Radiographic diagnosis of quadriceps tendon rupture: analysis of diagnostic failure.

In a multi-institution study, 18 knees with complete quadriceps tendon ruptures (QTRs) were reviewed to analyze the cause of failure in radiographic diagnosis. Only 6 of the 18 knees were diagnosed correctly initially. This occurred even though almost all knee radiographs showed more than three abnormalities compatible with QTR (obliteration of quadriceps tendon, suprapatellar mass, suprapatellar calcific density, or patella baja). Of the 12 diagnostic failures, only 3 were considered to be complete failure. Nine primary reports (50%) were classified as incomplete diagnosis and could be correctly diagnosed if the attention of radiologists was focused to the quadriceps mechanism. We conclude that better understanding of radiographic abnormalities in QTR is necessary for the improvement of primary radiological diagnosis.