Study on the safety and effectiveness of 3D printed artificial vertebral body reconstruction after en bloc resection of thoracolumbar tumor

English Keywords:Spinal tumor  Thoracolumbar  3D printing prosthesis  En bloc resection  Spondylectomy

English Abstract:

  【Abstract】 Objectives: To evaluate the safety and stability of 3D printed artificial vertebrae in reconstruction of thoracolumbar tumor after total en bloc resection on the early and middle follow-up results. Methods: Between May 2016 and January 2019, 42 cases(19 males and 23 females) aged from 10 to 71 years old (39.7±16.2) were analyzed retrospectively. 37 cases were with primary bone tumors and 5 cases with metastatic tumors. There were 10 cases of recurrent tumor. All the tumors involved thoracolumbar spine, including 22 cases of single segment, 6 cases of 2 segments, 11 cases of 3 segments, 2 cases of 4 segments and 1 case of 5 segments. The en bloc resection was performed in all cases. All of them used 3D printed artificial vertebral body as the anterior support structure. According to X-ray and CT images of patients who were followed up for more than 6 months, the fusion of prosthesis and adjacent vertebral body was evaluated. Results: There were 39 cases of total spondylectomy and 3 cases of sagittal resection. In this group, 19 cases were treated with standard 3D printed prosthesis. Among them, 15 cases were in 1 segment, 3 in 2 segments and 1 in 3 segments. The prostheses were placed from the posterior approach in 15 cases, and the anterior approach in 4 cases. 23 cases were treated with customized prosthesis. Among them, 7 cases were single segment, 3 cases were 2 segments, 10 cases were 3 segments, 2 cases were 4 segments, and 1 case was 5 segments. In 19 cases, the pedicle screw was used to screw into the internal screw hole of the prosthesis to connect with the posterior screw-rod system to achieve self-stabilization; in 4 cases, the screws were placed from the anterior approach and fixed to the adjacent vertebral body through the internal screw hole. Except one died of cardiovascular disease 4 months after operation without follow-up and 1 case lost follow-up, the rest 40 patients were followed up between 3 and 47 months, with a median follow-up period of 22 months. 36 patients were followed up for more than 6 months. There were 9 cases of fusion, 19 cases of probable fusion and 8 cases of probable non-fusion. There was no screw breakage or pull-out, no rod breakage, no prosthesis breakage or displacement. The overall fusion rate was 77.8%(28/36). In 2 cases, the prostheses subsided more than 2 mm, but the pains were mild without internal fixation. Conclusions: 3D printed prosthesis is conducive to prevent collapse because of its large end plate area. Microporous structure can promote bone growth and increase bone fusion. Customized design can make it connect with internal fixation system or directly fix in adjacent vertebral body to obtain better immediate stability. Therefore, 3D printed prosthesis can reduce the failure rate of internal fixation after thoracolumbar en bloc resection.