Impingement is one of the most common causes of pain in the adult shoulder.
Impingement syndrome occurs when tendons of the rotator cuff and the subacromial bursa (a fluid-filled sac that separates the bones of the shoulder joint) are compressed between the bones of the shoulder.
The shoulder is made up of three Bones: the scapula (shoulder blade), the humerus (upper arm bone), and the clavicle (collarbone).
The rotator cuff connects the humerus to the scapula. The rotator cuff is formed by the tendons of four muscles: the supraspinatus, infraspinatus, teres minor, and subscapularis.
Tendons attach muscles to bones.
Muscles move the bones by pulling on the tendons. The rotator cuff helps raise and rotate the arm.
The shoulder joint is a ball-and-socket type of joint. As the arm is raised, the rotator cuff also keeps the humerus (the ""ball"") tightly in the ""socket"" of the scapula. The upper part of the scapula that makes up the roof of the shoulder is called the acromion.
A bursa is located between the acromion and the rotator cuff tendons. A bursa is a lubricated sac of tissue that cuts down on the friction between two moving parts. Bursae are located all over the body where tissues must rub against each other. In this case, the bursa protects the acromion and the rotator cuff from grinding against each other.
Impingement syndrome occurs because the rotator cuff tendon and bursa (see below) are compressed against bone (the acromion) as the arm is elevated.
Impingement is common in both young athletes and middle-aged people. Young athletes who use their arms overhead for swimming, baseball and tennis are particularly vulnerable. Those who do repetitive lifting or overhead activities using the arm such as paper hanging, construction or painting are also susceptible. Pain may also develop as the result of minor trauma or spontaneously with no apparent cause.
Usually, there is enough room between the acromion and the rotator cuff so that the tendons slide easily underneath the acromion as the arm is raised. But each time you raise your arm, there is a bit of rubbing or pinching on the tendons and the bursa. This rubbing or pinching action is called impingement.
Impingement occurs to some degree in everyone's shoulder. Day-to-day activities that involve using the arm above shoulder level cause some impingement. Usually it doesn't lead to any prolonged pain. But continuously working with the arms raised overhead, repeated throwing activities, or other repetitive actions of the shoulder can cause impingement to become a problem. Impingement becomes a serious problem when it causes irritation or damage to the rotator cuff tendons.
Raising the arm tends to force the humerus against the edge of the acromion. With overuse, this can cause irritation and swelling of the bursa. If any other condition decreases the amount of space between the acromion and the rotator cuff tendons, the impingement may get worse.
Early Stage symptoms are usually mild.
Early Stage Symptoms:
- The most common symptom is pain with movement of the arm, particularly elevation and rotation of the arm. Examples include: pitching a baseball, gymnastics, painting the ceiling, combing your hair, etc..
- Pain usually begins in the front of the shoulder and radiates to the side of the arm.
- Pain may also occur when lifting heavy objects with the affected arm.
- Stiffness in the shoulder joint.
- Swelling localized to the front of the shoulder.
Later Stage Symptoms may include:
- All of the above symptoms become worse.
- Pain in the shoulder and upper arm at night which disturbs ones sleep.
- Loss of motion and power in the arm.
- A 'catching' sensation may be felt when the arm is lowered.
- A sharp pain when reaching into a back pocket.
Shoulder impingement, if treated early, will usually respond to conservative care. Conservative treatment involves:
In the later stages of shoulder impingement doctors may recommend:
- A formal physical therapy program that includes:
- Isometric stretches to restore range of motion.
Isotonic (fixed-weight) exercises to strengthen the shoulder muscles and arm.
Ultrasound and electrogalvanic stimulation may be suggested, along with transverse friction messages.
- Injections of cortisone into the shoulder joint to decrease inflammation and pain.
And finally, in some chronic or recurring situations, doctors may recommend a surgical procedure to correct shoulder impingement.
People with shoulder pain have also found these products to be effective: