Serial bone scintigraphy in Legg-Calvé-Perthes disease: correlation with the Catterall and Herring classification.

Radiographic classifications in Legg-Calvé-Perthes disease are difficult to use in the early stage of the disease. Changes on bone scintigraphy (revascularization versus recanalization pathway) precede the radiographic changes. Our purpose was to study the correlation between serial bone scintigraphy and radiographic classifications in Legg-Calvé-Perthes disease. In 86 patients, 95 hips that presented with Legg-Calvé-Perthes disease in the early stage were followed with serial bone scintigraphy and radiographs. Forty-four hips showed recanalization: pathway A on bone scintigraphy. Of these hips 96% were classified as Herring A or B and 66% as Catterall 2. Thirty-five hips showed revascularization: pathway B on bone scintigraphy. Of this group 82.8% were classified as Herring C and 17.1% as Herring B. All pathway B hips have Catterall 3 or 4. Sixteen hips showed pathway C: regression from pathway A to pathway B. They presented in 56% of cases with Herring B, 44% with Herring C, and in 81% with Catterall 3 or 4 classifications. We can conclude that there is a significant correlation between the vascularization pattern and the radiographic classification of Herring and Catterall.