Ankylosing hyperostosis of the spine: anatomy and possible mechanism of development

ABSTRACT

The morphologic characteristics of ankylosing hyperostosis of the spine [AHS] were studied in 57 human thoracic and lumbar vertebral segments with apparent bony ankylosis. A fairly constant pattern of ossification was observed in all the cases studied. The ossification was characterized by peculiar asymmetry with definite morphologic differences of the changes on the right and left sides. It was also found that 88.6% of cases with AHS were associated with a mild structural scoliosis. Such scoliosis was related mainly to intravertebral structural changes with definite change in the normal vertebral dimensions. This was confirmed by morphometric data obtained from direct measurement of the vertebrae. The direction of the observed scoliotic curves showed consistent relation with the well-recognized pattern of ossification on both sides of the affected spinal segment. On the light of these observations the present study suggested a possible correlation between the development of a scoliosis deformity and the pathogenesis of AHS