Juvenile kyphosis: an ultrastructural study.

Biopsy specimens of the spine, including intervertebral disc, vertebral plate, growth plate, and part of the vertebral body, were obtained from seven patients with juvenile kyphosis treated by anterior spinal arthrodesis. Histological and histochemical studies showed abnormal loose-appearing cartilage in both the vertebral plate and the growth plate. Both plates were missing in some vertebrae. Ultrastructurally the abnormal cartilage had a matrix rich in proteoglycans and very thin collagen fibrils. The mineralization and ossification of the vertebral plates were irregular. Vertebral bone growth was stunted under the areas of abnormal growth plates.