Biomechanical Evaluation Of An Adaptive-Motion Pedicle Screw Fixation System: Experimental And Numerical Analysis.

The current internal fixation equipment used in thoracolumbar spine surgery are mostly rigid fixation, which restricts the patient's thoracolumbar spine segments moving and is not conducive to postoperative rehabilitation. We developed an adaptive-motion pedicle and established a finite element model of the T12-L3 segment of the thoracolumbar spine in osteoporosis patients based on the CT image data of human spine. A variety of internal fixation finite element models were established for mechanical simulation analysis and comparison. The simulation results showed that compared with the conventional internal fixation system, the mobility of the new adaptive-motion internal fixation system was improved by about 13.8% and 7.7% under classic conditions.In vitro experiments were conducted simultaneously with fresh porcine thoracolumbar spine vertebrae, and the axial rotation condition was taken as an example to analyze the mobility . The in vitro results showed that the mobility of the adaptive-motion internal fixation system had better mobility characteristics under axial rotation conditions, which was consistent with the finite element analysis. The adaptive-motion pedicle screw can preserve a certain degree of vertebral mobility, avoid excessive vertebral restriction, and facilitate the postoperative rehabilitation of patients, and also increase the stress value of the intervertebral disc, which is closer to the normal mechanical transmission of the human body, avoiding stress masking and slowing down the degeneration of the intervertebral disc. adaptive-motion pedicle screws can reduce the peak stress of the implant and avoid surgical failure due to implant fracture.