European Journal of Radiology 81 (2012) e344–e351 Contents lists available at SciVerse ScienceDirect European Journal of Radiology journa l h o me pa ge: www.elsevier.com/locate/ejrad Review A meta-analysis of common risk factors associated with the diagnosis of developmental dysplasia of the hip in newborns Clara L. Ortiz-Neira a , Elizabeth Oddone Paolucci b , Tyrone Donnon c,* a Department of Radiology, Alberta Children’s Hospital, University of Calgary, Faculty of Medicine, 2888 Shaganappi Trail NW, Calgary, Alberta, Canada T3B 6A8 1 b Departments of Surgery & Community Health Sciences, Faculty of Medicine, University of Calgary, FMC, North Tower Room #1026, 1403 - 29 Street NW, Calgary, Alberta, Canada T2N 2T9 c Department of Community Health Sciences, Faculty of Medicine, University of Calgary, G13 Heritage Medical Research Centre, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1 a r t i c l e i n f o Article history: Received 29 July 2011 Received in revised form 24 September 2011 Accepted 3 November 2011 Keywords: Developmental dysplasia of the hip Meta-analysis Ultrasound Radiology Risk factors a b s t r a c t Background: Although there is no clear consensus about the process of screening for developmental dysplasia of the hip (DDH), there are six common risk factors associated with DDH in patients less than 6 months of age (breech presentation, sex, family history, first-born, side of hip, and mode of delivery). Methods: A meta-analysis of published studies was conducted to identify the relative risk ratio of the six commonly known risk factors. A total of 31 primary studies consisting of 20,196 DDH patients met the following inclusion criteria: (1) contained empirical data on at least one common risk factor, (2) were peer-reviewed from an English language scientific journal, (3) included patients less or equal to 6 months of age, and (4) identified method of diagnosis (e.g., ultrasound, radiographs or clinical examination). Results: Fixed effect and random effects models with 95% confidence intervals were calculated for each of the six risk factors. Reported relative risk ratio (RR) for each factor in newborns was: breech presentation 3.75 (95% CI: 2.25–6.24), females 2.54 (95% CI: 2.11–3.05), left hip side 1.54 (95% CI: 1.25–1.90), first born 1.44 (95% CI: 1.12–1.86), and family history 1.39 (95% CI: 1.23–1.57). A non-significant RR value of 1.22 (95% CI: 0.46–3.23) was found for mode of delivery. Conclusion: Results suggest that ultrasound and radiology screening methods be used to confirm DDH in newborns that present with one or a combination of the following common risk factors: breech presentation, female, left hip affected, first born and family history of DDH. © 2011 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Developmental dysplasia of the hip (DDH), formerly known as congenital dislocation of the hip (CDH) comprises a spectrum of abnormalities of the hip in infants and children that includes an immature hip, acetabular dysplasia with or without dislocation, subluxation of the femoral head as well as being dislocatable and subluxable [1]. Although some of these changes may resolve spon- taneously, if not diagnosed or monitored during infancy, the hip will worsen with time [2]. As some reports [3,4] have documented, dis- location or dysplasia of the hip can occur after a normal neonatal screening examination. Thus, the term DDH is preferred because it more accurately refers to a spectrum of abnormalities. These abnormalities include: abnormal acetabular shape (i.e., dysplasia, isolated dysplasia) and/or partial or incomplete displacement of the femoral head from the acetabulum (i.e., subluxed hip, subluxable * Corresponding author. Tel.: +1 403 210 9682; fax: +1 403 270 7507. E-mail address: tldonnon@ucalgary.ca (T. Donnon). 1 Tel.: +1 403 955 7985; fax: +1 403 210 7507. hip, dislocatable hip, and dislocated hip [4], while not excluding the possibility of the late development of the condition in underdiag- nosed or mild acetabular dysplasia that progresses to instability [5]. The preferred screening method for obtaining a prompt diag- nosis of DDH remains controversial. Presently, main methods for screening include clinical examination and ultrasound. Pelvic radiograph has been used after 4 months of age to assure bone congruency [6]. Clinical examination is the most commonly used method as universal screening for DDH. However, while some places in Europe have used ultrasound as a universal screening method, others (like in the USA and Canada) use it only for patients at risk for DDH. The American Academy of Pediatrics (AAP) sub- committee on DDH estimated that in about 15% of cases, DDH is not detectible at birth even by experienced examiners or ultrasonogra- phers [6,7]. One of the resulting implications of employing different definitions and diagnostic methods of DDH, is that reported inci- dence rates of DDH vary widely [8–11]. More importantly, failure to promptly and accurately diagnose DDH may result in serious long-term health care problems such as early degenerative arthritis [1,6]. 0720-048X/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2011.11.003