Good results after treatment with the Frejka pillow for hip dysplasia in newborns: a 3-year to 6-year follow-up study.

Because there is no consensus with regard to the efficiency of the Frejka pillow in the treatment of hip joint dysplasia in newborns, the aim of the present study was to evaluate our results with this device. During the 3-year period 1988 to 1990, the Frejka pillow was used in 108 newborns with clinically unstable hips verified by ultrasonography. There were three treatment failures (2.8%), defined as infants who needed additional treatment with an abduction splint or hip-spica cast. Avascular necrosis of the femoral head occurred in one patient (0.9%). At an age of 3 years to 6 years, 85 of the children attended a follow-up examination. An intoeing gait was observed in 17% and slightly reduced hip mobility in 20% of the patients. Compared with normal children, the patients had somewhat lower coverage of the femoral head by radiography, indicated by a lower centre-edge angle and a higher migration percentage, but the coverage was within the normal range in all cases. The mean anteversion angle was larger than that of normal children but only three patients had abnormally high anteversion angles. In conclusion, the results with the Frejka pillow were good, with few treatment failures and complications, and it is the most simple abduction device for the parents to handle. More rigid devices like the von Rosen splint seem to involve a slightly lower failure rate, but a higher risk of avascular necrosis. Therefore, we recommend the Frejka pillow when treatment is started within a few days of birth.