Effect of Interbody Composition on the Development of Pseudarthrosis Following Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective cohort study.

PURPOSE: To determine if polyetheretherketone (PEEK) or titanium alloy cages increase the rate of pseudarthrosis development or revision surgery rate compared with structural allograft following anterior cervical discectomy and fusion (ACDF) and identify if the cage type results in differences in patient-reported outcome measures (PROMs) versus structural allograft.

OVERVIEW OF LITERATURE: PEEK and titanium alloy cages have become popular options for ACDF intervertebral spacers. However, while data is beginning to emerge on how cage types affect arthrodesis rates, the effect of their composition on PROMs is less clear.

METHODS: All patients aged >18 years who underwent primary one- to four-level ACDF at a single institution were retrospectively identified. Propensity matching was performed to compare patients' PEEK or titanium alloy cages with structural allograft. Multivariate logistic regression analysis was performed to measure the effect of interbody spacer composition on the likelihood of pseudarthrosis development.

RESULTS: Of the 502 patients who received structural allograft and had 1-year postoperative dynamic radiographs, 96 patients were propensity matched to 32 patients who received a PEEK cage, and 162 patients were propensity matched to 54 patients who received a titanium alloy cage. Multivariate logistic regression analysis identified that PEEK cage implants (odds ratio [OR], 3.34; p =0.007) predicted pseudarthrosis development compared with structural allograft implantation. Titanium alloy cage (OR, 1.64; p =0.156) implantation was not predictive of pseudarthrosis. One-year postoperative PROMs were not significantly different between patients who received PEEK or titanium alloy cages and those who received structural allograft (all p >0.05).

CONCLUSIONS: Compared with structural allograft, receiving a PEEK cage increased the risk of pseudarthrosis development following ACDF, whereas receiving a titanium alloy cage had no significant effect on pseudarthrosis development. One-year postoperative patient-reported outcomes were similar between patients who received structural allograft, PEEK, and titanium alloy interbody spacers.