Idiopathic hip chondrolysis: a case report of a Caucasian HLA-B27 positive adolescent with a history of long walking.

Idiopathic hip chondrolysis is a rare disorder, the pathophysiology of which has not been fully elucidated. Several theories have been proposed regarding the cause of the disease with some of them involving autoimmune-mediated cartilage destruction. There are several similar features between idiopathic hip chondrolysis and rheumatologic diseases such as juvenile idiopathic arthritis, so whether these two disorders are different or not is still debatable. This case report aims to help comprehending this complex disorder by presenting a case of idiopathic hip chondrolysis with apparent risk factors, such as repetitive microtrauma and presence of HLA-B27 antigens. A 15-year-old HLA-B27 positive male presented with idiopathic hip chondrolysis after excessive walking. Initial treatment consisted of medications including corticosteroids, protected weight bearing and surgical soft tissue release. After failure of all these modalities in restoring the decreased range of motion of the hip, a course of a TNF-inhibitor, etanercept was tried. Alleviation of pain achieved early in the treatment period, but range of motion remained mainly unchanged. Although there was a brief improvement of stiffness for a short period after surgery which lasted for about 3 months, stiffness came back afterwards. Administration of a TNF inhibitor in the following period significantly improved his range of motion. The presence of laboratory findings indicating an autoimmune tendency in this patient supports the hypothesis of susceptibility of these patients to autoimmune reactions, while excessive walking was an apparent trigger factor. In future, traditional treatments may be abandoned in favor of novel medications targeting immunologic pathways.