Aseptic necrosis of femoral head - m. Perthes, lateral pillar classification by Herring

Herring classification was published in 1992 and it was based on observation of 86 patients treated by bracing.

Group Description
Group A the height of the lateral pillar is maintained and no density changes can be identified
Group B the lateral pillar is reduced between 50 nad 100% of original height
Group C the lateral pillar is <50% of the original height

References:

1. Salter RB, Thompson GH. Legg-Calvé-Perthes disease: the prognostic significance of the subchondral fracture and a two-group classification of the femoral head involvement. Journal of bone and joint surgery American volume. 66(4):479–89.
2. Herring JA, Neustadt JB, Williams JJ, Early JS, Browne RH. The lateral pillar classification of Legg-Calvé-Perthes disease. J Pediatr Orthop. 1992 Apr;12(2):143–50
.