Clinical Outcome of Microsurgical Bilateral Decompression via Unilateral Approach for Lumbar Canal Stenosis

Abstract

Study Design. A retrospective study. Objective. To evaluate minimum 5-year clinical outcome and radiologic changes in patients who underwent microsurgical bilateral decompression via a unilateral approach. Summary of Background Data. Some authors have reported satisfactory short-term results of minimally invasive decompressive procedures such as microscopic or microendoscopic decompressive laminotomy for lumbar spinal stenosis (LSS). However, there have been a few reports on the long-term clinical outcome of these procedures. Methods. The study consisted of 57 patients who underwent this surgery and had been followed for at least 5 years. The preoperative diagnoses were LSS without instability in 27 patients, degenerative lumbar spondylolisthesis (DS) in 20 patients, and degenerative lumbar scoliosis (DLS) in 10 patients. The mean duration of follow-up was 6 years. Clinical outcome was evaluated by Japanese Orthopedic Association (JOA) score. Complications, rate of reoperation, and radiographic changes after surgery on plain radiograph were evaluated. Results. The mean JOA score was 13.8 ± 3.6 points before surgery, and improved to 24.9 ± 3.1 points at 3 months and 22.6 ± 4.7 points at the latest follow-up. There were no significant differences in JOA score at the latest follow-up among patients with LSS, DS, and degenerative scoliosis (22.3 ± 5.3, 23.3 ± 4.4, and 21.6 ± 2.6, respectively). Four patients (7%) underwent reoperation; 2 had DS and 2 had DLS. The preoperative percentages of slippage in patients with LSS, DS, and DLS were 0.4% ± 2.2%, 13.2% ± 5.9%, and 0.0% ± 1.3%, respectively, whereas degrees of progression of slippage at latest follow-up were 1.2% ± 3.1 %, 2.4% ± 4.7%, and 0.0% ± 0.0%, respectively. There were no significant differences in progression of slippage among these 3 disease groups. Conclusion. Microsurgical bilateral decompression via a unilateral approach is a minimally invasive technique that yielded satisfactory surgical outcomes even on minimum 5-year follow-up.