Legg-calve-perthes disease: a review of cases with onset before six years of age.

BACKGROUND The prognosis for children in whom Legg-Calvé-Perthes disease develops before the age of six years was initially reported to be good, but later studies demonstrated a less favorable prognosis. To assess the natural history of this condition in this age group, we reviewed a large cohort of children who had received minimal treatment for the disease. METHODS The medical records and radiographs of all children with Legg-Calvé-Perthes disease seen at our institution between 1944 and 2000 were reviewed. The cases of 172 patients with a total of 188 affected hips were studied. The course of the disease and the final clinical and radiographic outcomes were evaluated in all patients. RESULTS Typical Legg-Calvé-Perthes disease was noted in 164 hips of 160 patients. According to the lateral patellar classification, seven of these hips were in group A; 101, in group B; twenty-seven, in the B/C border group; and twenty-nine, in group C. According to the Stulberg classification, there were 131 Class-I or II (good) results, fourteen Class-III (fair) results, and nineteen Class-IV (poor) results. The lateral pillar classification was highly correlated with the outcome, whereas treatment did not correlate with the outcome. Only lateral pillar group-B/C border and C hips with an onset of the disease between the ages of four years and five years and eleven months had a poor prognosis. We unexpectedly encountered a group of twelve patients with bilateral, simultaneous development of apparent Legg-Calvé-Perthes disease. In that group, there were twenty-one Stulberg Class-I or II (good), three Stulberg Class-III (fair), and no Stulberg Class-IV (poor) results, although fourteen of the twenty-four hips were in lateral pillar group C. The outcome in the hips in lateral pillar group C was significantly better when the patient had bilateral simultaneous involvement than when the patient had typical Legg-Calvé-Perthes disease. CONCLUSIONS The prognosis for patients with the onset of Legg-Calvé-Perthes disease before the age of six years is favorable, with 80% having a good result. Only children between the ages of four years and five years and eleven months with a B/C or C lateral pillar classification of involvement have a less favorable prognosis. Treatment was not found to influence outcome. Simultaneous bilateral disease, which had a more favorable prognosis, may represent a unique disorder.