[Unilateral biportal endoscopy-assisted decompression strategy for lateral lumbar spinal stenosis].

Objective: To explore decompression strategies for lateral lumbar spinal stenosis under unilateral biportal endoscopy (UBE) assistance.

Methods: A clinical data of 86 patients with lateral lumbar stenosis treated with UBE-assisted intervertebral decompression between September 2022 and December 2023 was retrospectively analyzed. There were 42 males and 44 females with an average age of 63.6 years (range, 45-79 years). The disease duration ranged from 6 to 14 months (mean, 8.5 months). Surgical levels included L _{2, 3} in 3 cases, L _{3, 4} in 26 cases, L _{4, 5} in 42 cases, and L ₅, S ₁ in 15 cases. According to Lee's grading system, there were 21 cases of grade 1, 37 cases of grade 2, and 28 cases of grade 3 for lumbar spinal stenosis. Based on the location of stenosis and clinical symptoms, the 33 cases underwent interlaminar approach, 7 cases underwent interlaminar approach with auxiliary third incision, 26 cases underwent contralateral inclinatory approach, and 20 cases underwent paraspinal approach; then, the corresponding decompression procedures were performed. Visual analogue scale (VAS) score was used to evaluate lower back/leg pain before operation and at 1 and 3 months after operation, while Oswestry disability index (ODI) was used to evaluate spinal function. At 3 months after operation, the effectiveness was evaluated using the modified MacNab evaluation criteria. The spinal stenosis and decompression were evaluated based on Lee's grading system using lumbar MRI before operation and at 3 months after operation.

Results: All procedures were successfully completed with mean operation time of 95.1 minutes (range, 57-166 minutes). Dural tears occurred in 2 cases treated with interlaminar approach with auxiliary third incision. All incisions healed by first intention. All patients were followed up 3-10 months (mean, 5.9 months). The clinical symptoms of the patients relieved to varying degrees. The VAS scores and ODI of lower back and leg pain at 1 and 3 months after operation significantly improved compared to preoperative levels ( P<0.05), and the indicators at 3 months significantly improved than that at 1 month ( P<0.05). According to the modified MacNab evaluation criteria, the effectiveness at 3 months after operation was rated as excellent in 52 cases, good in 21 cases, and poor in 13 cases, with an excellent and good rate of 84.9%. No lumbar instability was detected on flexion-extension X-ray films during follow-up. The Lee's grading of lateral lumbar stenosis at 2 days after operation showed significant improvement compared to preoperative grading ( P<0.05).

Conclusion: For lateral lumbar spinal stenosis, UBE-assisted decompression of the spinal canal requires the selection of interlaminar approach, interlaminar approach with auxiliary third incision, contralateral inclinatory approach, and paraspinal approach based on preoperative imaging findings and clinical symptoms to achieve better effectiveness.