Clinical and radiological outcomes of microscopic partial pediculectomy for degenerative lumbar foraminal stenosis.

STUDY DESIGN:Retrospective cohort study. OBJECTIVE:To investigate the clinical outcomes of microscopic partial pediculectomy for degenerative lumbar craniocaudal foraminal stenosis, risk factors for postsurgical scoliosis progression, and feasibility of postsurgical pedicle screw insertion. SUMMARY OF BACKGROUND DATA:Previous studies have evaluated surgical strategies for degenerative lumbar foraminal stenosis. Although less invasive decompression surgery is an option for surgical treatment, postsurgical instability and salvaging fusion surgery remain as problems. No analysis has focused on the radiological progression and feasibility of pedicle screw setting after pediculectomy. METHODS:Microscopic partial pediculectomy by our original method was performed as a first-choice surgical treatment for lumbar radiculopathy due to degenerative craniocaudal foraminal stenosis. This study included 50 consecutive patients followed up for a minimum of 2 years. Clinical outcomes were evaluated with Japanese Orthopaedic Association (JOA) scores and a numerical rating scale. Radiological changes were obtained from standing radiographs. Foraminal height and the minimum pedicle diameter were measured by reconstructed images on multidetector row computed tomography. RESULTS:The preoperative Japanese Orthopaedic Association score of 14.2 ± 4.2 significantly improved to 21.5 ± 6.2, and 60% of patients were satisfied. The numerical rating scale for lumbar back pain, leg pain, and leg numbness significantly improved. Nine patients (18%) showed lumbar Cobb angle progression of 5° or more within 2 years, and the risk factor for scoliosis progression was surgery at L3-L4 or L4-L5 by multivariate logistic regression analysis. Foraminal height was enlarged from 5.4 mm preoperatively to 8.9 mm postoperatively. The postoperative minimum pedicle diameter was 8.7 ± 1.6 (5.9-11.7) mm. CONCLUSION:Microscopic lumbar partial pediculectomy provided satisfactory clinical outcomes, but early postsurgical scoliosis progression was likely to occur in patients who underwent the surgery at L3-L4 or L4-L5. Even if a second surgical procedure is needed, pedicle screws can be set on the resected pedicle. LEVEL OF EVIDENCE:4.