阅读说明：本技术 基于CT扫描的Taylor支架参数测量方法 (Taylor support parameter measuring method based on CT scanning ) 是由 陆永华 张宇 梁立鹏 于 2019-10-14 设计创作，主要内容包括：本发明涉及Stewart平台参数求解技术领域,更具体的说,是基于CT扫描的Taylor支架参数测量方法。本发明包括S1：将Taylor支架经过手术装在打断的患者畸形腿骨上,根据骨折畸形部位和具体情况选择不同大小的环和不同长短的支撑杆,进行个体化安装；S2：对已安装好Taylor支架畸形腿骨和对应完好健康的腿骨进行CT扫描,取得DICOM格式文件并进行三维重建导出三维模型,去除软组织等干扰因素。本发明能对骨折畸形进行精确矫正复位,有利于骨折愈合及患肢功能恢复,具有很高的医学价值和社会效益。(The invention relates to the technical field of Stewart platform parameter solving, in particular to a Taylor support parameter measuring method based on CT scanning. The invention comprises S1: installing a Taylor bracket on the broken deformed leg bone of a patient through an operation, selecting rings with different sizes and supporting rods with different lengths according to the fracture deformed part and the specific condition, and performing individualized installation; s2: and carrying out CT scanning on the deformed leg bone with the installed Taylor bracket and the corresponding intact and healthy leg bone, obtaining a DICOM format file, carrying out three-dimensional reconstruction, deriving a three-dimensional model, and removing interference factors such as soft tissues. The invention can accurately correct and reset the fracture deformity, is beneficial to fracture healing and affected limb function recovery, and has high medical value and social benefit.)

1. The Taylor bracket parameter measuring method based on CT scanning is characterized in that:

s1: the Taylor bracket is arranged on the malformed leg bone of a broken patient through an operation, rings with different sizes and supporting rods with different lengths are selected according to the fracture malformed part and the specific situation, and individualized installation is carried out.

S2: and carrying out CT scanning on the deformed leg bone with the installed Taylor bracket and the corresponding intact and healthy leg bone, obtaining a DICOM format file, carrying out three-dimensional reconstruction, deriving a three-dimensional model, and removing interference factors such as soft tissues.

S3: acquiring normal, lateral and axial position images of the three-dimensional model of the malformed leg bone of the installed Taylor bracket, carrying out image processing on each image, selecting the midpoint of a proximal bone as an angulation rotation central point, and measuring 6 malformed parameters and 4 installation parameters of the Taylor bracket; and acquiring the normal position, lateral position and axial position images of the healthy leg bones, measuring 6 posture parameters after processing, and calculating the posture of the deformed leg bones after adjustment.

S4: establishing a mathematical model of the Taylor bracket, reading the initial rod length of 6 adjusting rods of the Taylor bracket arranged on the malformed leg bone, calculating the final rod length of the 6 adjusting rods of the Taylor bracket by utilizing a 6-dimensional parallel mechanism kinematic inverse solution model and parameters obtained by measurement, and determining the rod length adjusting length of each day according to the adjusting time.

2. The method for measuring Taylor stent parameters based on CT scanning according to claim 1, wherein: the image obtained by CT tomography is utilized, the image processing means is utilized, the interference factors such as soft tissues and the like are eliminated, the three-dimensional image of the target skeleton is constructed, and the accurate pose information of the target skeleton is obtained.

3. The method for measuring Taylor stent parameters based on CT scanning according to claim 1, wherein: respectively carrying out image processing on the positive position, lateral position and axial position images of the malformed leg and the normal leg, and obtaining 6 malformed parameters and 4 installation parameters of the Taylor bracket and ideal 6 posture parameters after correction by using a computer-aided measurement method.

4. The method for measuring Taylor stent parameters based on CT scanning according to claim 1, wherein: and calculating the final rod length of the 6 adjusting rods of the Taylor bracket by using a mathematical method of a 6-dimensional parallel mechanism kinematic inverse solution model, and calculating the daily adjusting quantity of each rod according to actual conditions.

5. The method for measuring Taylor stent parameters based on CT scanning according to claim 1, wherein: the malformed bones not only leg bones but also other extremity bones and ankles can be accurately corrected and repaired by the method.

Technical Field

The invention relates to the technical field of Stewart platform parameter solving, in particular to a Taylor support parameter measuring method based on CT scanning.

Background

At present, an external bone fixator is widely applied as a micro-invasive tool for reduction and fixation, can provide quick and effective treatment for complicated wound fracture, has the advantages of irreplaceable internal fixation, small wound and wide adaptation diseases, and can provide stable and elastic fixation for broken ends of bones. Taylor improved the Ilizarow external fixator system in 1994 according to Stewart platform and Charles theorem and used in the field of external fixation of bones, forming a taylor spatial external fixation scaffold.

The outer fixed bolster in taylor space has 6 telescopic bracing pieces, and both ends are connected on solid fixed ring, can freely rotate at the junction. As long as the length of any one of the support rods is adjusted, one ring changes spatial position relative to the other ring. The same framework treatment can be used for both simple and complex deformities. In combination with a specially designed computer program, it is possible to treat multiple angulation and displacement deformities simultaneously by simply telling the computer the parameters of the deformity of the bone and the parameters of the frame to adjust the support bar according to the given support bar length given by the computer. When performing deformity correction, the reference bone segment is considered stationary, so 10 parameters need to be measured, including 6 deformity parameters and 4 installation parameters.

At present, in order to obtain 10 parameters of the Taylor stent, the traditional method is to obtain X-ray films of the bone normal position, the side position and the axial position, and the X-ray films are directly measured by using a vernier caliper and a geometric method, and the method often has many errors: (1) x-ray films taken often cannot be standardized; (2) certain errors exist in the direct manual measurement on the X-ray film; (3) because of the projection problem, the shooting of the outer fixed ring is incomplete, and the error caused by the center of the ring cannot be accurately found; (4) because the axial rotation angle of the affected limb and the axial deflection angle of the reference ring cannot be accurately measured on the positive X-ray slice, the multiple errors are superposed together, and the resetting effect is unsatisfactory. At present, during measurement, the requirement of matched software is required to be carried out on a standard positive lateral X-ray, and because manual measurement errors necessarily exist, multiple times of shooting, measurement and adjustment are often needed to achieve satisfactory fracture reduction. And the limbs can not be ensured to be positioned at the same position during shooting each time, so that the limbs are easy to change in angle to cause inconsistent measurement before and after shooting.

Aiming at the problem, the invention provides a Taylor bracket parameter measuring method based on CT scanning. The method has the advantages that the specific three-dimensional model of the skeleton is reconstructed by the CT tomography data of the skeleton through the steps of threshold selection, image editing and the like, the 6 malformation parameters and 4 installation parameters required by the Taylor external fixation support system are accurately defined by computer-aided measurement, the fracture malformation is accurately corrected and reset, and the method is favorable for fracture healing and function recovery of affected limbs.

Disclosure of Invention

The invention aims to provide a method for processing three-dimensional model normal position, side position and axial position pictures acquired by CT scanning by utilizing an image processing mode to acquire 6 malformation parameters and 4 installation parameters of a Taylor external fixation bracket and 6 posture parameters of an intact healthy bone, so as to realize accurate correction of the Taylor external fixation bracket on skeletal malformation.

In order to achieve the purpose, the Taylor bracket parameter measuring method based on CT scanning mainly comprises the following processes:

s1: the Taylor bracket is arranged on the malformed leg bone of the interrupted patient through the operation, rings with different sizes and adjusting support rods with different lengths are selected according to the fracture malformed part and the specific situation, and the individualized installation is carried out.

S2: and carrying out CT scanning on the deformed leg bone with the installed Taylor bracket and the corresponding intact and healthy leg bone, obtaining a DICOM format file, carrying out three-dimensional reconstruction, deriving a three-dimensional model, and removing interference factors such as soft tissues.

S3: acquiring 3 images of the three-dimensional model of the malformed leg bone with the installed Taylor bracket at the right position, the lateral position and the axial position, processing the images of each image, measuring 10 parameters comprising 6 malformation parameters and 4 installation parameters, wherein the 6 malformation parameters refer to 3 angulation parameters and 3 displacement parameters of the right position, the lateral position and the axial position of the fracture part, the 4 installation parameters refer to the deviation of the bracket at the right position, the lateral position and the axial position and the rotation angle of the bracket, and selecting the midpoint of a broken line of a reference bone segment as an angulation rotation center point.

S4: acquiring 3 pictures of the three-dimensional model of the intact and healthy leg bones in the normal position, the lateral position and the axial position, carrying out image processing on each picture, measuring 6 posture parameters, and calculating the posture of the deformed leg bones after the regulation is finished, wherein the two leg bones of the human body are symmetrical.

S5: and (3) establishing a mathematical model of the Taylor bracket, reading the initial rod length of the 6 adjusting rods of the Taylor bracket arranged on the deformed leg bone, and calculating the final rod length of the 6 adjusting rods of the Taylor bracket by using the 6-dimensional parallel mechanism kinematic inverse solution model and 16 parameters obtained by measurement in the steps (3) and (4).

S6: determining the adjustment time according to the specific malformation condition of a patient, selecting a proximal bone segment as a reference bone segment and a distal bone segment as a movable bone segment, and determining the daily rod length adjustment length according to the rod length adjustment amount and the adjustment time of 6 adjustment rods, wherein the reference bone segment is considered to be stationary when performing the malformation correction.

Preferably, the image obtained by CT tomography is utilized, an image processing means is utilized, interference factors such as soft tissues and the like are eliminated, a three-dimensional image of the target skeleton is constructed, and accurate pose information of the target skeleton is obtained.

Preferably, the images of the normal position, the lateral position and the axial position of the malformed leg and the normal leg are respectively processed, and 6 malformed parameters and 4 installation parameters of the Taylor stent and ideal 6 posture parameters after the correction are obtained by a computer-aided measurement method.

Preferably, the final rod length of the 6 adjusting rods of the Taylor bracket is calculated by a mathematical method of a 6-dimensional parallel mechanism kinematic inverse solution model, and the daily adjusting quantity of each rod is calculated according to actual conditions.

Preferably, the malformed bones not only are leg bones, but also other extremity bones and ankle bones, and the method can be used for accurate deformity correction and repair.

Drawings

FIG. 1 is a flow chart of a method for measuring parameters of a Taylor external fixation bracket based on CT scanning according to the present invention;

FIG. 2 is a view of a Taylor external fixation bracket assembly;

fig. 3 is a flow chart for acquiring parameters by image processing of the reconstructed three-dimensional model of the deformed bone at the normal position, the lateral position and the axial position.

In the figure: 107-proximal bone segment; 108-adjusting lever 1; 109-adjusting rod 2; 110-adjusting rod 3; 111 — a distal bone segment; 112-adjusting rod 4; 113-adjusting rod 5; 114-adjustment lever 6.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, in the detection process, the Taylor stent parameter measurement method based on CT scanning includes the following steps:

step 101: according to the actual condition of the malformed bone of a patient, selecting adjusting support rods with different lengths and support rings with different sizes, installing a Taylor external bone fixing bracket in a personalized manner, and installing the Talor external bone fixing bracket on the malformed broken bone through an operation;

step 102: carrying out CT scanning on the deformed bone with the Taylor external bone fixing bracket and the healthy bone without any deformation to obtain a DICOM format file, carrying out three-dimensional reconstruction, removing interference factors such as soft tissues and the like, and obtaining a three-dimensional model;

step 103: acquiring normal position, lateral position and axial position pictures of the malformed bone model, and acquiring 4 installation parameters of the Taylor external fixing bracket and 6 malformed parameters of the malformed bone on which the Taylor external fixing bracket is installed in an image processing mode;

step 104: acquiring normal, lateral and axial position pictures of a healthy bone model, acquiring 6 posture parameters of a normal bone in an image processing mode, and acquiring posture parameters after correcting a deformed bone due to the symmetry of two human leg bones;

step 105: establishing a mathematical model of the Taylor external bone fixation bracket, and introducing the parameters obtained in the steps 103 and 104 and the initial rod lengths of the 6 adjusting support rods into the model by utilizing a 6-dimensional parallel mechanism kinematics inverse solution model to obtain the final 6 adjusting rod lengths after deformity correction;

step 106: the correction time is determined according to the specific malformation operation condition of the patient, and the daily adjustment amount of each adjusting support rod is determined.

As shown in fig. 3, in the image processing process, the implementation steps of obtaining 6 malformation parameters and 4 installation parameters of the malformed bone with the Taylor external fixation bracket installed are as follows:

112, for the processing of the picture in the normal position, firstly determining the longest diameter of a near-end ring (a reference ring), finding a middle point which is the center of a circular ring and is marked as an O point, finding the middle point of the cross section of a near-end bone at the fracture position and connecting with the middle point of an intercondylar crest of the tibia, namely a mechanical axis at the near end of the tibia, and intersecting with the long diameter of the near-end ring at a D point, similarly finding the middle point of the cross section of a far-end bone at the fracture position and connecting with the middle point of a connecting line of an inner ankle and an outer ankle, namely a mechanical axis at the far end of the tibia, prolonging the intersection of the mechanical axes of the far-end bone and the near-end bone segments at the C point, wherein the acute angle formed by the intersection of the two mechanical axes with the C point is the inward and outward turning angle of the far end of the fracture, which is marked as α, finding an A point on the fracture line of the near-end bone, simultaneously finding a B point on the fracture line at the far-end bone, wherein the anatomical relationship corresponding to the B point (namely, after reduction, the two points are exactly coincident with the B point), so that the center of the two points are marked as the right and left displacement distance of the near-end bone longitudinal axis is marked as a straight line of the near-end displacement distance;

113, for the processing of the picture on the lateral position, measuring a back-tension or flexion angle of the far end of the bone, which is recorded as α 2, a front-back displacement distance of the far end bone, which is recorded as S2, and a front-back offset distance of the center of the near-end ring relative to the center of the bone, which is recorded as L2;

step 114, for processing the axial picture, firstly connecting the middle point of the fracture line of the near-end bone and the middle point of the fracture line of the far-end bone, recording the projection of the connecting line on the extension line of the mechanical axis of the near-end bone as the shortening or separating displacement of the far-end bone as S3, obtaining the rotation malformation angle of the far-end bone of the bone in the axial direction and the rotation deviation angle of the near-end reference ring as α 3 and β, recording the rotation deviation angles of the near-end reference ring as L3, recording the rotation deviation angles of the near-end reference ring as the rotation deviation angles of the far-end bone of the bone as α and β, and recording the length of the segment DE as the axial distance from the near-end ring to the fracture end as.