RT Journal A1 Shore, Benjamin J. A1 Millis, Michael B. A1 Kim, Young-Jo T1 Vascular Safe Zones for Surgical Dislocation in Children with Healed Legg-Calvé-Perthes Disease JF The Journal of Bone & Joint Surgery JO The Journal of Bone & Joint Surgery YR 2012 FD April 18 VO 94 IS 8 SP 721 OP 727 DO 10.2106/JBJS.K.00362 UL http://dx.doi.org/10.2106/JBJS.K.00362 AB Background:  Legg-Calvé-Perthes disease consists of idiopathic osteonecrosis of the femoral head, causing proximal femoral growth deformity. Recent advances in surgical technique have permitted safe surgical dislocation of the hip, allowing for correction of femoracetabular impingement. The purpose of this study was to characterize the location and number of lateral epiphyseal arteries supplying the femoral head in children with healed Legg-Calvé-Perthes disease.Methods:  This retrospective study included nineteen children (twenty-two hips) with a diagnosis of Legg-Calvé-Perthes disease (the LCPD group) and a matched control group of seventeen children (twenty hips) with developmental hip dysplasia. All patients underwent high-resolution contrast-enhanced magnetic resonance imaging (MRI) to visualize the path of the medial femoral circumflex artery and the lateral epiphyseal artery branches supplying the femoral head.Results:  All patients in the LCPD group were classified as having Waldenström grade-4 disease. Their average age at the time of MRI was fifteen years (range, eleven to eighteen years). The lateral epiphyseal arteries reliably inserted on the posterior-superior aspect of the femoral neck from a superior-anterior to a superior-posterior position in both groups. An average of 2.63 (standard deviation [SD], 1.47) retinacular vessels were visualized in the LCPD group, compared with 5.20 (SD, 1.06) retinacular vessels in the dysplasia group (p < 0.0001).Conclusions:  The lateral epiphyseal arteries of the femoral head reliably insert in a narrow anatomic window on the femoral neck. Reperfusion of the medial femoral circumflex artery does occur in patients with Legg-Calvé-Perthes disease; however, the overall number of vessels is decreased as compared with that in patients with developmental hip dysplasia.