Posterior glenohumeral stiffness: capsular or muscular problem? A case report.

The impingement syndrome’s aetiology is multifactorial. The mechanical factors potentially contributing to this pathology are altered neuromuscular control, decreased force of the rotator cuff and peri-scapular muscles, the acromion’s morphology and posture and stiffness of the posterior capsule (Michener et al., 2003). Amongst these dysfunctions, the authors want to focus on the retraction of the posterior capsule, which can be seen clinically by a limitation in trans-thoracic adduction and internal rotation. Some authors (Warner et al., 1990; Tyler et al., 2000; Matsen and Artnz, 2004), maintain that a number of patients with impingement syndrome show a decreased trans-thoracic adduction and internal rotation caused by the thickening and shortening of the posterior glenohumeral capsule. From a clinical point of view, Tyler et al. (2000) and Lin and Yang (2006) have demonstrated that there is a strict correlation between loss of trans-thoracic adduction and limitation of internal rotation. The relationship between these two limitations is that 1 cm of transthoracic adduction corresponds to an internal rotation reduction of 41. Harryman et al. (1990), in their study on glenohumeral arthrokinematics, introduced for the first time the concept of obligate translation. Obligate translation