This depression is called the acetabulum


The shoulder joint is the most mobile joint in your body. It allows you to raise your arm, rotate it and reach over your head. It can rotate in many directions. However, this wide range of motion is possible at the expense of its lower stability.

Instability of the humerus occurs when the head of the humerus is pushed out of the acetabulum. This may be due to sudden trauma or excessive wear and tear.
Once the shoulder joint is dislocated, it becomes prone to relapse. When the arm is loose and slips out of place, this condition is called chronic instability of the shoulder joint.

Your shoulder joint is made up of three bones: the humerus, the scapula and the clavicle.
The head of the humerus is embedded in a shallow depression on the scapula. This depression is called the acetabulum. The strong connective tissue, called the articular bag, is a system of ligaments that hold the head of the humerus in the middle of the joint pan.
This tissue covers the humerus and attaches the upper end of the humerus to the scapula.
Your shoulder is also strengthened by strong tendons and muscles that keep the joint stable.


The dislocation of the humerus can be incomplete, it occurs when the head of the humerus moves only partially beyond the joint pan. It’s called pinching. A complete dislocation means that the head of the humerus moves completely outside the acetabulum.

When the ligaments, tendons and muscles of the shoulder become too loose or break, this leads to recurrent dislocations. Recurrent instability of the humerus occurs when these tissues are unable to support the humerus in the middle of the acetabulum.


Shoulder dislocation. A serious injury or injury is often the cause of the original joint dislocation. When the head of the humerus is dislocated, the acetabulum and ligaments in the anterior part of the shoulder are often damaged. Rupture of ligaments in the anterior part of the shoulder joint is called damage type bankarta. Serious primary sprain may result in recurrent sprain, loss of function or instability.

Repetitive joint strain

Some people with shoulder instability have never had a dislocation. Most of these patients have more loose ligaments in the shoulder joints. This excessive relaxation is sometimes their correct construction. Sometimes it is the result of performing repetitive movements with raised hands.

More loose ligaments can make it difficult to maintain joint stability. Repetitive or burdensome activities can be a big challenge for a weakened shoulder. This may result in a painful, unstable shoulder joint.

Multi-directional instability

In a minority of patients, the shoulder joint may become unstable even though there has been no trauma or repetitive strain injury. In such cases, the arm may be loose or dislocated in different directions, which means that the head of the humerus may move forward, backward and downward from the pelvis. This condition is called multidirectional instability. These patients have naturally loose joints throughout the body and may have what is known as hypermobility syndrome.


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