What Is Shoulder Impingement Syndrome?
Typing on a keyboard, driving a car, texting, and sitting at a desk. These ubiquitous movements of the modern world are some of the reasons behind the most common shoulder injury today: shoulder impingement syndrome.
In fact, shoulder injuries are so common that 30% of the US report having shoulder pain that has lasted for more than 6 months. This can be due to many conditions of the most mobile joint in the body, however, shoulder impingement syndrome is responsible for 44%-65% of all shoulder complaints.
In this article, you'll learn about the symptoms, the risk factors, and treatment options for this increasingly common shoulder condition. Plus we'll look at four tests to easily determine if you have shoulder impingement.
What Is Shoulder Impingement Syndrome?
Shoulder impingement, a.k.a. subacromial impingement syndrome or external impingement, is a common condition that occurs when the structures within the shoulder joint become compressed or irritated, leading to pain, inflammation, and limited range of motion. Shoulder impingement used to be considered a stand-alone diagnosis but now it's thought to be a combination of "a cluster of symptoms and anatomic characteristics." It primarily affects the rotator cuff tendons and the bursa, a fluid-filled sac that provides cushioning and reduces friction between tendons and bones.
To understand why shoulder impingement occurs, we first need to dive into the anatomy of the shoulder. The shoulder joint is a complex structure composed of three bones: the humerus (upper arm bone), the scapula (shoulder blade), and the clavicle (collarbone). The joint is surrounded by a network of muscles, tendons, ligaments, and bursae that work together to provide stability and enable a wide range of motion. Some of the muscles that allow it to move in these ranges are the rotator cuff muscles. The four rotator cuff muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis which originate from the scapula and attach to the humerus.
On the top of the scapula is a bony prominence called the acromion. The gap between this acromion and the top of the upper arm bone (the "head" of the humerus) is called the subacromial space. Shoulder impingement typically occurs when there is a narrowing of the subacromial space. This space is already narrow at 1-1.5cm wide and it further narrows as the arm is elevated. As you bring your arm up, the humerus compresses or "pinches" either the rotator cuff, the subacromial bursa, or both of these structures within this space creating shoulder impingement.
Shoulder Impingement Symptoms
Shoulder pain, typically located in the front or side of the shoulder.
Pain that may radiate down the arm, sometimes reaching the elbow. This type of pain is called referred pain.
Pain worsens with overhead activities, such as reaching or lifting.
Difficulty raising the affected arm fully.
Weakness or loss of strength in the shoulder.
Pain or discomfort when reaching behind the back, such as during tucking in a shirt or bra.
Pain or discomfort during sleep, particularly when lying on the affected side.
Limited range of motion in the shoulder joint.
Pain or stiffness when performing repetitive movements involving the shoulder.
Tenderness or swelling in the affected area.
Shoulder Impingement Risk Factors
Several factors can increase the risk of developing shoulder impingement. Here are some common risk factors and reasons why they contribute to the condition:
Poor Posture: Rounded or slouched shoulders can cause a forward shift of the humerus and reduce the subacromial space. This altered shoulder position leads to increased compression on the rotator cuff tendons and bursa during arm movements, raising the risk of impingement. One study, Subacromial impingement syndrome: the effect of changing posture on shoulder range of movement, found that combining taping of the shoulder and active correction of a slouched (kyphotic) posture provides short-term benefits to shoulder impingement.
Muscle Imbalances: Imbalances between the muscles that stabilize and move the shoulder can contribute to impingement. Weakness or tightness in certain muscles, such as the rotator cuff muscles or the muscles of the upper back, can alter the mechanics of the shoulder joint and lead to impingement.
Repetitive Overhead Activities: People who engage in repetitive overhead movements, such as athletes involved in throwing sports (e.g., baseball, swimming) or occupations that require frequent overhead reaching (e.g., painters, carpenters), are at a higher risk. These activities put strain on the shoulder joint, increasing the likelihood of compression and irritation of the tendons and bursa.
Structural Abnormalities: Certain anatomical variations or abnormalities in the shoulder joint can increase the risk of impingement. For example, the shape of the acromion is classified into three types: flat (type I), curved (type II), or hooked (type III). This shape directly affects the space between the humerus and the acromion (the subacromial space) and is correlated with rotator cuff injuries.
Previous Shoulder Injuries: Individuals who have experienced previous shoulder injuries, such as shoulder dislocations, fractures, or rotator cuff tears, may develop shoulder impingement as a secondary consequence. The injury can alter the normal biomechanics of the shoulder joint and predispose it to impingement.
Age: Shoulder impingement is more prevalent in individuals over the age of 40. As we get older, the structures within the shoulder joint, including tendons and bursae, may undergo degenerative changes, making them more prone to irritation and impingement.
Poor Rehabilitation or Conditioning: Inadequate rehabilitation following a shoulder injury or insufficient conditioning of the shoulder muscles can lead to muscle weakness, imbalance, and altered mechanics, all of which can contribute to impingement.
How To Test For Shoulder Impingement Syndrome
Here are four of the most common tests for shoulder impingement syndrome.
Hawkins-Kennedy Test
The Hawkins-Kennedy test is a commonly used test for shoulder impingement (video here).
Sit or stand with your arm flexed at 90 degrees and the elbow bent.
The examiner will then forcefully rotate your arm inward.
If pain is experienced in the shoulder during this movement, it may suggest impingement.
Empty Can Test (a.k.a. Jobe Test)
The empty can test is used to assess the integrity of the supraspinatus muscle and tendon (video here).
Stand or sit upright with your arms at your sides and thumbs pointing downward.
Raise your arms to a 90-degree angle with the thumbs pointing up as if you are pouring out a can.
The examiner will then apply resistance while you try to hold this position.
Pain or weakness during this movement may indicate supraspinatus impingement or tear.
Yocum Test
The Yocum test is used to assess the presence of impingement of the infraspinatus tendon between the acromion process and the coracoacromial ligament (video here).
Stand or sit upright with your arm relaxed by your side.
The examiner will then passively abduct your arm to 90 degrees.
While maintaining this position, the examiner will apply downward pressure on the acromion process.
If pain is elicited during this maneuver, it could suggest impingement.
Neer Test
The Neer test is used to assess impingement of the rotator cuff tendons under the acromion (video here).
Stand or sit upright with the arm relaxed by your side.
The examiner will passively elevate your arm while stabilizing the scapula.
If pain is felt during this upward movement, particularly at or below 90 degrees, it could indicate impingement.
Shoulder Impingement Treatment and Prevention
Strengthen the shoulder muscles: There are certain exercises that can make shoulder impingement worse and there are certain ones that can make it better. While there is not one straight forward exercise program for everyone with impingement, there are some tried and true exercises that, given enough time, work to correct the issue, in conjunction with the below strategies. Look forward to an upcoming article which highlights these exercises.
Use your phone in a squat: I saw Kelly Starrett, the famed PT and author of books like Becoming a Supple Leopard, use this technique back in the day and I've been an advocate ever since. For the times when you’ll be using your phone, especially for longer periods, do this: with your back against a wall, go into a deep squat, prop your elbows on your knees, and hold your phone in front of your face with both hands. This puts your body in a position with a neutral spine, externally rotated shoulders, and gives you a good stretch.
Maintain good posture: Pay attention to your posture throughout the day, especially when sitting or working at a desk. Keep your shoulders back and down. Avoid letting your chin get too ahead of your trunk. When you're walking, your thumbs should be swaying in a forward/backward direction (the sagittal plane) opposed to an inward position which indicates a muscle imbalance of the shoulders.
Avoid overuse and repetitive movements: Minimize repetitive overhead activities or movements that strain the shoulder joint for extended periods. If such activities are unavoidable, take frequent breaks, use proper form and technique, and consider implementing cross-training or varying your exercise routine to reduce the strain on your shoulder.
Modify your workspace and ergonomics: Ensure that your workspace, whether it's a desk or any other environment where you spend extended periods, is ergonomically designed. Adjust your chair height, desk height, and computer monitor position to maintain a neutral and comfortable shoulder position. For those who spend hours in the car each week, get a lumbar support and consider lowering the steering wheel height.
Listen to your body: Pay attention to any early signs of discomfort or pain in your shoulders. As annoying as it may be to modify your routine and rest, catching these signs early, and responding appropriately, will be well worth the sacrifice.
While these strategies can help reduce the risk of shoulder impingement, they don't guarantee complete prevention. If you have specific concerns or require personalized advice, consult with a healthcare professional, such as a doctor or occupational therapist, who can assess your individual situation and provide tailored recommendations.
FAQ
How Long Does It Take To Heal?
The recovery time for shoulder impingement can vary depending on several factors, including the severity of the condition, individual healing rates, adherence to treatment, and the effectiveness of rehabilitation efforts. In general, mild cases of shoulder impingement may take several weeks to a few months to resolve, while more severe or chronic cases may require a longer recovery period.
Should I get Surgery?
When it comes to any musculoskeletal issue, there is usually the lingering question of surgery. One systematic review and meta analysis looked directly at this question as it relates to shoulder impingement.
They found that there were no statistically or clinically significant differences observed between the group receiving surgical intervention with physiotherapy and the group undergoing surgery alone when it came to pain levels at 3 months, 6 months, 5 years, and 10 years. Additionally, no notable differences in function were found between the two groups at 3 months, 6 months, and 1 year follow-up, both statistically and clinically.
What I Do
I’ve had shoulder impingement a handful of times. Each time I was able to trace it back to a muscle imbalance with my anterior shoulder muscles dominating my posterior ones such as when I was riding my bike for longer periods, carrying my newborns for long frequently, and doing too much anterior chain work in the gym.
The recovery was slow and annoying but I had to remind myself to trust the process and each time the pain became a distant memory. Some strategies I use to avoid getting this are:
Doing about twice as much posterior chain work (rows, pullups, deadlifts) as anterior chain movements
Incorporating dead hangs into every gym session
Doing more yoga-based stretching between sets in the gym (downward dog, twists)
Modified my environment (more standing while working, lower steering wheel, and we use lumbar supports in each car).
Takeaway
Shoulder impingement syndrome is a condition that occurs when the structures within the shoulder joint become compressed or irritated, leading to pain, inflammation, and limited range of motion. It is a common condition that is responsible for as much as 65% of all shoulder complaints. There are many risk factors for shoulder impingement syndrome such as poor posture, repetitive movements, and muscle imbalances.
Fortunately, shoulder impingement is easy to test and diagnose. Once you’ve determined that you have it, immediately address it by improving your posture, strengthening your posterior shoulder muscles, and modifying your workspace. Talk to a medical professional to help customize a treatment plan for you.
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