The Herring classification divides the femoral head into three parts or pillars at 90° to the physis (Fig. 1). The central pillar is defined by central sequestration during the fragmentation stage of the disease and makes up approximately 50% of the epiphysis on a true AP radiograph. The lateral pillar makes up 15% to 30% of the femoral head, while the medial pillar makes up the remaining 20% to 35%. Herring Group A consists of lateral pillars without disease involvement, including no loss of height or density changes. Group B pillars measure between 50% and 100% of original height, and Group C pillars measure less than 50% of original height. Herring et al. [6] modified their classification in 2004 after a large, multicenter trial revealed a clinically important fourth category, the group B/C Border (Table 2). Pillars in the B/C border group fall into three distinct types: (1) tall and narrow, with greater than 50% of height maintained and 2 to 3 cm of width; (2) poorly ossified, with at least 50% height maintained, or (3) relatively depressed as compared with the central pillar, with exactly 50% of pillar height maintained [5].