CT scanning of the patellofemoral joint. The quadriceps relaxed or contracted?

A study of the patellofemoral joint in patients with patellofemoral pain has been carried out in 14 patients (18 knees) to compare CT scans with the knee extended fully and the quadriceps muscle contracted or relaxed. The purpose was to decide whether both examinations are necessary in young adults with suspected patellar malalignment. The patients were selected randomly. Thirteen knees were also examined in 20 degrees of flexion. The lateral patellar angle and the lateral patellar shift were measured. Linear regression analysis showed a proportional relationship between measurement with the quadriceps contracted and relaxed. Therefore, only one examination is needed and is easier to carry out in the relaxed state. Radiation to the patient and costs are reduced.