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Shoulder Dislocation Explained

12.01.2009 · Posted in General Articles

Dislocation of a joint means that the joint surfaces, which are normally closely applied to each other, are completely disrupted and do not touch each other any longer. The joint capsule surrounds the joint and supports it and is often damaged as the joint surfaces move apart from their normal position. Dislocations may also result in damage to the joint surfaces themselves as they move across each other in their journey to the dislocated position. Joint, ligament and nerve injuries can occur during dislocations.rnrnDislocations of the shoulder are the most common form of dislocation of a joint, making up almost half of all of this type of injury. The commonest form of dislocation is for the humeral head to be displaced forwards, known as an anterior dislocation. This occurs most often when the arm is out to the side, rotated externally and moved backwards and there is a forwards force on the upper arm, pushing the joint out in its position of vulnerability. A blow to the rear of the arm, a fall on an outstretched hand (FOOSH) and a strong outward rotation plus shoulder abduction can all result in a dislocation.rnrnDislocations backwards are not common and due to force applied to the arm when it is over the body and turned inwards, with epileptic seizures and electrocution being possible causes as the big chest and back muscles pull the joint out due to spasms. The joint can also dislocate downwards if the arm is moved outwards and sideways with excessive force, levering the joint out against the part of the shoulder blade above it. This type of injury needs careful monitoring as it is more likely to be associated with other soft tissue injuries such as nerve injury, damage to the blood vessels and tears to the rotator cuff muscles.rnrnAn atraumatic shoulder dislocation can occur with a tendency for the joint to be unstable in every direction, often present in patients with joint hypermobility. Multidirectional instability is the medical term given to this syndrome which presents in families, in younger people of less than 30 years and occurs in both shoulders. Subluxation of the joint can occur initially which involves one side of the joint coming off its opposite number to a degree and then relocating suddenly into position. Shoulders can be dislocated voluntarily in some cases, although this may normally be connected with psychiatric disorders.rnrnThe presentation of anterior dislocation of the shoulder is for the patient to hold their arm rotated outwards and slightly to the side, the arm bone head easily felt at the front of the joint. The shoulder muscles may be in a powerful spasm and trying to move the shoulder results in high levels of pain. A dislocation of the shoulder posteriorly shows itself by the patient keeping the arm close to the body and turned inwards, the head of the humerus being palpable at the rear of the joint, although this condition has been misdiagnosed as frozen shoulder.rnrnThe relocation of a shoulder dislocation is performed by surgeons in many different ways and the time from the incident to when the joint is finally relocated is the important matter. If the time is too long the muscle spasm increases and interferes with fixing the dislocation. An original way was to put a foot in the person’s axilla to make one end secure and traction the arm lengthways until the reduction is effected. Techniques have developed and an effective modern way is to abduct the shoulder whilst pushing the humeral head anteriorly, then rotate the arm externally and traction the arm, leading very often to success.rnrnPain is a major presentation problem in shoulder dislocation and there are many alternatives that the medical staff can apply to give good pain relief and ease the process of reduction. A recent reduction can be moderately easily relocated in the absence of strong painkillers or muscle relaxants. The most useful sedative drug will have a quick onset of action, be able to supply good muscular relaxation and with an action which goes off quickly to allow rapid recovery. After the joint is back in place a sling is used for up to three weeks to allow the capsular damage to heal.

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