What is Shoulder Dislocation?
Shoulder dislocation is an injury to the musculoskeletal system, characterized by the permanent release of the humeral head from the glenoid cavity of the scapula, the glenoid cavity usually housed to form the so-called scapulo-humeral joint.
Shoulder dislocation is also called glenohumeral dislocation.
Shoulder joint: a brief review
The shoulder is an extremely complicated area of the human body because it is made up of a set of 5 joints. Among these, the main one is called the scapolomeral or glenomeral as it connects the head of the humerus with the glenoid cavity of the scapula.
What is a dislocation?
Dislocation or dislocation is a traumatic event that causes the loss of reciprocal relations between the joint heads of a "joint. The cartilage slippage of the two bone ends is allowed by the rupture, at least partial, of the capsule and of the ligaments that stabilize the" articulation. Sometimes these injuries are associated with those of the articular cartilage, vessels, bones, skin (exposed dislocation) and nerves.
Dislocations are divided into complete and incomplete. In the first case there is a clear separation between the two articular surfaces, while in the second the bone heads remain partially in contact with each other. In both cases, an external intervention is required to bring the two joint surfaces back into place.
Types of Shoulder Dislocation
There are two types of shoulder dislocation:
- Anterior dislocation of the shoulder, in which the head of the humerus protrudes from the glenoid cavity of the shoulder moving forward and downward with respect to its physiological position, and
- The posterior dislocation of the shoulder, in which the head of the humerus protrudes from the glenoid cavity of the shoulder moving backwards with respect to the physiological position.
Anterior shoulder dislocation is the most common type of shoulder dislocation: it characterizes 95% of all cases of shoulder dislocation. Of the two possible types of shoulder dislocation, the most complex to treat is posterior dislocation.
Consequence of Shoulder Dislocation
Dislocation of the shoulder can cause the rupture of numerous anatomical structures (ligaments, bones, skin, joint cartilage, muscles and capsule). In particular, about 90% of anterior dislocations are accompanied by the detachment of the glenoid labrum, a sort of seal that allows the humerus to slide over the shoulder blade cavity of the same name.
After the injury, this cartilaginous lip tends to spontaneously reposition itself and heal but sometimes it assumes a spoiled position that decreases its functionality. This condition, called Bankart lesion, is one of the most common causes of recurrent dislocations and for this reason, especially in younger subjects, it is often treated surgically.
Dislocation can also be accompanied by rupture of the humeral head which is violently pushed against the anterior margin of the glenoid cavity (Hill Sachs injury). This fracture also increases the risk of recurrent dislocations but is more common in the elderly than in the young.
Causes and Risk Factors
Shoulder dislocation is a fairly common injury in contact sports such as hockey, basketball, rugby, baseball, skiing and wrestling. This condition occurs more frequently in men than in women (9: 1) and in the young compared to the elderly.
The injurious mechanisms are different but all attributable to a strong traumatic event that causes the humerus to displace from its natural location:
- Fall in support on an overturned arm (when you fall you tend to rotate the arm outwards in order to create a solid point of support to protect the rest of the body)
- Severe trauma to the intrarotated arm and adductus (posterior dislocation)
- Fall on the lateral side of the shoulder
- Brusque movement of the arm overhead (baseball throwing)
- Violent backward and outward tugging of the arm by an opponent
- Violent shoulder collision with an obstacle or opponent
- Congenital hyperlaxity (natural predisposition to "instability) or acquired (following a previous dislocation)
- Chronic incurability of the shoulder due to overtraining (chronic overload of the stabilizing muscles)
Symptoms
- Inability to move
- The arm remains dangling, externally rotated and close to the body (anterior injury)
- Violent and annoying pain
- The shoulder loses its characteristic roundness on palpation
Diagnosis
The diagnosis of dislocation is often quite immediate, since the joint damage is visible to the naked eye or otherwise palpable. However, to have a complete clinical picture, it is good to undergo diagnostic investigations such as x-rays and magnetic resonance imaging before repositioning. These tests are able to highlight any complications (bone fractures, injuries of vessels, nerves, etc.). The radiographic examination will then be repeated after the repositioning operation to check the joint alignment. In case you want to correctly highlight a posterior lesion, it is necessary to use special radiographic techniques.
Treatment and Rehabilitation
Like all sprains, dislocation of the shoulder also requires timely reduction (repositioning) surgery. This maneuver must be performed exclusively by a doctor, usually after an X-ray examination. Often, this operation is performed under local anesthesia to limit pain.
Especially in recurrent injuries, it is recommended to start early mobilization exercises associated with a subsequent muscle strengthening program. In young athletes, on the other hand, there is a tendency to prolong immobility to favor the complete healing of the injured anatomical structures. Even in these cases it is however important to regularly perform early mobilization exercises of the wrist, hand and elbow.
Statistically, the chances of relapsing shoulder dislocations are higher in patients under the age of 30 (approximately 80% of cases).Above this age, the chances of a future dislocation decrease significantly.
Also for this reason the rehabilitation treatment differs according to the "age of the subject, the severity of the dislocation and the recurrence of the pathology. It is in fact of fundamental importance to avoid new dislocation episodes since with each new dislocation the risk of damaging structures considerably increases." important anatomical. For this reason, surgery becomes almost mandatory in case of frequent dislocations.
A neglected dislocation can cause, with the passage of time, degenerative phenomena of the articular cartilage or in any case seriously compromise the functionality of the shoulder (pain, lack of strength, alterations in sensitivity).
For this reason and to counter the danger of new dislocation episodes in young athletes, arthroscopic repositioning of the glenoid labrum and joint ligaments is often carried out (shoulder arthroscopy). The results of the intervention are usually very good given that about 95% of patients resume normal sports and daily activities without undergoing new dislocations. The effectiveness of this intervention is comparable to that of the traditional open technique which further lowers the risk. of relapses, but it is rather invasive. Healing times after surgery are on average between 45 and 180 days, while for conservative treatment light physical activities can be undertaken as early as 2-4 weeks after the injury.
For further information: The Frozen Shoulder
