Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association
-
Thoracic hyperkyphosis, or loss of lumbar lordosis, is often equated with osteoporosis because vertebral fractures are assumed to be a major causative factor. However, recent evidence suggests that up to one-half of the patients with hyperkyphosis have no evidence of underlying vertebral fracture. The shape characteristics of the intervertebral discs and their role in determining kyphotic curvature have been investigated. The spinal sagittal parameters and segmental disc angles of elderly subjects were examined during a longitudinal follow-up. ⋯ A decrease in the total lumbar lordosis and the sacral inclination angle occurred with age. Increasing age correlated with a more forward sagittal vertical axis, depending on a decrease in the total lumbar lordosis. The cause of loss of lumbar lordosis in the subjects without vertebral fracture was anterior wedging of the segmental discs. Posterior wedging of the thoracic and lumbar segmental discs then could occur, compensating for the loss of lumbar lordosis.