Association of Spinopelvic Anatomy with the Level of Lumbar Disc Herniation.

Aim: The aim of this study was to investigate the association between the level of lumbar disc herniation (LDH) and individual spinopelvic anatomy.

Material and methods: Spinopelvic parameters were retrospectively evaluated in 57 patients with symptomatic LDH at L4/5 and L5/S1 undergoing minimal invasive sequestrectomy at our institution. LDH was diagnosed in 23 patients at L5/S1 and in 34 patients at L4/5. Patients with further segment degeneration at the index level were excluded from the study.

Results: Spinopelvic parameters between the two groups were significantly different. Patients with LDH at L5/S1 had statistically significant lower Pelvic Incidence (PI), Pelvic Tilt (PT), Relative Lumbar Lordosis (RLL) and PI-LL than patients with LDH at L4/5. C7 Sagittal Vertical Axis (C7SVA) was statistically significant lower in patients with LDH at L5/S1. Both groups had no sagittal imbalance. Patients with LDH at L5/S1 were significantly younger than patients with LDH at L4/5. There was a significant positive correlation between age and PT. We observed no significant differences for preoperative values of Lumar Lordosis (LL) and Sacral Slope between the two groups.

Conclusions: This is the first study to reveal individual spinopelvic anatomy and, in particular, PI to be associated with the distinct level of LDH. These findings substantiate the biomechanical influence of the sagittal profile on the pathogenesis of LDH. Individual spinopelvic compensatory mechanisms were available independently of the patient's age. Minimal invasive sequestrectomy is a reliable treatment for symptomatic LDH without further segment degeneration.