Evaluation of Screw Loosening in Patients Undergoing Semi-rigid Stabilization with Polyetheretherketone (PEEK) Rods

Polyetheretherketone (PEEK) rods, designed for semi-rigid stabilization, offer a lower elastic modulus than metallic rods, promoting physiological load sharing and reducing hardware-related complications. Nevertheless, their clinical efficacy-particularly regarding pedicle screw loosening-remains inadequately studied.

The aim of this study was to determine the rate of screw loosening and to evaluate potential contributing factors in patients who underwent semi-rigid stabilization with PEEK rods for lumbar degenerative pathologies.

A retrospective cohort study.

The data of 58 patients who underwent semi-rigid stabilization using PEEK rods between 2017 and 2023 and had a minimum follow-up of 12 months were retrospectively analyzed. Demographic characteristics, surgical details, preoperative and postoperative pain scores, and bone mineral density were measured using dual-energy X-ray absorptiometry (DXA). Screw loosening was assessed based on plain radiographs and computed tomography (CT) imaging.

The study population consisted of 67.2% female patients, with a mean age of 60.4 ± 12.7 years. The screw loosening rate was 13.8%, with six cases attributed to deficiency in preoperative planning, one case to Parkinson's disease-related physical rigidity, and one case with an osteoporosis. A significant association was found between screw loosening and lower DEXA values as well as higher postoperative VAS scores (p < 0.001). No significant differences were observed between screw loosening and diagnosis, gender, or surgical segment length.

Semi-rigid stabilization using PEEK rod systems maintains screw loosening rates within acceptable limits. However, surgical technique errors and low bone quality significantly increase the risk of loosening. Careful patient selection is critical for minimizing complication rates. PEEK rods should not be applied to patients with severe instability, anterior column insufficiency, and osteoporosis.