The Phenomenon of the Apparent (Double) Femoral Head in Infant Hip Sonography According to Graf-Description, Incidence and Clinical Relevance.

PURPOSE: Hip screening sonography according to Graf in rare cases yields the appearance of a double femoral head, aptly named the Double-Head-Sign. The goal of this retrospective study is to offer a definition of this rare sign, evaluate its incidence of occurrence and compare the sonographic findings with the clinical findings.

MATERIALS AND

METHODS

This Double-Head-Sign is caused by the overlap of the trochanter major with the actual head of the femur in cases of coxa vara. This was observed in 13 of 2800 neonates we screened as part of our sonographical neonatal hip screening.

RESULTS

13 neonates presented themselves with ultrasound findings in accordance with our description, yielding an incidence of 0,46% in our patient cohort. In correlation, these neonates also exhibited increased external and decreased internal rotation of the hip. Two had an underlying condition (achondroplasia).

CONCLUSION

In these rare cases, clinical examination of hip rotation in 90° hip flexion has proved helpful and further interdisciplinary examination of such infants to distinguish a possible underlying primary condition is recommended.