Construction method of personalized bone grafting guider for femoral neck fracture

Abstract

The invention provides a construction method of a personalized bone grafting guiding device for femoral neck fracture, which belongs to the technical field of digital medicine, and comprises the following steps: 1, three-dimensional reconstruction, 2, virtual reduction, 3, determination of bone grafting points, 4, determination of a bone attachment surface, using a 3-matic uniform offset tool to uniformly offset the extracted bone attachment surface to the outer side (i.e., the direction opposite to the bone surface) by 1-2 mm, and finally obtaining the personalized bone grafting guiding device for femoral neck fracture. 5, determining a bone grafting path, and 6, generating a kirschner wire sleeve based on the diameter of the kirschner wire so as to generate the bone grafting guider. Effective bony support is provided for the femur by attaching the attaching part to the rear side of the greater trochanter side of the femur of the patient, and the sleeve is guided through the generated kirschner wire. By using the bone grafting guiding device, a Kirschner wire can be accurately guided to a bone defect area, namely a bone grafting target area, in a femoral neck fracture closed reduction operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of digital medicine, and particularly relates to a construction method of a personalized bone grafting guide for femoral neck fractures. Background Art

[0002] Femoral neck fractures are often accompanied by bone defects at the fracture site. The location and volume of the bone defects directly affect the healing of the fractures, the incidence of nonunion, and the necrosis of the femoral head. Moreover, bone defects in different locations will cause corresponding changes in the surface stress of the implant.

[0003] To solve the problem of bone defects, the most direct method is bone grafting. Currently, the commonly used femoral neck bone grafting methods in clinical practice include bone flap transplantation and bone marrow transplantation. The former includes vascularized bone flaps and myocutaneous bone flaps with muscle pedicles. Its advantages are that it provides bony support for the defect site and has its own blood supply. The disadvantages are that open surgery is required, which will cause damage to the donor area, and it does not match the appearance of the donor, resulting in an increase in the surgical scope, time, and blood loss. At the same time, it also requires high microsurgical skills for the surgical staff. The latter has the advantage of minimally invasive operation, but using this method cannot provide effective bony support for the femur, nor can it accurately locate the defect site.

[0004] Therefore, a construction method of a bone grafting guide that can provide effective bony support for the femur and accurately locate the defect site is needed. Summary of the Invention

[0005] The purpose of the present invention is to provide a construction method of a personalized bone grafting guide for femoral neck fractures, which is characterized by including the following steps:

[0006] Step 1: Use the Mimics bone segmentation tool to initially segment the pelvis, the healthy femur, the affected femoral head, and the affected femoral shaft; use the multi-layer editing tool and the cavity filling tool to perform image segmentation and filling along the outer contours of the affected femoral head, the affected femoral shaft, and the healthy femur; use the create solid tool to three-dimensionally reconstruct the four bony structures of the pelvis, the healthy femur, the affected femoral head, and the affected femoral shaft, and save them as STL format files respectively.

[0007] Step 2: Import the four generated STL files into the post-processing software. Select the coccyx and pubic symphysis points on the pelvic file to determine the optimal mirror image. Along this mirror plane, mirror the healthy-side femur of the patient to the opposite side, denoted as the healthy-side femur mirror image file. Use the automatic registration tool based on the ICP algorithm. With the healthy-side femur mirror image file as the source point cloud Q1 and the patient's femoral shaft file as the target point cloud P1, register and reset the affected-side femoral shaft to the healthy-side femur mirror image file, denoted as the reset of the affected-side femoral shaft. Use the lasso tool to extract the fovea capitis regions on the surface of the affected-side femoral head and the healthy-side femur mirror image respectively, denoted as the fovea capitis of the affected-side femoral head and the fovea capitis of the healthy-side mirror image. Use the automatic registration tool based on the ICP algorithm. With the fovea capitis of the healthy-side mirror image as the source point cloud Q2 and the fovea capitis of the affected-side femoral head as the target point cloud P2, make the affected-side femoral head follow the fovea capitis of the affected-side femoral head and register it to the fovea capitis of the healthy-side mirror image, denoted as the reset of the affected-side femoral head.

[0008] Step 3: Use the measurement tool to take multiple points on the edge of the affected-side femoral shaft and measure the shortest distance from each point to the edge of the affected-side femoral head. Take the midpoint of the longest distance among the multiple shortest distances as the bone graft target point.

[0009] Step 4: The small lateral incision for inserting the cannulated screw in the femoral neck is usually located slightly below and posterior to the greater trochanter. Therefore, the bone graft guide and the screw insertion in the femoral neck share the same surgical incision. Based on this, set the bony surface area on the posterior side of the greater trochanter of the femur as the bone attachment surface. Use the uniform offset tool in 3-matic to uniformly offset the bone attachment surface 1 - 2 mm in the direction opposite to the relative bony surface to generate the fitting part.

[0010] Step 5: Taking the bone graft target point as an endpoint, calculate the distance from this point to each point on the bone attachment surface. To ensure that as much bone mass as possible is implanted during the bone graft surgery, take the point with the longest distance as the bone graft starting point, and use the line connecting the bone graft starting point and the bone graft target point as the bone graft path.

[0011] Step 6: Preferably select a Kirschner wire with a diameter of 2.5 mm. With the bone graft path as the axis, generate a Kirschner wire sleeve with an inner diameter of 2.6 mm, a wall thickness of 1 mm, and a length of 10 - 15 mm to guide the insertion of the Kirschner wire during the operation, and reserve fixing holes on the fitting part to finally complete the construction of the bone graft guide.

[0012] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in: The present invention proposes a design method for a personalized bone graft guide that can be used in the closed reduction surgery of femoral neck fractures. The bone graft guide designed based on this method has its inner surface attached to the posterior side of the greater trochanter of the patient's femur, which can provide effective bony support for the femur. And it is designed with a Kirschner wire guiding sleeve. Using this bone graft guide, the Kirschner wire can be accurately guided to the bone defect area during the closed reduction surgery of femoral neck fractures. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic flow chart of the construction method of a personalized bone grafting guide for femoral neck fractures of the present invention.

[0014] Figure 2 It is a schematic diagram after the three-dimensional reconstruction of the four bony structures of the pelvis, the healthy femur, the affected femoral head, and the affected femoral shaft in the second step of the present invention.

[0015] Figure 3 It is a schematic diagram of the mirror image file of the healthy femur in the method of the present invention.

[0016] Figure 4 It is a schematic diagram for confirming the bone grafting point in the method of the present invention.

[0017] Figure 5 It is a schematic diagram of the position of the bone attachment surface in the method of the present invention.

[0018] Figure 6 It is a schematic diagram for generating the fitting part in the method of the present invention.

[0019] Figure 7 It is a schematic diagram of the connection lines between the bone grafting target points and the points on the bone attachment surface in the method of the present invention.

[0020] Figure 8 It is a schematic diagram for confirming the bone grafting path in the method of the present invention.

[0021] Figure 9 It is a schematic diagram of the cooperation between the generated bone grafting guide and the posterior side of the greater trochanter of the femur.

[0022] Figure 10 It is a schematic diagram of the structure of the bone grafting guide generated by the present invention. Detailed implementation mode

[0023] The following will describe in more detail the construction method of a personalized bone grafting guide for femoral neck fractures of the present invention with reference to the schematic diagrams, in which the preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as a broad guidance for those skilled in the art and not as a limitation to the present invention.

[0024] As Figure 1 shown, a construction method of a personalized bone grafting guide for femoral neck fractures includes the following steps:

[0025] Step 1: Perform morphological reconstruction on the patient's pelvis, femur, femoral head, and femoral shaft.

[0026] 1): Obtain the patient's CT imaging data and read the data using three-dimensional reconstruction software;

[0027] 2): (This patent takes Mimics as an example). Use the Bone Segmentation tool in Mimics with a threshold of 180 - 200 HU to preliminarily segment the pelvis, the healthy side femur, the affected side femoral head, and the affected side femoral shaft;

[0028] 3): Use the multiple slice edit tool and the cavity fill tool to perform image segmentation and filling along the outer contours of the affected side femoral head, the affected side femoral shaft, and the healthy side femur;

[0029] 4): Use the Calculate Part tool to three-dimensionally reconstruct the four bony structures of the pelvis, the healthy side femur, the affected side femoral head, and the affected side femoral shaft, and save them as STL format files respectively.

[0030] Step Two: Virtual reduction

[0031] 1): Import the four generated STL files into the post-processing software 3-matic. Select points such as the coccyx and the pubic symphysis on the pelvis file to determine the best mirror image, and along this mirror plane, mirror the healthy side femur of the patient to the opposite side, denoted as the mirrored file of the healthy side femur, as Figure 2 shown.

[0032] 2): Generate the reduction file of the affected side femoral shaft and the reduction file of the affected side femoral head based on the mirrored file of the healthy side femoral head.

[0033] 1: Use the Global Registration tool based on the ICP algorithm. Take the mirrored file of the healthy side femur as the source point cloud Q1 and the patient's femoral shaft file as the target point cloud P1 to register and reduce the affected side femoral shaft to the mirrored file of the healthy side femur, denoted as the reduction of the affected side femoral shaft;

[0034] 2: Use the Lasso area mask tool to extract the fovea of the femoral head regions on the surfaces of the affected side femoral head and the mirrored healthy side femur respectively, denoted as the fovea of the affected side femoral head and the fovea of the mirrored healthy side femoral head;

[0035] 3: Use the Global Registration tool based on the ICP algorithm. Take the fovea of the mirrored healthy side femoral head as the source point cloud Q2 and the fovea of the affected side femoral head as the target point cloud P2 to make the affected side femoral head follow the fovea of the affected side femoral head and register it to the fovea of the mirrored healthy side femoral head, denoted as the reduction of the affected side femoral head, as Figure 3 shown.

[0036] Step Three: Determine the bone grafting points

[0037] Use the measurement tool to take several points on the edge of the affected side femoral shaft and measure the shortest distance from this point to the edge of the affected side femoral head, as followsFigure 4 As shown, P1, P3, P5, and P7 are points on the edge of the affected femoral shaft, and P2, P4, P6, and P8 are the closest points to the edge of the corresponding affected femoral head. Among them, the length of the line segment P7P8 is the longest, and the midpoint of the line segment P7P8 is used as the bone graft target point C.

[0038] Step Four: Determine the bone attachment surface

[0039] (Note: Explain the selection principle of the bone attachment surface) The small lateral incision for inserting the cannulated screw in the femoral neck is usually located below and posterior to the greater trochanter. Therefore, in this patent, the bone graft guide and the femoral neck screw insertion share the same surgical incision. Extract the bony surface area on the posterior side of the greater trochanter of the femur as shown Figure 5 and denote this area as the "bone attachment surface". Use the uniform offset tool of 3-matic to uniformly offset the extracted bone attachment surface 1 to 2 mm outward (i.e., in the direction opposite to the bony surface), generating a fitting part as shown Figure 6 .

[0040] Step Five: Determine the bone graft path

[0041] (Note: Determine the bone graft path). Taking the bone graft target point C as an endpoint, calculate the distances from point C to each point on the bone attachment surface as follows Figure 7 shown, which are the line segments CS1, CS2, CS3, CS 4…… CS n . To ensure that as much bone mass as possible is implanted during the bone graft surgery, in this patent, it is preferred that the point on the bone attachment surface with the longest distance to the bone graft target point C is used as the bone graft starting point, and the line segment connecting the bone graft starting point and the bone graft target point C is used as the bone graft path, as shown Figure 8 .

[0042] Step Six: Generate the bone graft guide

[0043] (Note: Briefly describe the parameters for generating the guide plate) In this patent, a Kirschner wire with a diameter of 2.5 mm is preferred. Using the bone graft path determined in the previous step as the axis, generate a Kirschner wire sleeve with an inner diameter of 2.6 mm, a wall thickness of 1 mm, and a length of 10 - 15 mm to guide the insertion of the Kirschner wire during the surgery. And reserve a fixing hole with a diameter of xx mm on the fitting part, as shown Figure 9 and 10 .

[0044] The above is only the preferred embodiment of the present invention and does not impose any limitation on the present invention. Any person skilled in the art within the technical field, without departing from the technical solution of the present invention, makes any form of equivalent substitution or modification and other changes to the technical solution and technical content disclosed by the present invention, which are all within the content of the technical solution of the present invention and still fall within the protection scope of the present invention.

Claims

1. A construction method of a personalized bone grafting guide for femoral neck fractures, characterized in that, It includes the following steps: S1: Obtain the patient's CT data, read the data using 3D reconstruction software, and perform 3D reconstruction on the patient's pelvis, healthy femur, affected femoral head, and affected femoral shaft; S2: Select multiple points in the pelvis to determine the optimal mirror plane, generate a healthy-side mirror femoral head concave file based on the optimal mirror plane, and register the affected femoral head following the affected femoral head concave area to the healthy-side mirror femoral head concave file; S3: Use a measurement tool to take multiple points on the edge of the affected femoral shaft, respectively measure the shortest distance from this point to the edge of the affected femoral head, and take the midpoint of the longest distance among the multiple shortest distances as the bone graft target point; S4: Set the osseous surface area on the posterior side of the greater trochanter of the femur as the bone attachment surface, and generate a fitting part based on the bone attachment surface; S5: Taking the bone graft target point as an endpoint, calculate the distance from this point to each point on the bone attachment surface, take the point with the longest distance as the bone graft starting point, and take the line connecting the bone graft starting point and the bone graft target point as the bone graft path; S6: Taking the bone graft path as the axis, generate a Kirschner wire sleeve to complete the construction of the bone graft guide; 2. The construction method of the personalized bone grafting guide for femoral neck fractures according to claim 1, characterized in that In the above S1, the 3D reconstruction specifically includes the following steps: S11: Use the Mimics bone segmentation tool to preliminarily segment the pelvis, healthy femur, affected femoral head, and affected femoral shaft; S12: Use the multi-layer editing tool and cavity filling tool to perform image segmentation and filling along the outer contours of the affected femoral head, affected femoral shaft, and healthy femur; S13: Use the create solid tool to perform 3D reconstruction on the four osseous structures of the pelvis, healthy femur, affected femoral head, and affected femoral shaft, and save them as STL format files respectively; 3. The construction method of the personalized bone grafting guide for femoral neck fractures according to claim 1, characterized in that, The above S2 specifically includes the following steps: S21: Import the four generated STL files into the post-processing software, select the coccyx and pubic symphysis points on the pelvis file to determine the optimal mirror, and along this mirror plane, mirror the patient's healthy femur to the opposite side, denoted as the healthy-side femur mirror file; S22: Use the automatic registration tool based on the ICP algorithm, taking the healthy-side femur mirror file as the source point cloud Q1 and the patient's femoral shaft file as the target point cloud P1, register and reset the affected femoral shaft to the healthy-side femur mirror file, denoted as the affected femoral shaft reset; S23: Use the lasso tool to extract the femoral head concave areas on the surfaces of the affected femoral head and healthy-side femur mirror respectively, denoted as the affected femoral head concave and healthy-side mirror femoral head concave; S24: Use the automatic registration tool based on the ICP algorithm, taking the healthy-side mirror femoral head concave as the source point cloud Q2 and the affected femoral head concave as the target point cloud P2, make the affected femoral head follow the affected femoral head concave and register it to the healthy-side mirror femoral head concave, denoted as the affected femoral head reset; 4. The construction method of the personalized bone grafting guide for femoral neck fractures according to claim 1, characterized in that In the above S4, use the uniform offset tool of 3-matic to uniformly offset the bone attachment surface 1-2 mm in the direction opposite to the relative osseous surface to generate a fitting part; 5. The construction method of the personalized bone grafting guide for femoral neck fractures according to claim 1, characterized in that, The above S6 is specifically: Select a Kirschner wire with a diameter of 2.5 mm, taking the bone graft path as the axis, generate a Kirschner wire sleeve with an inner diameter of 2.6 mm, a wall thickness of 1 mm, and a length of 10-15 mm to guide the intraoperative insertion of the Kirschner wire, and reserve a fixing hole in the fitting part to complete the construction of the bone graft guide.

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