The symptomatic hip in childhood: scintigraphic findings in the presence of a normal radiograph.

The principal causes in children of a non-acute painful hip are Perthes disease and synovitis (irritable hip). The 99mTc methylene diphosphonate (MDP) bone scan appearances in Perthes disease are well-known; in synovitis, the hip may show a diffuse increase in activity or may be normal. The significance of bone scintigraphy in the clinical setting of non-acute hip symptoms with normal skeletal radiography has been evaluated in 36 symptomatic children. The mean duration of symptoms prior to scan was 3 months (range 1 week-17 months). On the basis of final diagnosis, established by clinical findings, bone scan, X-ray and follow-up, the children were divided into two groups: synovitis or Perthes disease. Of the 33 scans in the 32 children with synovitis, 18 were normal and 15 showed diffusely increased activity on the painful side. All four patients with Perthes disease had focal femoral head abnormalities in the painful hip. Of the 18 children with normal scans, none went on to develop a skeletal disorder. In children with hip pain of over 1 week's duration, the main value of the bone scan is the early detection of Perthes disease. Diffuse increased activity on the painful side suggests synovitis. A normal scan virtually excludes significant skeletal abnormality.