Clinical examination of the unstable shoulder.

The clinical history is usually a very helpful guide for identifying frank traumatic glenohumeral joint dislocations. Glenohumeral dislocation most commonly occurs in the anterior direction (>95%) with the shoulder forcibly abducted and externally rotated. Atraumatic, multidirectional and subtler glenohumeral instability are often harder to diagnose. The presence of a sulcus of two or more centimetres beneath the acromion while pulling the arm inferiorly is predictive of multidirectional instability [likelihood ratio (LR) 9]. The O'Brien's sign is helpful for diagnosing superior labral detachment (LR 3 to 50). Load and shift tests, when positive, are extremely predictive for instability (LR >80), but when absent are poor at ruling out posterior and inferior instability. The apprehension sign and its variations (augmentation, relocation and release) have reasonable inter-examiner reliability (intraclass correlation coefficient 0.5 to 0.7) and are highly predictive for anterior instability (LR 8 to 100).