Comparison of the Fixation Strengths of Screws between the Traditional Trajectory and the Single and Double Endplate Penetrating Screw Trajectories Using Osteoporotic Vertebral Body Models Based on the Finite Element Method

• Published in: Asian spine journal Vol. 18; no. 1; pp. 12 - 20
• Main Authors: Takeuchi, Takumi, Takamizawa, Yuhei, Konishi, Kazumasa, Sano, Hideto, Takahashi, Masahito, Kouno, Hitoshi, Hosogane, Naobumi
• Format: Journal Article
• Language: English
• Published: Korea (South) Korean Society of Spine Surgery 01.02.2024; Korean Spine Society; 대한척추외과학회
• Subjects: Clinical Study; diffuse idiopathic hyperostosis; double endplate penetrating screw trajectory; finite element; osteoporotic vertebral fractures; single endplate penetrating screw trajectory; 정형외과학; Single endplate penetrating screw trajectory; Diffuse idiopathic hyperostosis; Osteoporotic vertebral fractures; Double endplate penetrating screw trajectory; Finite element
• ISSN: 1976-1902; 1976-7846
• DOI: 10.31616/asj.2023.0238

This is a finite element (FE) study. To compare the fixation strength of traditional trajectory (TT) and single and double endplate penetrating screw trajectories (SEPST/DEPST) to the osteoporotic vertebral body model based on the FE method. SEPST/DEPST have been developed to enhance the fixation strength in patients with diffuse idiopathic hyperostosis (DISH). This technique was also applied to patients with osteoporosis. However, determining the superiority of SEPST/ DEPST is difficult because of the heterogeneous patient backgrounds. Twenty vertebrae (T12 and L1) from 10 patients with osteoporosis (two males and eight females; mean age, 74.7 years) were obtained to create the 10 FE models. First, a single screw was placed with TT and SEPST/DEPST, and the fixation strength was compared by axial pullout strength (POS) and multidirectional loading tests. Second, two screws were placed on the bilateral pedicles with TT and SEPST/DEPST, and the fixation force of the vertebrae in the constructs in flexion, extension, lateral flexion, and axial rotation was examined. SEPST and DEPST had 140% and 171% higher POS values than TT, respectively, and the DEPST result was statistically significant (p =0.007). The multidirectional fixation strength was significantly higher in DEPST and SEPST than in TT in the cranial, caudal, and medial directions (p <0.05) but not in the lateral direction (p =0.05). The vertebral fracture strength at the lower instrumented vertebra of the DEPST tended to be higher than that of TT. The vertebral motion angles in SEPST and DEPST were significantly smaller in lateral bending (p =0.02) and tended to be smaller in flexion and extension than in TT (p =0.13). This study may provide useful information for spine surgeons in deciding whether to choose the SEPS or DEPS technique for augmenting fixation in osteoporotic vertebral fracture surgery.