Protective effects of preserving the posterior complex on the development of adjacent-segment degeneration after lumbar fusion

120 patients, age 35-60, with degenerative lumbar disorders were randomized into 1 of 3 treatment groups: complete-laminectomy, facet joint resection and L4-5 fusion, or semilaminectomy and fusion to compare clinical outcomes and the occurrence of adjacent-segment degeneration (ASD) during a long term follow-up. At final follow-up (mean 5.9 years) patients who were in the complete-laminectomy group had significantly lower JOA scores, significantly higher rates of ASD, and exhibited lower disc height and total lumbar lordosis than the other treatments. Additionally, those who were part of the complete laminectomy group experienced significantly higher dynamic angular ROM, disc angles, and listhesis.