Cement augmentation of pedicle screw constructs as a modifier of hardware failure risk in instrumented metastatic spine surgery: a systematic review and meta-analysis.

Abstract

Hardware failure (HF) after instrumented fixation for spinal metastases affects 2-22% of patients. Despite growing adoption of cement-augmented pedicle screw fixation (CAPS), no meta-analysis has quantified its effect on HF rates. We aimed to provide pooled HF estimates for CAPS versus conventional fixation and explore the Spinal Instability Neoplastic Score (SINS) as a potential effect modifier. A systematic review and meta-analysis were conducted following PRISMA 2020 guidelines, searching five databases through April 2026. Pooled HF rates were computed using Freeman-Tukey double arcsine transformation with DerSimonian-Laird random-effects models. Sensitivity analysis was performed restricting to SINS-reporting studies. Certainty of evidence was assessed using GRADE. Thirteen studies (n = 886) met eligibility criteria. The pooled HF rate was 4.3% (95% CI 1.8-7.9%; I² = 46.8%) in CAPS arms (k = 10, n = 349) versus 12.5% (95% CI 2.9-27.5%; I² = 93.3%) in non-augmented controls (k = 5, n = 537). The sole comparative study demonstrated OR 0.13 (95% CI 0.02-0.81; p = 0.029). Sensitivity analysis restricted to SINS-reporting studies confirmed stability (4.5%, I² = 23.4%). All outcomes were rated low to very low certainty. CAPS was associated with a numerically lower pooled HF rate compared to conventional fixation in metastatic spine surgery (4.3% vs. 12.5%; indirect comparison). While certainty of evidence was low to very low, these findings may inform implant strategy decisions and highlight the need for standardised HF definitions. INPLASY registration: INPLASY202640045.