Hydroxyapatite associated disease in an elderly female: differentiation from aseptic necrosis

The crystal arthropathies caused by monosodium urate and calcium pyrophosphate dihydrate are commonly recognised, but the destructive arthropathy associated with the deposition of calcium hydroxy-apatite is less well known in general clinical practice. We describe a case with many of the classical features of hydroxy-apatite associated disease and discuss the features differentiating the condition from aseptic necrosis.