Shoulder dislocation

By 7th March 2009 August 27th, 2013 Uncategorized

WHERE alpine injuries are concerned, the upper body is less frequently injured than the lower. However, one relatively common winter sports injury is the dislocated shoulder. A dislocated shoulder is when the ball comes out of the socket and stays ‘out of the joint’. A subluxation is where the ball comes partway out of the socket, usually resting on the edge, and then goes back in on its own. Dislocation is often confused with an AC joint separation which is where the clavicle (collar bone) pulls away from the acromion (tip of shoulder blade).

The shoulder (glenohumeral joint) is the most frequently dislocated joint in the body. This is essentially due to its anatomical design. There is a ball (the head of the humerus), that sits in quite a small socket (the glenoid of the scapula). This has been likened to a golf ball on a tee, with the socket covering less than a third of the circumference of the ball. While this is great for allowing lots of movement in different planes, it does make for an inherently unstable joint. While there are ligaments, a joint capsule and a labrum (cartilage in the glenoid) helping to provide stability, these are not overly effective, particularly in a ‘ligamentously lax’ (hyper-flexible) person. The majority of the stability in the shoulder comes from four muscles collectively known as the rotator cuff. These muscles run from the shoulder blade (scapula) and attach into the humeral head. Together these muscles help to control and hold the ball in the socket as the arm is moved. Good functioning of these muscles and shoulder blade stability is the key to a stable shoulder joint. Consequently re-training rotator cuff function is a major part of most shoulder rehabilitations.

Shoulder dislocation is more common in snowboarders than skiers, largely due to the demands of the sport, which makes it more likely to outstretch the arms upon falling. With the development of terrain parks it has become even more prevalent. The majority (over 90 per cent) of shoulder dislocations occur ‘anteriorly’ out the front of the shoulder. The group most susceptible is males aged between 16-25 years old.

Most shoulder dislocations occur in the ’90/90’position. This is when the arm is abducted (taken to the side) 90 degrees and externally rotated (turned backwards) 90 degrees. Generally, if you are male and under 25 and shoulder dislocation occurs via trauma there is a 90 per cent chance it will happen again regardless of what non-operative rehabilitation you undertake.
 
What does a dislocated shoulder feel like?
Most patients will know straight away that they have dislocated their shoulder, as they have a feeling that it has come out of its socket. There will be a lot of pain, difficulty moving the arm, and a loss of the normal shoulder shape. Sometimes the arm will be held outwards. Muscle spasm will usually occur as a protective mechanism, and this can make it hard to put back in.
 
What do I do if my shoulder dislocates?
The general school of thought is that a joint is ‘better in than out’. The longer the joint stays out, the more pain, muscle spasm and stretching of ligaments occur. Furthermore, there may be risk of damaging the blood vessels and nerves in that region. In saying that, only trained people (namely emergency or sports doctors) should be relocating these. A neurovascular check of sensation and circulation should be performed, as well as an x-ray after a dislocation. Ice or anti-inflammatory medications may help ease the initial pain.

Do I need a sling?
A sling may ease pain in the early phases. There is little evidence to suggest that wearing a routine sling with the arm on the stomach in internal rotation actually reduces recurrence rates. It is more for pain relief. A younger patient may benefit from a sling for a longer period of three to four weeks to allow things to settle. Elderly people should not be in a sling more than one-to-two weeks, as there is a risk of a stiff or ‘frozen shoulder’ developing. A Japanese study showed there is reasonably good evidence that for first-time dislocators, a sling where the arm is held in external rotation (away from the body) helps with healing and prevents recurrence. The main problem with this is it is hard to encourage. as many people don’t fancy walking around with their arm sticking out for a month!

Other than stretching the ligaments, can other damage occur upon dislocating a shoulder?
The answer is yes. More often than not a Bankart lesion will occur. This is where the front of the labrum is damaged as the ball knocks it upon coming out the front of the socket. Another less frequent injury is a Hills Sachs lesion. This is similar to a dent in a golf ball, where the head of the humerus (the ball) is damaged upon the shoulder coming out. MRI scan or specific x-ray views will generally help show both of these. In older patients, a tear of the rotator cuff is common. Occasionally blood vessel and nerve damage can occur and even fracture of the bone in a more serious case.

How do I stop it recurring?
Rehabilitation via physiotherapy focusing on a rotator cuff strengthening and shoulder blade stability program will help this in several cases. This may take up to three months, and some diligence. Bracing or taping by restricting the shoulder getting into risk positions may help to some extent. As stated previously, young males have a high risk of recurrence and often surgery is the best bet. A ‘three strikes and you’re out’ rule is generally useful in the amateur athlete, whereby if you have three instability events, surgery is recommended. Surgery generally involves tightening up the joint and fixing any other joint damage. Depending on severity this can be done via camera, but sometimes needs to be done openly. Post-operatively, rehabilitation is required and the patients can return to sport over a six-to-nine-month period.

I hope this answers a few questions for you. Happy riding!
 

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