Instability of the shoulder joint

Recurrent dislocation of the shoulder with a sense of uncertainty in the joint is determined as instability. This occurs most often after dislocation as a result of injury. It rarely occurs due to general soft tissue laxity. There are many components of joint stability:

Normal bone shape, hem synovial joint capsule with ligaments, muscles surrounding the joint. The coordination of the joint is a complex process which involves the in nervous and muscular system. Abnormalities in any of these elements can lead to instability.

Signs of instability

  • fear of performing certain movements,
  • impression of instability,
  • recurrent dislocations,
  • symptoms of pain while performing certain moves in certain positions,
  • the skip the joint with a distinctive “click” noise.


The patient should be interviewed by a doctor and a physical exam based on specific tests for the instability in the front, rear or bottom should be performed . The diagnosis should be complemented by an X-ray examination , ultrasound , and computed tomography or magnetic resonance imaging .

Methods of Treatment

Treatment without surgery – an indication for this type of treatment is non-traumatic instability of joint laxity. Laxity is increased mobility in the joint, which does not necessarily cause pain, but may, for example, be genetically determined. In the group of non-traumatic instability, are cases of developmental abnormalities of the articular surface shape and cases of tissue disease. Pain in the shoulder is mainly caused by the inflammation of the muscles responsible for stabilizing the humeral head during physical activity. Some people may experience instability of the shoulder, accompanied by subluxation.

Instability, which is not due to trauma, usually is treated conservatively. This treatment involves patient education, the modification of physical activity and rehabilitation.  Intensive exercise reproduces the correct patterns of movement, strengthening the muscles of the shoulder girdle and centering the head of the humerus and give satisfactory results.

Surgical treatment – the most common cause of instability is trauma, more specifically -the dislocation of the shoulder. In 90-95% of cases, this is a front sprain, which occurs upon impact, when the limb is in abduction and external rotation. Injury may lead to the rupture of the joint capsule and the displacement of the humeral head. Recurrent dislocations can lead to two additional lesions: Bankart lesion – is an injury of the anterior (inferior) glenoid labrum of the shoulder due to repeated (anterior) shoulder dislocation; and

the Hill –Sachs lesion,  a cortical depression in the posterolateral head of the humerus bone. It results from forceful impaction of the humeral head against the anteroinferior glenoid rim when the shoulder is dislocatedanteriorly.

A far less common injury is a rear sprain,  which could result from stretching or tearing the back of the articular capsule and the acetabular labrum of the shoulder blade. Such sprains can cause damage to the subscapularis . Dislocations of this type are difficult to diagnose.

When a fracture covers 20% of the acetabulum, there is a possibility of stability joint loss. In this case, it is recommended to operate the fracture. With chronic injuries it is advisable to perform a bone graft to restore the normal acetabular surface and restore full abduction and external rotation to an angle of 90 º without the risk of dislocation. After surgery, the operated limb is placed in a brace. After about 12 weeks of rehabilitation patients show significant improvement and can perform weight training exercises.


In cases of instability occurring due to injury being treated conservatively , the risk of re- dislocation is high. In case of persistent symptoms of instability, surgical treatment should be considered. After surgery and rehabilitation have been completed, the prognosis for patient recovery is good. There is an increased risk of relapse among contact sports athletes.


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