Titanium Cage versus Structural Allograft for Anterior Cervical Discectomy and Fusion: A Propensity Score Matched Analysis

Introduction: Structural allografts and synthetic grafts such as titanium cages have been frequently utilized for anterior cervical discectomy and fusion (ACDF). While the biomechanical properties have been compared between these two graft types, there remains limited data on their comparative performance for cervical procedures. Through a propensity score matched analysis, we sought to understand the unique strengths of titanium cages for ACDF while characterizing radiological and clinical outcomes associated with graft material.

Methods: We assembled a cohort of patients who underwent an ACDF procedure with a structural allograft or titanium cage between 2013 and 2023 at a tertiary care medical center and community hospital. All patients were operated on by a single surgeon to control for operative technique. Demographic features, clinical symptoms, and radiographic parameters were extracted for each patient, including rate of fusion, cage subsidence, pseudoarthrosis, revisions needed, and symptom progression. To standardize comparisons on patient outcomes, a 1:1 propensity-score matched cohort was assembled using optimal pair matching and a generalized linear model.

Results: Of 376 included patients, 269 received a structural allograft and 107 received a titanium cage (median age at surgery: 56 years). There was significant variability amongst pre-operative health status. 42.8% of ACDFs studied 42.8% were multi-level fusions. Across both graft materials, ACDFs had a relatively safe complication profile with a low intraoperative blood loss. Further, there was durable symptom relief for patients, with 94.5% reporting improved to resolved symptoms at last follow-up. Post-operative radiographic assessment showed patients with titanium cages had significantly greater cervical Cobb angle change compared to patients with structural allografts (p < 0.001). After propensity-score matching, there was no significant difference between the rate of fusion, cage subsidence, pseudoarthrosis, or need for revision surgery between titanium cages and structural allografts.

Conclusion : Titanium cages demonstrate a similar safety and efficacy profile to structural allografts while likely enabling greater cervical Cobb angle changes. A longer neurosurgical follow-up interval may be required to monitor radiographic and clinical changes that may contribute to differential patient outcomes across cage materials.