Aims: To investigate the pathogenetic mechanisms of haemophilic arthropathy (HA) by comparing end-stage arthropathy with osteoarthritis (OA; a degenerative joint disorder) and rheumatoid arthritis (RA; an inflammation-mediated joint disease).

Methods and results: Cartilage and synovium from patients with HA (n=10), RA (n=8), OA (n=14) and normal control subjects (n=6) were examined morphologically, biochemically and histochemically. Cartilage in HA exhibited characteristics of degenerative joint disease (OA), as evidenced by morphological, histochemical (Safranin-O fast green-iron haematoxylin, Mankin grade) and biochemical (proteoglycan synthesis, glycosaminoglycan content and DNA content) changes, whereas synovium in HA showed characteristics of inflammation-mediated joint disease (RA), as evidenced by histochemical (inflammation, haematoxylin and eosin (H&E) and iron deposition, Perls' blue) and biochemical changes (interleukin (IL)-1, IL-6, tumour necrosis factor (TNF)alpha and catabolic properties).

Conclusion: Haemophilic arthropathy shows characteristics of both inflammatory and degenerative joint disease. On the basis of these results and published information, it appears that degenerative cartilage changes have a dominant role in HA and are augmented by relatively mild inflammation of the synovium.