The Use of MRI in Evaluating Knee Pain in Patients Aged 40 Years and Older

The use of MRI is increasing when evaluating patients with knee pain because it is highly sensitive for detecting intra-articular pathology. However, such changes can be associated with degenerative joint disease, which may be demonstrated with weight-bearing radiographs. The purpose of this study was to determine how often MRI was obtained before orthopaedic referral in patients aged ≥40 years with knee pain, how often weight-bearing radiographs were obtained before MRI, and whether such imaging influenced treatment recommendations.

In a study of 599 new patients, participating physicians documented the presence of a prereferral MRI and/or plain radiographic studies, the results of weight-bearing radiographs, treatment recommendations, and the impact of any prereferral imaging.

Prereferral use of MRI occurred in 130 patients (22%). Of these patients, plain radiographic studies were obtained for 58% before MRI and 13% had weight-bearing radiographs. Ultimately, 17% had weight-bearing radiographs that demonstrated >50% loss of joint space. Forty-eight percent of prereferral MRIs did not contribute to treatment recommendations. In patients with >50% loss of joint space, MRI was considered unnecessary in 95% of the cases.

Many prereferral MRIs do not contribute to clinical decision making. Weight-bearing radiographs can help identify those patients in whom MRI is unlikely to be helpful.

Level III.