MIR Arthrography of the Labral-Capular-Ligamentous Complex : Normal Variations and Pitfalls

Hahn, Sung Ho; Yang, Bo Kyu; Kim, Chi Hong; An, Tae Won; Chu, Wu Jun

Abstract

MR arthrography is a useful modality for evaluating the labrocapsular ligamentous complex (LCLC) of the shoulder. This study was performed to describe normal anatomic variations and pitfalls in image interpretation related to evaluation of the LCLC. MR arthrogram of 56 shoulders in 41 asymptomatic young, active, male volunteers were prospectively reviewed to evaluate the labral shapes, capsular insertions and images which may mimic the lesions of glenohumeral instability. The anterior and posterior parts of the labra, respectively, varied in shape: triangular (72%,36%), round (13%,35%), cleaved (8%,1%), notched (2%,0%), flat (5%,24%), and absent (0%,4%). The anterior and posterior capsular insertions, respectively, varied in site: Mosely and Oevergaard type I (82%,62%), type II (13%,36%), and type III (5%2%). A number of pitfalls in image interpretation were discovered. Articular cartilage undercutting the labrum (29%) and middle glenohumoral ligament in proximity to anterior labrum (5%) simulated a labral tear. Joint fluid interposed in the central, superior portion of the sublabral sulci (25%) simulated a SLAP lesion. Synovial fold (38%) in the axillary pouch resembled a loose body. Knowledge of normal variations and pitfalls in MR arthrogram image interpretation of labral-capsular-ligamentous complex will help the orthopedist to accurately detect debilitating derangements associated with the glenohumeral instability.