Polyetheretherketone Versus Titanium Cages for Posterior Lumbar Interbody Fusion: Meta-Analysis and Review of the Literature

Abstract

Objective: Lumbar fusion with implantation of interbody cage is a common procedure for treatment of lumbar degenerative disease. This study aims to compare the fusion and subsidence rates of titanium (Ti) versus polyetheretherketone (PEEK) interbody cages after posterior lumbar interbody fusion and investigate the effect of clinical and radiological outcomes following fusion on patient-reported outcomes.

Methods: A systematic search strategy of 4 electronic databases (MEDLINE, Embase, Web of Science, and Cochrane) was conducted using different MeSH (medical subject headings) terms until January 2020. Pooled odds ratios (ORs) with 95% confidence intervals (CI) were calculated using fixed and random-effect models based upon the heterogeneity (I2) to estimate the association between interbody cages and the measured outcomes.

Results: A total of 1,094 patients from 11 studies were reviewed. The final analysis included 421 patients (38.5%) who had lumbar surgery using a Ti and/or a Ti-coated interbody cage and 673 patient (61.5%) who had lumbar surgery using a PEEK cage. Overall, PEEK interbody devices were associated with a significantly lower fusion rate compared with Ti interbody devices (OR, 0.62; 95% CI, 0.41-0.93; p = 0.02). There was no difference in subsidence rates between Ti and PEEK groups (OR, 0.91; 95% CI, 0.54-1.52; p = 0.71). Also, there were no statistically significant differences in visual analogue scale (VAS)-low back pain (p = 0.14) and Japanese Orthopedic Association scale (p = 0.86) between the 2 groups. However, the PEEK group had lower odds of leg pain after surgery compared to the Ti group (OR [VAS-leg], 0.61; 95% CI, 0.28-0.94; p = 0.003).

Conclusion: Ti and Ti-coated PEEK cages used for posterior lumbar interbody fusion are associated with similar rates of subsidence, but a higher rate of fusion compared to PEEK interbody cages. Randomized controlled trials are needed to better assess the effect of cage materials and potential factors that could influence the outcomes of interbody lumbar fusion.

Keywords: Interbody cage; Lumbar spine; Polyetheretherketone; Spinal fusion; Titanium.

Fig. 1.

PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis) flow diagram.

Fig. 2.

Forest plot showing the effect sizes and 95% confidence intervals (CIs) of studies comparing the fusion rates of PEEK vs. Ti. PEEK shows less odds of fusion compared to titanium cage for lumbar interbody fusion (odds ratio, 0.62; 95% CI, 0.41–0.93; p=0.02). PEEK, polyetheretherketone; Ti, titanium; df, degrees of freedom.

Fig. 3.

Forest plot showing effect sizes and 95% confidence intervals (CIs) of studies comparing subsidence rates for titanium and PEEK interbody cages. Titanium and PEEK have similar odds of subsidence (odds ratio, 0.91; 95% CI, 0.54–1.52; p=0.71). PEEK, polyetheretherketone; Ti, titanium; df, degrees of freedom.

Fig. 4.

Forest plot showing effect sizes and 95% confidence intervals (CIs) of studies comparing visual analogue scale (VAS) scores for low back pain (A) and leg pain (B), and the Japanese Orthopedic Association (JOA) score for low back pain (C) for titanium and PEEK interbody cages. PEEK, polyetheretherketone; df, degrees of freedom.

Fig. 5.

Funnel plot to assess for publication bias.