title: Is Age or Surgical Approach Associated With Osteonecrosis in Patients With Developmental Dysplasia of the Hip? A Meta-analysis.
abstract: BACKGROUND
  Osteonecrosis of the femoral head is a major complication that negatively impacts the clinical and radiographic long-term outcome after treatment of developmental hip dysplasia (DDH). There are conflicting results in the literature whether age at the time of closed or open reduction and a specific surgical approach are associated with osteonecrosis. Better understanding of the impact of age at reduction and surgical approach is important to reduce the risk of osteonecrosis in patients with DDH.
  
  
  OBJECTIVE
  We aimed to evaluate the association between occurrence of osteonecrosis and (1) age at closed reduction; (2) age at open reduction; and (3) medial versus anterior operative approaches.
  
  
  METHODS
  A systematic review identified studies reporting osteonecrosis occurrence after treatment of DDH and at least 2 years of followup. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Methodologic quality was assessed using the methodologic index for nonrandomized studies. Generalized logistic models were used to estimate pooled odds ratios (ORs) in the meta-analysis. Sixty-six studies were included in the systematic review and 24 in the meta-analysis. Data on 481 hips treated by closed reduction and 584 hips treated by open reduction were available to evaluate the association between osteonecrosis and age. The association between osteonecrosis and operative approach was assessed using data on 364 hips treated by medial open reduction and 220 hips treated by anterior open reduction.
  
  
  RESULTS
  Age at reduction (> 12 months versus ≤ 12 months) was not associated with osteonecrosis after closed reduction (OR, 1.1; 95% confidence interval [CI], 0.4-3.2; p = 0.9) or open reduction (OR, 1.1; 95% CI, 0.7-1.9; p = 0.66). The overall, adjusted incidence of osteonecrosis (≥ Grade II) was 8.0% (95% CI, 2.8%-20.6%) among patients treated with closed reduction at or before 12 months of age and 8.4% (95% CI, 3.0%-21.5%) among those treated after 12 months. Similarly, the odds of osteonecrosis after open reduction did not differ between patients treated after the age of 12 months compared with those treated at or before 12 months (OR, 1.1; 95% CI, 0.7-1.9; p = 0.7). The incidence of osteonecrosis (≥ Grade II) was 18.3% (95% CI, 11.7%-27.4%) among patients who had index open reduction at or before 12 months of age and 20.0% (95% CI, 13.1%-29.4%) among those who had index open reduction after 12 months of age. Among hips treated with open reductions, there was no difference in osteonecrosis after medial versus anterior approaches (18.7% medial versus 19.6% anterior; OR, 1.1; 95% CI, 0.5-2.2; p = 0.9). Conclusions We did not find an association between closed or open reduction performed at or before 12 months of age and an increased risk of osteonecrosis of the femoral head. Delayed treatment past 1 year of age as a strategy to reduce the development of osteonecrosis was not supported by this meta-analysis. Open reduction through a medial or anterior approach may be recommended based on surgeon's preference, because we found no association between development of osteonecrosis and the type of surgical approach. However, many of the studies in the current literature are nonrandomized Level III or IV observational studies of inconsistent quality. Higher quality evidence is needed to better understand the effects of age at reduction and operative approach on the development of osteonecrosis after DDH treatment.
  
  
  METHODS
  Level III, therapeutic study.
authors.affiliation: Department of Orthopaedic Surgery, Children's Hospital Colorado, 13123 East 17th Avenue, B600, Aurora, CO, 80045, USA. eduardo.novais@childrenscolorado.org.
authors.forename: Eduardo N
authors.initials: EN
authors.lastname: Novais
authors.affiliation: Department of Orthopaedic Surgery, Children's Hospital Colorado, 13123 East 17th Avenue, B600, Aurora, CO, 80045, USA.
authors.forename: Mary K
authors.initials: MK
authors.lastname: Hill
authors.affiliation: Department of Orthopaedic Surgery, Children's Hospital Colorado, 13123 East 17th Avenue, B600, Aurora, CO, 80045, USA.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Carry
authors.affiliation: Department of Physical Medicine & Rehabilitation, University of Colorado School of Medicine, Denver, CO, USA.
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Heyn
mesh_terms: D000367:Age Factors; D005271:Femur Head Necrosis / Q000175:diagnosis / Q000209:etiology*; D006618:Hip Dislocation, Congenital / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D006621:Hip Joint / Q000002:abnormalities / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D016017:Odds Ratio; D019637:Orthopedic Procedures / Q000009:adverse effects*; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome