Subtotal capsulectomy for idiopathic chondrolysis of the hip: A clinical, radiological and histological study

Abstract

BACKGROUND: Idiopathic chondrolysis (IC) of the hip is a rare, disabling condition affecting mainly adolescent females. Cartilage necrosis results in a stiff, painful hip which in the majority of cases have a poor outcome. The aetiology still remains unknown and the treatment is controversial and relatively unsuccessful. Subtotal capsulectomy with soft tissue releases has been reported to give good results METHODS: Five female adolescents with IC of the hip were reviewed in order to shed light on the aetiology, delineate the role of magnetic resonance imaging (MRI) pre- and post-operatively and assess the outcome of a subtotal capsulectomy. The surgical technique was performed as originally described with concomitant releases of the deformities. Samples of synovium and cartilage were sent for histology and culture (including tuberculosis culture). Pre- and post-operatively the patients were evaluated regarding pain, deformity and range of motion (ROM). Follow-up radiographs and MRI scans were performed and compared to pre-operative imaging RESULTS: Blood tests for auto-immune markers were negative in all cases. MRI pre-operatively showed erosions and mainly destruction of the superomedial acetabular cartilage. Histology of the synovium showed chronic, non-specific inflammation with a plasma cell infiltrate, suggesting an auto-immune cause. Histology of the cartilage confirmed cartilage necrosis. At follow-up (mean 11 months) four of the five patients were pain free and one patient reported an improvement in pain. There was an improvement in deformity and range of motion in four cases. Post-operative imaging (radiographs and MRI) at a mean of eight months, however, showed deterioration of the pathology with increase of the erosions, joint space narrowing and cartilage destruction CONCLUSIONS: We conclude that the aetiology is most likely an auto-immune process. MRI was helpful in delineating the cartilage pathology. A subtotal capsulectomy offers early post-operative clinical relief. Radiological deterioration however suggests that the surgery does not prevent deterioration of pathology. LEVEL OF EVIDENCE: Level IV: Case series