Magnetic resonance arthrography (MRA) in the postoperative shoulder

To evaluate changes in capsular mechanisms and the labroligamentous complex with magnetic resonance arthrography (MRA) after shoulder surgery and to e stablish possible criteria for the expected post-operative appearance of th e shoulder. MRA of the shoulder was performed in 16 patients, before and 6 months after undergoing arthroscopic surgery for recurrent unidirectional d islocation, MR studies were performed after application of a constant amoun t of contrast solution (2 mmol Gd-DTPA), Axial and coronal oblique T-1-weig hted images were obtained with and without fat suppression techniques, Ante rior (a)and posterior (p) capsular distances were measured, and the p/a rat io was established. Capsule thickness, capsular leaking, estimation of the volume of the axillary recess, appearance of the glenohumeral ligaments, an d evidence of labral lesions were compared on pre- and postoperative images . Mean anterior capsular distance (a) decreased from 9.73 +/- 1.03 mm preop eratively to 5.27 +/- 2.49 mm postoperatively, whereas dorsal capsular dist ance (p) increased from 6.13 +/- 2.36 to 8.93 +/- 2.37. The p/a ratio incre ased from 0.64 +/- 0.25 to 2.36 +/- 2.54 (p = 0.007). Capsular leaking was suspected preoperatively in seven patients, but was not evident postoperati vely. Capsular thickness and the estimated volume in the axillary recess di d not change significantly. Contrast extension into pre-existent labral tea rs (nine patients) decreased or were not evident postoperatively. Changes i n the appearance of the glenohumeral ligaments were found in six patients. Changes in capsular distances might be indicative of a decreased capsular l axity and could be a valuable criterion in the evaluation of the postoperat ive shoulder. Postoperative follow-up of labral tears is demonstrated by a decrease in contrast extension into or under a tear, Reactive capsular thic kening or scar tissue formation can be reactive or preexistent. Changes in ligaments might be secondary to surgery. MRA may be helpful in the reevalua tion of patients with suspected recurrent instability. (C) 1999 Elsevier Sc ience Inc.