Minimum 10-Year Follow-up Study of Anterior Lumbar Interbody Fusion for Degenerative Spondylolisthesis: Progressive Pattern of the Adjacent Disc Degeneration

STUDY DESIGN Retrospective study. PURPOSE The aims of the current study are to evaluate the minimum 10-year follow-up clinical results of anterior lumbar interbody fusion (ALIF) for degenerative spondylolisthesis. OVERVIEW OF LITERATURE ALIF has been widely used as a treatment regimen in the management of lumbar spondylolisthesis. Still much controversy exists regarding the factors that affect the postoperative clinical outcomes. METHODS The author performed a retrospective review of 20 patients with degenerative spondylolisthesis treated with ALIF (follow-up, 16.4 years). The clinical results were assessed by the Japanese Orthopaedic Association (JOA) score for low back pain, vertebral slip and disc height index on the radiographs. RESULTS The mean preoperative JOA score was 7.1 ± 1.8 points (15-point-method). At 1 year, 5 years, and 10 years or more after surgery, the JOA scores were assessed as 12.4 ± 2.2 points, 12.7 ± 2.6 points, 12.0 ± 2.5 points, respectively (excluding the data of reoperated cases). The adjacent disc degeneration developed in all cases during the long-term follow-up. The progressive pattern of disc degeneration was divided into three types. Initially, disc degeneration occurred due to disc space narrowing. After that, the intervertebral discs showed segmental instability with translation at the upper level. But the lower discs showed osteophyte formation, and occasionally lead to the collapse or spontaneous union. CONCLUSIONS The clinical results of the long-term follow-up data after ALIF became worse due to the adjacent disc degeneration. The progressive pattern of disc degeneration was different according to the adjacent levels.