The traction technique is particularly valuable in obtaining a spontaneous pneumoarthrogram when applied to joints, such as the hip, in which effusions are difficult to diagnose by physical examination. This study shows that whether an intra-articular lucency will be produced by traction will depend on the amount of fluid in the joint and the amount of traction employed. If a lucent crescent forms in the joint space with traction in the supine position, it probably excludes an effusion and if the femoral head separates from the acetabulum without such a lucent crescent, it is diagnostic of excess fluid.
- Hip joint
- Vacuum phenomenon
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging