The influence of MRI on treatment decisions regarding knee injuries.

This study evaluated whether the information gained from magnetic resonance imaging (MRI) of the knee would provide information that was useful in the treatment algorithm. Three orthopedic surgeons completed a questionnaire immediately after the initial evaluation of a patient with a knee injury and for whom an MRI also was ordered by that surgeon. The questionnaire asked the surgeons' what their proposed clinical diagnoses and treatment plans would be if MRI was not available. Eighty-five patients were included in the study. Initial treatment recommendation was altered for 18 patients (21%) solely because of the MRI results. The physicians and MRI were most accurate for anterior cruciate ligament (ACL) tears followed by medial meniscus tears, and lateral meniscus tears, and significantly behind in accuracy for patellofemoral chondral pathology. These diagnoses were more frequently missed in the face of acute ACL pathology for the clinician and MRI. In 19 cases in which the surgeon was confident of ACL insufficiency, in only 1 (5%) case did the MRI scan provide useful information. In 19 cases in which an ACL reconstruction was performed, the decision to proceed with the reconstruction was hastened in 3 patients because of the MRI results. These results indicate that the use of MRI for decision making in acute ACL tears is not of much benefit unless the diagnosis of ACL insufficiency is in question. Magnetic resonance imaging is more useful for the decision-making process when the pathology involves the menisci or chondral surfaces. In this study, MRI of the knee beneficially altered the treatment plan of the orthopedist in 18% of the patients and resulted in the prolongation of symptoms in 4% of patients.