MECHANISM OF VERTICAL POSTURE FORMATION AND PARAMETERS OF SAGITTAL SPINOPELVIC BALANCE IN PATIENTS WITH CHRONIC LOW BACK PAIN AND SCIATICA

Objective. To study parameters of sagittal spinopelvic balance in patients with chronic low back pain and sciatica, and mechanism of vertical posture formation in a sagittal plane. Material and Methods. Total of 100 patients (32 female and 68 male, mean age 38.7 years) with chronic low back pain and sciatica underwent clinical and radiological examinations. Pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), and global lumbar lordosis (GLL) were measured on lateral standing radiograms. Statistical analysis of the obtained data was performed. Results. The mean value of PI (50.7°) in patients with back pain and sciatica and in healthy volunteers was almost equal, while SS and GLL were significantly lower in patients, and PT – higher, than those in volunteers. Number of patients with PI ≤ 35 was significantly higher than that of volunteers. Pearson’s correlation coefficient between GLL and PI was 0.916, between GLL and SS – 0.902, and between GLL and PT – 0.326. Vertical posture in patients with chronic low back pain and lumbar sciatica is characterised by backward pelvic rotation relative to hip and by hypolordotic shape of the lumbar spine. Conclusion. Vertical posture in patients with low back pain and sciatica is determined by a backward rotation of the pelvis, therefore SS and GLL decrease, and PT increases. A prevalence of extremely low values of PI (≤35°) may be considered as a risk factor for lumbar spine degenerative diease. Alteration of vertical posture is a kind of protective mechanism.