Is minimally invasive surgery superior to open surgery for treatment of lumbar spinal stenosis? A systematic review

Purpose: The purpose of this study is to review the updated evidence comparing outcomes between minimally invasive surgery (MIS) and conventional open surgery (COS) for lumbar spinal stenosis (LSS). Methods: All randomized controlled trials (RCTs) published from January 2005 to August 2016 were identified through PubMed and MEDLINE databases. Only RCTs including patients with LSS and with direct comparison between COS and MIS were selected for analysis. The intra- and post-operative effects of different MIS and COS on patients with LSS were evaluated for any differences. Results: We reviewed 10 RCTs comparing the effect of MIS and COS for LSS. Most trials showed that MIS rendered a shorter duration of hospital stay, lower reoperation rate, visual analogue scale (VAS), 36-Item Form Health Survey (SF-36) score, creatinine phosphokinase-skeletal muscle (CPK-MM) levels and a higher Japanese Orthopaedic Association (JOA) score. However, the intergroup differences were not statistically significant for all comparisons and were only present for selected mild cases of spinal stenosis. Conclusions: This systematic review suggests that MIS reduces operating time, duration of hospital stay and CPK-MM levels. However, the evidence for these parameters is weak. Moreover, there is no conclusive evidence that MIS reduces reoperation or has better improvement in pain and outcome scores like VAS, SF-36 and JOA scores. The evidence is limited due to poor standardization of MIS definition, methodology and details of surgeon experience. MIS techniques should not be studied as a group, as each procedure is vastly different from each other.