Weight-Bearing X-Rays for Knee Pain Preferable to MRI

Weight-bearing radiographs performed on patients older than 40 presenting with knee pain may be more efficient and effective than MR imaging of the knee, according to a study published in the Journal of the American Academy of Orthopaedic Surgeons.

Researchers from Washington University and St. Louis Center for Cartilage Restoration and Repair in St. Louis, MO, undertook a descriptive study to assess patients, aged 40 and older, who presented to a sports medicine division for evaluation of knee pain, comparing how often MRI was obtained by orthopedic referral, how often weight-bearing radiographs were obtained prior to the MRI, and if the imaging influenced treatment recommendations.

A total of 599 patients participated in the study. Physicians documented the presence of a pre-referral MRI and/or plain radiographic studies, the results of weight-bearing radiographs, treatment recommendations, and the impact of any pre-referral imaging.[[{"type":"media","view_mode":"media_crop","fid":"52077","attributes":{"alt":"Musculoskeletal imaging","class":"media-image media-image-right","id":"media_crop_3136446566246","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"6450","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 170px; width: 170px; border-width: 0px; border-style: solid; margin: 1px; float: right;","title":"©decade3d - anatomy online/Shutterstock.com","typeof":"foaf:Image"}}]]

The results showed that 130 patients (22%) had undergone pre-referral MRI, and of these patients, plain radiographic studies were obtained for 58% before they underwent MRI, and 13% underwent weight-bearing radiographs.

Seventeen percent had weight-bearing radiographs that demonstrated more than 50% loss of joint space. According to the researchers, 48% of pre-referral MRIs did not contribute to treatment recommendations. In patients with more than 50% loss of joint space, MRI was considered unnecessary in 95% of the cases.

The researchers concluded that many pre-referral MRIs do not contribute to clinical decision making. Weight-bearing radiographs can help identify those patients in whom MRI is unlikely to be helpful.