The Effect of Arm Position on the Repaired Capsulolabrum after Arthroscopic Bankart Repair: Magnetic Resonance Imaging Study

Kim, Seung Ho; Yoo, Jae Chul

Abstract

PURPOSE
To evaluate and describe the findings of immediate postoperative, magnetic resonance (MR) arthrography of repaired capsulolabrum using two different arm positions (internal rotation and external rotation) for patients who had undergone arthroscopic Bankart repair. MATERIALS AND METHODS: Arthroscopically-repaired Bankart lesions were examined in the axial T2-weighted images of MR-arthrogram in twenty-two shoulders on the immediate postoperative day. We measured three parameters (height, slope, and medial overhang) on the axial images at the anteroinferior portion of the glenoid in internal and external rotation of the adducted arm. The mean internal rotation of the arm was 30degrees (range, 14degrees to 45degrees) and the mean external rotation was 19degrees (range, 2degrees to 44degrees). The two heights and slopes were compared using the paired t-test. For medial overhang, crosstable McNemar test was used. Statistical analyses were performed with the SPSS software package. RESULTS: There were 21 male and 1 female patients with a mean age of 24 years (range, 17 to 36 years). The arms in internal rotation position showed a loss of capsulolabral buttress in all patients. When the arm was in external rotation, the height and slope of the labrum were both greater, being on average 1.47 mm and 7degrees, respectively (p<0.001 for both measures), than those in the internal rotation position. Medial overhang on the glenoid rim was 81% positive when the arm was in the internal rotation position but 86% negative with the arm externally rotated (p<0.001). CONCLUSION: Loss of repaired capsulolabral buttress seems to be inevitable when the arm is immobilized in the internal rotation position after arthroscopic Bankart repair. To prevent this, we recommend immobilization of the arm in external rotation after the surgery.