Ossification of the ligamentum teres as a possible mechanism of lateral subluxation in coxopathy associated with ankylosing spinal hyperostosis.

The cases are reported of two patients with coxopathy associated with ankylosing spinal hyperostosis who showed ossification of the ligamentum teres. It is suggested that considerable ossification at the medial acetabular floor including the ligamentum teres can explain the mechanism of development of coxopathy with lateral subluxation of the femoral head which is often seen in patients with ankylosing spinal hyperostosis.