Triple innominate osteotomy for Legg-Calvé-Perthes disease in children: does the lateral coverage change with time?

Abstract

Triple innominate osteotomy (TIO) is one of the modalities of surgical containment in Legg-Calvé-Perthes disease (LCPD). However, overcoverage with TIO can lead to pincer impingement. We therefore asked (1) whether TIO contained the femoral head in Catterall Stages III and IV of LCPD; (2) whether the center-edge (CE) angle, acetabular roof arc angle (ARA), and Sharp's angle changed during the growing years; and (3) what percentage of patients had radiographic evidence of pincer impingement beyond a minimum followup of 3 years. We identified 19 children who had 20 TIOs performed for Catterall Stages III and IV LCPD. Two blinded observers assessed sequential radiographs. Each observer made two sets of readings more than 2 weeks apart. Femoral head extrusion index, CE angle of Wiberg, ARA, and Sharp's angle were measured. Minimum followup was 3 years to document continued acetabular growth (mean, 3.8 years; range, 3-7 years). All patients exhibited femoral head containment at last followup. Eleven of 20 hips demonstrated no radiographic evidence of pincer morphology beyond a minimum followup of 3 years (mean, 3.8 years). Patients with CE angle corrected to 44° or less and an ARA of greater than -6° after TIO did not demonstrate a pincer morphology at last followup. TIO resulted in femoral head containment in all cases. Lateral acetabular coverage changed during the growing years in all patients. Surgical correction beyond 44° of CE angle and -6° of ARA should be avoided to prevent pincer morphology later.