title: Predictive factors for unsuccessful treatment of developmental dysplasia of the hip by the Pavlik harness.
abstract: BACKGROUND
  The Pavlik harness is a widely used and effective means of initial treatment of developmental dysplasia of the hip (DDH), but some hips fail to stabilize with the use of harness and avascular necrosis (AVN) of the femoral head can occur. Predictive factors for unsuccessful Pavlik harness treatment should be determined for appropriate indication of the treatment and prevention of AVN.
  
  
  METHODS
  The outcome of Pavlik harness treatment for DDH was retrospectively examined in 221 hips of 210 patients who were treated initially at our institution and followed up for at least 1 year after the application of the harness. Univariate analysis was performed to determine predictors for failure of reduction and for the incidence of AVN by using the Mann-Whitney U test for continuous variables and the Fisher exact test or the Pearson test for categorical variables. Next, independent multivariate predictors for the failure of reduction and the incidence of AVN were identified using logistic regression analysis.
  
  
  RESULTS
  One hundred and eighty-one hips were reduced and the overall rate of reduction was 81.9%. AVN that was diagnosed according to the criteria of Salter et al was identified in 16 of the 181 reduced hips and the rate of incidence of AVN was 8.8%. Bilaterality and decreased distance "a," as defined by Yamamuro and Chene, were statistically significant univariate and multivariate risk factors for the failure of reduction. Between them, distance a was the most powerful predictor. Adduction contracture of the hip (abduction with the hips flexed to 90 degrees <60 degrees) was the only significant univariate and multivariate predictor for the incidence of AVN.
  
  
  CONCLUSIONS
  Distance a and adduction contracture of the hip were important predictors for the outcome of Pavlik harness treatment. We concluded that the Pavlik harness is a very safe and effective means of DDH treatment for the hips with abduction > or = 60 degrees and distance a > or = 6 mm.
  
  
  METHODS
  Therapeutic studies, level III (retrospective study).
authors.affiliation: Department of Orthopaedic Surgery, Nagoya University School of Medicine, Nagoya, Aichi, Japan. hkitoh@med.nagoya-u.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitoh
authors.forename: Motoaki
authors.initials: M
authors.lastname: Kawasumi
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishiguro
mesh_terms: D005260:Female; D005271:Femur Head Necrosis / Q000209:etiology*; D005500:Follow-Up Studies; D006618:Hip Dislocation, Congenital / Q000628:therapy*; D006801:Humans; D007223:Infant; D007593:Joint Instability / Q000209:etiology; D016015:Logistic Models; D008297:Male; D009989:Orthotic Devices; D012189:Retrospective Studies; D012307:Risk Factors; D018709:Statistics, Nonparametric; D017211:Treatment Failure; D016896:Treatment Outcome