Outcomes of 1 level MIS decompression by operated lumbar vertebra.

Introduction: Degenerative lumbar pathologies often result in significant back and leg pain and impair patients’ quality of lives. Treatment in these patients begins with physical therapy and medical pain management. Usually, only once these treatment modalities fail, is surgical intervention considered. In these patients, surgical treatment may be indicated in the form of a decompression or surgical fusion. Decompression is a less invasive surgical option which has been shown to produce largely favorable outcomes. The anatomy of the lumbar spine changes as we move more cranial in the lumbar spine which can make the technical challenges of preforming an MIS decompression greater. The purpose is to analyze whether outcomes following MIS decompression differ based on level operated on in the lumbar spine.

Methods: The current study is a retrospective review of patients undergoing primary single level minimally invasive (MIS) decompression for the treatment of degenerative conditions of the lumbar spine. Patient reported outcome measures (oswestry disability index, visual analogue scale-back/leg, short form 12-physical function score) were all collected at preoperative and postoperative time points up to 2 years. Outcomes were compared between patients operated on at each level. Patients were then categorized as operated on at the upper lumbar spine (L1-L4) and lower lumbar spine (L4-S1) and outcomes were similarly compared.

Results: A total of 457 patients were included in the analysis of which 7 were operated on L1-L2, 25 were operated at L2-L3, 87 were operated at L3-L4, 330 were operated at L4-L5, and 58 were operated at L5-S1. On the mutli-test ANOVA, there existed no significant differences at preoperative or postoperative PROMs between the groups. When dichotomized to upper and lower lumbar spine, patients operated on at the upper lumbar spine demonstrated a worse SF12-PCS at the early time point. Patients also had a worse preoperative VAS-back but had significant and similar improvement. There were no other differences between the cohorts.

Conclusion : Patients operated on the at the upper lumbar spine did experience slower regain of physical function. However, there were no significant differences between long term outcomes in those operated at the upper and lower lumbar spine.