BackgroundPredictors of failure of the Pavlik harness in reducing and stabilizing an Ortolani-positive hip remain ‘unclear’. The purpose of this study is to investigate the success of the Pavlik harness when treating Ortolani-positive hips, to look for predictors of failure of the harness and to analyze the arthrographic findings among these failures.Materials and methodsThe medical records of 39 consecutive patients with an Ortolani-positive hip treated initially with a Pavlik harness were reviewed. Data regarding birth order, problems during pregnancy, presentation at birth, delivery, family history of DDH, gender, side involved, bilaterality, onset of treatment, problems related to use of the harness, and time until the harness reduced and stabilized the hip or was abandoned because of a failure were recorded. The presence of plagiocephaly, torticollis or foot deformity was also noted. We looked for predictors of failure among these aspects and report the arthrographic findings of the failures.ResultsThe mean age when the harness was started was 16.7 days. The mean time until success or failure of the harness in reducing and stabilize the hip was 18.5 days. There were 8 (20.5 %) failures. Multigravida (p = 0.026) and foot deformity (p = 0.023) were associated with failure of the harness. On the other hand, problems during pregnancy (p = 1), presentation at birth (p = 0.078), c-section (p = 0.394), family history of DDH (p = 1), gender (0.313), torticollis (p = 1), bilaterality (p = 1) and onset of treatment (p = 0.485) were not associated. Arthrographic abnormalities were found in all failures.ConclusionThe Pavlik harness failed to reduce and stabilize the hip in 20.5 % of the newborns with an Ortolani-positive hip. Multigravida and foot deformity were statistically associated with failure of the harness. An anatomical obstacle for reduction was found in all hips with a harness failure. A more teratological than mechanical hip dislocation could be the reason for failure of the Pavlik harness.Level of evidenceIV, Retrospective case series.