title: Predicting the outcome of Legg-Calve-Perthes' disease in children under 6 years old.
abstract: In this study, we investigated the outcome of Legg-Calve-Perthes disease in children presenting under 6 years old. Firstly, we wished to know the outcome in terms of femoral head deformity in this age group. Secondly, we investigated the potential for improvement in femoral head deformity with growth and remodelling after the Perthes lesion had healed. Thirdly, we assessed the ability of Herring's lateral pillar classification to predict femoral head deformity in this age group.
  
  
  
  The outcome in this group was assessed using Stulberg's classification of femoral head deformity and compared to that for older children with Perthes seen at our institution over the same period. To investigate the potential for improvement of Stulberg grade with growth we assessed the hips at the stage of final healing (Waldenstrom IV) and again at skeletal maturity. To assess whether Herring's classification of lateral column collapse is predictive of deformity at this age we recorded the Herring class A, B or C at the time of maximum fragmentation and compared this to Stulberg grade.
  
  
  
  Out of a total of 127 children (131 hips) seen at our institution, 67 children (69 hips) presented before the age of 6 years. The number of Stulberg III and IV hips was 14 (20%) and 10 (15%), respectively. Chi-squared test of age against outcome confirmed that the younger children overall had a better outcome (P < 0.001). Stulberg grade did not improve predictably after the stage of final healing. Twenty-three hips graded as Stulberg III and IV at Waldenstrom IV were reassessed at skeletal maturity. Three changed from Stulberg III to IV and five changed from Stulberg IV to III, but none had improved to Stulberg I/II. Herring's classification was predictive of outcome, with 96% of Herring A hips having Stulberg I or II outcome, 61% of Herring B hips having Stulberg I or II outcome, while 60% of Herring C hips (18 hips) had significant femoral head deformity, and 10 hips Stulberg III and 6 hips Stulberg IV.
  
  
  
  Perthes in children presenting before 6 years of age can result in significant femoral head deformity which does not predictably improve with time. The risk of a poor outcome can be predicted by Herring's classification of lateral pillar collapse.
authors.affiliation: Department of Orthopaedics, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD, UK.
authors.forename: Edward
authors.initials: E
authors.lastname: Gent
authors.forename: Prasad
authors.initials: P
authors.lastname: Antapur
authors.forename: Rajnikant L
authors.initials: RL
authors.lastname: Mehta
authors.forename: Vastara M
authors.initials: VM
authors.lastname: Sudheer
authors.forename: Nicholas M P
authors.initials: NM
authors.lastname: Clarke