The inheritance of tarsal coalition and its relationship to spastic flat foot.

Tarsal coalition is not a modern phenomenon. Archaeological findings have demonstrated this anomaly in a Mayan civilisation in Guatemala (Harris 1965) and in a pre-Columbian Indian civilisation in Ohio (Heiple and Lovejoy 1969), both dated around 900-950 A.D. Buffon (1769) was probably the first to recognise the occurrence of tarsal coalition, although the undated specimen in the Museum of the Royal College of Surgeons of England described by John Hunter probably dates from 1760 to 1 770 (Allen 1973). Calcaneo-navicular coalition was first described anatomically by Cruveilhier (1829) and talo-calcaneal coalition by Zuckerkandl (1877). Holl (1880) made a tentative suggestion relating peroneal spastic flat foot and intertarsal bars. Pfitzner (1896) proposed that tarsal coalitions were caused by the incorporation of accessory ossicles into major adjacent tarsal bones. This idea has received support from the work of Slomann (1921), Cave (1926), Badgeley (1927), Harris and Beath (1948), Chambers (1950), Outland and Murphy (1953) and Hark (1960). Leboucq (1890), Solger (1890), Dwight (1907), Trolle (1948) and Jack (1954) proposed that tarsal coalitions were the result of a failure of differentiation and segmentation of primitive mesenchyme. Harris (1955) demonstrated that such anomalies can occur in the foetus and her results confirm the proposal that a mesenchymal defect is the cause. Pfltzner’s hypothesis of incorporation of accessory ossicles is not acceptable because it fails to explain the disorder in the foetus. In spite of Sir Robert Jones’s clinical description of peroneal spastic flat foot in 1897, it was not until the work of Slomann (1921), Badgeley (1927) and Harris and Beath (1948) that tarsal coalitions were conclusively linked with peroneal spastic flat foot. It is now appreciated that with early recognition the treatment of peroneal spastic flat foot due to tarsal coalition may be successful (Jack 1954, Blockey 1955, Harris 1965, Mitchell and Gibson 1967). Occasional reports have appeared in the literature suggesting that tarsal coalitions are inherited. Rothberg, Feldman and Shuster (1935), Boyd (1944), Webster and Roberts (1951) and Bersani and Samilson (1957) reported the anomaly in members of single families, but although they drew attention to the occurrence of painful feet, they did not comment on the presence of peroneal spastic flat foot. Wray and Herndon (1963) reported three generations of a family in which calcaneonavicular coalitions were found in each generation. They concluded that some and perhaps all cases of calcaneo-navicular bar were caused by a specific gene mutation which possibly behaved as an autosomal dominant with reduced penetrance. They suggested that this gene was distinct from each of several genes responsible for other fusion defects in the bones of the hand and foot, including multiple fusions, gross anomalies and varieties of symphalangism. Glessner and Davis (1966) reported monozygotic twins with peroneal spastic flat foot and tarsal coalition and suggested that the condition was of genetic etiology. Tarsal and carpal coalitions are known to be present in phocomelia, hemimelia and other gross limb anomalies (O’Rahilly 1953). They are also found in other congenital disorders (Nievergelt 1944), and the occurrence of symphalangism with tarsal and carpal coalitions has been documented by Drinkwater (1917) and Austin (1951).