Shoulder instability

Shoulder joint includes the humerus and a cavity on the scapula, called the glenoid cavity. The glenoid cavity is surrounded by a fibrous cartilage, which increases the contact surface between it and humerus, which is called cushion. Cushion is like a curb on the glenoid cavity of the scapula, which helps keeping the humerus head in the joint.

The shoulder is the body joint thatis sprained the easiest.

First dislocation can occur as a result of a violent accident (sports, car….) or as a result of a fall.

In case of an accident, by dislocation, the humeral head snatches a part of the cushion (of the anterior edge of the glenoid cavity) and detaches the capsule normally fixed to the bone.

Frequent absence of scarring of these injuries promotes relapses, which is expressed by instability. As the first dislocation occurs sooner, the higher is the risk of relapse. For example, when the first dislocation occurs at 20 years, statistically the risk of recurrence is 80%; after 50 years of age, relapses are rare, less than 10%. The injury required for a new dislocation will be increasingly less important over relapses; sometimes dislocations occur even during sleep.


Figure 1 the humerus extremity sprains anteriorly!

Patients sometimes may exhibit episodes of sub-dislocation.

These sub-dislocations are remedied spontaneously at the end of a few seconds, but the shoulder remains unstable and especially painful.

This pain is sometimes associated with fear of certain positions, especially when throwing an object or arming the arm (e.g., tennis serving, sleeping with hands behind the head, etc.).

The patient thinkshis/her shoulder is about to displace.

X-ray is first exam to rule out any fractures. The testthatprovides the best information is an arthrogram. Injecting a contrast agent into a joint followed by scanning, shows whether the capsule detached from the tip of the scapula. This should be reattached.


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Begins the second day after surgery. This is done according to a scheme to be given to patients before their discharge and serves as a basis for follow-up rehabilitation. (See the rehabilitation plan uploaded on the website).

What are the possible complications?

  • Relapse: Percentage of relapse varies between 3 and 6% for arthroscopic techniques.
  • Algodystrophy is an unpredictable reaction of unknown nature, which after an inflammatory phase leads to stiffness similar to retractile capsule.
  • A retractable capsule or “frozen shoulder” is very rare, but possible. This consists in a stiff shoulder that can span on several months. Recovery is done in several months, after dozens of kinesiotherapy sessions.
  • A haematoma is possible.
  • Postoperative infection is quite easily mastered when diagnosis is early (pulsatile pain, swelling and large redness). Re-operation is always possible. Infections are rare after arthroscopy.

    Currently, due to advanced implants, arthroscopic results are superior to classical, old techniques, when 15 cm-incisions weremade, muscles were cut to reach a joint where the loose “cushion” was fixed.

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