Tendons are composed of collagen which is the building block of our connective tissues. In tendons, this collagen is arranged into fibers and fibers are arranged into bundles much like a rope. This highly organized arrangement allows tendons to transmit the force generated by a muscle to the adjacent bone. Collagen is manufactured by cells within the tendon called tenocytes. These cells are responsible for maintaining tendon health and for tissue repair and remodeling. Most tendons have relatively little blood supply. Consequently, tendon healing can be very slow. When tendons heal, new collagen must be formed through a repair process. This collagen must then mature from early scar tissue into organized tendon tissue. Not until this reorganization process is complete and the tissue reconditioned are tendons capable of withstanding the demands of everyday activities.
Rotator Cuff Anatomy:
The rotator cuff is composed of four tendons that surround the humeral head (ball). In addition to moving the shoulder joint, the rotator cuff compresses the ball into the socket. This compression helps stabilize the shoulder joint, providing the shoulder the widest range of motion of any joint in the body.
The most common tendon involved in tendinosis and rotator cuff tears is the supraspinatus tendon. This tendon is positioned between the humeral head and the acromion bone which provides a roof above the ball and socket joint.
Tendinosis refers to internal tendon degeneration. This occurs because on an imbalance between tendon breakdown and tendon repair. Thus, tendinosis can result either from an increase in breakdown such as from overuse or injury, or from a decrease in the healing response.
Tendonitis refers to tendon inflammation. While this term is commonly used to describe activity related pains in various joints of the body, recent studies have shown that there is very little inflammation present in the majority of cases of tendon-related pain. Bursitis is another commonly used term to describe shoulder pain. The bursa is a fluid filled sack located between the acromion bone and supraspinatus tendon. This bursa can becomes inflamed, swollen and scarred in chronic rotator cuff conditions. As with tendonitis, however, the bursa is frequently not found to be significantly inflamed in most cases of rotator cuff tendinosis. Thus, the common conception that shoulder pain is a result of bursitis is probably only true a fraction of the time and cases of shoulder pain diagnosed as bursitis are likely more commonly rotator cuff tendinosis.
Rotator cuff tendinosis has many possible causes that may act alone or in combination to result in tendon degeneration. The causes are listed as follows:
Age: as we age, our tendons and ligaments lose strength and their internal capacity for tissue repair and healing decreases. Thus, they are equally more prone to injury and less likely to recover quickly.
Overuse: repetitive use of the arms, especially at or above shoulder level may cause fatigue and damage to the rotator cuff tendons. If the rate of tissue breakdown exceeds the rate of tissue healing, tendon degeneration may occur. This may be know as Repetitive Strain Injury (RSI). Giving the damaged tissue sufficient time to heal is essential to recovery. Continued pain during activity is an indicator of internal tissue damage and should not be ignored. Efforts to work through the pain will likely only result in further injury.
Poor Posture: forward slumping of the shoulders causes the shoulder blade to tilt forward and down. This narrows the space available for the rotator cuff tendons and may cause abrasion of the tendons surface. In addition, excess pressure from the downward sloping acromion bone may wring out the tendons blood supply resulting in tissue breakdown.
Weakness: many people who engage in repetitive motion activities, whether through work, sport or recreation, develop fatigue in the rotator cuff muscles. If the muscles are not allowed sufficient time to rest, recover and remodel, fatigue can lead internal damage to the muscle and tendon. In addition, fatigue promotes faulty mechanics in the ball and socket mechanism that accelerate this damage.
Stiffness: injury to the shoulder, whether from a single incident or from repetitive overuse, often causes the capsule surrounding the ball and socket joint to contract and tighten. This is particularly true for the posterior capsule of the shoulder. Posterior capsule tightness causes the ball to slide upwards on the socket during many activities such as reaching and lifting. This abnormal movement of the ball on the socket results in abrasion of the rotator cuff on the acromion bone and coracoacromial ligament which form the roof above the tendons.
Instability: some people are born with particularly elastic connective tissue and may have shoulder joints that are very lax (wide range of motion). Such hyperlaxity may predispose some people to develop subtle shoulder instability whereby the ball does not stay properly centered in the shoulder socket during shoulder movement. This condition may be associated with impingement of the rotator cuff on the acromion bone and coracoacromial ligament.
Smoking: as with many other tissues in the body, the connective tissues of the musculoskeletal system are adversely affected by smoking. Specifically, smoking damages the circulation to tendons and bones. This not only places these tissues at risk for injury but also slows or prevents their healing during a recovery period.
Symptoms and Signs
Symptoms: Progressively worsening pain both with use and at night are typical features of rotator cuff tendinosis. Most patients cannot recall a single incident that caused the onset of pain. Pain with reaching and lifting, especially at or above shoulder height, are common complaints. Many patients may be unable to sleep on the affected side or may be awoken at night when they roll onto the that side. Most patients are relatively comfortable at rest with the arm at the side. Because the tendon is structurally intact and not torn, strength is generally unaffected but limited by pain. Some patients have pain that radiates into the neck, back or upper arm due to shoulder fatigue.
Signs: the physical exam of rotator cuff tendinosis typically reveals pain when the arm is passively elevated in front of the body. This called an arc of pain. Maneuvers which tighten the posterior shoulder capsule also typically worsen pain because they compress the rotator cuff against the acromion bone. Strength testing generally indicates intact rotator cuff function however testing of supraspinatus strength may result in increasing pain by placing stress on the diseased tendon. This is called a tendon sign.
How is Rotator Cuff Tendinosis Diagnosed?
In straight forward cases, the patients history and physical exam may be all that is necessary to make a diagnosis of cuff tendinosis. In some patients, extreme pain may make it difficult to adequately assess the degree of tendon disease, raising suspicion of a possible partial or full thickness rotator cuff tear.
Plain X-rays are generally obtained to screen for other possible causes of shoulder pain including arthritis or calcific tendonitis. These films also show the shape of the acromion bone, presence of abnormal bone spurs and the relationship of the ball to the socket. If the clinical history and exam are suspicious of a possible rotator cuff tear, an MRI with dye injected into the shoulder joint is the most accurate diagnostic study to assess the integrity of the tendon and look for tendinosis versus rotator cuff tear. Swelling and fluid in the tendon substance where it inserts into the humerus bone are consistent with rotator cuff tendinosis.
What is the Natural History of Rotator Cuff Tendinosis?
Tendinosis tends to be a self-limited process that resolves with adequate treatment. Tendon healing, however, is a slow process that may take many weeks and up to a few months. During this time, the patient must avoid exposing the tendon to the same conditions that caused tendonitis in the first place, especially overuse of the arm. In some cases, tendinosis may progress to a rotator cuff tear. Progressive weakening of the tendon fibers and internal tendon damage may result in partial or complete tendon failure. This is unusual before the age of 40 but becomes increasing common with advancing age.
How is Rotator Cuff Tendinosis Treated?
The goal of treatment for rotator cuff tendinosis is fourfold. The first goal is to promote tendon healing by promoting rest and avoidance of aggravating activities. The second goal is to correct any underlying mechanical abnormalities that may have promoted the development of tendinosis. The third goal is to promote tendon strengthening and remodeling once adequate healing has occurred. The fourth goal is to prevent recurrence through a maintenance program of flexibility, strengthening and aerobic conditioning. If a thorough course of non-operative treatment fails to result in resolution of pain and restoration of shoulder function, surgical treatment may be necessary. Generally surgery is not entertained or recommended until 3-6 months of non-operative treatment have been completed.
Activity Modification and Rest: Tissue healing can only begin when repeated injury stops. Those activities that result in worsening pain must be avoided to prevent continued tissue injury during the recovery phase. Activities that can be performed in a range of motion that does not cause pain are encouraged to prevent muscle atrophy and stiffness which can occur from disuse.
Ice: Cold therapy acts to decrease tissue swelling and reduce pain. It is especially important after exercise sessions. Apply ice or a cold pack to for 15 to 20 minutes, 4 times a day for several days to keep swelling down. Wrap the ice or cold pack in a towel. Do not apply the ice directly to your skin.
Non-steroid Anti-inflammatory Medications (NSAIDS): these medications include Ibuprofen, Motrin, Advil, Naprosyn, Alleve, Vioxx, Bextra, Celebrex, and many others. They active both to reduce inflammation and to relieve pain. They may be more effective in the early phases of rotator cuff tendinosis when inflammation is more prevalent. Long term use of NSAIDS may be associated with risks such as irritation of the stomach lining, ulcers and kidney problems. Patients should become informed about the possible short and long-term side effects of each medication prior to use.
Physical Therapy: the goals of physical therapy are to correct any mechanical abnormalities that may be resulting in rotator cuff tendinosis. This includes the following: 1) stretching exercises to restore proper flexibility to the shoulder capsule; 2) exercises the strengthen the rotator cuff muscles once adequate healing has occurred; 3) exercises to improve posture and strengthen the muscles that control the position and coordination of the shoulder blade; 4) aerobic conditioning exercises to improve fatigue tolerance; 5) transitioning back to work or sport related activities that place significant demands on the shoulder.
Home Exercise Program: Because formal physical therapy may only be performed 2 or 3 times per week, it is essential that patients have a structured home exercise program to perform on the in-between days. This is especially true for stretching exercises as the shoulder is prone to re-stiffen if these exercises are not performed daily if not several times a day.
NOTE: Many patients will have engaged in a previous program of physical therapy but may have failed to improve. Often these programs will have focused on early rotator cuff strengthening before abnormalities such as posterior capsular tightness have been corrected. Our repeated observation is that may patients who have failed previous physical therapy will benefit from further treatment once the appropriate diagnosis has been established and the exercises focused on correcting underlying mechanical deficiencies. This in combination with a properly performed home exercise program will often provide substantial benefit with time and persistence. Most importantly, patients must recognize that recovery is a slow process. One should not give up if immediate and early gains are not seen.
Other Medications: Narcotic pain medications, muscle relaxants and sleeping pills are generally not recommended for rotator cuff tendinosis as prolonged use may diminish their effectiveness and may cause medication dependence or even addiction.
Cortisone Injections: Cortisone is a powerful anti-inflammatory medication that can be injected adjacent to the rotator cuff into the subacromial bursa. Although rotator cuff tendinosis is not primarily an inflammatory condition, cortisone acts to modify pain receptors in the tissue so that pain is diminished. This effect may last anywhere from a week to several months and is variable between patients. Repeated cortisone injections can cause weakening of the tendon tissue and may cause more harm than good.
Who Should Consider Surgery?
Surgery may be considered if a concerted effort at non-operative treatment has failed to result in improvement in comfort and function after 3-6 months. Surgery is entirely elective. The decision should be based on how the rotator cuff tendinosis affects a persons quality of life and ones tolerance for waiting out the healing process. The success of surgery can be maximized if patients are motivated and committed to the recovery process. Thus, one should not consider this course unless a substantial allotment of time and effort can be devoted to the goal of a comfortable and functional shoulder.
What Does Surgery Entail?
Surgery must be directed at the underlying cause of rotator cuff tendinosis. Typically, surgery involves a diagnostic shoulder arthroscopy. This involves putting a small camera inside the shoulder that allows the surgeon to look directly at all of the tissues including bones, ligaments, tendons, cartilage, and bursa. Assuming that the rotator cuff is not partially or completely torn, the shoulder is manipulated to break up any adhesions and scar tissue that may result in tightness of the posterior capsule. Sometimes a portion of this capsule is resected so that capsular tightness does not recur during the healing process. The biceps tendon is carefully inspected for evidence of fraying or tissue damage and any inflamed capsule is removed.
The main part of the procedure involves releasing the coracoacromial ligament from the acromion bone and beveling the undersurface of the acromion so that it is smooth. This process creates more room for the tendon and prevents pressure on the tendon from wringing out its blood supply during shoulder motion. This procedure is called an acromioplasty or a subacromial decompression.
In some patients, if there is symptomatic arthritis in the joint between the end of the collarbone and the acromion, this must treated as well. This involves removing the end of the collarbone to prevent bone on bone abrasion. This is not necessary in every case. This procedure is called a distal clavicle resection.
What Does Recovery Involve?
As long as no tendon repair process is performed, the recovery process is relatively quick. Patients are encouraged to start immediate range of motion exercises to prevent shoulder stiffness. In order to allow the diseased tendon a chance to heal, active use of the shoulder for strenuous activities such as lifting, pushing and pulling anything heavier than 5 pounds is discouraged for a few weeks.
Exercises to strengthen the rotator cuff and shoulder girdle muscles are started after the tendon has healed and after full range of motion is recovered. The aim of these exercises is to restore shoulder strength and endurance much of which may be lost during the tendinosis process as patients favor the shoulder.
Outpatient physical therapy starts 5-7 days after surgery and generally includes 2-3 visits per week. Patients are instructed in a home exercise program and it is essential that daily flexibility exercises are performed a few time per day. Routine use of ice packs helps to alleviate pain in the immediate postoperative period.
Potential Risks and Complications of Surgery:
The risks of surgery include, but are not limited to, infection, damage to nerves and blood vessels, infection, shoulder stiffness, recurrent shoulder pain and complications related to anesthesia. While these risks and complications are infrequent, they can occur in anyone. Patients should consider these when electing to undergo surgery. Any one of these problems can limit the outcome of the procedure.
What are the Results of Surgery?
Surgery can be very successful in patients who have failed to respond to non-operative measures, assuming that the correct diagnosis has been made. The results of surgery depend on two important factors. First is that the surgeon has performed an adequate assessment of the shoulder and an adequate decompression. Second is that the patient adhere to the postoperative regimen. A perfect decompression can be unsuccessful if the shoulder develops postoperative stiffness or if the tendon is not given sufficient time to heal.
Tendinosis affects millions of Americans and the cost to society from medical care and lost productivity is measured in billions of dollars. For this reason, a host of centers are investigating methods of augmenting the tendon healing response. The studies are pursuing artificial tendon tissue, therapeutic injections to boost the rate of tendon healing and other biological remedies. Although none of this research has yet reached fruition in terms of treating patients with tendinosis, there is a high likelihood that within 5-10 years, we will have novel regenerative approaches to managing this chronic condition.