The impact of magnetic resonance imaging of the knee on surgical decision making.

Although magnetic resonance imaging (MRI) of the knee is known to be an accurate technique for diagnosing soft tissue disorders of the knee, the value of MRI in improving patient outcome is controversial. The purpose of this project was to study the value of MRI in a subgroup of patients with knee pain and disability whose diagnosis was uncertain after standard orthopaedic evaluation. An extensive database was recorded prospectively for each of 208 patients providing clinical data as well as diagnoses from clinical, MRI, and surgical observations. These data were analyzed to determine the effect of MRI on diagnosis and patient outcome regarding surgical decision making. The overall diagnostic accuracy of MRI was determined to be 97% in patients undergoing arthroscopy. MRI differed from the clinical diagnosis in 33% of cases, the most common variance being diagnosis of meniscal tear. After combining the MRI and clinical information, surgical decision making was altered in 27% of cases. In a group of patients with acute knee symptoms, the decision not to proceed with surgery was made in 64% of cases. The study shows that MRI of the knee is a valuable tool for augmenting the diagnostic process. The data further show that MRI is a cost-effective technique for avoiding unnecessary surgery and affects patient outcome by improving surgical decision making.