The effect of shoulder magnetic resonance imaging on clinical decision making.

One hundred cases were prospectively evaluated to determine the impact of magnetic resonance imaging on clinical decision making in an orthopaedic practice devoted to the treatment of disorders about the shoulder. Each was analyzed for changes in the clinical diagnosis or treatment. A change that either changed the primary diagnosis or type of treatment (operative versus nonoperative) was classified as category one. If additional clinically relevant findings were noted on the imaging studies without altering the primary diagnosis, or if the form of treatment was modified but not changed from operative or nonoperative, it was considered category two. Among the 100 imaging studies reviewed, category one and two changes were observed in 11 and 7 cases, respectively. Magnetic resonance imaging was particularly helpful in diagnosing ganglion cysts about the shoulder, a category one change in three out of three cases. For specific diagnoses a category one or two change was observed in 17% (10 of 59), 29% (4 of 14), 8% (1 of 13),and 100% (2 of 2) for rotator cuff disease, glenohumeral instability, adhesive capsulitis, and biceps disease, respectively. In 35 cases magnetic resonance imaging was considered to be unnecessary for the diagnosis or treatment of the patient. For the 65 patients who underwent magnetic resonance imaging, category one and two changes were noted in 10 and 5 patients, respectively. Statistical significance was demonstrated for category one changes in the entire group (100 cases) and the in subgroup recommended for magnetic resonance imaging (65 cases) (p < 0.05), indicating that the judicious use of magnetic resonance imaging can have a significant increase its impact on clinical decision making. Magnetic resonance imaging was found to be of limited diagnostic value in patients with an isolated primary clinical diagnosis of adhesive capsulitis, glenohumeral or acromioclavicular arthritis, brachial plexopathy, and cervical degenerative disk disease.