title: The need for total hip arthroplasty in Perthes disease: a long-term study.
abstract: BACKGROUND
  Legg-Calvé-Perthes disease (LCPD) was described a century ago. In previous long-term reports of patients with LCPD, nonoperative treatment varied considerably. The likelihood of hip osteoarthritis (OA) developing in patients with LCPD and possible need for THA are not well defined.
  
  
  OBJECTIVE
  The purpose of the study was to determine whether nonoperatively treated patients with LCPD (1) had an increased prevalence of THA compared with gender- and age-matched control subjects, (2) if patients with Stulberg Classes III/IV/V femoral heads had an increased risk of THA compared with those with Classes I/II femoral heads. Given the limitation in the study, we (3) evaluated whether patients with LCPD were at risk for having radiographic hip OA more commonly than control subjects and (4) whether hips with Classes III/IV/V femoral heads had an increased prevalence of OA compared with hips with Classes I/II femoral heads.
  
  
  METHODS
  The study population consisted of 167 patients with LCPD treated with a Thomas splint. The control population consisted of gender- and age-matched control subjects who were participants in the Copenhagen City Heart Study: the Osteoarthritis Substudy. Radiographs at skeletal maturity were classified according to the classification system of Stulberg et al. Data from the Danish Hip Arthroplasty Register and the Registries of the National Board of Health were collected to obtain the number of patients with LCPD having THA. At a mean followup of 47 years later (range, 37-58 years), weightbearing pelvic radiographs were obtained. Radiographic OA was defined as a joint space width of 2.0 mm or less.
  
  
  RESULTS
  Thirteen percent of patients with LCPD had THAs compared with none in the control group. Seven percent of the patients with LCPD had OA compared with 1% in the control group. The prevalence of THA and OA was increased in hips with Classes III/IV/V femoral heads compared with hips with Classes I/II femoral heads.
  
  
  CONCLUSIONS
  Patients with LCPD have an increased risk of having THA compared with a gender- and age-matched control group. Our data suggest that patients with LCPD have a greater risk of having radiographic OA develop than a gender- and age-matched control group. It seems that patients with Classes III/IV/V femoral heads have an increased risk of THA and OA compared with patients with Classes I/II femoral heads.
  
  
  METHODS
  Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Kolding Hospital, Kolding, Denmark, lonniefroberg@yahoo.dk.
authors.forename: Lonnie
authors.initials: L
authors.lastname: Froberg
authors.forename: Finn
authors.initials: F
authors.lastname: Christensen
authors.forename: Niels Wisbech
authors.initials: NW
authors.lastname: Pedersen
authors.forename: Søren
authors.initials: S
authors.lastname: Overgaard
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003718:Denmark; D018450:Disease Progression; D005260:Female; D006801:Humans; D007873:Legg-Calve-Perthes Disease / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D011859:Radiography; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013165:Splints; D013997:Time Factors; D016896:Treatment Outcome