The von Rosen splint compared with the Frejka pillow. A study of 408 neonatally unstable hips.

101 children in Tromsö, Norway, treated with the Frejka pillow for 4.5 months because of neonatal hip instability (NHI) were compared with 307 children in Malmö, Sweden, treated with the von Rosen splint for 3 months. The pelvic radiographs, taken when the treatment was terminated, were assessed by the acetabular index (AI) and the cases of failure were evaluated. The AI showed no difference between the two groups. The Frejka group had 4 patients who received further treatment because of remaining acetabular dysplasia and/or subluxation while the von Rosen group had none. The difference in risk of failure might partly be explained by different criteria for failure.