Digital clubbing and hyperthrophic osteorthropathy: The underlying mechanisms

Abstract

Finger clubbing has been recognized as a sign of pulmonary disease since the observations of Hippocrates (460-375 BC) and Aretaeus (AD 81-138). During the second half of the nineteenth century pachydermoperiostosis (Friedreich 1868) and hypertrophic osteoarthropathy (HOA) (Bamberger 1889, 1891; Marie 1890) were described. Initially they were confused with acromegaly, to which they bear a superficial resemblance Most early authors distinguished these conditions from finger clubbing, but Locke (1915), in a review of the reported cases, noted that HOA was invariably associated with clubbing. He proposed that clubbing was an early stage of HOA and this view found wide acceptance over the next 40 years. However, although clubbing and HOA have many causes in common, their prevalence in individual diseases is very different. Clubbing is almost universal in cyanotic congenital heart disease and common in primary biliary cirrhosis, cryptogenic fibrosing alveolitis and subacute bacterial endocarditis; HOA is very uncommon in these conditions (Williams et al. 1963; Epstein et al. 1979). In addition it is now recognized that HOA can occur without clubbing (Holling & Brodey 1961). It is probably better at present to consider clubbing and HOA as separate entities which have many similarities. Much of the difficulty in distinguishing between the conditions has arisen because of confusion over their definitions. Both clubbing and HOA are essentially descriptive terms. Clubbing is the painless uniform swelling of the soft tissues of the terminal phalanx of a digit, but HOA is not so clearly defined. It is usually regarded as a condition affecting both bones and joints and characterized by radiological signs of periosteal new bone formation (Ginsburg 1963; Fischer et al. 1964). However, these radiological changes may be present in otherwise typical examples of HOA without bone pain, ankle oedema, joint pain or stiffness or synovial effusions. In such patients, syphilis, scurvy and poisoning by fluorine, strontium, vitamin A and vitamin D should be excluded since they can cause a similar periosteal reaction (Salih & Halim 1978). More rarely the typical clinical features of HOA are obvious but there are no radiological abnormalities (Horn 1980). ggmTechnetium pyrophosphate bone scans are more sensitive than radiographs in detecting new bone formation (Lokich 1977) and may be useful in difficult cases. Clubbing occurs in over 90% of patients with other features of HOA (Hammarsten & O’Leary 1957) and is often gross. Coury (1960) considers it to be an essential feature of HOA but this is a minority view. HOA is, by definition, secondary to some other condition. Pachydermoperiostosis can mimic it exactly in its presenting features and therefore can be diagnosed with certainty only by excluding all the recognized causes of HOA. A family history of