The shoulder joint is a synovial ball and socket joint and is also known as a universal joint due to its exceptional range of movement however some amount of stability is sacrificed for this mobility, making the shoulder one of the most easily dislocated joints in the body.
A partial subluxation is when the head of the humerus (the ball part of the shoulder joint)
attempts to come out of the socket. This is often followed by a “spontaneous reduction” meaning that it popped straight back in by itself.
A full dislocation is when the whole ball displaces out of it’s socket, most commonly forwards, but can also go downwards or backwards which is less common.
The cause of a subluxation or dislocation is usually a fall onto an outstretched arm or a direct blow as seen in contact sports such as rugby or martial arts, on board the yachts it is often caused by a fall down an open hatch.
Recurrent dislocating shoulders may also be caused by a genetic anomaly where the cup or glenoid, has a diminished concavity which causes the shoulder to be less stable under outside pressure. This can be easily diagnosed with an x ray.
A dislocated shoulder usually occurs under a traumatic circumstance so the signs and symptoms include immediate pain which increases in intensity with attempted movement as the resulting muscle spasm kicks in. There is weakness in all muscle groups of the affected arm and the shape of the shoulder joint changes. In an anterior dislocation the ball of the humerus can be seen and felt under the armpit and the contour of the shoulder appears to collapse. There will eventually be widespread bruising around the shoulder and chest.
The sufferer should be immediately taken to a clinic no matter whether you think it is a subluxation or a dislocation as there are many nerves and blood vessels in this area which can be compromised and medical attention is required even if the shoulder has popped back by itself.
The procedure to put the joint back into alignment is called a Shoulder Reduction. There are several methods to reduce a shoulder joint such as the Hippocratic, Kocher, Milch and Stimson method. The choice of reduction will depend on the direction of the dislocation and the intensity of muscle spasm. Reduction of the shoulder joint is usually performed under anaesthetic or sedation as it is a painful procedure. Once the shoulder is back in place the muscle spasms from the Rotator Cuff will subside and the pain quickly diminish.
Reduction of a dislocated shoulder should be performed by a medical professional however in the case of Recurrent Dislocation the patient may be experienced in reducing their own shoulder.
Recurrent dislocations can cause great instability of the shoulder joint. Every time there is a subluxation or dislocation, the capsule and ligaments become more and more slack as they are stretched at each occasion. Ultimately an operative procedure will be required to help tighten up these soft tissues.
After the shoulder has been reduced it will then be immobilized for some weeks in a sling which holds the arm across the chest. After a time designated by the orthopaedic specialist, physiotherapy rehabilitation will commence. The aim of the physio is to regain full range of movement of the shoulder while controlling the pain. Gradual exercise is introduced to improve muscle tone which stabilizes the shoulder joint. Once full movement has been achieved resisted exercise may begin to strengthen and help prevent a recurrent dislocation or subluxation.