Recurrent haemarthrosis results in chronic synovitis and destructive arthropathy. The long-term effect of a single haemorrhage is not known. To investigate the histopathological changes following a single, but major joint haemorrhage, an animal model of massive haemarthrosis without mechanical trauma was developed and is described in this manuscript. The knee joint capsule of mice deficient in coagulation factor VIII or IX and non-haemophilic wild type mice was punctured to induce a one time, but massive haemorrhage. The single joint puncture resulted in acute haemarthrosis in both types of haemophilic mice but not in wild type mice. Subsequent to injury, the changes in the knee joints were analysed using gross, histological and radiographic assessments and compared with the uninjured knee. In addition, a novel imaging modality, micro-computed tomography, was used to document the structural damage to the joint. Our results indicate that the long-term changes classically observed in patients with advanced haemophilic arthropathy are evident following a single massive haemarthrosis. This model will allow a thorough investigation of the pathobiology of blood-induced joint disease and will be useful to test the efficacy of innovative therapeutic strategies to prevent haemophilic synovitis and arthropathy.

Haemophilia has been recognized as the most severe among the inherited disorders of blood coagulation since the beginning of the first millennium. Joint damage is the hallmark of the disease. Despite its frequency and severity, the pathobiology of blood-induced joint disease remains obscure. Although bleeding into the joint is the ultimate provocation, the stimulus within the blood inciting the process and the mechanisms by which bleeding into a joint results in synovial inflammation (synovitis) and cartilage and bone destruction (arthropathy) is unknown. Clues from careful observation of patient material, supplemented with data from animal models of joint disease provide some clues as to the pathogenesis of the process. Among the questions that remain to be answered are the following: (i) What underlies the phenotypic variability in bleeding patterns of patients with severe disease and the development of arthropathy in some but not all patients with joint bleeding? (ii) What is the molecular basis underlying the variability? (iii) Are there strategies that can be developed to counter the deleterious effects of joint bleeding and prevent blood-induced joint disease? Understanding the key elements, genetic and/or environmental, that are necessary for the development of synovitis and arthropathy may lead to rational design of therapy for the targeted prevention and treatment of blood-induced joint disease.

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