Abstract
In order to meet the clinical requirements of spine surgery, this paper proposes the fabrication of the customized template for spine surgery through computer-aided design. A 3D metal printing-selective laser melting (SLM) technique was employed to directly fabricate the 316L stainless steel template, and the metal template with tiny locating holes was used as an auxiliary tool to insert spinal screws inside the patient’s body. To guarantee accurate fabrication of the template for cervical vertebra operation, the contact face was placed upwards to improve the joint quality between the template and the cervical vertebra. The joint surface of the printed template had a roughness of Ra = 13 ± 2 μm. After abrasive blasting, the surface roughness was Ra = 7 ± 0.5 μm. The surgical metal template was bound with the 3D-printed Acrylonitrile Butadiene Styrene (ABS) plastic model. The micro-hardness values determined at the cross-sections of SLM-processed samples varied from HV0.3 250 to HV0.3 280, and the measured tensile strength was in the range of 450 MPa to 560 MPa, which showed that the template had requisite strength. Finally, the metal template was clinically used in the patient’s surgical operation, and the screws were inserted precisely as the result of using the auxiliary template. The geometrical parameters of the template hole (e.g., diameter and wall thickness) were optimized, and measures were taken to optimize the key geometrical units (e.g., hole units) in metal 3D printing. Compared to the traditional technology of screw insertion, the use of the surgical metal template enabled the screws to be inserted more easily and accurately during spinal surgery. However, the design of the high-quality template should fully take into account the clinical demands of surgeons, as well as the advice of the designing engineers and operating technicians.
Highlights
Due to developments in spinal surgery, it is necessary for many complicated surgeries to fix screws into the pedicle of the vertebral arch in the spine and insert appropriate bone tissue substitutes for structural reconstruction [1,2,3]
Kaneyama et al [13] studied the effectiveness of the tailor-made screw guide template (SGT) system for the placement of C2 screws, including in cases with abnormalities, the study mainly focus on the clinical usage of a non-metal template, it demonstrates that the SGT system provided extremely accurate C2 cervical screw insertion
T can be explained by the fact that the wall of the two holes in the axis template was as thin as 110 μm, whereas the laser spot was only 70 μm
Summary
Due to developments in spinal surgery, it is necessary for many complicated surgeries (e.g., cervical spine surgery, thoracic spinal surgery, spinal deformity surgery) to fix screws into the pedicle of the vertebral arch in the spine and insert appropriate bone tissue substitutes (e.g., an inter-body fusion cage or titanium mesh) for structural reconstruction [1,2,3]. Designing of a customized surgical template through computer aided program is emerging as a simple and feasible method [6,7,8]. In this method, images of the spine at the surgery site are collected using high-speed spiral CT before reconstructing the computer-based 3D design. Some researchers successfully fabricated the non-metal template for inserting screws into the cervical vertebra and pedicle of vertebral arch in the thoracic vertebrae [9,10,11], resulting in improvements in precise insertion of screws. Kaneyama et al [13] studied the effectiveness of the tailor-made screw guide template (SGT) system for the placement of C2 screws, including in cases with abnormalities, the study mainly focus on the clinical usage of a non-metal template, it demonstrates that the SGT system provided extremely accurate C2 cervical screw insertion
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