Posteroanterior weight-bearing radiographs, made with the knee in 45
degrees of flexion, were compared with conventional radiographs for
fifty-five patients who had surgical treatment for a lesion causing pain in
one knee. Narrowing of the cartilage space of two millimeters or more was
defined as indicative of major degeneration (grade III or IV). Comparison
of the intraoperatively observed degeneration with the narrowing that was
seen on the radiographs revealed that the posteroanterior weight-bearing
radiographs that were made with the knee in 45 degrees of flexion were more
accurate (p less than 0.01), more specific (no false-positives) (p less
than 0.01), and more sensitive (fewer false-negatives) than the
conventional extension weight-bearing anteroposterior radiographs.