title: Predictive value for femoral head sphericity from early radiographic signs in surgery for developmental dysplasia of the hip.
abstract: BACKGROUND
  Avascular necrosis after treatment for late developmental dysplasia of the hip can result in deformity of the femoral head and long-term morbidity. This study aims to analyze the clinical and radiographic factors that are associated with femoral head deformity in the early stage of avascular necrosis.
  
  
  METHODS
  Thirty patients with unilateral developmental dysplasia of the hip treated by the same operation before 3 years of age and who developed early signs of avascular necrosis, were studied. Avascular necrosis was diagnosed by either broadening of the femoral neck, fragmentation of the capital epiphysis, or the presence of a metaphyseal growth disturbance line in the first postoperative year. After 10-year follow-up, the hips were classified into spherical head or deformed head by irregularity <2 mm or more to analyze the associated factors.
  
  
  RESULTS
  Sixteen hips had spherical femoral heads and the other 14 hips had deformed femoral heads. Age, sex, side, Tonnis classification, and preoperative or postoperative acetabular index were not associated with the outcome after avascular necrosis. Among the early signs of avascular necrosis, fragmentation of the capital epiphysis was significantly associated with later head deformity. Fragmentation was a sign with high sensitivity (79%) and high specificity (88%) in predicting a deformed head. Broadening of femoral neck had a high sensitivity (93%), but a low specificity (38%) in outcome prediction.
  
  
  CONCLUSIONS
  Fragmentation and flattening of the femoral epiphysis are the worst radiographic signs indicating subsequent growth disturbance and deformity of the proximal femur. Broadening of the femoral neck exhibited high sensitivity in predicting later deformity, and physicians should be alerted to subsequent epiphyseal fragmentation. A metaphyseal growth disturbance line is a sign of avascular necrosis, but the predictive value is limited.
  
  
  METHODS
  Diagnostic level 3.
authors.affiliation: Department of Pediatric Orthopedics, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Chia-Hsieh
authors.initials: CH
authors.lastname: Chang
authors.forename: Wen-E
authors.initials: WE
authors.lastname: Yang
authors.forename: Hsuan-Kai
authors.initials: HK
authors.lastname: Kao
authors.forename: Chun-Hsiung
authors.initials: CH
authors.lastname: Shih
authors.forename: Ken N
authors.initials: KN
authors.lastname: Kuo
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging / Q000473:pathology*; D005271:Femur Head Necrosis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000473:pathology; D005500:Follow-Up Studies; D006618:Hip Dislocation, Congenital / Q000601:surgery*; D006801:Humans; D007223:Infant; D008297:Male; D011237:Predictive Value of Tests; D011859:Radiography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity