Minimally invasive surgical treatment of lumbar spinal stenosis: Two-year follow-up in 54 patients

OBJECTIVE: Minimally invasive surgery has seen increasing application in the treatment of spinal disorders. Treatment of degenerative spinal stenosis, with or without spondylolisthesis, with minimally invasive technique preserves stabilizing ligaments, bone, and muscle. Satisfactory results can be achieved without the need for fusion in most cases. METHODS: Fifty-four consecutive patients underwent bilateral decompressions from a unilateral approach for spinal stenosis using METRx instrumentation. Visual Analog Scale (VAS) pain scores were recorded preoperatively and patients were interviewed, in person or by phone, by our office nurse practitioner (LD) to assess postoperative VAS scores, and patient satisfaction with the clinical results 21-39 months postoperatively (median 27 months). RESULTS: Fifty-four patients underwent decompression at 77 levels (L4/5 = 43, L3/4 = 22, L5/S1 = 8, L1/2 = 4, L2/3 = 4), (single = 35, double = 16, triple = 2, quadruple = 1). There were 39 females and 15 males. The average age was 67 years. The average operative time was 78 minutes and the average blood loss was 37 ml per level. Twenty-seven patients had preoperative degenerative spondylolisthesis (Grade 1 = 26, Grade 2 = 1). Eight patients had discectomies and four had synovial cysts. Patient satisfaction was high. Use of pain medication for leg and back pain was low, and VAS scores improved by more than half. There were three dural tears. There were no deaths or infections. One patient with an unrecognized dural tear required re-exploration for repair of a pseudomeningocele and one patient required a lumbar fusion for pain associated with progression of her spondylolisthesis. CONCLUSIONS: Minimally invasive bilateral decompression of acquired spinal stenosis from a unilateral approach can be successfully accomplished with reasonable operative times, minimal blood loss, and acceptable morbidity. Two-year outcomes in this series revealed high patient satisfaction and only one patient progressed to lumbar fusion.