Adjacent Level Degeneration in the Lumbar Spine after Single-Level Fusion versus Arthroplasty: Five-Year Clinical and Radiographic Outcomes
Study Design: Retrospective review of a prospective, randomized, controlled single-site investigation of an FDA IDE trial. Objective: Compare baseline and 5 year adjacent disc degeneration and outcomes of lumbar arthroplasty and fusion groups. Summary of background data: Degenerative Disc Disease (DDD) has historically been surgically managed with arthrodesis. However, fusion treatment is associated with accelerated adjacent segment degeneration. Method: Patients completed pre and post-operative Oswestry Disability Index and Visual Analog Scale as well as radiographic studies out to 5 years postoperatively. Adjacent (cephalad) disc height was measured by 6 examiners using the Farfan index on radiographs blinded to caudal level treatment. After exclusion of patients with incomplete follow-up data, 35 disc arthroplasty and 13 fusion patients had complete sets of information from pre-operative and 5 year follow-up available for final analysis. Results: Both disc arthroplasty and fusion groups demonstrated significant improvement in ODI and VAS back scores from preoperative status to 5 year follow up (all groups p<0.0001). However, no significant differences were found when comparing observed improvements for either ODI or VAS back scores between the disc arthroplasty or fusion groups. Furthermore, no significant differences were found in adjacent disc height change as determined by the Farfan index was found between the two cohorts at 5 year follow up. Conclusion: While both TDA and circumferential fusion can offer clinically meaningful pain and disability relief for symptomatic DDD, no significant reduction of radiographic adjacent segment degeneration was seen in the TDA group compared to the fusion group at 5 year follow up.