Rotator interval closure involves plicating the anterior-superior region of the capsule by suturing the superior and middle glenohumeral ligaments together. This has been advocated as a treatment for certain recurrent instability patterns such as multi-directional instability (MDI). It was felt to address inferior subluxation in patients with a sulcus sign, however, the greatest effect is a decrease in external rotation. In general, a tighter anterior capsule tends to decrease external rotation most, and a tighter posterior capsule causes a decrease in internal rotation. The study by Gerber et al performed selective capsular plications around the shoulder in cadavers and measured the resulting changes in motion. Anterosuperior capsular plication, the area where a rotator interval closure is performed, most markedly affected external rotation of the adducted arm, decreasing it by a mean of 30.1 degrees. The study by Plausinis measured the effects of different interval closure suture patterns in 12 cadavers and found the greatest decrease was in external rotation (10 degs) compared to flexion.
Plausinis D, Bravman JT, Heywood C, Kummer FJ, Kwon YW, Jazrawi LM. Arthroscopic rotator interval closure: effect of sutures on glenohumeral motion and anterior-posterior translation. Am J Sports Med. 2006 Oct;34(10):1656-61.
PMID:16832127 (Link to Abstract)
Gerber C, Werner CM, Macy JC, Jacob HA, Nyffeler RW. Effect of selective capsulorrhaphy on the passive range of motion of the glenohumeral joint. J Bone Joint Surg Am. 2003 Jan;85-A(1):48-55.
PMID:12533571 (Link to Abstract)