Sagittal Alignment Affects Spinal Load and Mobility

Changes in sagittal alignment affect segmental mobility and disc degeneration

THURSDAY, June 2 (HealthDay News) -- Changes in sagittal alignment may lead to kinematic changes in the lumbar spine and may influence load bearing and disc degeneration, according to a study published in the May 15 issue of Spine.

Gun Keorochana, M.D., from Ramathibodi Hospital in Bangkok, Thailand, and colleagues investigated the effects of total sagittal lordosis on spinal kinematics and degree of disc degeneration in the lumbar spine. Patients with low back pain with or without leg pain were divided into three groups based on total lordosis: 84 with straight or kyphosis (less than 20 degrees), 294 with normal lordosis (20 to 50 degrees), and 52 with hyperlordosis (more than 50 degrees). Magnetic resonance imaging was used to grade the degree of disc degeneration and to measure segmental mobility, including translational motion and angular variation.

The investigators found that, compared with the normal lordosis group, the segmental motion in patients with hyperlordosis tended to be lower at the border of lordosis and higher at the apex, with a significant difference in angular motion at L2-L3, with the apical segments contributing more to total angular mobility. In contrast, patients with straight or kyphosis had increased segmental motion at the border, and lower at the apical segments of lordosis, with significant differences in angular motion at L1-L2, and translational motion at L3-L4. Border segments contributed more to total angular morbidity in these patients. Disc degeneration tended to be increased at all levels in hyperlordosis, and at L1-L2 and L5-S1 in straight or kyphosis.

"Sagittal alignment, disc degeneration, and segmental mobility likely have a reciprocal influence on one another," the authors write.

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