The infant hip: assessment with real-time US.

Real-time ultrasonography (US) of the infant hip provides an accurate image of anatomic relationships as well as valuable information concerning function. US clearly images the cartilaginous femoral head and enables accurate assessment of hip size, shape, and symmetry. The dynamic relationship of the cartilaginous head to the acetabulum is clearly defined, and instability, subluxation, and dislocation can be demonstrated. The size, shape, and position of the hip can be monitored with the infant in a spica cast, brace, or harness. Findings of 212 sonograms of infant hips were correlated with those of radiography, orthopedic examination, or both. There were no false-negative or false-positive results among infants with congenital hip dysplasia, and, to the authors' knowledge, US revealed anatomic details more accurately than any other currently employed imaging modality, including computed tomography.