Rotator cuff tears (RCT) are a frequent concomitant injury of glenohumeral dislocations. Whereas especially in young patients a persistent instability is the most common challenge [12], the problem in the elderly is the associated cuff pathology leading to functional impairments [3, 8]. The incidence of an associated cuff tear increases with patients’ age and number of dislocations [14]: in patients between 51 and 60 years of age, the rate after a primary dislocation was less than 10%, whereas 40% of recurrent dislocations resulted in related RCT [8].

Moreover, there are age-linked differences regarding the extent of a tear [11]: an isolated supraspinatus tendon tear mostly occurs during the early fifties. During the mid-fifties, mostly a combination of supra- and infraspinatus tears can be expected, whereas patients with a mean age of 58 years suffer from complex and massive tears of the supra-, infra-, as well as subscapularis tendon.

Shoulder muscles are an important stabilizer of the glenohumeral joint by a concavity-compression mechanism enabling a concentric rotation [6]. Especially during the mid-ranges of motion, they act as primary stabilizer of the shoulder joint [5] and can decrease strains on the capsular-ligamentous complex at the end ranges of motion [5]. Different studies showed that rotator cuff activity increases the compressive forces at the glenohumeral joint and decreases the amount of humeral head translation [7, 18]. They postulate that a decrease in rotator cuff muscle forces results in an increase of anterior humeral head displacement. Equally, Pouliart et al. revealed in a cadaveric model that the humeral head might dislocate easily when rotator cuff tears are present [11].

The anterior dislocation mechanism results in a lesion of the anterior capsular-ligamentous complex as well as an abrupt eccentric load on the posterior rotator cuff. This often results in partial articular-sided or complete lesions of the supra- and infraspinatus tendon [1, 8, 9] and is postulated to be the “anterior mechanism.” Moreover, lesions of the upper two-thirds of the subscapularis tendon may be associated with shoulder dislocations. These humeral-sided lesions mostly occur in combination with an injury of the capsule and a humeral avulsion of the inferior glenohumeral ligament (HAGL lesion).

In contrast, forced abduction, flexion, and external rotation frequently consequence a posterosuperior RCT, mainly in patients suffering from pre-existing weakening or partial lesions of the rotator cuff. This phenomenon is postulated to be the “posterior mechanism” [2].

Loew et al. evaluated a decreased frequency of capsulo-labral lesions in patients with increased age [8]. In their prospective overview, only 10% of patients older than 40 had combined lesions (RCT lesion of the capsular-ligamentous complex), but 89% of them were combined lesions after more than one dislocation. Therefore, it seems to be more likely for older patients to suffer from RCT after the first shoulder dislocation than from a combined lesion of the capsular-ligamentous complex. This is contrary to repetitive shoulder dislocations in this patient group where combined lesions are common.