Percutaneous Endoscopic Lumbar Decompression for Lumbar Lateral Spinal Canal Stenosis: Classification of Lateral Region of Lumbar Spinal Canal and Surgical Approaches.

PURPOSE: The purpose of the present study was to provide a new classification of the lateral region of the lumbar spinal canal (LLSC) and evaluate the clinical outcomes of surgical treatment of LLSC stenosis guided by the classification. METHODS: We developed a new functional classification of the LLSC by dividing the region into 5 zones. Thirty random lumbar imaging studies from patients with single-level LLSC stenosis in our department from January 2015 to June 2015 were evaluated by 3 examiners to validate its reliability. Subsequently, a prospective clinical outcome study of 76 patients with single-level LLSC stenosis from July 2015 to July 2016 with 2-year follow-up available was undertaken. All the patients had undergone either percutaneous endoscopic transforaminal decompression with foraminoplasty or percutaneous endoscopic interlaminar decompression, according to the classification. The dinical outcomes were evaluated using MacNab criteria, and pre- and postoperative leg pain were evaluated using the visual analog scale. RESULTS: We observed a 93.3% agreement among examiners. The mean follow-up duration was 15.6 months (range, 3-24). We found good and excellent outcomes in 93.4% of the patients at the last follow-up examination. The mean preoperative visual analog scale score was 5.72 +/- 1.18 (range, 4-9), which had decreased to 1.26 +/- 0.81 (range, 0-3) at the third month postoperatively and to 0.78 +/- 0.62 (range, 0-1) by the last follow-up visit. Dural tears appeared in 2 patients, and migrated bone had moved into the spinal canal after the surgery in 1 patient. CONCLUSIONS: The new classification of LLSC can provide objective criteria for full-endoscopic surgery that could lead to better clinical outcomes.