Pathogenesis (development of disease)
The following forms of shoulder dislocation can be distinguished.
- Anterior shoulder dislocation – forward dislocation of the shoulder (>90% of cases); there is stretching or tearing of the inferior glenohumeral ligamentIf, in addition, the anterior portion of the labrum (glenoid lip) has been damaged and tears away from its bony support, the condition is called a Bankart lesion.
- Anterior-inferior shoulder dislocation – dislocation of the shoulder anteriorly downward.
- Posterior shoulder dislocation – dislocation of the shoulder backward.
- Others: axillary shoulder dislocation, paracorcacoidal shoulder dislocation, luxatio erecta (dislocation in which the head of the humerus is dislocated downward with the arm additionally held vertically upward).
Shoulder dislocation can result from direct and indirect force, such as a fall (direct force on the humeral head). Similarly, a congenital or acquired hyperlaxed (stretchy) ligamentous apparatus of the shoulder can lead to shoulder dislocation (= habitual shoulder dislocation). Forward shoulder dislocation results from an abduction/external rotation motion (splaying and outward rotation) of the arm. Posterior shoulder dislocation results from an adduction/internal rotation motion (inward rotation and pulling the arm toward the body) of the arm.
Etiology (Causes)
Disease-related causes.
Musculoskeletal system and connective tissue (M00-M99).
- Hyperlaxity ligamentous (extensible ligaments) guidance of the shoulder.
Neoplasms – tumor diseases (C00-D48).
- Epilepsy (seizure) – here often bilateral shoulder dislocation.
Injuries, poisoning and other consequences of external causes (S00-T98).
- Electrical accident – here often bilateral shoulder dislocation.
- Previous dislocations
- Fall on the shoulder
