الفهرس 
Anatomy of the glenohumeral joint:Only 14 pages are availabe for public view
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Abstract
Shoulder instability is a condition in which the upper end of the humerus slides partially or completely out of the shoulder socket. Normally, the head of the humerus, moves within the confines of the shoulder socket. Instability occurs when the head slips outside its normal position. The humeral head may moves in one or more directions. The disorder is classified by how much this bone moves and by the direction it moves: subluxation in which the humeral head moves part way out of the shoulder socket. Dislocation in which the humeral head moves completely out of the socket.
Anterior instability, the humeral head moves toward the front,this is the most common form,which typically occurs in young men.Atheletes with great shoulder flexibility are more prone to the disorder.Reinjury is more common in teens and young adults,because they have more elasticity in their shoulder capsule and ligaments ,this can lead to later chronic instability. Posterior instability the humeral head moves toward the back, this is often caused by a severe muscle spasm,such as during an electric shock or seizure.it less commonly happens as a Consequence of direct trauma,which can lead to later chronic instability.
Multidirectional instability, this usually occurs in atheletes born with very loose joints. Certain sports that require great shoulder range of motion,such as swimming may lead to multidirectional instability. In some less common instance,patients purposely contract or relax muscles to create an instability episode,which is sometimes associated with psychological problems.
Shoulder instability often results from an initial acute injury producing a dislocation that,even with healing ,leads to stretching of the shoulder capsule and ligaments, this type of injury could be due to a fall,a direct hit,or force applied to the outstretched arm,more rarely,shoulder instability develops slowly without any history of previous injury. In some cases,the shoulder may slips out of place at predictable times,such as when lifting a suitcase or even when shaving.
There is risk factors that increase the chance for getting the shoulder instability include atheletic activity as baseball,weight lifting-congenital collagen disorders as Marfan syndrome,Ehler Danlos syndrome-family members with shoulder instability.
Shoulder instability can be diagnosed by taking the patient s history, and by the physician performing clinical examination, radiological investigations such as
shoulder x-ray films or MRI,may be needed to provide the informations needed to make an appropriate treatment rcommendation.
The treatment of primary acute shoulder dislocation consists of closed reduction, immobilisation in a special sling or bandage for three to six weeks, followed by a rehabilitation programme, consisting of exercises to strengthen the rotator cuff and scapular stabilizers.
Operative treatment can be open (through a small incision) or closed (actually minimally invasive - through arthroscopic portals). The indications for the surgical treatment of glenohumeral instability are pain, recurrent dislocation and limitation of sporting activity.
More than a hundred operative procedures have been described for traumatic anterior instability of the shoulder. They are classified into four groups as follows:
1. Procedures which limit external rotation by tightening the anterior structures such as the Magnusson-Stack and the Putti-Platt techniques.
2. Bony blocks which prevent anterior translation of the humeral head such as the Bristow Latarjet procedure – technique preffered in the case of athletes.
3. Osteotomies either of the glenoid or the humerus to change their position if modifications are noted.
4. Suture of the disrupted anteroinferior capsulolabral complex, such as the Bankart procedure. The Bankart procedure remains the procedure of choice frequently in association with the previously described techniques, as it restores normal glenohumeral anatomy and function.