What is the rotator cuff and what is a tear?
The Rotator Cuff is a group of four muscles that start on the shoulder blade (scapula) and end as tendons on the arm (humerus).
The Cuff is responsible for motion of the arm in space. The cuff lies directly on top of the humeral head, and directly below the
acromion process, a part of the scapula bone. Between the acromion and the rotator cuff is the subacromial bursa, which occupies space,
provides cushioning and contributes to smooth gliding of the cuff between the humeral head and the acromion. In some patients, normal wear
and the aging process of the rotator cuff will lead to tears in the tendons of these muscles as they attach to the humerus.
This normal progression may never become painful and might not ever be noticed by some patients, but in other patients it can be
a source of pain and functional disability. When patients have a rotator cuff tear that is causing problems, the ability to do
overhead activity can be severely impaired and strength of the shoulder in general is decreased.
How do rotator cuff tears occur?
Some patients possess bony architecture that can predispose them to impingement of the rotator cuff.
The baseline shape of the acromion can vary significantly from patient to patient.
Additionally, when the muscles of the cuff become weak or unbalanced, the humeral head can migrate upwards and decrease the room for the tendons of the cuff.
Muscles of the rotator cuff act to compress the humeral head into the socket (glenoid).
Weakened cuff muscles allow the head to migrate superiorly (up) and contact the bone spur under the acromion resulting in impingement.
The acromion reacts by making bone spurs to help contain the humeral head and prevent the shoulder from becoming unstable.
The combination of additional spurs and a predisposing acromial shape can lead to impingement syndrome.
Impingement syndrome occurs when a bone spur on the acromion causes friction on the tendons of the cuff when the shoulder moves in space.
This can cause irritation of the protective lining of the cuff (also known as tendonitis) or the bursal sac of fluid that cushions the
tendons against the bone (bursitis) and can eventually lead to catching of the cuff between the bone of the arm and the acromion leading to tears.
Still other patients can develop a rotator cuff tear from acute trauma to the arm.
If the tendon is already weakened from impingement or by the natural process of aging, the tear may occur with less force than needed
for a healthy tendon. Seemingly trivial injuries can cause large rotator cuff tears when the cuff is vulnerable. Lifting luggage
from overhead compartments in airplanes, taking boxes off of shelves above shoulder level, lifting heavy bags off the floor, and sudden
movement of the arm when it’s position is fixed in space (as in a motor vehicle accident) are all common causes of rotator cuff tendinopathy.
How is a rotator cuff problem diagnosed?
A rotator cuff problem can be diagnosed by a physician after a physical exam. Frequently, patients will demonstrate pain with overhead activity,
and weakness of the arm. In certain situations, an injection of the patients shoulder with a novocaine type of drug can be useful in making
the diagnosis. The injection has the potential to provide long-standing relief in some patients. Other patients however require further
diagnostic tests to confirm the extent of the damage. MRI scanning of the shoulder allows physicians to visualize the integrity of the
rotator cuff and other structures that are not visible on plain x-rays.
The cuff, ligaments surrounding the humeral head, the bursa, other tendons in the shoulder, and some bony changes can be seen
reasonably well on MRI scanning.
A contrast MRI involves injecting dye into the shoulder joint and obtaining images before and after injection.
The use of this technique helps increase the sensitivity of the MRI for certain conditions. Overall, MRI is useful confirm
diagnostic impressions as well as for assisting in planning potential operative interventions.
Do all rotator cuff problems need surgery?
Rotator cuff problems do not always require surgery to return a patient to his/ her previous functional level.
In some cases, a combination of injections, oral anti-inflammatory medication and a physician directed physical therapy
program could yield a successful outcome. This is possible because the rotator cuff is four muscles that fuse into a
collective tendon that attaches onto the humerus. If the tendon for one muscle is injured, the other muscles can be
strengthened to compensate for the loss of one muscle. Additionally, there is a loss of coordination of the shoulder
muscles which occurs when an injury takes place. Therapy can re-train the remaining muscle / tendon units and allow
for more coordinated function.
Physical therapy exercises that may be prescribed include stretching of the shoulder girdle, pain relief modalities, and
strengthening of the rotator cuff and the muscles of the shoulder girdle. Ice and moist heat can be very helpful in reducing
inflammation and preparing the shoulder for exercise.
Some patients, because of the size of the tear, failure of non-operative treatment or age will require surgery for repair of the rotator cuff.
During this surgery, the orthopedist reattaches the torn edge of the tendon to the bone.
The torn tendon can be seen arthroscopically, and may be repairable with an arthroscopic procedure, not requiring any formal
incisions to address the tear.
The tendon may also be repaired through a small incision over the shoulder, moving the torn tendon back to where it belongs,
attached to the humeral head.
Physical therapy is required after rotator cuff repair and results are usually very good.