The shoulder is a very complex piece of machinery. Its elegant design gives us the ability to do many things. This design gives the shoulder joint great range of motion but not much stability. As long as the parts of the machine are in working order, the shoulder can move freely. Let's see how the machine is put together and what might cause a breakdown.
Tendons attach muscles to bones. Muscles are able to move bones by pulling on these tendons. The tendons of four muscles form the rotator cuff. These include the supraspinatus, infraspinatus, teres minor, and subscapularis. This cuff connects the humerus with the shoulder blade (scapula) and helps raise and rotate the arm. As the arm is raised, the rotator cuff keeps the humerus in the socket (glenoid) of the scapula, and from rubbing against the acromion. The bursa is a fluid-filled sac that protects the muscles and tendons as they move.
Impingement occurs to some degree in everyone’s shoulder, caused by day to day activities that we do using the arm above shoulder level. Working with the arms raised overhead , repeated throwing activities, or other repetitive actions of the arm can cause impingement to become a problem.
Let look at where Impingement occurs. Raising the arm tends to
force the humerus against the edge of the acromion. This results
in a pinching
action on the bursa and tendons of the rotator cuff and a
rubbing action against the bursa and tendons. Bone spurs can
further reduce
the space available for the bursa and tendons to move under
the acromion.
With overuse this can cause irritation
and swelling of the bursa. Bone
spurs can develop, making impingement worse.
Early symptoms of Impingement Syndrome include generalized aching of the shoulder, pain when raising the arm out from the side or in front of the body. A very reliable sign of impingement is a sharp pain when trying to reach into your back pocket. As the process continues, discomfort increases and the joint may become stiffer. Sometimes a "catching" sensation is felt when the arm is lowered. Weakness and inability to raise the arm may indicate that the rotator cuff tendons are actually torn. Diagnosis
The diagnosis of impingement and bursitis is usually made on the basis of the history and physical examination. X-rays may confirm the presence of an abnormal acromion, or spurs from the AC joint.The MRI scan, or arthrogram may be performed if there is also a suspected tear of the rotator cuff tendons. In some cases, injection of a local anesthetic into the bursa can be used to make sure that the pain is in fact coming from the shoulder, and not radiating from the neck.
During the early stages, first aid measures will assist in calming the area, decreasing pain and insuring early healing.
Following an evaluation, treatment may begin with antiinflammatory modalities by the physical therapist. Several choices are available to limit inflammation and pain associated with shoulder pain. Examples include ice, heat, iontophoresis, TENS, MENS, ultrasound, or phonophoresis (refer to module on specific treatments).
Treatment sessions may also include joint mobilization to limit pain while assisting with overall motion in the shoulder and surrounding joints. Your therapist may perform manual stretching techniques to increase mobility. As healing continues different types of exercises are used. Early on, isometrics help maintain muscle mass without overloading tissue. Later, progressive resistive exercises are used to increase endurance and strength. These may be performed with free weights, therapeutic bands, pulleys, or isokinetic equipment. Strength and coordination exercises will focus on muscles of the shoulder blade and upper thorax. It is very important to maintain the strength in the muscles of the Rotator Cuff. These muscles help control the stability of the shoulder joint and strengthening these muscles can actually decrease the impingement of the acromion on the rotator cuff tendons and bursa.
Prevention and Long Term Management
Long term management of this problem should address worksite alterations to reduce the need for overhead activity. A posterior capsular stretching program and rotator cuff strengthening program can be initiated to keep the shoulder supple and reduce the irritation from impingement.
Medication
Initial treatment for bursitis from impingement usually includes rest, a mild anti-inflammatory medication, and a gentle physical therapy program. If these measures fail to improve your pain, an injection of cortisone into the bursa may be suggested. Cortisone is a potent anti-inflammatory medication that may ease your discomfort.
Surgery
Surgery to relieve the constant rubbing of impingement is not uncommon. The major goal is to remove any spurs under the acromion that are rubbing on the rotator cuff tendons and bursa. A portion of the acromion may be removed as well to give the tendons more space and allow them to move without rubbing on the underside of the acromion. If there is indication that the joint between the clavicle and the acromion is arthritic, the end of the clavicle may be removed as well. Scar tissue fills the space left between the clavicle and the acromion to form a false joint. In some cases this can be done arthroscopically, and you may be able to go home the same day. In other cases, an open incision is made to allow removal of the bone. This may require you to stay a night or two in the hospital.
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