CN108766539A - Implant features parameter edit methods towards the preoperative planning of orthopaedics - Google Patents

Abstract

The invention discloses an implant feature parameter editing method for orthopedic preoperative planning, which includes the following steps: Step 1: constructing an implant feature model library, and classifying implants according to fracture information and implant feature parameters ;Step 2: Select an implant model from the implant feature model library according to the patient's bone three-dimensional shape parameters and fracture type; Step 3: Adjust the feature parameters of the selected implant model to meet the needs of individual patients stress requirements. The present invention can design implants for individual patients that conform to their own anatomical characteristics and disease conditions, and has the characteristics of rapidity and high efficiency. A series of postoperative complications such as malunion occurred.

Description

Implant feature parameter editing method for orthopedic preoperative planning

technical field

The invention relates to a computer-aided preoperative planning technology, in particular to an implant characteristic parameter editing method for orthopedic preoperative planning, and belongs to the technical field of computer-aided design.

Background technique

Orthopedic preoperative planning is a key stage in the treatment of bone defects and lesions. Implant selection and design is an important part of orthopedic preoperative planning. Individual patients have significant differences in anatomical structure and behavioral movement, and the displacement of fracture ends and fragmentation of bone fragments are complex and diverse. Although the size or geometric structure of existing implants can meet the diagnosis and treatment needs of most patients, they cannot meet the patients at both ends of the population distribution. Faced with the mismatch between the implant and the bone, orthopedic surgeons often solve it through cold treatment such as bending based on subjective guesswork. This treatment method not only reduces the structural performance of the implant, but also contains many uncontrollable factors. Doctors need to use imaging equipment to repeatedly compare and contrast, which not only prolongs the operation time, but also increases the risk of infection for patients.

It can be seen that it is necessary to design implants for individual patients according to their own anatomical characteristics and conditions. Biomechanical requirements are one of the important factors considered in implant design. In recent years, the stress and deformation of the fracture internal fixation system have been analyzed by modifying the parameters of the implant, which provides a scientific theoretical basis and application basis for the design of the implant. However, the existing methods ignore the impact of specific fracture types and the order of modification of implant characteristic parameters on implant design, resulting in shortcomings such as unclear medical semantics, long cycle time, and difficult editing in implant design.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for editing feature parameters of implants for orthopedic preoperative planning. This method can design implants for individual patients that conform to their own anatomical characteristics and conditions, and has the advantages of rapidity, high efficiency, etc. Features, the designed implant has a good matching degree with individual patients, and reduces the occurrence of a series of postoperative complications such as loss of reduction after fixation, fracture nonunion or malunion.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A method for editing feature parameters of implants for orthopedic preoperative planning, including the following steps:

Step 1: Build an implant feature model library, and classify implants according to fracture information and implant feature parameters;

Step 2: Select an implant model from the implant feature model library according to the three-dimensional shape parameters of the patient's bone and the fracture type;

Step 3: Adjust the characteristic parameters of the selected implant model to meet the stress requirements of individual patients.

Step one includes:

Step 1a: constructing an implant feature model library;

Based on the feature modeling technology, the surface features and volume features of the implant are sequentially constructed, and the feature parameters are set according to the medical semantics, and then the constructed implant model is added to the implant feature model library;

Step 1b: Classify the implant feature parameters;

The characteristic parameters that can reflect the overall shape of the implant set in step 1a are collectively called the main characteristic parameters, and the characteristic parameters that reflect the local shape of the implant are collectively called the detailed characteristic parameters;

Step 1c: Classify the implants according to the fracture information and the implant feature parameters;

Firstly, the implants are classified according to the bone type and the fracture type to which the implant is applicable, and then the implants are classified according to the main characteristic parameters and the detailed characteristic parameters of the implant in step 1b.

Feature modeling technology is one of the key technologies of CAD/CAM integrated system.

Implants are classified according to the bone type and fracture type to which the implant is applicable, that is, femoral implants are divided into femoral intramedullary implants and femoral surface implants, and femoral surface implants are further divided into proximal femoral implants. end implants, femoral stem implants and distal femoral implants.

Classify the implants according to the main characteristic parameters and detailed characteristic parameters of the implant in step 1b, that is, divide the bone plate into wide type and narrow type according to the width value of the bone plate; according to the bending value of the intramedullary nail at the key position , to classify the bending shape of the intramedullary nail.

Step two includes:

Step 2a: constructing a three-dimensional model of the patient's skeleton;

Based on the CT data of individual patients, image segmentation, 3D reconstruction, and model optimization are used to quickly construct the patient's fracture fragments, and then realize bone fragment splicing;

Step 2b: Obtain the three-dimensional overall shape parameters of the skeleton;

Measure several three-dimensional shape parameters that can reflect the overall shape of the skeleton on the three-dimensional bone model constructed in step 2a, including bone size parameters;

Step 2c: determine the type of fracture;

For different bone types, select several features that reflect the fracture characteristics, and then calculate the classification decision function by training a large number of samples, and finally input the individual patient data, that is, the three-dimensional overall shape parameters of the bone in step 2b, into the classification decision function, and output the fracture type;

Step 2d: Pick a preliminary implant feature model;

Determine the value of the main characteristic parameters of the implant according to the mapping relationship between the three-dimensional overall shape parameters of the bone and the main characteristic parameters of the implant, and combine the fracture type obtained in step 2c to initially select from the implant characteristic model library in step 1a Create an implant model.

Step three includes:

Step 3a: Prioritizing implant characteristic parameters;

Setting the main feature parameters takes precedence over the detail feature parameters, and at the same time set the priority order for the main feature parameters and detail feature parameters in turn;

Step 3b: Construction of fracture fixation assembly system model and its stress analysis;

Use fixtures to assemble the implant to the bone solid model, then import the fixation system into the finite element analysis software, and set the material properties, constraint relationships, boundary conditions and load-bearing parameters in sequence, and finally analyze the maximum VonMises stress value of the implant ;

Step 3c: Hierarchical editing of implant features;

According to the priority order of the implant characteristic parameters in step 3a, the characteristic parameters are edited layer by layer from high to low until the preset conditions are met.

In step 1b, the main characteristic parameters of the implant refer to parameters that can reflect the overall shape and size of the implant, including the thickness, length, head width, and tail width of the volar bone plate of the radius; the detailed characteristic parameters of the implant refer to The parameters that can reflect the local shape and size of the implant include information about the fixation hole of the bone plate on the volar side of the radius, and the information about the fixation hole includes the center position and radius of the fixation hole.

In step 2a, splicing bone fragments refers to realizing optimal splicing of broken bone fragments by constructing an objective function, determining constraint conditions, and constructing a dynamic programming equation based on a template strategy.

In step 2c, the several features reflecting the fracture characteristics refer to the position and shape information of the fracture line on the three-dimensional model of the skeleton; the classification decision function refers to the combination of statistical decision-making and decision tree according to the selected characteristics reflecting the fracture characteristics Calculated decision function for judging fracture type.

In step 3a, setting the priority order of the main characteristic parameters and the detailed characteristic parameters in turn refers to sorting the characteristic parameters of the implant according to the degree of influence on the force of the implant when the characteristic parameters of the implant are changed from high to low .

The fixture includes screws, and the fixation system includes a solid model of the bone fitted with the fixture.

The fixing holes include screw holes.

The invention provides an implant feature parameter editing method oriented to orthopedic preoperative planning. This method starts with the characteristic parameters of the implant, first evaluates the influence of each characteristic parameter of the implant on the mechanical properties of the implant, sets the priority order of the characteristic parameters of each layer, and then edits the implant model layer by layer according to this order Modify until the implant mechanical properties meet the actual needs of the individual patient. This method has the characteristics of rapidity and high efficiency, and the designed implant has a good matching degree with individual patients, thereby reducing a series of postoperative complications such as loss of reduction after fixation, fracture nonunion or malunion.

The beneficial effects of the present invention are that the method for editing feature parameters of implants oriented to orthopedic preoperative planning is applied in the fields of medical orthopedic surgery and medical equipment manufacturing, providing scientific basis for editing and selection of implants, and improving the design quality of implants. and efficiency are important.

Description of drawings

Fig. 1 is a schematic diagram of the present invention;

Fig. 2 is a schematic diagram of implant main characteristic parameters and detail characteristic parameters;

Fig. 3 is a schematic diagram of implant classification;

Fig. 4 is a schematic diagram of fracture type judgment;

Fig. 5 is a schematic diagram of the position and shape of the femoral fracture line;

Fig. 6 is a schematic diagram of hierarchical editing and modification of implant feature parameters.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, the method for editing feature parameters of implants for orthopedic preoperative planning includes the following steps:

Step 1: Build an implant feature model library, and classify implants according to fracture information and implant feature parameters;

Step one includes:

Step 1a: constructing an implant feature model library;

Based on the feature modeling technology, the surface features and volume features of the implant are sequentially constructed, and the feature parameters are set according to the medical semantics, and then the constructed implant model is added to the implant feature model library;

Feature modeling technology is one of the key technologies of CAD/CAM integrated system;

Step 1b: Classify the implant feature parameters;

The characteristic parameters that can reflect the overall shape of the implant set in step 1a are collectively called the main characteristic parameters, and the characteristic parameters that reflect the local shape of the implant are collectively called the detailed characteristic parameters;

As shown in Figure 2, the main characteristic parameters of the implant refer to parameters that can reflect the overall shape and size of the implant, such as the thickness H, length L, head width W ₁ , and tail width W ₂ of the volar bone plate of the radius. The detailed feature parameters of the implant refer to parameters that can reflect the local shape and size of the implant, such as the screw hole information of the volar bone plate of the radius, including the position and radius of the screw hole center, etc.;

Step 1c: Classify the implants according to the fracture information and the implant feature parameters;

First, the implants are divided into several categories according to the bone type and fracture type to which the implants are applicable, and then the implants are divided into several subcategories according to the main feature parameters and detail feature parameters of the implants in step 1b. kind.

Implants are divided into several categories according to the bone type and fracture type to which the implant is applicable, that is, femoral implants are divided into femoral intramedullary implants and femoral surface implants, and femoral surface implants It is further divided into proximal femoral implants, femoral stem implants and distal femoral implants;

According to the main characteristic parameters and detail characteristic parameters of the implant in step 1b, the implants are divided into several subcategories, that is, according to the width value of the bone plate, the bone plate is divided into wide type and narrow type; The bending value at the position, classifying the bending shape of the intramedullary nail;

As shown in Figure 3, the fracture type is coded progressively, and the implant classification is represented by four digits. The first digit indicates the name of the bone to which the implant is applicable (can be represented by 1, 2, 3...); the second digit represents the specific fracture type (can be represented by 1, 2, 3..., as shown in Figure 4 for the femur Common fracture types); the third character divides the implant into several specifications with different sizes according to the main characteristic parameters of the implant (can be expressed by 1, 2, 3...); the fourth character divides the implant according to the detailed characteristic parameters The implants of each size specification are subdivided to adapt to the anatomical differences of different individuals (may be represented by 1, 2, 3...).

Step 2: Select an implant model from the implant feature model library according to the three-dimensional shape parameters of the patient's bone and the fracture type;

Step two includes:

Step 2a: constructing a three-dimensional model of the patient's skeleton;

Based on the CT data of individual patients, image segmentation, 3D reconstruction, and model optimization are used to quickly construct the patient's fracture fragments, and then realize bone fragment splicing;

Bone splicing refers to the optimal splicing of bone fragments by constructing objective functions, determining constraints, and constructing dynamic programming equations based on a template strategy.

Step 2b: Obtain the three-dimensional overall shape parameters of the skeleton;

Measure several three-dimensional shape parameters that can reflect the overall shape of the bones on the three-dimensional bone model constructed in step 2a, mainly referring to bone size parameters;

Step 2c: determine the type of fracture;

As shown in Figure 5, for different bone types (such as femur, tibia, pelvis, radius, etc.), select several features that can reflect the fracture characteristics (mainly refer to the position and shape information of the fracture line), and then use statistical decision-making and The method of combining decision trees, through training a large number of samples to calculate the decision function for judging the fracture type, finally input the individual patient data into the decision function, and output the fracture type;

Step 2d: Pick a preliminary implant feature model;

Determine the value of the main characteristic parameters of the implant according to the mapping relationship between the three-dimensional overall shape parameters of the bone and the main characteristic parameters of the implant, and combine the fracture type obtained in step 2c to initially select from the implant characteristic model library in step 1a Create an implant model.

Step 3: Adjust the characteristic parameters of the selected implant model to meet the stress requirements of individual patients.

Step three includes:

Step 3a: Prioritizing implant characteristic parameters;

Setting the main feature parameters takes precedence over the detail feature parameters, and at the same time set the priority order for the main feature parameters and detail feature parameters in turn;

Setting the order of priority for the main characteristic parameters and the detailed characteristic parameters refers to sorting the characteristic parameters of the implant according to the degree of influence on the force of the implant when the characteristic parameters of the implant are changed, from high to low.

Step 3b: Construction of fracture fixation assembly system model and its stress analysis;

Fixtures are used to assemble the implant to the bone solid model, and then import the fixation system into the finite element analysis software (such as ANSYS), and set the material properties, constraint relationships, boundary conditions and load-bearing parameters in turn, and finally analyze the implant. Maximum Von Mises stress value;

Step 3c: Hierarchical editing of implant features;

According to the priority order of the implant characteristic parameters in step 3a, the characteristic parameters are edited layer by layer from high to low until the preset conditions are met.

As shown in Figure 6, the olecranon-shaped bone plate model was first fixed on the fractured bone, and the finite element model was constructed; when the stress of the implant did not meet the preset requirements, the main characteristic parameters of the implant (thickness h ₁ , length of the tail l ₁ , length of the head l ₂ , widths of key parts of the head w ₁ , w ₂ , w ₃ ), and then adjust the detailed feature parameters of the implant (screw hole parameters d ₁ , d ₂ , d ₃ and s ₁ ) until the adjusted implant stress meets the stress needs of the patient.

The fixture includes screws, and the fixation system includes a solid model of the bone fitted with the fixture.

The fixing holes include screw holes.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also possible. It should be regarded as the protection scope of the present invention.

Claims (10)

1. the implant features parameter edit methods towards the preoperative planning of orthopaedics, which is characterized in that include the following steps：

Step 1：Implant features model library is built, and is classified to implantation material according to fracture information and implant features parameter；

Step 2：According to subjects bones' three-dimensional configuration parameter and classification of fracture, one is picked out from implant features model library Implantation material model；

Step 3：The characteristic parameter of the selected implantation material model of adjustment, so that it meets the stress requirement of individual patient.

2. the implant features parameter edit methods according to claim 1 towards the preoperative planning of orthopaedics, which is characterized in that Step 1 includes：

Step 1a：Build implant features model library；

Feature based Modeling Technology builds the region feature and body characteristics of implantation material successively, and feature is arranged according to medicine semanteme and joins Number, is added to implant features model library by the implantation material model of structure later；

Step 1b：To implant features parametric classification；

It can reflect that the characteristic parameter of implantation material global shape unitedly calls as main characteristic parameter by what is be arranged in step 1a, will reflect The characteristic parameter of implantation material local shape is collectively referred to as minutia parameter；

Step 1c：Classified to implantation material according to fracture information and implant features parameter；

The bone types and classification of fracture being applicable in first according to implantation material classify implantation material, then successively according in step 1b The main characteristic parameter and minutia parameter of implantation material classify implantation material.

3. the implant features parameter edit methods according to claim 2 towards the preoperative planning of orthopaedics, which is characterized in that Step 2 includes：

Step 2a：Build subjects bones' threedimensional model；

CT data based on individual patient, using image segmentation, three-dimensional reconstruction, model optimization rapid build patient bone folded block, so After realize the splicing of broken bone；

Step 2b：Obtain bone three-dimensional configuration parameter；

Several three-dimensional configuration parameters that can reflect bone configuration are measured on the bone threedimensional model of step 2a structures, are wrapped Include skeletal size parameter；

Step 2c：Judge classification of fracture；

To different bone types, then several features of selection reflection fracture characteristic calculate classification by training great amount of samples Decision function, finally by individual patient data, i.e. bone three-dimensional configuration parameter in step 2b is input to categorised decision letter Number, and export classification of fracture；

Step 2d：Select a preliminary implant features model；

Implantation owner's feature is determined according to the mapping relations between bone three-dimensional configuration parameter and implantation owner's characteristic parameter Parameter value is tentatively picked out in combination with the classification of fracture that step 2c is obtained from the implant features model library in step 1a One implantation material model.

4. the implant features parameter edit methods according to claim 2 or 3 towards the preoperative planning of orthopaedics, feature exist In step 3 includes：

Step 3a：Priority ranking is carried out to implant features parameter；

Main characteristic parameter is set prior to minutia parameter, while main characteristic parameter and minutia parameter are set gradually excellent First grade sequence；

Step 3b：The structure of fracture fixation assembly system model and its stress analysis；

Implantation material is assembled to by bone physical model using fixing piece, fixed system is then imported into finite element analysis software, And material properties, restriction relation, boundary condition and bearing load parameter are set gradually, the maximum Von of ultimate analysis implantation material Mises stress values；

Step 3c：The stratification of implant features is edited；

According to the priority orders of implant features parameter in step 3a, characteristic parameter is successively edited from high to low, until meeting Preset condition.

5. the implant features parameter edit methods according to claim 2 towards the preoperative planning of orthopaedics, which is characterized in that In step 1b, implantation owner's characteristic parameter refers to that can reflect the parameter of implantation material global shape and size, including radial-palmar The thickness of bone plate, length, head width, tail width；Implantation material minutia parameter refers to that can reflect implantation material part The parameter of shape and size, includes the mounting hole information of radial-palmar bone plate, and the mounting hole information includes mounting hole center Position, radius.

6. the implant features parameter edit methods according to claim 3 towards the preoperative planning of orthopaedics, which is characterized in that In step 2a, broken bone splicing refers to being based on template-policy, by building object function, determining constraints, structure Dynamic Programming Equation realizes the optimal splicing of broken bone block.

7. the implant features parameter edit methods according to claim 3 towards the preoperative planning of orthopaedics, which is characterized in that In step 2c, several features of reflection fracture characteristic are the location and shape information of fracture line on phalanges bone threedimensional model；It is described Categorised decision function refers to the method meter combined with decision tree using statistical decision according to the feature of the reflection fracture characteristic of selection The decision function for judging classification of fracture calculated.

8. the implant features parameter edit methods according to claim 4 towards the preoperative planning of orthopaedics, which is characterized in that In step 3a, it refers to according to each characteristic parameter of implantation material to set gradually priority orders to main characteristic parameter and minutia parameter The influence degree of implantation material stressing conditions is from high to low ranked up implant features parameter when change.

9. the implant features parameter edit methods according to claim 4 towards the preoperative planning of orthopaedics, which is characterized in that Fixing piece includes screw, and fixed system includes the bone physical model for being assembled with fixing piece.

10. the implant features parameter edit methods according to claim 5 towards the preoperative planning of orthopaedics, feature exist In mounting hole includes screw hole.