General Medical and Metabolic Diseases

Abstract

Both haemophilia A (factor VIII) and haemophilia B (factor IX) are inherited as X-linked recessive diseases and in both the functional defect is in the intrinsic pathway, the extrinsic tissue-factor-dependent pathway being the only mechanism left intact to subserve haemostasis. The most important consequence of haemophilia is arthritis and it is interesting that synovial tissue is deficient in tissue factor, which may explain this association. Arthritis occurs only in those patients who are severely affected, with concentrations of circulating antihaemophiliac globulin of less than 5%, and onset is usually in childhood. The knee and the elbow joints are most commonly involved and may become swollen acutely either spontaneously or after only the most minor trauma. Range of movement, usually preserved after the first episode, is progressively lost with subsequent attacks and severe joint destruction and deformity may follow. Extra-articular bleeding is also common.