Carbon Fiber-reinforced PEEK vs. Titanium Implants for Posterior Instrumentation in Patients Undergoing Decompressive Surgery Followed by Radiosurgery: Outcomes Analysis

Introduction: Carbon fiber-reinforced polyetheretherketone (CFRP) implants have advantages over titanium in reducing imaging artifacts and minimizing radiation interference, which may be relevant for treating spinal metastases requiring surgical hardware. These factors could influence tumor control after spine stereotactic radiosurgery (SSRS). This study compared local tumor control in patients with spinal metastases who underwent decompression and instrumentation with CFRP versus titanium implants, followed by SSRS. The occurrence of hardware failure was also examined.

Methods: This was a single-center, retrospective cohort study approved by the institutional review board. Patients were excluded if they had: 1) cervical spine hardware, 2) mixed implant types, 3) SSRS conducted more than 60 days post-surgery, or 4) imaging follow-up shorter than 3 months. Only tumor progressions within the irradiated zone were considered for analysis.

Results: A total of 55 spinal segments with titanium implants and 28 with CFRP implants (across 82 patients) were analyzed. Baseline differences included the number of radiation fractions, use of single-fraction 24Gy, and the equivalent dose of 2Gy per fraction (EQD2). The average MRI follow-up period was 20.7 months (range, 3-70 months). Local progression occurred in 15 cases in the titanium group versus 1 case in the CFRP group (P=0.009). Progression-free survival, considering death as a competing risk, was significantly higher in the CFRP group (HR=0.127; P=0.044). The median time to progression after radiation was 9.27 months (IQR, 4.5-15.65 months). On univariate analysis, higher EQD2, single-fraction 24Gy, and CFRP were linked to improved local control, with single-fraction 24Gy and CFRP remaining significant in multivariate analysis (P=0.047 and P=0.0468). There was no significant difference in hardware failure between the groups (titanium=4, CFRP=2; P>0.05).

Conclusion : CFRP implants and single-fraction 24Gy were associated with improved local control and extended progression-free survival. The study's retrospective design and potential confounding variables should be considered when interpreting these findings.