Protocol for the Request of Knee Magnetic Resonance Imaging in Elderly Patients with Suspected Osteoarthritis: Reduction in Test Requests and Impact on Management and Diagnosis.

Objective  To develop an evidence-based protocol to guide magnetic resonance imaging (MRI) requests in elderly patients with suspected knee osteoarthrosis and to evaluate its effectiveness after implementation. Methods  The institutional protocol was developed after reviewing the literature during the first semester of 2018. The control group was defined as patients cared for in the first semester of 2018, before the implementation/dissemination of the institutional protocol, and the study group was composed by patients cared for during the second semester of 2018 after the standardization of MRI requests for suspected knee osteoarthrosis. Results  Our sample included 826 patients undergoing knee MRI, with a mean age of 69.3 years. Protocol implementation decreased MRI requests and increased radiograph requests ( p  < 0.001). After the implementation of the protocol, the MRI changed the diagnosis or treatment in only 11.2% of the cases. Conclusion  Protocol implementation resulted in a 47.5% reduction in the number of requests for knee MRI, with most (89%) patients with alteration in diagnosis or treatment. Level of evidence: case-control study (IIIB).