Rates and risk factors for failure of reduction in closed reduction in developmental dysplasia of the hip: a systematic review and meta-analysis

center dot Objective: In developmental dysplasia of the hip (DDH), concentric reduction of dislocated hips cannot be achieved by closed reduction in many cases, and open reduction is required ('failure of reduction'). The incidence of cases requiring open reduction and the significance of risk factors for unsuccessful reduction remain unclear. We investigated the overall rate and the risk factors for failed closed reduction in DDH. center dot Methods: We followed the Cochrane recommendations in our systematic review and meta-analysis. We performed a systematic search in three medical databases to identify all studies reporting on pediatric patients with hip dislocation in DDH on 2 July 2022. Eligible studies reported on the rate of failure in children younger than 36 months. We calculated odds ratios (ORs) with 95% CIs from two-by-two tables (event rate in risk group, event rate in non-risk group). center dot Results: We identified 13 316 studies and included 62 studies (5281 hips) for failure rate and 34 studies (3810 hips) for risk factor analysis. The overall rate of failure in closed reduction was 20%. The risk of failure of reduction increased with the grade of dislocation and was significantly higher for high dislocations (group 0-24: IHDI 4 vs IHDI 2 OR: 17.45, CI: 9.26-32.92; T & ouml;nnis 4 vs T & ouml;nnis 2 OR: 14.67, CI: 1.21-177.37; Graf IV vs Graf III OR: 3.4, CI: 2.27-5.09). Male gender was also a significant risk factor (OR: 2.27, CI: 1.13-4.56) in group 0-36. center dot Conclusion: Higher grade dislocations and male gender are significant risk factors for failure of reduction in closed reduction in hip dislocation in DDH.