[The application of classification of lateral region of lumbar spinal canal for treatment of lumbar spinal stenosis in geriatric patients using full endoscopic transforaminal decompression surgery].

Objective: To assess the reliability, effectiveness, and the safety of full endoscopic transforaminal decompression (FETD) under local anesthesia guided by the classification of lateral region of the lumbar spinal canal (CLLSC) in treating lumbar spinal stenosis (LSS) in geriatric patients.

Methods: The clinical data of 63 geriatric patients with LSS met the inclusion criteria underwent FETD surgery between June 2015 and July 2017 were retrospectively analyzed. There were 37 males and 26 females, with a median age of 76 years [interquartile range (IQR), 73-80 years], and a median symptomatic duration of 55 months (IQR, 16-120 months). There were 17 cases of grade B and 46 cases of grade C based on the Schizas morphological grading system. CLLSC was used for imaging evaluation for the stenotic condition, and intra-class correlation coefficients (ICC) were used to test intra-observer and inter-observer reliability of CLLSC. The stenotic condition of patients was re-evaluated by the surgeon after operation, and the results were compared with the findings of preoperative CLLSC. The visual analogue scale (VAS) score for low back pain and leg pain recorded before operation, and at 1 day, 3 months, and 6 months after operation, and last follow-up were used to assess the pain relieving; the functional improvement was evaluate by Oswestry disability index (ODI); the modified Macnab criteria were used to self-evaluate the surgical satisfaction.

Results: The operation were successfully performed for all patients, with a median operation time of 75 minutes (IQR, 65-85 minutes), postoperative hospitalization stay of 48 hours (IQR, 48-72 hours), and the time to ambulation after operation of 24 hours (IQR, 24-24 hours). Sixty-three patients were followed-up and with a median follow-up time of 18 months (IQR, 13-20 months). Based on preoperative CLLSC classification, there were 72 stenotic zones, distributed 16 in zone 1, 6 in zone 2, 3 in zone 3, 2 in zone 4, 7 in zone 5, 34 in zones 1+2, 2 in zones 3+4, and 2 in zones 4+5. Perioperative complications occurred in 4 cases (6.3%), including 2 cases of intraoperative dural sac tear, 1 of preoperative numbness symptom aggravation, and 1 of postoperative urinary retention. VAS score of leg pain and ODI score at each time point after operation were significantly improved compared with those before operation ( P <0.05). VAS scores of low back pain showed no significant difference between pre- and post-operation ( P >0.05). At last follow-up, based on the modified Macnab criteria, 19 cases were excellent, 37 were good, 6 were fair, and 1 was poor, and the excellent and good rate was 88.9%. The reliability analysis showed that CLLSC had substantial intra-observer reliability in the geriatric population, with an average ICC of 0.78. There was also a substantial inter-observer reliability, with an average ICC of 0.73. While comparing the preoperative CLLSC results with the postoperative CLLSC results, 53 patients (73.6%) were in full agreement, 15 patients (20.8%) were in partial agreement, and 4 patients (5.6%) were not.

Conclusion: CLLSC has high reliability in the diagnosis of LSS in the geriatric patients. Combined FETD with CLLSC, accurate diagnosis, and minimal invasion can be performed to achieve safe and effective result.