A joint dislocation occurs when the two joint surfaces, which normally sit in intimate contact with each other, are wrenched away from each other to lie apart without any relationship. Joints have a surrounding ligamentous bag called a joint capsule and this can be typically injured as the surfaces force their way past each other. The surfaces of the joints themselves can be damaged as they hit each other on the way to becoming dislocated. Other injuries which can occur include damage to the local nerves and ligaments.
Dislocations 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.
Dislocations 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.
There may be no trauma in some cases of shoulder dislocation and instability of the shoulder may occur in all joint directions, typical presenting in patients who have hypermobile joints. This condition is called multidirectional instability and tends to happen in both shoulders, run in the family and be in younger people under thirty. A joint subluxation is often the start of these problems, where the joint slips partly off its partner to an amount and then clicks back into place. An ability to voluntarily dislocate the shoulder can occur, perhaps related to psychiatric difficulties in this group of people.
The 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.
The 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.
Pain 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. - 14130
Dislocations 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.
Dislocations 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.
There may be no trauma in some cases of shoulder dislocation and instability of the shoulder may occur in all joint directions, typical presenting in patients who have hypermobile joints. This condition is called multidirectional instability and tends to happen in both shoulders, run in the family and be in younger people under thirty. A joint subluxation is often the start of these problems, where the joint slips partly off its partner to an amount and then clicks back into place. An ability to voluntarily dislocate the shoulder can occur, perhaps related to psychiatric difficulties in this group of people.
The 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.
The 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.
Pain 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. - 14130
About the Author:
Jonathan Blood Smyth is the Superintendent of Physiotherapy at an NHS hospital in the South-West of the UK. He writes articles about back pain, neck pain, and injury management. If you are looking for physiotherapists in Sheffield visit his website.
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