Double patellae in multiple epiphysial dysplasia.

This paper describes the association of double patellae of an unusual type with multiple epiphysial dysplasia in three siblings. The patellae are ofthe type first described by BUttner(l925) and Haenisch (1925). Other examples have been described by Paas (1931), Schwarz (1932), Weber (1935, cited by Lodes 1949), Gorzawski (1937), Marquardt (1938) and Lodes (1949). The abnormality common to these patellae is that they possess a larger anterior part that embraces a smaller posterior part. In addition, habitual dislocation may be present, and one or both of the component layers may be multipartite. For convenience I shall refer to such patellae as double-layer patellae. Multiple epiphysial dysplasia was first described as a clinical entity by Fairbank (1947) who reported his findings in twenty cases. Since then many examples have been recorded (Fairbank 1951 ; Scott 1952 ; Watt 1952 ; Waugh 1952 ; Jackson, Hanelin and Albright 1954; Maudsley 1955; Shephard 1956; Levy, Mazumdar and Morales 1957; and Barrie, Carter and Sutcliffe 1958) but in none were double-layer patellae found. The only abnormalities of the patella that have been noted are mottling of the patellae (Fairbank 1947), unilateral absence of the patella (Waugh 1952), thin and irregular patellae (Waugh 1952), and in one case a dense central nucleus enclosed by less dense bone (Shephard 1956). The cases of double-layer patellae previously described, twelve in all, were found to have other skeletal abnormalities. The hips were invariably affected and the hands, feet, elbows and shoulders were often involved. The disorder was clearly familial in Lodes’s (1949) four patients. Lodes reviewed the literature and considered that all the cases could be classified as atypical chondrodystrophy (Morquio’s disease) : atypical in that none of them showed the characteristic vertebral flattening. He considered the patellar changes to be an integral part of the dystrophy. However, it is surely significant that double-layer patellae have never been described in unequivocal cases of Morquio’s disease (that is, in patients showing the typical vertebral changes). I therefore regard Lodes’s (1949) conclusion that the twelve patients with double-layer patellae were examples of Morquio’s disease as doubtful. In my opinion they were more likely to have been examples of multiple epiphysial dysplasia. The published descriptions and radiographic findings are certainly compatible with this diagnosis, and they