Shoulder Instability, Anterior

Shoulder Instability, Anterior



Description


Anterior shoulder instability is an injury to the shoulder joint that causes the upper arm bone (humerus) to be displaced from its normal position in the center of the socket (glenoid) so that the joint surfaces no longer touch each other. The most common dislocation is anterior (more than 90%), in which the humerus is in front of and below the glenoid. Because the shoulder has more motion than any other large joint in the body, it is the most commonly dislocated large joint.


The shoulder is like a golf ball on a golf tee. A few of the many structures that provide shoulder stability include the cartilage rim (labrum), which helps provide depth to the socket; the capsule, with thickenings that make up the ligaments of the shoulder; and the muscles of the rotator cuff, which surround the shoulder. To dislocate the shoulder, the rotator cuff muscles must be stretched or torn and the capsule and ligaments must be stretched; often the labrum is pulled off the glenoid.


Another common sports injury is subluxation of this joint, which is when the ball of the humerus does not stay centered in the socket with shoulder motion; it feels like the humerus is slipping out of place. Subluxation of the shoulder causes overuse of the rotator cuff muscles, which attempt to keep the shoulder in the center of the socket, resulting in rotator cuff symptoms. Further, fatigue of the rotator cuff muscles may push the humeral head up to the roof of the shoulder (acromion) as the deltoid muscle contracts, pinching the subacromial bursa and supraspinatus tendon (part of the rotator cuff).



Common signs and symptoms



• Severe pain in the shoulder at the time of injury

• Loss of shoulder function and severe pain when attempting to move the shoulder

• A feeling that your shoulder is slipping out of place

• Tenderness and swelling

• Deformity marked by a fullness in the armpit and a prominent acromion (roof of shoulder)

• Pain with moving the shoulder, especially when reaching overhead

• Pain with heavy lifting

• Pain that awakens you at night

• Loss of strength

• Numbness or paralysis in the upper arm and deltoid muscle from pinching, stretching, or pressure on the blood vessels or nerves

• Crepitation, a crackling sensation, when the injured area is touched or with shoulder motion

• Decreased or absent pulse at the wrist because of blood vessel damage (rare)


Causes



• A direct blow to the shoulder

• Backward force on an extended arm or elbow

• Repetitive throwing motion

• Swimming

• End result of a severe shoulder sprain

• Congenital abnormality (birth defect), such as a shallow or malformed joint surface

• Powerful muscle twisting or violent muscle contraction

• Some people can willfully produce a recurrent dislocation.


Factors that increase risk



• Contact sports (football, wrestling, and basketball)

• Sports that involve repetitive overhead activity (baseball, volleyball, swimming)

• Sports that require forceful lifting, hitting, or twisting

• Previous shoulder dislocations or sprains

• Shoulder fracture

• Repeated shoulder injury of any kind

• Poor physical conditioning (strength, flexibility)


Preventive measures



• Appropriately warm up and stretch before practice and competition.

• Maintain appropriate conditioning that includes cardiovascular fitness and shoulder strength, flexibility, and endurance training.

• For participation in contact sports, wear protective shoulder pads.


Expected outcome


With appropriate repositioning (reduction) of the joint and immobilization for 3 to 6 weeks, healing of ligaments can be expected in 6 weeks. The potential for repeated shoulder dislocations depends on associated shoulder injury, the amount of trauma required to cause the first dislocation, and age at the time of injury; a younger age at the time of the first dislocation leads to a higher risk of recurrent dislocations (if you are younger than 18 at the first dislocation, there is a more than 90% risk of another dislocation of the same shoulder). If reduction and immobilization do not prevent a recurrence, athletic activities should be modified until surgery can be performed to fix the problem.



Possible complications



• Damage to nearby nerves or major blood vessels, causing temporary or permanent weakness, paralysis, numbness, coldness, and paleness of the arm or hand

• Fracture or joint cartilage injury as a result of the dislocation or as a result of the reduction (repositioning) of the dislocation

• Prolonged healing or recurrent dislocation if activity is resumed too soon

• Rotator cuff tear (usually if you are older than age 40 at the time of the first dislocation)

• Repeated shoulder dislocations, particularly if the previous dislocation is not healed completely or is not appropriately rehabilitated; most recurrent dislocations are caused by repeated injury, but with an increasing number of dislocations, less force is necessary to cause dislocation.

• An unstable or arthritic shoulder following repeated injury, or if there is associated fracture


General treatment considerations


After repositioning (reduction) of the bones of the joint by trained medical personnel, treatment consists of ice and medications to relieve pain. Reduction usually can be performed without surgery, which may be needed, although rarely, to restore the joint to its normal position and to also repair ligaments. Immobilization by sling or immobilizer for 3 to 8 weeks is usually recommended to protect the joint while the ligaments heal. After immobilization, stretching and strengthening of the stiff, injured, and weakened joint and surrounding muscles are necessary because of the injury and the immobilization. These exercises may be done with or without the assistance of a physical therapist or athletic trainer. Surgery is rarely recommended after the first dislocation to tighten the shoulder ligaments and repair the labrum; it is usually reserved for those who have recurrent dislocations despite appropriate rehabilitation. Surgery can be done arthroscopically or through a standard, open incision.



Medication



• General anesthesia or muscle relaxers may be used to help make the joint repositioning possible.

• Nonsteroidal antiinflammatory medications, such as aspirin and ibuprofen (do not take for 7 days before surgery), or other over-the-counter pain relievers, such as acetaminophen, are often recommended. Take these as directed by your physician, and contact your doctor immediately if any bleeding, stomach upset, or signs of an allergic reaction occur.

• Stronger pain relievers may be prescribed as necessary. Use these only as directed, and take only as much as you need.


Cold therapy


Cold is used to relieve pain and reduce inflammation. It should be applied for 10 to 15 minutes every 2 to 3 hours as needed after injury and immediately after any activity that aggravates your symptoms. Use ice packs or an ice massage.



When to call your doctor



• Pain, tenderness, or swelling worsens despite treatment.

• You have another dislocation.

• You experience pain, numbness, or coldness in your arm.

• A blue, gray, or dusky color appears in your fingernails.

• New, unexplained symptoms develop. Drugs used in treatment may produce side effects.
image

Figure 1


From Economou SG, Economou TS: Instructions for surgery patients, Philadelphia, 1998, W.B. Saunders, p 551.


image

Figure 2


From Economou SG, Economou TS: Instructions for surgery patients, Philadelphia, 1998, W.B. Saunders, p 671.



Range of Motion and Stretching Exercises


Shoulder Instability, Anterior


These are some of the initial exercises you may use to start your rehabilitation program, after your surgeon has said that you may begin moving your shoulder. The length of time your shoulder will need to be immobilized, often 2 to 6 weeks, will vary depending on the type and severity of your injury. Continue these exercises as instructed until you see your physician, physical therapist, or athletic trainer again, or until your symptoms resolve. You should attempt to avoid motions that place both your hands and your elbows behind the midline of your body with your arms at shoulder height or above. Please remember:



• Flexible tissue is more tolerant of the stresses placed on it.
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Jul 19, 2016 | Posted by in SPORT MEDICINE | Comments Off on Shoulder Instability, Anterior

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