Roentgenographic analysis of patellofemoral congruence

Abstract

The aim of paper was to present a new method for the roentgenographic evaluation of the knee that is reproducible and accurate. Whilst the patient is supine, the knees are fl exed to 45° so that the lower legs and feet extend beyond the table and the feet move below the table. The X-ray beam is angled 30° below horizontal such that it strikes the cassette fi lm at 90°. The cassette is placed distal to the patellae. The angular relationship between the intercondylar sulcus and the patellar ridge was measured to give the congruence angle of the patellofemoral joint. In a sample of 100 healthy control participants, a congruence angle of greater than 16° was found to be abnormal.