Microendoscopic Decompression for Lumbar Spinal Stenosis With Degenerative Spondylolisthesis: The Influence of Spondylolisthesis Stage (Disc Height and Static and Dynamic Translation) on Clinical Outcomes.

Study Design: This study was a retrospective subgroup analysis of prospective cohort data.

Objective: The main objectives of this study were to develop a classification of degenerative spondylolisthesis (DS) and concurrent lumbar spinal stenosis (LSS) based on pathologic stage, and to determine how these subtypes of DS affect outcomes for minimally invasive (MIS) decompression SUMMARY OF BACKGROUND DATA:: DS with LSS is a common clinical scenario, yet there is no consensus on optimal treatment. Natural history of DS is described as early degenerative damage, followed by instability, and eventual restabilization via spondylotic changes. MIS decompression surgery has become increasingly popular, but the effect of DS subtypes on clinical outcomes after MIS decompression is unknown.

Patients And Methods: From 2008 to 2013, all patients who underwent microendoscopic laminotomy for single-level LSS with DS were included. In total, 218 patients (91 male, 127 female individuals) were reviewed. DS pathologic staging was defined as early, advanced, or end stage, based on percent slippage (10% slippage), degree of dynamic instability (3 mm), and disc height. The following variables were evaluated preoperatively and >2 years postoperatively and compared among groups: Japanese Orthopaedic Association (JOA) score, JOA recovery rate, and Visual Analog Scale low back pain.

Results: In total, 173 patients were included in final analysis. Final follow-up period was 2.3 years. Average JOA recovery rate was 63.8%. There were no significant differences in JOA recovery and Visual Analog Scale among 3 DS stages (P>0.05). In total, 9.8% of patients required additional spine surgery, with 5% requiring subsequent fusion. All patients who required subsequent fusion were in the advanced stage DS group.

Conclusions: Microendoscopic decompression is an effective treatment for patients with DS and concurrent LSS, with only 5% of patients requiring subsequent fusion at over 2-year follow-up, and another 5% requiring revision or adjacent segment decompression. The advanced stage DS group, indicating a >10% anterolisthesis and/or >3 mm of dynamic instability, was more likely to require additional surgery.