Retrospective analysis on correlation factors of preserving the ligamentum flavum in microendoscopic discectomy

The present study was conducted to investigate the correlation factors of successful preservation of the ligamentum flavum (LF) in microendoscopic discectomy.

This retrospective review was carried out on 78 consecutive patients who underwent single segment microendoscopic discectomy projecting to preserve the LF between January 2012 to January 2013. The demographic and clinical data including age, gender, duration of disease, area of interlaminar space, disc level and position type of lumbar disc herniation were recorded. Intraoperative outcomes including duration of operation and peri-operative bleeding were recorded. Clinical outcomes were assessed by Oswestry disability index (ODI) and visual analog scale (VAS), and fibrosis formation was detected using computed tomographic scans with IV iopamidol injection. The follow up lasted six months.

LF was successfully preserved in 54 patients (69.2%) and 24 patients (30.8%) underwent microendoscopic discectomy without preservation of LF. In multivariate logistic analysis, factors including age (OR, 1.17; 95% CI, 1.07-1.28; P<0.001) and area of the laminar space (OR, 0.09; 95% CI, 0.01-0.67; P=0.018) significantly associated with the preservation of LF. Other factors including gender, duration of ill course, disc level and position type seemed not associated with the preservation of the LF. In addition, there was no significant difference of the duration of the operation (P=0.689) as well as the peri-operative bleeding (P=0.147) between patients with preservation of the LF and patients without. However, patients with preservation of the LF showed significantly improved clinical outcomes (ODI: P=0.006, VAS: P=0.035) and less fibrosis formation than those without LF (P=0.018).

Microendoscopic discectomy with preservation of the LF could achieve better clinical outcomes and less epidural fibrosis, while elder patients with smaller area of the laminar space should be deliberated on the preservation of the LF during the microendoscopic discectomy.