MR-IMAGING OF PATIENTS WITH LATERAL EPICONDYLITIS OF THE ELBOW (TENNIS ELBOW) - IMPORTANCE OF INCREASED SIGNAL OF THE ANCONEUS MUSCLE

OBJECTIVE. The purpose of this study was to determine what changes mig ht be detected on MR images of patients with chronic lateral epicondyl itis (tennis elbow) that could explain why some cases are resistant to therapy. SUBJECTS AND METHODS. Seven consecutive patients with chroni c lateral epicondylitis were included. The diagnosis was based on symp toms and signs characteristic of the disease, as determined by each pa tient's orthopedic surgeon. Three volunteers with normal elbows were c ontrol subjects. All patients had MR imaging of the involved elbow, an d control subjects had MR imaging of the nondominant elbow. Short tau inversion-recovery (STIR) MR imaging was chosen because of its sensiti vity to changes in the water content of muscle and its suppression of the fat signal. The images were analyzed visually and on an MR worksta tion to measure the signal intensity of the elbow muscles. RESULTS. In all seven patients, MR images showed increased signal intensity of th e anconeus muscle. This increase in signal intensity was not observed in the control subjects, and to our knowledge it has not been reported previously. CONCLUSION. Increased signal intensity of the anconeus mu scle on MR images in patients with chronic lateral epicondylitis sugge sts involvement of the muscle. Increased signal intensity is seen with edema, granulation tissue, and inflammation, which may explain the fi ndings in this study. Our results are inconclusive as to whether this increased signal intensity contributes to the chronicity of patient sy mptomatology or is associated with abnormal elbow motion because of th e symptoms.