Ultrasonographic findings in hips with a positive Ortolani sign and their relationship to Pavlik harness failure

Background: In developmental dysplasia, Pavlik harness treatment of hips with a positive Ortolani sign fails in up to 40% of such patients; however, no study has described factors for failure associated with ultrasonographic parameters. The goal of this study was to describe unique ultrasonographic markers in hips with a positive Ortolani sign that are associated with Pavlik harness failure. Methods: A retrospective review was performed of all patients less than six months old who were treated for developmental dysplasia of the hip with a Pavlik harness from 1991 to 2005 at a single institution. Inclusion criteria for this study were patients with a hip that was dislocated but reducible (a positive Ortolani sign), treatment with a Pavlik harness, and an ultrasound examination performed within four weeks after the initiation of treatment. The initial coronal ultrasound studies were graded with use of the Graf classification, the percentage of femoral head coverage, labral morphology, and two new measurements: superior femoral head displacement relative to the labrum and total femoral head displacement. Results: Eighty-five patients with 115 hips fitting the inclusion criteria were identified. Pavlik harness treatment was successful in seventy-two hips (63%) and failed in forty-three hips (37%). Increased beta angle, decreased femoral head coverage, an inverted labrum, decreased superior femoral head displacement relative to the labrum, and decreased total femoral head displacement were significantly correlated with Pavlik harness failure (p < 0.001 for all). A finding of 0° of superior femoral head displacement relative to the labrum was seen in 98% of the hips with successful Pavlik harness treatment. Total femoral head displacement of less than -30° was found in 89% of the hips with a failure of Pavlik harness treatment. Conclusions: We identified two new objective measurements on static ultrasound examinations of the hip that are associated with the outcome of Pavlik harness treatment in patients with developmental dysplasia and a positive Ortolani sign. A femoral head positioned below the labrum is strongly associated with success of the Pavlik harness treatment, whereas a hip with a femoral head that is located substantially superior and lateral to the labrum is associated with Pavlik harness treatment failure. The presence of a deficient cartilaginous anlage and an inverted labrum may provide a pathoanatomical explanation for Pavlik harness treatment failure. Level of Evidence: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.