Classifications in brief: the Herring lateral pillar classification for Legg-Calvé-Perthes disease.

Classifications of Legg-Calvé-Perthes disease (LCPD) may be divided into three categories: those defining the stage of the disease, those attempting to prognosticate outcome, and those defining outcome. Although Arthur Legg MD [13], Jacques Calvé [2], and Georg Perthes MD [17] share credit for their descriptions of the disease published between 1909 and 1910, according to Wenger and Pandya, Henning Waldenstrom of Norway published on LCPD in 1909, mistaking it for tuberculosis of the hip [24]. Although Waldenstrom’s name does not appear in the disease eponym, he is credited with development of the first classification of the disease in 1922, which recognized four stages of radiographic progression: initiation, fragmentation, reossification, and healed [10]. Outcome classifications also are based on radiographic characteristics. The classification of Stulberg et al. groups mature hips by shape of the femoral head and congruency in the joint and is the most widely used outcome measure [11, 23]. Several prognostic classification systems for use at disease onset have been proposed. Catterall [3] was the first to publish a widely accepted prognostic classification in 1971. This system described four categories based on the location of involvement of the femoral head as viewed on AP and lateral radiographs. In 1984, Salter and Thompson [22] proposed a two-category system based on a review of 1057 children with 1264 involved hips. They determined that subchondral fracture was predictive of eventual degree of involvement of the femoral head and also believed that a two-category classification could increase reliability. This system has been criticized as difficult for less experienced surgeons to use as the subchondral fracture line can be quite subtle and not always present [14]. Finally, Herring et al. [7] followed a group of 86 patients (93 hips) longitudinally and correlated their presenting radiographs to their Stulberg classification and found that the height of the lateral column on AP radiographs was predictive of the final outcome of the disease. This is considered to be the most reproducible classification system and consequently has grown in popularity [11, 14, 16].