A Multicenter Study to Evaluate the Safety and Efficacy of a Stand-Alone Anterior Carbon I/F Cage for Anterior Lumbar Interbody Fusion Two-Year Results From a Food and Drug Administration Investigational Device Exemption Clinical Trial

Study Design. Two-year prospective multicenter clinical trial. Objective. To determine the safety and efficacy of the anterior I/F Cage in the primary treatment of single-level degenerative disc disease. Summary of Background Data. A carbon fiber-reinforced polymer cage was designed to replace the traditional allograft/autograft structural graft used in an anterior lumbar interbody fusion (ALIF). Although the outcomes of various types of ALIF cages have previously been reported, the safety and efficacy of the I/F cage are unknown. Methods. Between June 2000 and June 2004, 112 patients were prospectively enrolled at 12 study sites for the current study. Efficacy was evaluated clinically and radio-graphically. "Patient success" was declared only when the following 4 criteria were present at final follow-up: (1) "clinical success": improvement of 15 points on Oswestry Disability Index, (2) absence of a new neurologic abnormality, (3) successful radiographic fusion, and (4) no subsequent secondary surgical intervention at 24-month follow-up. Safety was inferred by way of an objective summary of complications and adverse events, as reported at regular intervals throughout the course of the study. Results. A total of 112 patients (mean age: 41.7 years) underwent a single-level ALIF procedure (L5-S1: 95 patients, L4-L5: 17 patients). The mean surgical time was 126 minutes, the mean estimated blood loss was 134 mL, and the mean duration of hospitalization was 3.3 days. There were 80 patients available for 24-month follow-up. Overall patient success was 25% (20/80). Clinical success was present in 46.3% (37/80), fusion success was 57.5% (46/80), and 87.5% of patients (70/80) avoided a subsequent secondary surgical intervention. Disc space height had significantly increased after surgery, and this increase was maintained at 2 years follow-up period. Complications and adverse events included the following: 8 infections (7.1%) (7 superficial, 1 deep), 2 vascular injuries (1.8%) (left common iliac vein), and 12 secondary surgical interventions (15%). Conclusion. This safety and efficacy study suggests that the anterior I/F Cage is a safe surgical option in the treatment of single-level lumbar degenerative disc disease. As a stand-alone construct, the I/F Cage yields suboptimal radiographic and clinical outcomes. Additional benefit may be gained from adjunctive posterior stabilization.