The rotator cuff is a collection of muscles originating on or about the shoulder blade. These muscles act on the shoulder by anchoring onto the humerus, or ball. The workhorse for this complex is the rotator cuff tendons. Due to generalized use, overuse, or injuries, these tendons are susceptible to damage.
The subscapularis originates from the anterior, or front, portion of the shoulder. It stabilizes the shoulder and provides internal rotation (follow through of a throwing motion).
The supraspinatus originates from the superior, or top, aspect of the back portion of the scapula, or shoulder blade. This muscle stabilizes the shoulder as well as being involved in elevating the shoulder above eye level. The tendon corresponding to the supraspinatus is most commonly damaged.
The infraspinatus originates from the inferior, or bottom, of the scapula below the supraspinatus. This muscles externally rotates the shoulder and stabilizes the shoulder joint.
The tendon is the functional unit connecting the muscles to the bone. Therefore this is the rope connecting the muscle to the ball. While each muscle and its corresponding tendon has a slightly different function, they act in concert to stabilize the humerus within the glenoid. This attachment can be thought as four fingers holding a baseball. If the force through all fingers is equal, the ball will be thrown straight. However, greater force through either the inner or outer fingers will cause the ball to curve inward or outward.
The rotator cuff tendon is susceptible to damage as we age. Generalized wear and tear seems to be the most common culprit. A wide variety of factors play a role: our age, our occupation, our genes, and any single or repetitive traumatic events. The tendon can be damaged in one of two ways. The first is when the tendon looks alright by the naked eye, however if visualized under a microscope a large amount of swelling is present. The second scenario involves frank tearing of the tendon. This most commonly occurs at the attachment site of the tendon on the humerus. The supraspinatus is most commonly involved in both scenarios.
Once the tendon is damaged, it often continues to be aggravated by a portion of the shoulder blade called the acromion. In the image above, the shoulder is being looked at from a side angle. When the tendon is swollen, the amount of space available for the rotator cuff tendon to clear the acromion is decreased. The undersurface of the acromion therefore continues to aggravate an already bad situation. A sac overlying the swollen tendon called the bursa becomes inflammed as well creating further damage.
The end result of damage to the rotator cuff is tearing. Typically, the tendon rips off its attachment to the humerus.
The muscle bellies themselves continue to fire and pull on the tendon whether it is attached or not. Therefore, once a tendon is torn it will not spontaneously heal to the bone. Over time the muscle corresponding to the torn portion of the tendon will begin to atrophy since it doesn't have the normal amount of resistance from the tendon being anchored. Surgical results become more unpredictable if muscle atrophy is present. A torn tendon predisposes one to more tearing. Up to 50% of tears increase in size over a five year period.
Rotator cuff tendonitis typically causes pain with activity. This may occur with overhead movements (reaching for objects) or overhead sports (e.g. tennis, throwing, or swimming). Pain with arm rotation (e.g. reaching for the seat belt or into the back seat) also is quite common. Pain with sleeping is common as well.
Rotator cuff tears often present in a similar manner. Pain with reaching, rotating, and lifting is common. Night pain is a hallmark as well. Weakness of the shoulder often is appreciated.
Many other conditions may coexist with either an inflamed or torn rotator cuff. Shoulder arthritis, AC joint arthritis, labral tears, and frozen shoulder also may be present. Treatment may be altered in the presence of one or some of these.
Orthopaedic evaluation is critical in determining the diagnosis of your pain. Many conditions can mimic either an inflamed or torn rotator cuff. These may stem from the shoulder, shoulder blade, neck (cervical spine), or arm. History and physical examination is 90% effective in making an accurate diagnosis. MRI is the test of choice to determine the presence or absence of a rotator cuff tear. Unfortunately MRI is not as accurate as we might like. The accuracy rate is about 90%. Ultrasound and CT arthrograms are useful in patients unable to undergo an MRI.
The arrow below is pointing to a tear in the rotator cuff on a MRI.
Treatment for a rotator cuff tendonitis centers on nonoperative measures. The goal is restoration of full pain free activity and motion. This is accomplished by reducing inflammation of the tendon and improving the mechanics and strength of the shoulder.
Inflammation typically is reduced by icing after activity and anti-inflammatory usage (e.g. Advil or Aleve). Prolonged anti-inflammatory usage by itself has not proven to be effective in eliminating tendonitis. Corticosteroid injections should be considered if night pain is present, prior therapy has failed, or if oral anti-inflammatories aren't able to be taken. Steroids are potent anti-inflammatories delivered at a high concentration. Since they are delivered locally, the side effects of traditional anti-inflammatories (ulcers or kidney disease) aren't issues.
Physical therapy is the other mainstay of treatment. Tight capsule (or shoulder lining), poor shoulder blade mechanics, and muscle weakness due to the inflammation all prevent a rotator cuff tendonitis from spontaneously healing on its own. Therapy focuses on correcting poor mechanics and developing a stretching and strengthening program.
The success rate of either a corticosteroid injection or physical therapy in isolation is 30-40%. The combination of these two raises one's chances to 70%. Unfortunately, 30% of people either must live with their discomfort or undergo surgical treatment.
Arthroscopic surgery for an inflamed rotator cuff is performed as an outpatient procedure. Surgery consists of two parts. The inflamed bursa or sac overlaying the rotator cuff tendon is removed. Bone spurs and prominent portions of the acromion then are smoothed down. This is called an acromioplasty. The success rate of surgery is 90-95%. Recovery consists of wearing a sling for comfort and immediate physical therapy for restoration of motion and strength recovery. Complete recovery typically is six to eight weeks.
Treatment-Rotator Cuff Tear
Rotator cuff tears do not spontaneously heal. Therefore the following facts should be remembered.
Full-thickness (complete) tears do not heal
Up to 50% of tears increase in size within a five year period
Many torn rotator cuff tears are asymptomatic. A sore rotator cuff may become asymptomatic with appropriate nonoperative treatment.
Large enough tears will result in persistent weakness.
Atrophy may develop in long-standing tears. Atrophy usually is not reversible.
Fresh tears heal more predictably and reliably than longer standing tears.
The healing rate is best for small tears and worst for massive tears.
Smoking impairs the body's ability to heal a surgically repaired rotator cuff tendon.
Corticosteroid injections impair the body's ability to heal a surgically repaired rotator cuff tendon.
Arthritis can develop in shoulders with massive tears and significant muscle atrophy.
Factors coming into play regarding surgical treatment include one's age, occupation, pain, dominant shoulder, health, and demands. As a general rule, individuals 65 and younger should strongly consider surgical repair while those 80 and older should maximize nonsurgical measures. Individuals 65 to 80 years old often will fit better in either the surgical or nonsurgical camp.
Nonsurgical treatment is identical to that outlined for rotator cuff tendonitis. Anti-inflammatories (pills or corticosteroid injections) and physical therapy are the cornerstones for nonsurgical treatment. The success rate is extremely variable depending on the size of the tear. Persistent symptoms may be treated with surgical repair.
Surgery involves reattachment of the torn tendon back to the bone. This typically is performed as an arthroscopic procedure. Certain types of tears or associated damage may require this to be fixed through a small incision. The healing rate and outcome is identical in either scenario.
The success rate of surgery is excellent in relieving pain and restoring function with 90-95% satisfaction. Recovery consists of maintaining the arm in a sling for one month to allow the tendon and the bone to heal together, and following this with an addition three months of physical therapy to restore motion and strength. It may take up to 6 to 12 months to get back to "normal".
The main complication of rotator cuff repair surgery is retearing of the repair. The majority of the time the portion that has retorn is smaller than the initial tear. Furthermore, the initial pain is significantly improved. Therefore even if a portion has retorn surgery is not necessarily a failure. The retear rate and return of strength depends on the initial size of the tear.
1) Small Tear (portion of one tendon torn)
Approximately 5-10% retear rate following surgical repair
typically excellent return of strength
2) Medium Tear (one complete tendon torn)
Approximately 10-20% retear rate following surgical repair
typically good return of strength
3) Large Tear (one to two tendons torn)
Approximately 10-30% retear rate following surgical repair
typically fair to good return of strength
4) Massive Tear (two or more tendons torn)
Approximately 30-90% retear rate following surgical repair
typically fair return of strength
A compelling argument for surgical treatment of a small tear therefore rests on fixing the tear when it has the smallest retear rate rather than living with it and dealing with it three years later when it is a large tear with some associated muscle atrophy.
Success of surgery is dependent on many factors in the hands of the patient. Therapy is critical to the success of this procedure. DO NOT go through the surgery unless you are committed to the therapy. Smoking can inhibit the torn rotator cuff from healing. DO NOT go through surgery if you are planning on continuing smoking. The precautions of keeping your arm by your side and/or wearing a sling for the first month are critical. The knots and stitches used to fasten the torn rotator cuff only are so strong. Repetitive reaching or overhead motion may cause the repair to fail. DO NOT go through the surgery if you are not willing to follow the precautions.
Surgical treatment consists of the following steps.
1. A diagnostic arthroscopy is performed
2. The torn rotator cuff is identified, and the tear pattern is determined.
3. The attachment site on the bone is freed from all scar tissue. This will allow the bone to grow back into the tendon.
4. An anchor is placed into the rotator cuff attachment site. An anchor is a bioabsorbable screw with stitches attached to it. The anchors dissolve within eighteen months.
5. Instruments are used to pass the stitches through the torn rotator cuff.
6. Knots are used to secure the rotator cuff to the bone. The freshened bone will grow back into the tendon. Typically this reattachment becomes biologically secure in approximately two to three months.
Rotator cuff tendonitis and tears unfortunately are quite common. Tendonitis usually can be successfully treated nonoperatively. Tears are much more problematic and surgical treatment often may be the more "conservative" management.