Athletic activity in adolescence as an etiological factor in degenerative hip disease.

Degenerative hip disease (osteoarthritis) is common in this country. It may cause symptoms at any age in adult life, but the peak incidence is in the sixth decade, sex incidence being approximately equal. In men particularly, this age largely corresponds to the years of greatest productivity. Osteoarthritis of the hip is known to be secondary sometimes to such disorders as acetabular dysplasia, Perthes’ disease and epiphysiolysis. In most cases, however, no precipitating factor has been recognised. The descriptive terms “primary” or “idiopathic” were used in reports by Gade (1947), Lloyd-Roberts (1955), Adam and Spence (1958) and Nicoll and Holden (1961), who together recorded a total of 499 cases, of which 258 were so classified. In a previous report (Murray 1965) on the etiology of 200 cases of so-called “primary” osteoarthritis of the hip the earliest antero-posterior radiograph was studied. Because lateral projections were seldom available these were disregarded. On the first detailed inspection of each a decision was made whether the hip architecture was fundamentally normal or abnormal. Whenever reasonable doubt existed, particularly when degenerative changes were already advanced, it was assumed that no basic anatomical abnormality had been present. The pre-existing anatomical configuration of the affected hips was concluded to have been completely normal in no more than 35 per cent. Serial radiographs of many cases in this group showed progressive changes comparable to rheumatoid arthritis and a subclinical form of this, or some allied disorder, was suggested as the cause of the degeneration of the hip. Some support for this was found in the sex incidence which was similar to that in established rheumatoid arthritis. The remainder had minor anatomical abnormalities and the resultant incongruity of the hip was considered to be the precipitating cause of degenerative changes. These abnormalities were thought to he the least manifestations of the important predisposing factors mentioned above. Evidence of acetabular dysplasia was found in 25 per cent of the series, the sex incidence of 4 l females to one male, corresponding to the incidence of true congenital dislocation, of which this condition may be regarded as a forme fruste. Stigmata of unrecognised Perthes’ disease, not seen in the original series, have occurred since in small numbers, probably less than 2 per cent of the total. It became increasingly evident that the most common minor anatomical abnormality, occurring in approximately 40 per cent, was comparable radiologically to the appearance of previous epiphysiolysis. The remarkable contrast in sex incidence which was found, 56 males being affected for every female, required explanation. The abnormality consists of a medial angulation of the femoral head in relation to the femoral neck and, to define this, the term “tilt deformity” was proposed. The appearance was so common that it might easily be regarded as a normal variant, and to appreciate its nature it is necessary to consider the clinical aspects and radiological features of frank epiphysiolysis or slipping of the capital epiphysis.