title: Adverse Outcomes in Infantile Bilateral Developmental Dysplasia of the Hip.
abstract: BACKGROUND
  It is believed that bilateral developmental dysplasia of the hip (DDH) has poorer outcomes with higher rates of avascular necrosis (AVN) and reintervention, compared with unilateral DDH. However, there is limited evidence in the literature, with few studies looking specifically at bilateral cases.
  
  
  METHODS
  A retrospective review of 36 patients (72 hips) with >4 years of follow-up. Patient population included surgically treated DDH including late presentations and failures of conservative treatment. The dislocated hips underwent either simultaneous closed or 1 open and 1 closed, or sequential open reduction. AVN and secondary procedures were used as endpoints for analysis as well as clinical and radiologic outcomes.
  
  
  RESULTS
  At the last follow-up, 33% of hips had radiologic signs of AVN. Those hips that had no ossific nucleus (ON) at the time of surgery had an odds ratio of developing AVN of 3.05 and a statistically significant association between the 2 variables, whereas open/closed or simultaneous/sequential reduction did not increase the risk for AVN. In addition, 45.8% of those hips required further surgery. The estimated odds ratio of needing additional surgery after simultaneous reduction was 4.04. Clinically, 79.2% of the hips were graded as McKay I, whereas radiologically only 38.8% were Severin I.
  
  
  CONCLUSIONS
  The AVN rate in bilateral DDH treated surgically is greater than the rate noted in unilateral cases from the same institution undergoing identical protocols. There was no difference in AVN rates between simultaneous and sequential or between the first and second hip to be sequentially reduced. Presence of ON decreases the risk for AVN, suggesting that in bilateral cases, awaiting the appearance of the ON is an important tool to reduce the incidence of AVN.
  
  
  METHODS
  IV.
authors.affiliation: *Southampton General Hospital †Department of Child Health, University Hospital Southampton NHS Foundation Trust ‡University of Southampton and Child Health, University Hospital Southampton NHS Foundation Trust, Southampton, Hampshire, UK.
authors.forename: Abigail H M
authors.initials: AH
authors.lastname: Morbi
authors.forename: Belen
authors.initials: B
authors.lastname: Carsi
authors.forename: Vitalli
authors.initials: V
authors.lastname: Gorianinov
authors.forename: Nicholas M P
authors.initials: NM
authors.lastname: Clarke
mesh_terms: D057210:Delayed Diagnosis / Q000009:adverse effects; D005260:Female; D005271:Femur Head Necrosis / Q000453:epidemiology / Q000209:etiology; D005500:Follow-Up Studies; D006618:Hip Dislocation, Congenital / Q000453:epidemiology / Q000601:surgery / Q000628:therapy; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D019637:Orthopedic Procedures / Q000009:adverse effects / Q000379:methods; D009989:Orthotic Devices / Q000009:adverse effects*; D017063:Outcome Assessment, Health Care; D010808:Physical Examination; D012189:Retrospective Studies; D012307:Risk Factors; D061665:Time-to-Treatment; D006113:United Kingdom