title: Can residual leg shortening be predicted in patients with Legg-Calvé-Perthes' disease?
abstract: BACKGROUND
  Although Legg-Calvé-Perthes' disease (LCPD) is frequently associated with varying degrees of femoral head deformity and leg length discrepancy (LLD), no factors that predict residual shortening have been clearly identified.
  
  
  OBJECTIVE
  We attempted to determine whether (1) the extent of femoral head involvement; (2) varus osteotomy; and (3) patient demographic characteristics are associated with LLD at skeletal maturity in patients with LCPD.
  
  
  METHODS
  We retrospectively reviewed the records of 168 skeletally mature patients with unilateral LCPD. The mean age at diagnosis was 7 years (range, 2-14 years). The extent of femoral head involvement was determined from the initial radiographs using the Herring lateral pillar and Catterall classifications. LLD was defined as shortening by ≥ 1.0 cm as measured from scanograms. The patient's sex and the treatment modalities used were also recorded.
  
  
  RESULTS
  LLD ranging from 10 to 38 mm (mean, 19 mm) occurred in 93 (55%) patients and was associated with the extent of femoral head involvement. Varus osteotomy was not associated with residual shortening. The patient's age at diagnosis did not affect the LLD at skeletal maturity. The strongest predictor of LLD was a lateral pillar classification of B/C or C (odds ratio, 3.5; 95% confidence interval, 1.39-8.79).
  
  
  CONCLUSIONS
  The extent of femoral head involvement, but not the patient's age at diagnosis or sex or the treatment modality, can predict the LLD at skeletal maturity in patients with unilateral LCPD.
authors.affiliation: Institute for Rare Diseases and Department of Orthopaedic Surgery, Korea University Medical Center, Guro Hospital, 80, Guro-Dong, Guro-Gu, Seoul, 152-703, Korea.
authors.forename: Kwang-Won
authors.initials: KW
authors.lastname: Park
authors.forename: Kyu-Seon
authors.initials: KS
authors.lastname: Jang
authors.forename: Hae-Ryong
authors.initials: HR
authors.lastname: Song
mesh_terms: D000293:Adolescent; D000367:Age Factors; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D007870:Leg Length Inequality / Q000175:diagnosis / Q000209:etiology*; D007873:Legg-Calve-Perthes Disease / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D010027:Osteotomy; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D013997:Time Factors; D016896:Treatment Outcome