CN106236256A - A kind of manufacture method of personalized Thoracolumbar disk sagittal curvature mould rod - Google Patents

Abstract

The invention relates to a manufacturing method of a personalized thoracolumbar sagittal curvature mold rod, the sagittal curvature mold rod manufacturing method is: based on medical images, computer software reconstructs a three-dimensional model of the thoracolumbar vertebrae to be fixed; Perform simulated reduction on the model; according to the sagittal curvature of the thoracolumbar spine after reset, create an individualized sagittal curvature mold stick stl file in the computer software; finally use 3D printing or other rapid prototyping methods to manufacture it. The sagittal curvature mold stick is an individualized auxiliary surgical tool, and pedicle screw distraction or pressurized marking points are additionally designed on the mold stick to ensure that the vertebral body and intervertebral space are restored while the sagittal curvature is restored individually. height; eliminates the subjectivity and blindness of pre-bending connecting rods during the operation, and reduces the number of C-arm perspectives during the operation; it is suitable for thoracolumbar fractures, slippage, lumbar disc herniation, etc.; easy to operate, and meets the requirements of doctors Lower operation risk, higher operation efficiency, and lower operation cost.

Description

A method for making a personalized thoracolumbar sagittal curvature mold stick

technical field

The invention relates to the field of computer-aided technology and medical equipment, in particular to a method for making a personalized thoracolumbar sagittal curvature mold stick.

Background technique

Thoracolumbar fractures refer to the destruction of the continuity of the thoracolumbar spine due to external force. This is the most common spinal injury. Among young and middle-aged patients, high-energy injuries, such as car accidents and falls from heights, are the main cause of injury. Due to the existence of osteoporosis in elderly patients, the injury factors are mostly low-violence injuries, such as slips and falls. Patients with thoracolumbar fractures are often associated with neurological impairment, and because the injury factor is basically high-energy injury, they are often associated with other organ injuries, which brings great difficulties and challenges to treatment.

Spinal fractures, spondylolisthesis, and herniated intervertebral discs are common clinically. This type of disease often requires surgical treatment. The purpose of treatment is to reduce the fracture or dislocation, restore spinal stability and relieve nerve compression. Posterior pedicle fixation system is the first choice to deal with such injuries by reducing fractures and dislocations through the holding force of the three columns of the spine. However, the sagittal curvature of the thoracolumbar spine varies greatly, and each patient The heights of the vertebral bodies are also different. How to restore the normal sagittal curvature and the height of the vertebral body (intervertebral space) individually during the operation is a clinically difficult problem.

At present, the commonly used posterior spinal internal fixation device is the GSS pedicle screw system. After the screw is locked, its tail is perpendicular to the connecting rod, so the sagittal curvature of the fixed segment can be adjusted through the radian of the connecting rod, but in actual clinical operation Most of the pre-bending of the connecting rod is performed by the experience of the surgeon, which lacks objectivity. This will inevitably lead to repeated blind rod bending during the operation, prolonging the operation time and unsatisfactory recovery of the sagittal curvature after surgery.

Contents of the invention

In order to solve the above technical problems, the present invention provides a convenient and efficient personalized thoracolumbar sagittal curvature through the preoperative analysis of the mechanical properties of the individually designed thoracolumbar sagittal curvature mold rod in the physiological function state. The production method of the mold rod can effectively improve the recovery of the sagittal curvature and the height of the vertebral body (intervertebral space) during the operation. It can achieve fast and accurate operation without requiring the surgeon to receive special training, improve safety, and reduce operation costs. .

A personalized thoracolumbar sagittal curvature mold rod and its manufacturing method in the present invention that solves the above technical problems are characterized in that: comprising the following steps:

(1) Perform CT scan on the thoracolumbar spine of the patient to be fixed, and obtain data in DICOM format:

(2) Import the data into the 3D modeling software Mimics to reconstruct the 3D model of the thoracolumbar spine;

(3) Carry out segmentation modeling with the fractured or dislocated vertebral body as the boundary:

Use Mimics software to modify the erase function in the mask tool, and manually separate the upper and lower articular processes of the fractured or dislocated vertebral body, that is, manually separate the head and tail sides layer by layer in the software, and then use the region growing tool and Boolean operations to form different mask, and use this mask to create a 3D model of different colors;

One model is divided into different colors for easy reset. The number of different color divisions is 2 or more. For example, two colors are enough for patients with slippage.

(4) Simulated surgery to correct the dislocation and restore the height of the fractured vertebral body and simulate the implantation of pedicle screws:

Simulate the surgery in the 3D model segmented in step (3) to restore the normal sagittal curvature and intervertebral space height; use the optimal pedicle screw entry point to simulate and design the pedicle screw entry channel; measure After the simulation operation, the sagittal curvature of the thoracolumbar spine of the segment to be fixed, the total length of the segment to be fixed, and the distance between the pedicle screws of each segment were recorded, and their values were recorded;

For patients with fractures, the heights of the anterior and posterior borders of the fractured vertebra after the simulated operation are the mean values of the heights of the anterior and posterior borders of the craniocaudal vertebral bodies, respectively. For patients with dislocation, they are in accordance with the conditions of complete correction of dislocation after the simulated operation and the cranial and caudal heights of the dislocated vertebral bodies. The heights of the anterior and posterior borders of the intervertebral space were the heights of the anterior and posterior borders adjacent to the normal intervertebral space, respectively.

In the above three-dimensional model, first use the moving tool to simulate and correct the lateral and anteroposterior dislocation of the vertebral body, and use the rotating tool to rotate around the upper and lower articular processes of the diseased vertebra respectively to correct the angle of the sagittal plane. The heights of the anterior and posterior borders were the average heights of the anterior and posterior borders of the craniocaudal vertebral body, and the heights of the anterior and posterior borders of the dislocated vertebral head and caudal intervertebral space were the heights of the anterior and posterior borders of the adjacent normal intervertebral space, respectively.

Import the STL format file into the reverse engineering software Geomagic, locate the 3D reference plane, design the screw entry point and the direction of the screw path of the vertebral pedicle of the segment to be fixed, and simulate the screw placement, and define the head and tail vertebrae of the segment to be fixed before the simulation operation The included angle of the vertical line of the endplate on the body is the sagittal curvature of the segment to be fixed, and then the normal sagittal curvature of the segment to be fixed is used as the radian of the individualized sagittal curvature model rod, and the mutual relationship between the center lines of the sagittal screws The distance is the length of the connecting rod;

(5) Sagittal curvature die stick design:

In the software Geomagic, make a three-dimensional model of a mold rod with a diameter of 6 mm based on the sagittal curvature and length in step (4), and make marker points on its surface, and save it as an STL format file;

(6) Transfer to a 3D printer for physical printing.

In the step (1), the slice thickness of the spiral CT scan is 0.625mm, and the matrix is 512??512.

The matrix is equivalent to a pixel, which refers to an image of 512*512 pixels. The thinner the layer thickness, the higher the accuracy and the longer the CT scanning time. But the thickness of the layer should not be too thin.

The specific operation of bone fracture simulation reset in the step (2) is to select the threshold value selection tool to obtain the original mask of the thoracolumbar spine to be fixed, and then use the region growth tool to shrink and modify the above mask to generate a new mask; then, select this new mask. Three-dimensional modeling of the mask and smoothing, that is, the three-dimensional model of the thoracolumbar spine of the required fixed segment;

In the step (4), the sagittal screw entry direction is parallel to the upper endplate of the vertebral body and the vertical distance between the bilateral pedicle screws of the same vertebral body and the upper endplate is consistent.

The curvature designed by the sagittal curvature mold stick in the step (4) conforms to the sagittal curvature of the thoracolumbar spine of the segment to be fixed after the simulated operation.

The mark points made on the surface in the step (5) conform to the preoperatively planned distance of distraction or compression of each screw (distance between each screw). Sagittal curvature die sticks do not need to be made to fit snugly with the above signs.

The material used for physical printing in the step (6) is a photosensitive resin material. Other materials can also be used, such as nylon, and nylon has better biological characteristics and can be in short-term contact with the human body.

In the present invention, the personalized sagittal curvature mold stick obtains the most ideal sagittal curvature parameter of the patient by simulating the operation before operation, and prints this parameter into a real object through 3D printing, and assists in connection during the operation after the real object is sterilized Rod pre-bending, so that patients can get the ideal sagittal curvature after operation. The most ideal pedicle screw distraction height was also obtained, and this parameter was marked on the above-mentioned sagittal curvature mold stick by 3D printing. After the object was sterilized, the distraction and pressure of the screw were assisted during the operation. At the same time, it can also assist in the selection of the total length of the implanted connecting rod. The width of the mold stick is made by simulating the individualized sagittal curvature of the operation, and the distance of the marker points is made by simulating the distance of the individualized pedicle screw of the operation.

Geometric accuracy is important for the validity of stick models of the sagittal curvature of the thoracolumbar spine. This model is "made to order" in advance with special materials. According to reports, the shape of the custom-made thoracolumbar sagittal curvature mold stick follows the anatomical characteristics of the original bone, maintains the function, has the advantages of individualization and customization, and at the same time has less surgical trauma.

The manufacturing method of the individualized thoracolumbar sagittal curvature mold stick in the present invention, reconstructs the three-dimensional model of the spine through the CT data of the patient before operation, measures the relevant data, and uses this data as the basis to simulate and correct the dislocation and restore the patient on the computer For the sagittal curvature, relatively accurate data related to the normal sagittal curvature of the fixed segment were obtained, and finally these data were implemented in clinical operations through 3D printing individualized sagittal curvature mold sticks and photoelectric navigation systems. Eliminates the pre-bending subjectivity of the connecting rod, repeated fluoroscopy operations, etc.; suitable for spinal fractures, distortions, slippage, pedicle fractures, etc.; easy to operate, lower requirements for doctors, reduces surgical risks, and improves Surgical efficiency, thereby reducing surgical costs. The designed interactive personalized sagittal curvature mold rod can assist the pre-bending of the connecting rod and the restoration of the height of the vertebral body (intervertebral space) during the operation, restore the normal structure of the vertebral body, and improve the quality of life of the patient.

detailed description:

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the embodiments. Obviously, the patent of the present invention includes but is not limited to the embodiments described below.

Example 1

In order to restore the fractured vertebral height and sequence better individualized during the operation, the normal vertebral height and sagittal curvature of the segment to be fixed were obtained by the simulated operation function of the Mimics software (Materialise, Switzerland) before the operation, and the screw placement was simulated. And planning the operation, the specific steps of making the personalized sagittal curvature mold stick are as follows:

(1) Perform a 64-slice spiral CT scan on the patient's thoracolumbar spine to obtain DICOM data:

Before operation, patients underwent 64-slice spiral CT scanning examination, with a slice thickness of 0.625mm and a matrix of 512??512. Mimics 14.11 software was used to import the original Dicom format data.

(2) Establishment and measurement of 3D model:

First, select the threshold selection tool (Thresholding) to obtain the original mask of the thoracolumbar spine to be fixed; then, select the region growing tool (Rregion growing), shrink and modify the above mask to generate a new mask; and then select this new mask The three-dimensional modeling (Calculate 3D from Mask) of the diseased vertebra (Calculate 3D from Mask) is smoothed accordingly, and finally the three-dimensional model of the thoracolumbar spine of the required fixed segment is obtained; finally, the height of the head and tail of the diseased vertebra and the height of the intervertebral space are accurately measured on this model.

(3) Carry out segmentation modeling with the fractured and dislocated vertebral body as the boundary:

Use the Erase function in the Edit mask tool to manually separate the head and tail sides of the fractured and dislocated vertebral body with the upper and lower articular processes as the boundary, and use the region growing technique (Rregion growing) and Boolean Operations (BooleanOperations) again Three new masks are formed respectively, and three 3D models of different colors are established with these masks.

(4) Simulated surgery to correct dislocation and restore height of fractured vertebral body

In the above three-dimensional model, first use the move tool (Move) to simulate and correct the lateral and anteroposterior dislocation of the vertebral body, and use the rotation tool (Rotate) to rotate around the upper and lower articular processes of the diseased vertebra respectively to correct the sagittal plane angle. The heights of the anterior and posterior borders of the fractured vertebra after the simulated operation are the average heights of the anterior and posterior borders of the craniocaudal vertebral body, and the heights of the anterior and posterior borders of the dislocated vertebral head and caudal intervertebral space are the anterior and posterior borders of the adjacent normal intervertebral space, respectively. high.

For patients with fractures, the heights of the anterior and posterior borders of the fractured vertebra after the simulated operation are the mean values of the heights of the anterior and posterior borders of the craniocaudal vertebral bodies, respectively. For patients with dislocation, they are in accordance with the conditions of complete correction of dislocation after the simulated operation and the cranial and caudal heights of the dislocated vertebral bodies. The heights of the anterior and posterior borders of the intervertebral space were the heights of the anterior and posterior borders adjacent to the normal intervertebral space, respectively.

In the above three-dimensional model, first use the moving tool to simulate and correct the lateral and anteroposterior dislocation of the vertebral body, and use the rotating tool to rotate around the upper and lower articular processes of the diseased vertebra respectively to correct the angle of the sagittal plane. The heights of the anterior and posterior borders were the average heights of the anterior and posterior borders of the craniocaudal vertebral body, and the heights of the anterior and posterior borders of the dislocated vertebral head and caudal intervertebral space were the heights of the anterior and posterior borders of the adjacent normal intervertebral space, respectively.

Import the STL format file into the reverse engineering software Geomagic, locate the 3D reference plane, design the screw entry point and the direction of the screw path of the vertebral pedicle of the segment to be fixed, and simulate the screw placement, and define the head and tail vertebrae of the segment to be fixed before the simulation operation The included angle of the vertical line of the endplate on the body is the sagittal curvature of the segment to be fixed, and then the normal sagittal curvature of the segment to be fixed is used as the radian of the individualized sagittal curvature model rod, and the mutual relationship between the center lines of the sagittal screws The distance is the length of the connecting rod.

(5) Sagittal curvature die stick design:

Export the above model in Mimics in STL format, and import it into Geomagic Studio 2013 software (Geomagic, USA), locate the 3D reference plane, design the optimal screw entry point and screw path direction of the vertebral pedicle of the segment to be fixed, and simulate For screw placement, it is required that the direction of screw insertion in the sagittal position is parallel to the upper endplate of the vertebral body and the vertical distance between the bilateral pedicle screws of the same vertebral body and the upper endplate is consistent.

Define the included angle of the vertical line of the upper endplate of the craniocaudal vertebral body of the segment to be fixed before the simulated operation as the sagittal curvature of the fixed segment, and the included angle of the vertical line of the upper endplate of the craniocaudal vertebral body of the segment to be fixed after the simulated operation is defined as " Normal sagittal curvature of the segment to be fixed". The "normal sagittal curvature of the segment to be fixed" was taken as the radian (curvature) of the individualized sagittal curvature stick, and the distance between the center lines of the sagittal screws was taken as the length of the connecting stick.

(6) Transfer to a 3D printer for physical printing. The real object can be sterilized and brought into the operation, visually assisting the operation. The material used for physical printing is photosensitive resin material. Other materials can also be used, such as nylon, and nylon has better biological characteristics and can be in short-term contact with the human body.

Production of 3D printed individual mold rods: In Geomagic, a three-dimensional model with a diameter of 6mm is made with the above-mentioned radian and length, and mark points are made on its surface to indicate the pre-operative planning distance of each screw, and saved as an STL format file Passed to the 3D printer for 3D physical printing. Landmark points are designed on the sagittal mold stick, and the distraction or compression distance of the dislocated vertebral body can be objectively controlled during the operation through these landmark points. The diameter of the mold stick is 6mm, and the diameter of the marked point is 4mm. The width of the mold stick is made by simulating the individualized sagittal curvature of the operation, and the distance of the mark point is made by simulating the distance of the individualized pedicle screw of the operation.

The shape of the personalized sagittal curvature mold stick follows the anatomical characteristics of the original bone and maintains the bone function. It has the advantages of individualization and customization, and at the same time, the surgical trauma is small.

The performance indicators of personalized sagittal curvature mold rods are breaking strength, stress-strain distribution, service life and so on. The biomechanical performance of the design after mechanical analysis is better than that of the restoration designed only by experience. So far, more than 20 patients have been used and observed for about 2 years. No adverse complications such as fracture and exposure have occurred, and further clinical observation is still underway. .

Test one:

An experimental group and a control group are set up, and the specific operations of the experimental group are as described in Example 1.

Experimental time and subjects: From May 2012 to September 2014, 84 patients with spondylolisthesis were included in the study, 44 cases in the traditional PLIF surgery group (control group), using 3D printing individualized sagittal curvature mold stick and photoelectric navigation technology Line PLIF operation group (observation group) 40 cases.

There was no statistically significant difference between the two groups in age, gender, spondylolisthesis, type, VAS score of low back pain and other general data (P>0.05), and they were comparable. The operation time and intraoperative blood loss of the two groups were recorded. The postoperative image data were used to compare the sagittal plane screw placement angle, screw placement accuracy, slippage rate, intervertebral space height recovery rate, fixed segment sagittal curvature recovery rate, and low back and leg pain VAS scores between the two groups.

The operation time of the control group and the experimental group were (151.7±19.3) and (153.9±17.3) min respectively, and the blood loss was (625.5±125.0) and (610.0±75.0) ml respectively, and there was no significant difference between the two groups (P>0.05); however, the times of fluoroscopy and sagittal screw angle (SSA) in the control group were (8.5±2.7) times and (8.5±3.7)°, which were significantly higher than those in the experimental group (5.6±1.4) times , (2.0±1.8)°, the difference was statistically significant (P<0.05); the nail placement accuracy rate was 84.0% (121/144), which was significantly lower than the experimental group 91.7% (110/120), the difference was statistically significant ( P<0.05). Immediately after operation and at the last follow-up, the slippage rate, intervertebral space height recovery rate, and sagittal curvature recovery rate of the experimental group were significantly better than those of the control group, and the differences were statistically significant (P<0.05). Immediate postoperative slippage rate, intervertebral space height recovery rate, sagittal curvature recovery rate, and VAS score of the last postoperative low back pain were 9.1±3.2%, 80.8±3.2%, 82.5±7.9% and 3.7% in the control group, respectively. ±2.5 points, the experimental group was 3.1±1.5%, 92.7±7.2%, 93.9±4.9% and 1.2±1.1 points respectively, and there was a statistical difference between the two groups ( P< 0.05).

From the above, it can be seen that the application of 3D printing individualized sagittal curvature mold stick and photoelectric navigation technology in the posterior approach of lumbar spondylolisthesis, compared with traditional surgery, the intraoperative blood loss and operation time are basically the same, but the dislocation can be better corrected And restore the sagittal curvature, improve the symptoms of postoperative low back pain in patients.

The manufacturing method of the personalized sagittal curvature mold stick in the present invention obtains more accurate sagittal curvature data (measured by the vertical line of the upper endplate of the adjacent vertebral body) through software simulation operation before operation, and takes this The data is used to make a sagittal curvature mold stick with a suitable length through the 3D printer; the length and pre-bending of the connecting rod in the operation can get good clinical results according to the above mold stick; in addition, the operation of this mold stick is simple and convenient, and the operator does not need to accept special procedures. It can be used immediately after training, and can quickly and accurately assist the pre-bending and selection of connecting rods, improve surgical efficiency, and reduce surgical risks; based on digital design and manufacturing, remote assistance in design and production can be realized. Hospitals do not need to purchase rapid prototyping machines and related software, reducing hospital costs. It can reduce operation time and intraoperative bleeding, better reduce fractures and dislocations, and restore sagittal curvature. Patients can also get better neurological function after surgery and improve postoperative low back pain symptoms.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (7)

1. a kind of manufacture method of personalized thoracolumbar sagittal curvature mold stick, is characterized in that: comprise the following steps: (1) Perform CT scan on the thoracolumbar spine of the patient to be fixed, and obtain data in DICOM format: (2) Import the data into the 3D modeling software Mimics to reconstruct the 3D model of the thoracolumbar spine; (3) Carry out segmentation modeling with the fractured or dislocated vertebral body as the boundary: Use Mimics software to modify the erase function in the masking tool, manually separate the head and tail sides of the fractured or dislocated vertebral body with the upper and lower articular processes as the boundary, and then use the region growing tool and Boolean operations to form different masks respectively. Build 3D models of different colors; (4) Simulated surgery to correct the dislocation and restore the height of the fractured vertebral body and simulate the implantation of pedicle screws: Simulate the operation in the 3D model divided in step (3), restore the normal sagittal curvature and intervertebral space height, use the pedicle screw entry point to simulate the design of the pedicle screw entry channel, and measure the simulated operation The sagittal curvature of the thoracolumbar spine of the segment to be fixed, the total length of the segment to be fixed, and the distance between the pedicle screws of each segment, and record their values; (5) Sagittal curvature die stick design: In the software Geomagic, use the sagittal curvature and length in step (4) to make a three-dimensional model of the mold rod, and make marker points on its surface, and save it as an STL format file; (6) Transfer to a 3D printer for physical printing. 2. The method for making a personalized thoracolumbar sagittal curvature mold rod according to claim 1, characterized in that: in the step (1), the slice thickness of the spiral CT scan is 0.625mm, and the matrix is 512? ?512. 3. A method for making a personalized thoracolumbar sagittal curvature mold rod according to claim 1, characterized in that: the specific operation of bone fracture simulation reset in the step (2) is to select a threshold value selection tool to obtain It is intended to fix the original mask of the thoracolumbar spine, and then use the region growth tool to reduce and modify the above mask to generate a new mask; then, select the 3D modeling of the new mask and perform smoothing to obtain the thoracic segment of the fixed segment. 3D model of the lumbar spine. 4. The manufacturing method of a personalized thoracolumbar sagittal curvature mold stick according to claim 1, characterized in that: in the step (4), the direction of sagittal screw insertion is parallel to the upper endplate of the vertebral body And the vertical distance between the bilateral pedicle screws of the same vertebra and the upper endplate is the same. 5. A method for making a personalized thoracolumbar sagittal curvature mold stick according to claim 5, characterized in that: the curvature designed by the sagittal curvature mold stick in the step (4) conforms to the patient's intended fixation Segmental normal sagittal curvature. 6. The manufacturing method of a personalized thoracolumbar sagittal curvature mold stick according to claim 1, characterized in that: in the step (5), the mark points made on the surface conform to the preoperative planning. The distance the screw is stretched or compressed. 7. The method for making a personalized thoracolumbar sagittal curvature mold stick according to claim 1, characterized in that: the material used for physical printing in the step (6) is photosensitive resin material.