ULNAR COLLATERAL LIGAMENT IN THE GROWING ELBOW - MR-IMAGING OF NORMAL DEVELOPMENT AND THROWING INJURIES

PURPOSE: To study the magnetic resonance (MR) imaging appearance of the ulnar collateral ligament (UCL) and its insertion into the medial epicondyle. MATERIALS AND METHODS: Sixteen normal and 20 symptomatic elbows were examined with a 1.5-T unit. Normal elbows were imaged with axial T2*-weighted three-dimensional Fourier transform sequences. Symptomatic elbows were imaged with coronal T1-, T2-, and T2*-weighted and/or short-inversion time inversion-recovery sequences. RESULTS: In normal immature elbows, the ulnar periosteum was seen as an extension of the UCL, and its enthesis had signal intensity characteristics that differed from those of the mature ligament. In symptomatic elbows imaged before epiphyseal fusion, segmentation and subchondral bone resorption of the ossification center were seen with or without a capsular tear. After epiphyseal fusion, a full-thickness or a partial UCL tear at the site of its insertion, with or without subcortical bone resorption, was seen. CONCLUSION: The MR imaging characteristics of the developing elbow differ from those of the mature elbow. MR imaging is useful in assessing UCL, damage.