PREOPERATIVE EVALUATION OF THE ULNAR COLLATERAL LIGAMENT BY MAGNETIC-RESONANCE-IMAGING AND COMPUTED-TOMOGRAPHY ARTHROGRAPHY - EVALUATION IN25 BASEBALL PLAYERS WITH SURGICAL CONFIRMATION

A prospective study was completed on 25 baseball players with medial s ide elbow pain. They were evaluated preoperatively with both computed tomography arthrogram and magnetic resonance imaging examinations of t he elbow to assess the ulnar collateral ligament. At surgery, 16 of 25 patients had an abnormal ulnar collateral ligament and 9 patients had a normal ulnar collateral ligament. The computed tomography arthrogra m detected abnormalities in 12 of the 14 patients with ulnar collatera l ligament tearing (sensitivity, 86%). The magnetic resonance imaging scan indicated abnormalities in 8 of 14 patients (sensitivity, 57%). T he specificity of the computed tomography arthrogram was 91% and the m agnetic resonance imaging was 100%. A newly described ''T-sign'' was s een on the computed tomography arthrogram in the patients with an unde rsurface tear of the ulnar collateral ligament. This represented the d ye leaking around the detachment of the ulnar collateral ligament from its bony insertion but remaining contained within the intact superfic ial layer of the ulnar collateral ligament and capsule. Both the compu ted tomography arthrogram and the magnetic resonance imaging scan were accurate in diagnosing a complete tear of the ulnar collateral ligame nt preoperatively in all cases. The main advantage of the computed tom ography arthrogram was in evaluating the partial undersurface tear.