Shoulder Injuries: How, Why and What
Shoulder injuries are a very common injury mostly associated with high intensity sports where there are great chances of bodily collision with one another. The most common form of shoulder injuries are shoulder dislocations. In fact, about half the dislocations reported in emergency departments are shoulder injuries.
What is a shoulder dislocation?
A shoulder dislocation is when there is loss of contact between the two bony surfaces of the shoulder; that is the ball end of the humerus and the socket of the glenoid. It occurs when the arm is pulled away and backwards from the body which may occur when there is fall on an outstretched arm.
A shoulder dislocation is not be confused with a shoulder subluxation where this partial loss of contact between the bony surfaces. Another common mix-up could be with a shoulder separation. This is when the end of the clavicle separates from the scapula (shoulder blade)
A shoulder dislocation can be anterior, posterior and inferior. Anterior dislocation is most common accounting for 90% of the cases. Clinically anterior dislocations are anteroinferior dislocations. A posterior dislocation is extremely rare and is most commonly caused in extremely vigorous muscle contractions seen in epileptic seizures caused by electrocution.
Why does a shoulder dislocation occur?
The shoulder joint usually has a number of different structures that stabilize it. There is the cavity of the glenoid into which the ball of the humerus enters, though it does not help much as it is not deep enough to provide enough constraint. Glenohumeral ligaments, coracohumeral ligaments and transverse humeral ligaments help provide further stability. Additional stability is also provided by the labrum, which is a cup shaped rim of cartilage that reinforces the ball and socket joint of the shoulder. Rotator cuff muscles (subscapularis, supraspinatus, infraspinatus and teres minor) and shoulder blade muscles (rhomboids, trapezius, latissimus) also play a vital role in dynamic stability.
Blunt physical force usually as a result of collision sports, falls or tackles cause result in injury to the dynamic stabilizers of the shoulder joint. This can be due to muscle damage or labral tear, which causes the shoulder to pop out of the glenoid cavity and dislocate.
Signs and Symptoms:
- Pain that can usually radiate down towards the arm
- A feeling that the shoulder is ‘moving’ during abduction and external rotation
- External rotation of the arm and shoulder (seen in anterior dislocation)
- Visible dislocation where the shoulder appears abnormally square
- Numbness of the arm
- No palpable bone on the side of the shoulder
In case of a suspected shoulder dislocation, the shoulder should be immobilized and a visit to the emergency department will be necessary if it does not go back into its own place spontaneously. In the ER, an X-ray will be ordered to assess the dislocation.
A shoulder reduction, where the shoulder is returned to its normal position, will be carried out. This can be done by a number of methods such as:
- Traction-Counter Traction
- External Rotation
- Stimson technique
- Cunningham technique
- Milch technique
- Scapular manipulation.
The people maybe sedated or have lidocaine injected into the joint to help deal with pain
An ER visit should be followed with a visit to the primary care doctors so they can recommend a more specialized doctor such as orthopedic surgeon or sports medicine specialist for a more cohesive treatment plan. The age, sex and physical activity level of the patient are very important in determining a treatment plan which usually include two steps:
- The first step is to immobilize the shoulder joint, which can be aided with an arm sling. Icing is recommended to deal with pain. Anti-inflammatory medicines can also be part of the treatment.
- The second step, after sufficient healing has occurred, is to strengthen the dynamic stabilizers.
A shoulder dislocation can cause damage to the structures surrounding the shoulder joint, as a result there can be:
- Labral and ligament tears
- Rotator cuff tears
- Damage to the axillary nerve by compression of the humeral head
- Damage to the radial nerve cause by stretching due to the ‘lengthening’ effect of the humerus.
- Fractures, usually to the glenoid cavity
- Other complications: Bankart lesions and Hill Sachs lesions
- Surgery becomes necessary when there is a rotator cuff muscle tear. These are more common in older individuals as their tissue tends to be tougher. MRIs are used to assess soft tissue damage and decide the need for surgery.
- Surgery is also used to treat fractures that may occur when there is a dislocation.
- Surgery is also needed to fix the dislocation if the dislocation is a frequent occurrence.
- Surgery can also be used for the first time, if there is probability of the injury happening as with young males who play collision sports.
A common surgical method to fix anterior shoulder dislocation is the Bankart repair, named for British surgeon Arthur Sydney Blundell Bankart, who was the first to describe it. In this procedure, the detached torn labrum is sewed to the joint capsule. This can be done as an open surgery or by minimally invasive arthroscopic techniques.
Other surgical techniques need to be employed if there is bone loss, usually with multiple dislocations. The Bankart procedure will not work. Latarjet operation can be done to help with bone augmentation.
To lessen the chances of a shoulder dislocation the easiest thing would be to eliminate the cause of shoulder dislocations. Since most dislocations are caused by collision sports such as rugby, football, dodge ball and wrestling, it would be best to avoid these sports.
Shoulder dislocations can also be prevented by strengthening the dynamic stabilizers of the shoulder joint. This can be done by exercises that target the rotator cuff muscles.
In the long term, one shoulder dislocation usually increases the risk of a further dislocation by 20% . The likelihood of this takes into considerations factors like sex, age and activity levels. Arthritis is also a long term problem often seen with multiple dislocations.