To compare hip joint space on supine and weight-bearing anteroposterior digital radiographs.
Fifty anteroposterior views of the hip in 25 patients were taken in supine and weight-bearing positions on a fluoroscopic unit. Two observers in a double-blind study assessed the width of the joint space on an Easy Vision unit with an indirect method of measurement (metric index).
Inter-observer and intra-observer variabilities of the metric index were less than 4.1%. There was no significant difference of the metric index of the hip (P>0.05), between supine and weight-bearing positions.
There is no significant difference of the width of the joint space of the hip between supine and weight-bearing anteroposterior radiographs. Measuring joint space loss in osteoarthritis of the hip with anteroposterior views should be done with radiographs of the hip in the supine position to improve image quality.