[Radiologic correlation between the lateral pillar classification stages and the presence of femoroacetabular impingement in patients with Legg-Calvé-Perthes disease].

BACKGROUND: Lateral pillar classification has proven to be useful for the prognosis and treatment of patients with Legg-Calvé-Perthes disease. Most patients progress to skeletal maturity with some kind of morphologic alteration. Femoroacetabular impingement is a condition that results in early osteoarthrosis. The objective of this study was to determine whether there is a correlation between the initial lateral pillar classification and the presence of final femoroacetabular impingement. MATERIAL AND METHODS: A retrospective review of 61 patients with Legg-Calvé-Perthes disease was conducted (68 hips); they were classified into three groups according to the lateral pillar classification. At the time of skeletal maturity the radiographic presence of femoroacetabular impingement was determined and the correlation between both variables was analyzed. RESULTS: The use of the lateral pillar classification resulted in seven hips considered as type A, 37 as type B, and 24 as type C. Three of the type A hips had radiographic findings of cam femoroacetabular impingement, three of pincer femoroacetabular impingement, and one of mixed femoroacetabular impingement. Among type B hips, radiographic data of cam femorocetabular impingement were found in17, of pincer femoroacetabular impingement in 12, and of mixed femoroacetabular impingement in 10. Twenty-three of the type C hips had radiographic data of cam femoroacetabular impingement, 15 of pincer femoroacetabular impingement, and 15 of mixed femoroacetabular impingement. CONCLUSION: Patients with Legg-Calvé-Perthes disease have a directly proportional relationship between the initial lateral pillar classification and subsequent femoroacetabular impingement.