or more buses. Although specific buses are described and illustrated in this invention, this disclosure contemplates any suitable bus or interconnect.

[0041] In addition, in conjunction with the method for calculating and evaluating the difference between offset and length after hip replacement surgery in the above embodiments, the present invention also provides a computer storage medium for implementation, wherein the computer storage medium stores computer program instructions, and the computer program instructions are executed by a processor to implement the above-mentioned method for calculating and evaluating the difference between offset and length after hip replacement surgery.

[0042] The computer storage medium provided in this invention can be any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. For example, a computer-readable storage medium can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this invention, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0043] This invention provides a method and apparatus for calculating and evaluating the difference between offset and length after hip replacement surgery, which has the following technical advantages compared with the prior art: 1. Obtaining the calculation and assessment results of the eccentricity and length difference immediately after surgery facilitates doctors' timely evaluation of the surgical effect and determines whether on-site revision is necessary; 2. It simplifies the surgical procedure and operation for calculating and assessing postoperative length difference and eccentricity, saves surgical time, reduces the amount of extra work required by doctors during surgery, and provides a more accurate calculation and assessment method.

[0044] It should be clarified that this disclosure is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this disclosure is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this disclosure.

[0045] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this disclosure are programs or code segments used to perform the required tasks. Those skilled in the art can write computer program code for performing the operations of this invention in one or more programming languages ​​or combinations thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages—such as the "C" language or similar programming languages. Furthermore, the program or code segment can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. A machine-readable medium can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc.

[0046] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0047] The above description is merely a specific embodiment of this disclosure. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this disclosure is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this disclosure, and these modifications or substitutions should all be covered within the protection scope of this disclosure.

Claims

1. A device for calculating and evaluating the difference between offset and length after hip replacement surgery, characterized in that, The device includes: a processor, a memory, and computer program instructions stored in the memory and executable on the processor, wherein the processor is used to execute the computer program instructions stored in the memory to implement a method for calculating and evaluating the difference between offset and length after hip replacement surgery. The method for calculating and evaluating the difference between the offset and length after hip arthroplasty includes the following steps: S101, before the operation, the femur in the CT image is aligned according to the feature points using preoperative planning software, and the length difference and offset before hip replacement surgery are calculated. S102, during the operation, the patient's hip bone is registered to the coordinate system of the navigation camera, the femur on the operated side is positioned in its natural position, a marker pin is installed at the edge of the greater trochanter of the femur, an electrode pad is attached to the lower edge of the patella of the knee joint, and a probe with an array is used to register the positions of the marker pin and the electrode pad to the navigation camera respectively. S103, after the operation, the femur on the operated side is positioned in its natural position, and the positions of the marker pins and electrode pads at this time are registered to the navigation camera using a probe with an array, and the positioning is corrected. S104, calculate the length difference and eccentricity after hip replacement surgery, and evaluate the surgical effect; The placement correction described in S103 includes the following steps: According to the preoperative planning, the coordinates of the center point of the acetabulum in the CT coordinate system are obtained and transformed into the hip bone array coordinate system. At the same time, the coordinates of the two points, the preoperative marked pin position and the electrode position, form plane A. Because the center point of the acetabular fossa after the prosthesis replacement differs from the preoperatively planned center point of the acetabular fossa, a probe is used to collect 6 points along the rim of the acetabular cup after the prosthesis replacement. The 6 collected points are then fitted into a circle using software calculation methods to obtain the center of the circle. The fitted center point, together with the postoperative marking pin position and the electrode pad position, form plane B. Using software calculation methods, plane B is rotated around the fitted center point until it is parallel to plane A, thus obtaining the rotation matrix P; Based on rotating plane B to be parallel to plane A, the line connecting the postoperative marker pin position and the electrode position is rotated around the fitted center point to be parallel to the line connecting the preoperative marker pin position and the electrode position, thus obtaining the rotation matrix L; The positions of the postoperative marker pins were multiplied by rotation matrix P and rotation matrix L respectively to obtain the postoperative marker pin positions after positioning correction.

2. The device for calculating and evaluating the difference in eccentricity and length after hip replacement surgery according to claim 1, characterized in that, S101 describes the preoperative alignment of the femur in the CT image using preoperative planning software, based on feature point alignment, and the calculation of the length difference and offset before hip replacement surgery, including: Before the operation, the femur in the patient's CT image was aligned according to the feature points using preoperative planning software, that is, the femoral range of motion, internal rotation, abduction, and flexion were all 0. By obtaining the CT coordinate system under the natural alignment of the femur, and combining the coordinates of the bilateral anterior superior iliac spines and the lesser trochanter of the femur with the position of the midline, the length difference and eccentricity before hip replacement surgery are calculated.

3. The device for calculating and evaluating the difference in eccentricity and length after hip replacement surgery according to claim 1, characterized in that, The calculation of the length difference after hip replacement surgery as described in S104 includes: In the hip bone array coordinate system, calculate the distance from the preoperative and postoperative marking pin positions to the anterior superior iliac spine of the femur on the surgical side; Subtract the obtained distances to get the distance difference between a point on the same femur position and the anterior superior iliac spine of the femur on the operated side before and after the operation. Combine this with the length difference of the femur in its natural alignment state calculated by CT before the operation to get the length difference after the operation.

4. The device for calculating and evaluating the difference between offset and length after hip replacement surgery according to claim 1, characterized in that, The calculation of the eccentricity after hip replacement surgery described in S104 includes: In the hip bone array coordinate system, calculate the distance from the preoperative and postoperative marking pin positions to the midline of the hip bone, respectively; Subtract the obtained distances to get the distance difference between a point on the same femur position and the midline of the hip bone before and after the operation. Combine this with the preoperative eccentricity of the femur calculated from CT scans in a naturally aligned state to obtain the postoperative eccentricity.

5. A device for calculating and evaluating the difference between offset and length after hip arthroplasty, based on the method for calculating and evaluating the difference between offset and length after hip arthroplasty according to any one of claims 1-4, characterized in that, include: The module for calculating preoperative length difference and offset uses preoperative planning software to align the femur in the CT image according to the feature points before surgery and calculates the preoperative length difference and offset of hip replacement surgery. The registration module registers the patient's hip bone into the coordinate system of the navigation camera during the operation, positions the femur on the operated side in its natural position, installs a marker pin on the edge of the greater trochanter of the femur, attaches an electrode pad to the lower edge of the patella of the knee joint, and uses a probe with an array to register the positions of the marker pin and the electrode pad into the navigation camera respectively. The positioning correction module positions the operated femur to its natural position post-surgery, and uses an array of probes to register the positions of the marker pins and electrode pads to the navigation camera for positioning correction. The calculation and evaluation module calculates the length difference and eccentricity after hip replacement surgery and evaluates the surgical outcome.

6. A computer storage medium for calculating and evaluating the difference between offset and length after hip replacement surgery, characterized in that, The computer storage medium stores computer program instructions, which, when executed by a processor, implement the method for calculating and evaluating the difference between offset and length after hip replacement surgery as described in any one of claims 1 to 4.

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