Long - Term Analysis of a Conservative Approach in Legg - Calvé - Perthes Disease

In 1910, Legg, Calvé and Perthes described almost simultaneously the major features of a disease, which was, by that time, confused with hip tuberculosis. The disease is described as a self-limiting disorder affecting the hip, and is characterized by total or partial aseptic necrosis of the femoral head, yielded by blood supply interruption, followed by subchondral fracture, revascularization and bone repair(1). A concept exists that the Perthes disease is caused by numerous episodes of blood supply reduction at the proximal femoral epiphysis, leading to alternate periods of osteonecrosis and repair. However, the etiology and physiopathology of the disease remain unclear, despite of reports providing with important contributions. Waldenström, in 1930, described in details its pathogenic behavior and created a classification based on progression stages. He reported, with an accuracy that remains updated, the necrosis phase, followed by fragmentation of the affected bony block, and subsequent reossification. He did not consider, however, the influence of treatment, although having concluded about its prognosis(2,3). The Catterall’s classification(4) is the most known and used one, and it is based on the extension of the femoral head’s affected area, subdividing the patients into four groups. Catterall has also noted that patients in groups I and II presented with a good prognosis and evolved well, even without treatment, while children in groups III and IV should be treated, because they were likely to have a bad prognosis. Herring et al.(5), described a classification based on the femoral head’s lateral pillar height during fragmentation stage. The degree of lateral pillar’s affection would indicate a better or worse prognosis, implying in the need to treat it or not intending the restraint of the femoral head in the acetabulum. There are basically two classifications for previewing a prognosis after treatment. Mose’s classification(6) proposes the evaluation of femoral head’s roundness upon concentric circles. And the classification by Stulberg et al.(7), which uses x-ray studies for evaluation, describes the joint congruency in patients with a mature skeleton, both trying to provide a prognosis of a hip that may eventually evolve to osteoarthrosis in the future. The objective of this study is the analysis of the long-term results achieved in patients with the Perthes’ disease being conservatively treated at the initial phase of the onset of symptoms.