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Key components and take away message with rotator cuff injury:
The rotator cuff can be injured from overuse and wear and tear while also being exposed during trauma from impact or a fall.
Rotator cuff injuries and pathology are very common in all types of individuals including athletes, active people and those that are generally sedentary.
Rotator cuff injuries usually occur from the gradual wearing of the tissues where a small percentage can occur from a single injury or trauma.
At some point, everyone has at least heard of the rotator cuff and its general function. Shoulder pain has been found to be the third most common cause of musculoskeletal pain with it commonly found in individuals over the age of 45 reporting issues to their primary care physician.
The shoulder is a very dynamic joint and it requires an incredible balance of mobility and stability for proper function.
Injuries can range from minor to very severe, producing major levels of dysfunction if not addressed properly.
In this article, we will discuss the function of the rotator cuff, mechanisms of injury, and what the latest research demonstrates regarding treatment and rehabilitation techniques.
The rotator cuff is comprised of 4 primary muscles that basically act as a “cuff” to the glenohumeral joint or in other words, the head of the shoulder.
These are the:
Like all muscles in the human body, the names are Latin and named after their origin and function. The muscles originate on the scapula and insert onto the humerus where they wrap around and provide a balance of control for the arm as it is moved into different planes of motion.
Other muscles such as the trapezius, serratus anterior, levator scapulae, rhomboids, and latissimus dorsi also contribute towards proper shoulder function but are far less likely to become injured.
The rotator cuff has a high disposition towards injury due to its function, location and the demands of the muscles during activity.
The rotator cuff provides an essential function for the shoulder.
It has to provide a balance of force to move the arm in multiple directions while compressing and centering the humeral head within the glenoid fossa (the head of your shoulder into the socket).
This is called dynamic stability and in order to prevent excessive superior translation of the humerus from the actions of the deltoid, the rotator cuff has to work efficiently.
When there is an imbalance in forces from bigger muscles such as the deltoid and pectoralis compared to the rotator cuff, subacromial impingement occurs.
This is where there is impingement; “trapping” or “jamming” of one of the rotator cuff tendons.
It usually is the supraspinatus tendon since it is the one that travels in this space. This is the most common type of impingement. Other types of impingement can occur deeper in the joint and in other areas, affecting other rotator cuff muscles.
There is a fine balance of movement that occurs in the shoulder with a ratio of degrees between the humeral head and scapula from the rotator cuff function. This is referred to as the scapulohumeral rhythm.
The scapula rotates in the frontal plane (front of the body) with elevation of the arm occurring approximately 1 degree for every 2 degrees of humeral elevation to around 120 degrees of elevation.
Once the arm gets past 120 degrees or to the point where the elbow starts approaching the side of the face, the ratio is 1:1. When this rhythm is off, problems occur.
Individuals with rotator cuff pathology demonstrate deficient muscle firing patterns as shown on EMG findings and those with increased laxity and instability in their shoulders also demonstrate deficient muscle function.
EMG stands for electromyography, which is how objective muscle function is measured most accurately.
The image above is demonstrating the angle of pull of the muscles of the shoulder
The angles of pull of the shoulder muscles with elevation of the arm
The rotator cuff muscles work mostly to begin elevation of the arm at the side or in front of the body. They also work to coordinate rotational movements of the arm at the side of the body or overhead.
Once the arm reaches greater heights, the bigger muscles such as the deltoid take over but the rotator cuff is still functioning to help coordinate the arm.
Exercise prescription during the rehabilitation of these muscles is targeted based on specific movements to ensure the isolation of the proper muscles.
Due to the dynamic nature of the shoulder, it is very easy for certain muscles to compensate for weakness in areas. Ensuring proper positioning of the arm and torso during exercise will promote proper muscle activation.
The above image demonstrates an exercise used to target the lower trapezius muscle. In this position it is important to ensure that there is no compensation from the upper trapezius or levator scapule muscle. If compensation is occurring, shoulder shrugging or neck tension is often noted.
Poor posture is often a contributing factor towards rotator cuff pathology. The poor positioning of the thoracic spine and torso affects the shoulder girdle and the mechanics of the scapula.
Sedentary individuals or those at a desk job can be predispositioned towards rotator cuff issues due to poor posture. A slouched posture prevents proper upward rotation and scapulohumeral rhythm, which then puts a strain on the rotator cuff through impingement.
This is why it is important for overhead athletes such as quarterbacks, volleyball players, pitchers and tennis players to maintain proper posture.
Try this at home: Stand with yourself slouched and with rounded shoulders and try to raise your arm up. Then stand up tall with your shoulder blades pinched back and raise your arm. You will notice you can raise your arm higher and easier when standing tall. It is pure biomechanics.
Scapular winging is a classic sign of deficient rotator cuff function as noted in the image below with a wall press test.
The individual performs a wall push up and the medial border of the scapula tends to pop or wing out due to improper function of the scapula stabilizing muscles.
The most common muscle affected here is the serratus anterior, which provides the function for protraction or forward movement of the scapula. This is often termed the “superman” muscle due to its correlation with the action and performance of punching.
The muscle looks like goose feathers alongside the rib cage. Scapula winging can also occur from a lesion to the nerve that innervates the serratus anterior. Improper function in supporting muscles such as the serratus anterior contributes towards aberrant movements of the scapula as noted with winging, and can also contribute to strain on the rotator cuff.
When an injury occurs to the rotator cuff, it results in inflammation to the area, fraying or tearing of the tendon and deficient function of the shoulder.
It can occur from overuse such as repetitive movements ranging from a baseball pitcher throwing high volume with poor mechanics or someone painting the ceiling in their house for a number of hours straight.
Usually, instability combined with a high volume of activity can cause issues but the stress of high volume activity alone even with good stability can cause issues as well.
This is mostly due to the limited space the rotator cuff tendons have to move around so the slightest aggravation can cause issues. There is little room for error.
Acromion anatomy types can also contribute to rotator cuff issues. This, unfortunately, is mostly genetics. Some individuals have a steep angle to their acromion, which can predisposition them to impingement.
Unfortunately, this may require surgery to correct if problematic. This anatomy variation combined with excessive overhead activity is the perfect combination for rotator cuff pathology.
Rotator cuff injury can also occur from traumatic incidents, although more uncommon, falls or blows to the shoulder can also cause an impact injury to the rotator cuff tendons resulting in partial or even full tearing.
Tears are usually classified by size and the amount of the tissue involved.
Rotator cuff tendinopathy and tears can be treated conservatively. Research has demonstrated that shoulder function can still be adequate even with disruption to some of the rotator cuff muscles.
If a tendon presents with a high-grade tear but is still intact, the integrity of the muscle and tendon can be strengthened.
Complete tears will obviously require surgical repair but there are many factors to consider before surgery.
First, tissue integrity needs to be considered. Someone with poor tissue quality will not have a good outcome. Tissue quality can be seen on an MRI, which may display more fatty tissue and substance as opposed to muscle integrity.
When a surgeon enters into a shoulder during surgery, they may find that there is more damage than revealed on imaging and the tissue does not take well to the anchors and sutures.
Poor tissue quality is like sewing wet tissue paper together. This is why surgery is often not advised in the elderly or those with a lot of metastatic diseases and comorbidities that may affect tissue quality and healing.
The individual’s lifestyle and goals also need to be considered in that someone who does not engage in a lot of overhead activity can live with rotator cuff tears while having a functional shoulder.
Surgical repair is definitely considered, if appropriate, for overhead athletes and active individuals.
Most commonly individuals will see their primary care physician or an orthopedic specialist when they are having shoulder pain. Since physical therapists have doctorate degrees now, it opens the door for patients to go that route right away as well.
When seeing an orthopedic physician, it is common for pain-relieving injections to be administered such as cortisone. Cortisone in combination with a local anesthetic has been shown to have benefits towards reducing inflammation and pain but can have side effects in regards to negatively impacting tissue quality.
Cortisone can tend to weaken tendons and ligaments, which is why injections are issued sparingly. Injections are also short-lived in that the effects are not long-term.
They usually are issued to provide a patient with a window of relief so they can engage in rehab with improved comfort.
These injections can mask symptoms and sometimes give individuals the false sense of security that they are better but even though inflammation and pain is reduced, the neuromuscular and structural integrity issues are still present.
Injections are often administered into the subacromial space, which is the area under the acromion bone where the rotator cuff tendon runs. Sometimes the injections need to be placed elsewhere based on landmarks and anatomy if other structures are aggravated. Usually the injections are guided under ultrasound for a better view and accuracy.
Platelet-Rich Plasma is when red blood cells are centrifuged to separate from the platelet-rich protein. It is then used in the form of an injection to help with healing.
It uses the individual’s own healing system to help with injuries by isolating out the right proteins and injecting them directly into the affected area. More research is required to find the right algorithm of dosage, frequency, centrifuge parameters and considerations of the person’s anatomy and physiology for the best results.
There are a lot of components that still need to be ironed out before finding definitive answers and results regarding PRP usage which is why insurance does not cover this treatment at this time.
Prolotherapy is another form of an injection where hypertonic dextrose solution is injected into the area to promote collagen synthesis and tissue healing. It acts to basically harden and strengthen the area.
It is almost like injecting caulk into the area. No definitive research results are available regarding prolotherapy and its use for shoulder injuries.
Physical therapists and physicians will often use special tests to be provocative to the rotator cuff to test if there are deficits.
These tests may produce a false negative after injections in that they would be positive before the injection but can present nonsymptomatic afterward. Sometimes the deficits are very involved and despite injections, the pain can still be elicited.
Examples of two common rotator cuff provocation tests. Sensitivity and specificity are usually good with most of these tests meaning they are generally accurate for finding the correct deficits.
Conservative therapy consists of restoring normal mobility, range of motion, isolated rotator cuff strength and shoulder stability. If a patient continues to present with pain and weakness with no improvement, surgery is usually warranted.
Conservative therapy can have very beneficial effects and should be considered before surgery.
If an individual still requires surgery, they at least had some time to improve deficits beforehand so it will help their outcome after surgery.
Common isolated rotator cuff band exercises.
Strengthening the rotator cuff is done by performing movements in the isolated positions that focus on the action of the muscle.
Use of bands and weights is often implemented and since the rotator cuff works to provide coordination and endurance of maintaining the shoulder in certain positions, lighter resistances with higher repetitions are most beneficial.
The rotator cuff is not strengthened with heavy loads and weights. The bigger muscles such as the deltoid, pectorals, and trapezius are there for bigger loads.
Example of isolated scapula exercises to target the rotator cuff and ensure proper control of the scapula in targeted positions.
Once a person can demonstrate good control and strength in the isolated movements, they then are challenged to pull it all together in what is called dynamic stability.
This is where an individual learns to control their shoulder against forces and external stimuli of all sorts to ensure proper functionality of the shoulder.
The basic rotator cuff exercises can be compared to basic exercises such as bicep curls and dips while the dynamic stability is equivalent to translating those basic muscle functions over into a more complex movement such as a muscle-up.
Bicep curls and dips are isolated exercises while the muscle-up is the dynamic stability.
Example of a dynamic shoulder exercise. The patient is maintaining a straight arm against the ball while focusing on scapula position to control the ball while the practitioner is providing a perturbation or external force by tapping it around to challenge the patient’s control.
If surgery is required, rehabilitation is still absolutely essential towards restoring function. The rehabilitation prognosis and duration are based on the type of surgery, size of the tear, tissue integrity, patient compliance, patient overall health, and activity level.
Examples of suture patterns used to adhere the tendon back to the bone.
Larger tears require more sutures often referred to as “double-bundle” patterns. Research has shown mixed findings with the use of different bundles in that more sutures can produce more secure healing of the tendon but can also produce more stiffness and pain.
The size of the tear dictates the pace of therapy. Larger tears with more tissue damage or tissue that was repaired under a lot of tension warrant slower therapy.
The range of motion is gradually restored as aggressive therapy can produce re-tearing.
Re tear rates are already very high for rotator cuff repairs, especially in athletes due to too fast of a rate of return to activity.
It takes a minimum of 12 weeks AT LEAST for the tendon to begin adhering to the bone through what are called “Sharpey fibers”. Larger tears will take longer.
These are the structural components that allow the healing of the tendon to bone. You cannot fast forward Mother Nature and respecting the repair is crucial to ensure proper return without setbacks during rehab.
About The Author:
Michael St. George, PT, DPT (@icore_stgeorge on Instagram) is a physical therapist who works for Excel Physical Therapy and Fitness, which is a private practice that is based around the greater Philadelphia region and suburbs. He is FMS, SFMA, Y Balance, and Motor Control Test Certified with eight years of experience in outpatient orthopedics and sports medicine. His training consists of experience working with physicians and surgeons from the Rothman Institute and therapists in his field specializing in various manual techniques and advanced treatment procedures.