A Modified Laminotomy for Interlaminar Endoscopic Lumbar Discectomy: Technical Report and Preliminary Results.

Objective: To introduce a technique of laminotomy using a common trephine to enlarge the interlaminar space at L4/5 segment for interlaminar endoscopic lumbar discectomy (IELD) and report the anatomical basis of this procedure, technical details, as well as primary clinical outcomes of a consecutive patient cohort with L4/5 lumbar disc herniation (LDH).

Methods: On anteroposterior fluoroscopy, the intersection of the medial edge of the inferior articular process and the inferior endplate of L4 vertebra was taken as the target. Using a common trephine, laminotomy was performed to remove a big portion of the posterior wall of the canal under the guidance of endoscopy. From June 2018 to December 2021, the consecutive patients who underwent L4/5 IELD were prospectively studied. Clinical outcomes were assessed at the day before surgery, 1 day, 1 month, 3 months, 12 months after surgery, and the last follow-up. Numerical Rating Scale, Roland-Morris Disability Questionnaire (RMDQ), and MacNab criteria were used to evaluate back and leg pain, the quality of life, and clinical efficacy, respectively.

Results: There were 64 men and 44 women, with an age of 50.3 ± 14.9 years. The operating time was 74.54 ± 17.42 minutes. The mean follow-up time was 32.7 ± 18.6 months (range, 12-64 months). The complications of IELD included numbness, neck pain, and recurrence. Both leg pain (6.2 ± 1.9 vs. 1.8 ± 0.8, p < 0.001) and back pain (3.1 ± 2.3 vs. 1.7 ± 0.9, p < 0.001) quickly improved after this procedure and maintained (1.1 ± 1.5, 1.1 ± 1.3) at final follow-up. Physical disability due to back pain, as assessed using RMDQ, was improved remarkably after surgery (15.0 ± 5.8 vs. 2.9 ± 4.1, p < 0.001). In addition, MacNab outcome grade was evaluated as good-to-excellent in 96 cases (88.9%).

Conclusion: A convenient technique of laminotomy using a common trephine was proposed for the L4/5 IELD. It can efficiently enlarge the interlaminar entry to perform endoscopic discectomy. This procedure is particularly suitable for treating LDH with concomitant lumbar spinal stenosis and migrated herniated disc.