Incidence, Risk, and Outcome of Pedicle Screw Loosening in Degenerative Lumbar Scoliosis Patients Undergoing Long-Segment Fusion

Study Design: Retrospective study. Objective: To investigate the incidence, risk factors, and outcomes of pedicle screw loosening in degenerative lumbar scoliosis (DLS) undergoing long-segment spinal fusion surgery. Methods: One hundred and thirty DLS patients who underwent long-segment fusion surgery with at least a 12-month follow-up were studied. The incidence and risk factors of screw loosening were investigated. VAS, SRS-22, and ODI scores were obtained preoperatively and at follow-up. Results: One hundred and sixty-eight of 1784 (9.4%) screws showed evidence of loosening in 71 (54.6%) patients. Three patients required revision surgery. Screw loosening rates according to vertebral insertion level were lowest instrumented vertebra (LIV): 45.4%; uppermost instrumented vertebra (UIV):17.7%; one vertebra above the LIV: 0.5%; 2 vertebrae above the LIV: 0.4%. Multiple logistic regression analysis of possible risk factors indicated that preoperative lateral subluxation >= 8 mm (odds ratio [OR]: 2.68, 95% confidence interval [CI]: 1.16-6.20), osteopenia (OR: 5.52, 95% CI: 1.64-18.56), osteoporosis (OR: 8.19, 95% CI: 2.40-27.97), fusion to sacrum (OR: 2.55, 95% CI: 1.12-5.83), postoperative TLK greater than 10 degrees (OR: 2.63, 95% CI: 1.14-6.04) and SVA imbalance (OR: 3.44, 95% CI: 1.17-10.14) were statistically significant. No difference was noted in preoperative, follow-up, and change of VAS, ODI, and SRS-22 scores. Conclusions: Screw loosening in DLS underwent long-segment surgery is common and tends to occur in the LIV or UIV. Lateral subluxation >= 8 mm, osteopenia, osteoporosis, fusion to the sacrum, postoperative TLK greater than 10 degrees, and SVA imbalance were the independent influencing factors. Screw loosening can be asymptomatic, while longer-term follow-up is required.

Automated summary

This retrospective study aimed to investigate the incidence, risk factors, and outcomes of pedicle screw loosening in degenerative lumbar scoliosis (DLS) patients undergoing long-segment spinal fusion surgery. The results showed that screw loosening was common and tended to occur in the lowest instrumented vertebra (LIV) or uppermost instrumented vertebra (UIV). Risk factors for screw loosening included lateral subluxation >= 8 mm, osteopenia, osteoporosis, fusion to the sacrum, postoperative TLK greater than 10 degrees, and SVA imbalance.