Computed tomography of the hip joint capsule.

In 95% of cases, computed tomography (CT) enables the articular capsule of the hip joint to be directly visualized. Articular effusion in the hip joint can also be recognized in the CT image. In inflammatory arthritis and active osteoarthrosis of the hip joint, thickening of the articular capsule or articular effusion appears in the CT image. In addition, "undulation" of the articular capsule sometimes occurs. However, we have also observed this wavy configuration of the hip joint capsule in discrete latent osteoarthrosis of the hip joint. It is, therefore, unequivocally indicative of disease only when seen in association with articular effusion or thickening of the capsule. Focal fatty accumulation of the capsule distinguished from articular capsule tissue by its low density.