Signs and symptoms
Significant pain, sometimes felt along the arm past the shoulder. Sensation that the shoulder is slipping out of the joint during abduction and external rotation. Shoulder and arm held in external rotation (anterior dislocation), or adduction and internal rotation (posterior dislocation). Resistance of all movement. Numbness of the arm. Visibly displaced shoulder. Some dislocations result in the shoulder appearing unusually square. No palpable bone on the side of the shoulder. Diagnosis
A diagnosis of shoulder dislocation is often suspected based on the persons history and physical examination. Radiographs are made to confirm the diagnosis. Most dislocations are apparent on radiographs showing incongruence of the glenohumeral joint. Posterior dislocations may be hard to detect on standard AP radiographs, but are more readily detected on other views. After reduction, radiographs are usually repeated to confirm successful reduction and to detect bone damage. After repeated shoulder dislocations, an MRI scan may be used to assess soft tissue damage. In regards to recurrent dislocations, the apprehension test (anterior instability) and sulcus sign (inferior instability) are useful methods for determining predisposition to future dislocation.There are three main types of dislocations: anterior, posterior, and inferior. Anterior (forward)
In over 95% of shoulder dislocations, the humerus is displaced anteriorly. In most of those, the head of the humerus comes to rest under the coracoid process, referred to as sub-coracoid dislocation. Sub-glenoid, subclavicular, and, very rarely, intrathoracic or retroperitoneal dislocations may also occur.Anterior dislocations are usually caused by a direct blow to, or fall on, an outstretched arm.
Damaged ligaments, including labral tears, occurring as a result of posterior dislocations may be treated arthroscopically.There remains those situations characterized by multidirectional instability, which have failed to respond satisfactorily to rehabilitation, falling under the AMBRI classification previously noted. This is usually due to an overstretched and redundant capsule which no longer offers stability or support. Traditionally, this has responded well to a reefing procedure known as an open inferior capsular shift. More recently, the procedure has been carried out as an arthroscopic procedure, rather than open surgery, again with comparable results. Most recently, the procedure has been carried out using radio frequency technology to shrink the redundant shoulder capsule (thermal capsular shrinkage); while long-term results of this development are currently unproven, recent studies show thermal capsular shrinkage have higher failure rates with the highest number of cases of instability recurrence and re-operation. Prognosis
After an anterior shoulder dislocation, the risk of a future dislocation is about 20%. This risk is greater in males than females. See also
Shoulder problems

References


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