Enthesitis of the ligamentum teres during ankylosing spondylitis: histopathological report.

Enthesitis of the ligamentum teres during ankylosing spondylitis: histopathological report We were interested to read the article by Inoue et al' on ossification of the medial acetabular floor, including the ligamentum teres as a possible mechanism of lateral sub-luxation in coxopathy associated with anky-losing spinal hyperostosis. A few years ago we saw a patient suffering from ankylosing spon-dylitis (AS) with right coxitis including inflammatory enthesopathy of the ligamentum teres (ligamentum capitis femoris). A 57 year old man with a five year history of a painful right hip was first seen at the rheumatology clinic in 1976, when the diagnosis of AS was made (HLA B27 was present). Anteroposterior radiography of the pelvis demonstrated joint space narrowing in the right hip, sclerosis and new bone formation on the right acetabular rim, enthesophytes of the femoral head, and an ankylosis in the sacro-iliac joints. Due to persistent pain and major disability, an arthroplasty was performed on the right hip. On opening the capsule, the synovium was inflamed around the ligamentum capitis femoris although there was no obvious pannus the articular cartilage was considerably ulcerated at the femoral head. Histological examination showed an intense vascular proliferation in the central area of attachment of the femoral head ligament to the fovea capitis, especially in the deep sub-chondral perivascular area (figure). Lympho-plasmocytic cells had spread along the proliferating vessels which dissociate the elk iv X :-"' 4 ,.f vertical collagen fibres at the ligamentum teres attachment. In the narrow spaces surrounding the damaged area there was evidence of chondrocyte proliferation. Ossifying enthesitis was also present on the attachment of the capsule in the acetabular labrum. Published reports are scant concerning the histopathology in the early stage of AS. Nevertheless, several papers have underlined the role of enthesitis in the pathogenesis of AS and related spondylarthropathies.SA Ossifying enthesopathies on the great trochanter and capsular enthesiophytes are common features in AS5 and Forestier's disease6 with the resulting tendency to anky-losis of the hip. Enthesopathies include all changes, whether traumatic, degenerative, metabolic or inflammatory of enthesis.7 8 As entheso-pathies usually produce ossification, they are very useful diagnostically and nosologically, especially when they are diffuse or multiple.5 The most extreme example of metabolic enthesopathy is diffuse idiopathic skeletal hyperostosis (DISH, more commonly known as Forestier's disease). Conversely, AS, which is the archetype of spondylarthro-pathies, is the more classic inflammatory enthesopathy. The most distinctive feature of the natural history of …