Magnetic resonance imaging in children with acute hip pain.

45 children presenting with acute hip pain were prospectively evaluated with conventional radiography, radioisotope bone scan, and magnetic resonance imaging (MRI). The final diagnoses were transient synovitis (n = 17), septic arthritis (n = 2), Legg-Calve-Perthes disease (LCPD, n = 13), epiphyseal dysplasia (n = 2), other conditions (n = 4), and normal findings (n = 7). In the work-up MRI provided more morphologic information than other techniques and enlarged the diagnostic possibilities. It was the only imaging technique able to give an early indication of bone marrow involvement in systemic diseases. For the early diagnosis of LCPD, MRI was as sensitive as isotope bone scan and more precise than conventional radiography. In the follow-up of LCPD patients MRI was not able to indicate the start of revascularisation of the necrotic area, which bone scans showed reliably in six patients: but MRI provided excellent evaluation of the position, form and size of the femoral head and the surrounding soft tissues.