A dislocation of the shoulder involves having the head of the humerus being outside of its socket, the glenoid fossa. Most dislocations are unilateral unless there is serious trauma, such as is seen in a motor vehicle accident.Types of Shoulder Dislocation
There are three major types of shoulder dislocations.
Anterior or forward dislocation. This accounts for 95 percent of all shoulder dislocations. Most are sub-coracoid, under the clavicle, retroperitoneal or intrathoracic. They are usually caused by a direct blow onto the outstretched arm.
When arriving at the emergency room, the patient has their arm rotated externally and a bit abducted. This type of injury can damage the axillary nerve as well as the axillary artery. If the axillary nerve is damaged, the patient can have persistent paralysis or weakness of the deltoid muscle. Eventually, the deltoid muscle atrophies so that the normal shoulder shape is permanently deformed.
The person with an anterior dislocation and damage to the axillary nerve will be unable to abduct the arm more than 15 degrees away from the body. It relies only on the supraspinatus muscle, which can only abduct the shoulder and arm so far. This leads to a major disability of the affected arm.
Posterior or backward dislocation. These dislocations can be caused by an electric shock or by a seizure. They can also be caused by a strength imbalance of the rotator cuff muscles. Patients hold their arm internally rotated and completely adducted (next to the body). The anterior shoulder is obviously flattened and the coracoid process is more prominent than normal. Posterior dislocations can easily be overlooked in a patient who is elderly or comatose. In one study, the average time from injury to a correct diagnosis in 40 patients was one year.
Inferior or downward dislocations. This is the least likely type of dislocation, occurring about 1 percent of all types of dislocation. The Latin name for this injury is called luxatio erecta. This is because the arm is permanently held upward or up behind the head. The dislocation happens due to an excessive abduction of the arm the pushes the humeral head up against the acromion. These types of dislocations have a high rate of complications because many vascular and neurological structures are damaged as are tendons and ligaments.
There is often a great deal of pain and swelling associated with any type of dislocation. The pain originates in the shoulder and radiates to other parts of the body, such as down the arm, the neck and down the back or chest.
There is an inability to move the arm from the position it seems to prefer because of the dislocation. This is especially true in positions where the arm is held from the body and when the top of the arm is twisted posteriorly.
There can be numbness of the affected arm along with a visibly deformed shoulder. Some dislocations make the shoulder look boxy following the injury. There is no bone palpable in the area of the shoulder.
Causes of Shoulder Dislocations
Shoulder joints are the most frequent joints in the body to dislocate. This is partly because it has the greatest range of motion of any joint in the body. It can dislocate completely or partially in almost any direction. The dislocation can occur with or without disruption of the supporting tendons and ligaments.
The shoulder can dislocate due to a sudden blow directed at the shoulder. It pulls the bones out of place in the shoulder. If there is marked rotation of the shoulder, the humerus can pop out of the glenoid fossa, leading to a partial or total dislocation.
The major causes of a dislocated shoulder include:
- Trauma: A strong blow to the shoulder from a motor vehicle or motorcycle accident can result in a dislocation.
- Sports Injuries: dislocations can easily happen in several kinds of contact sports, such as hockey or football, as well as in sports that involve the potential for falling, such as snow skiing, volleyball, and gymnastics.
- Falls: If you fall from a ladder or trip on a loose rug, you can easily suffer a dislocation.
There are certain risk factors for those who get a shoulder dislocation. These risk factors include the following:
- Being male: If you are male, you engage in those activities that are more likely to lead to a dislocation of the shoulder.
- Being in your twenties: This is the age group more likely to engage in the intense physical activity that can lead to a dislocated shoulder.
The diagnosis of a dislocated shoulder depends on a careful history of the incident and the patient, including:
- How the injury happened
- When did the history happen?
- Previous serious injuries, including previous shoulder dislocations
- Prior health problems
After a brief physical examination, there is a detailed examination of the injured shoulder. The doctor looks at the deltoid muscle, which is often flatter on the injured side of the body. Movement of the arm causes extreme pain. He or she often checks the individual’s pulses at the wrist and elbow and assesses the sensation of touch and the movement of the fingers on the affected side.
Diagnostic testing includes a plain film x-ray. Anterior-Posterior and lateral views are required to tell if the dislocation is partial or complete and the direction the humeral head has gone.
An MRI examination might be necessary because plain films can be difficult to read and to assess the exact location of the humeral head. Fractures of the humeral head can also accompany the dislocation and it is often difficult to see in a plain film x-ray.
The MRI will use powerful magnets and radio waves to detect the presence of the dislocation using cross-sectional images of the shoulder and arm. Soft tissue injuries like ligamentous tears can be seen on an MRI study and can tell the doctor if surgery is necessary.
An EMG or electromyogram may be necessary to tell if there has been nerve damage as a result of the injury. It detects the electrical activity in the muscle, which will be diminished if the innervation of the muscle has been compromised.Treatment for a Dislocated Shoulder
During the treatment of a dislocated shoulder, the doctor may give medications to lessen the pain as well as medications to relax the individual and relax the muscle in order to facilitate reduction of the shoulder. The patient may need a sedative or even general anesthesia in order to relax the muscles enough to have the reduction happen.
Most individuals can be treated in the ER; however, the most difficult cases are handled in the operating room.
There are many different techniques used to reduce a dislocated shoulder and sometimes it takes multiple techniques before relocation is successful. One particular technique involves sedating the patient and partially abducting the arm, applying strong traction to the arm so the head of the humerus slips into the glenoid fossa. The techniques may be slightly different, depending on the type of dislocation it is.
Once the shoulder is relocated, it is imperative to keep it close to the body with the elbow in a flexed position. A sling or shoulder immobilizer is used to keep the shoulder in one position until the ligaments and muscles heal. The doctor often prescribes prescription painkillers to ease the pain for a few days.
Often the sling is used for about 1-3 weeks. In general, the arm should be placed in the internal rotation while it is in the sling. Even while in the sling, it is encouraged to have the patient use the elbow, hand, and wrist in order to keep these joints from stiffening up. The patient needs to work with his or her parascapular muscles while in the sling in order to strengthen them before actually getting out of the sling.
When the three weeks are up, there should be extensive physical therapy which involves both active and passive flexion, extension, internal rotation, external rotation, extension and abduction of the shoulder and arm. Work with the parascapular muscles should continue. On average, there will be about ten degrees of improvement in motion during the course of each week. Actually, going too fast in these motions can be detrimental and can lead to re-injury. Instead, the rehab should bring back a normal range of motion in just about 6-8 weeks. Rehabilitation should be gentle without pushing it too far.
A good idea is to keep the hand in view whenever looking forward and moving the shoulder. This should be the case for the first three weeks following the injury. After that, the exercises can improve the range of motion and the hand can travel outside the forward field of vision.
Nonoperative care for the dislocation of the shoulder is obviously preferred. Some patients, however, need surgical management. These are the patients that have recurrent instability of the shoulder and who need surgery to restore the stability of the shoulder. Both open surgery and arthroscopic surgery can be used to prevent further dislocations.Complications of Shoulder Dislocation
A common complication of a shoulder dislocation is a humeral head fracture. It is estimated that up to 25 percent of shoulder dislocations have an associated humeral head fracture. In addition, up to 75 percent of patients with an anterior dislocation of the shoulder have what’s known as a Hill-Sachs deformity of the shoulder.
There is a distinct possibility of a nerve injury as a result of the shoulder fracture. More often, it is the circumflex axillary nerve is damaged during the injury. When it is injured, there is a patch of numbness located in a small area outside of the arm near the shoulder. Fortunately, the nerve usually recovers itself after a few weeks. It can affect the strength of the deltoid muscle if it does not come back.
In older people who suffer a dislocation, there can be rotator cuff injuries. It often isn’t picked up on until after the patient has gotten off the sling and is moving the shoulder around.
A rare complication of shoulder dislocation is the tearing or rupture of the axillary artery. This is the main artery that supplies blood to the arm. Another possibility is damage to the brachial plexus. This is the body of nerves that supply innervation to most of the arm. The nerves and artery can be damaged both during the initial injury and during attempts at relocating/reducing the dislocation.Recurrent Shoulder Dislocations
Some people with a dislocated shoulder go on to develop recurrent shoulder dislocation because of disruption of the supportive ligaments. The shoulder ligaments can become lax without an acute injury, and athletes who must throw a ball overhand on a repeated basis can get an unstable shoulder that frequently dislocates with little effort.
The joint can become unstable when the head of the humerus is wider than the glenoid fossa. In most cases, the glenoid is also very shallow so that it relies on the soft tissue to keep the joint together. When the joint dislocates, it disrupts the labrum. This is called having a Hill-Sach’s lesion. There is also the Bankart’s lesion, which involves the disruption of the labrum, capsule, and ligaments to the front of the shoulder.
With these types of injury, there is a greater chance of having a recurrent dislocation of the shoulder. The younger the individual at the time of initial injury, the greater is the risk of suffering from recurrent dislocations. Such a problem with the shoulder can be treated conservatively with physical therapy or with arthroscopic or open surgery.An Experienced Personal Injury Lawyer
I'm Ed Smith, a personal injury lawyer for Northern California. Shoulder injuries can occur from work accidents, car accidents, and falls. If you or a loved one has suffered a shoulder injury due to someone else's negligence, give me a call today for free and friendly advice. I can be reached at (916) 921-6400 or toll-free at (800) 404-5400
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