Massive Rotator Cuff Tear and Secondary Arthritis or Rotator Cuff Arthropathy may be very disabling. Osteoarthritis (arthritis from wear of the shoulder joint), develops as a consequence of massive cuff tears which allow the humeral head (ball of the upper arm) to migrate through the Rotator Cuff Tear, hitting the acromion (the bone which caps the shoulder). This may lead to pain, limited range of motion, grinding of the shoulder, and poor functional capacity of the upper extremity. Normally, the Deltoid muscle elevates the arm and the Rotator Cuff acts to balance this upward force to maintain the shoulder in its normal relationship with the cup (glenoid). This balance is disrupted by a massive Rotator Cuff Tear (review the image to the left).
Shoulder Arthritis may be very disabling. Osteoarthritis (arthritis from wear of the shoulder joint), may be caused or aggravated by prior dislocation of the shoulder, fracture, prior surgical intervention or other trauma to the shoulder. Rheumatoid arthritis may also cause similar wear and disability. This may lead to pain, limited range of motion, grinding of the shoulder, and poor functional capacity of the upper extremity.
Tear of a rotator cuff tendon of the shoulder is the most common tendon tear in the body. The function of the rotator cuff tendons is three-fold. First the tendons rotate the shoulder. Second, the rotator cuff helps to stabilize the shoulder, acting like the reins of a horse to hold the head in position. Third, and most important, the rotator cuff tendons act to depress (hold the shoulder down), while the deltoid lifts the shoulder up. Rotator cuff tendon tear is usually the result of chronic impingement. This results from tendon abrasion between the acromion (shoulder cap), and the head of the humerus (ball of the shoulder joint). This is similar to kneeling on the knee of your pants until they fray and finally tear through. Tears of this kind occur with little or no trauma. In the case of shoulder dislocation in the patient over 40years old, despite normal tendon strength, rotator cuff tear may occur because of tendon overload. In the younger patient, rotator cuff tear may occur with acute tendon overload as in throwing sports.
The shoulder is the most mobile joint in the body. Its remarkable range of motion is achieved by a design with less stability than a ball and socket joint like the hip. The shoulder resembles a golf ball sitting on a tee. It falls off easily (dislocates) and the normal restraints for this are the capsule with its incorporated ligaments and the rotator cuff. The rotator cuff is a sleeve of tendons whose muscles originate primarily from the shoulder blade (scapula). The tendons of these muscles insert in a ring at the perimeter of the humeral head (ball of the joint). These muscles are so named because they provide rotational motion of the arm. They also act to hold the head of the humerus down, by their general downward inclination from the humerus to the scapula. The deltoid is the most superficial muscle over the shoulder and covers it like a hood. It elevates the arm but at the same time, elevates the humeral head against the acromion. The deltoid originates from the acromion (shoulder cap), the clavicle, and the spine of the scapula, and inserts halfway down the upper arm.
The shoulder is the most mobile joint in the human body. Greater mobility, however, increases the risk of shoulder dislocation. Simply, the more contact between cup and ball, the more stable the joint. The hip is a simple example of this. Three major forces hold the shoulder joint in place. First, there is a suction between the ball and cup. Second, the capsule and incorporated ligaments of the capsule provide the primary restraint against dislocation. The capsule is often torn or detached from the cup (glenoid) of the joint with an acute traumatic dislocation. Third, the muscles of the rotator cuff act like the reins of a horse holding the humeral head or ball of the joint in place (located). The rotator cuff acts as a dynamic secondary stabilizer. The labrum (lip), a cartilage border between the capsule and cup, also increases the conformity of the joint and the effective diameter of a small glenoid (cup) relative to the large humeral head (ball) of the joint.