Risk factors for developmental dysplasia of the hip: a meta-analysis

Early detection and subsequent treatment of developmental dysplasia of the hip (DDH) is thought to improve its prognosis. Frequently reported risk factors for DDH are a positive family history of DDH, female sex and breech presentation, but there is not a lot of systematic knowledge about DDH risk factors. We performed a systematic review and meta-analysis of the available evidence on DDH risk factors. We searched Medline, EMBASE and The Cochrane Library from conception up until October 2011 for primary articles on the subject. All studies reporting on potential risk factors for DDH that allowed construction of a two-by-two table were selected. Language restrictions were not applied. Two reviewers independently selected studies, extracted data and assessed study quality. The association between risk factors and DDH was expressed as a common odds ratio (OR) with a 95% confidence interval (CI). We identified 30 relevant studies reporting on 1,494,387 children; 26 studies were cohort studies and four studies used a case-control design. The risk of DDH was strongly increased in case of breech delivery (OR 5.7, 95% CI 4.4-7.4), female sex (OR 3.8, 95% CI 3.0-4.6) a positive family history of DDH (OR 4.8, 95% CI 2.8-8.2) and clicking hips at clinical examination (OR 8.6, 95% CI 4.5-16.6). This meta-analysis shows that infants born in breech presentation, female infants, infants with a positive family history and clicking hips at clinical examination have an increased risk for DDH. This knowledge can be helpful in the development of screening programs for DDH.