MRI reveals unrecognized treatment failures after application of Fettweis plaster in children with unstable hip joints.

We evaluated the success of treatment of unstable hip joints with the Fettweis plaster followed by MRI to detect potential treatment failures. A total of 132 ultrasound-detected unstable hips of type D, III, or IV according to Graf were treated with closed reduction and Fettweis plaster, followed by MRI. We examined 19 type D, 55 type III, and 58 type IV. Mean age at diagnosis was 84.5 days (SD: ± 55.4). Treatment period was 63.2 days (SD: ± 22.2). In 13 cases, the MRI showed a poor reduction. After repetition of this treatment, all 13 showed a concentric reduction. The use of MRI detects 9.8% of treatment failures. We recommend an MRI examination after each closed reduction to ensure the success of the therapy.