Titanium versus polyetheretherketone versus structural allograft in anterior cervical discectomy and fusion: A systematic review

INTRODUCTION: Anterior cervical discectomy and fusion (ACDF) is a common procedure to address cervical spine pathology. The most common grafts used are titanium, polyetheretherketone (PEEK), or structural allograft. Comparison of fusion rate is difficult due to non-standardized methods of assessment. We stratified studies by method of fusion assessment and performed a systematic review of fusion rates for titanium, PEEK, and allograft. RESEARCH QUESTION: Which of the common implants used in ACDF has the highest reported rate of fusion? MATERIALS AND METHODS: An experienced librarian performed a five-database systematic search for published articles between 01/01/1990 and 08/07/2021. Studies performed in adults with at least 1 year of radiographic follow up were included. The primary outcome was the rate of fusion. Fusion criteria were stratified into 6 classes based upon best practices. RESULTS: 34 studies met inclusion criteria. 10 studies involving 924 patients with 1094 cervical levels, used tier 1 fusion criteria and 6 studies (309 patients and 367 levels) used tier 2 fusion criteria. Forty seven percent of the studies used class 3–6 fusion criteria and were not included in the analysis. Fusion rates did differ between titanium (avg. 87.3%, range 84%–100%), PEEK (avg. 92.8%, range 62%–100%), and structural allograft (avg. 94.67%, range 82%–100%). DISCUSSION AND CONCLUSION: After stratifying studies by fusion criteria, significant heterogeneity in study design and fusion assessment prohibited the performance of a meta-analysis. Fusion rate did not differ by graft type. Important surgical goals aside from fusion rate, such as degree of deformity correction, could not be assessed. Future studies with standardized high-quality methods of assessing fusion, are required.