Standards for ultrasonographic measurements of the hip joint in Indian adults.

Synovitis in the hip joint, in contrast to that in other limb joints, is extremely difficult to evaluate clinically. In the hip joint synovitis manifests as an increase in the distance between the iliofemoral ligament and the femoral neck. The present ultrasonographic study was undertaken in 110 healthy Indian adults to establish standards for the depth of the normal hip joint space in the normal Indian adult population. The shortest distance was 4 mm, the longest was 9 mm. The mean distance was 6.4 (S.D. 1.1) mm. The mean difference between the right and left hips was 0.42 (S.D. 0.49) mm. An age-specific reference curve with 95% confidence limits was constructed. No correlation was found between hip joint space and the subjects' height, weight, age or sex. It is concluded that a distance between the iliofemoral ligament and the femoral neck of more than 9 mm or a difference in measurement between the hips of 1 mm or more suggests an intracapsular effusion or active synovitis. These figures are at variance with the measurements obtained in studies on Western white populations.