Shoulder impingement syndrome is a catch-all term for shoulder pain that comes with a "pinching" sensation. Here's how the two main types differ, what causes them, the most common symptoms, and how treatment depends on the stage of the condition.
Internal vs. subacromial shoulder impingement
A shoulder impingement is usually classified as either an internal impingement, where pain is felt in the back of the shoulder, or a subacromial impingement, where pain is felt in the front.
- Internal impingement is typically felt when the arm is brought back into an overhead throwing position: rotated outward and raised out to the side, away from the body.
- Subacromial impingement is most often felt when the arm is lifted in front of the body, rotated inward, and/or brought across the body.
Which structures are involved?
Numerous anatomical structures can be involved in a shoulder impingement diagnosis. Most often, subacromial impingement results from compression of the supraspinatus tendon, one of the four rotator cuff muscles. Internal impingement is most often associated with compression of the supraspinatus and infraspinatus tendons, two of the four rotator cuff muscles. Other structures that can be involved include bursae, the joint capsule, ligaments, and bony growths.
What causes shoulder impingement?
Shoulder impingement syndrome is thought to be caused by repetitive stress from activities that involve frequent overhead shoulder movement. Weightlifting, tennis, baseball, and volleyball have higher incidences of shoulder impingement because they require overhead arm movements.
That doesn't mean these activities are "bad" for your shoulder. But athletes in overhead sports, and in activities with repeated upper extremity use, will likely benefit from performance programs that focus on strength, mobility, and control of the upper extremities.
Stiffness, hypermobility, and control
When assessing what contributes to a specific case of shoulder impingement, it's important to consider the range of motion, strength, and control of the involved arm. Impingement can develop from a joint that is either too stiff or too "hypermobile," meaning the joint is flexible but lacks sufficient strength and control. People diagnosed with shoulder impingement commonly lack strength and control in the shoulder and shoulder blade muscles.
Shoulder impingement symptoms
The most common complaint is the feeling of a pinch when the arm is brought into certain positions. As the condition progresses, the pain often becomes more constant and is felt through larger portions of the shoulder's range of motion. Other common symptoms include:
- Pain when sleeping on the affected side
- Pain that radiates into the arm and forearm
- Fatigue and weakness of the muscles around the shoulder
How to treat shoulder impingement
The right treatment strategy depends on a multitude of factors, and determining the stage of the condition is essential.
- New and worsening pain: the best course likely includes a few days of rest or decreased activity, followed by exercises to improve shoulder strength, range of motion, and control.
- Steady pain for a few weeks or months: it's likely OK to maintain a higher level of activity while you do rehab exercises.
- Chronic pain, active for more than 3 to 6 months without improvement: exercises that emphasize eccentric contraction of the rotator cuff may be appropriate.
The only way to determine the right treatment is to understand the specific issues contributing to your shoulder impingement. That starts with a comprehensive examination and an accurate diagnosis. Once the most significant impairments are identified, developing an effective treatment plan is easy.
Dealing with a pinch in your shoulder? Our physical therapists can find what's driving it and build a plan around it.
book a sessionthe takeaway
Shoulder impingement is a catch-all for pinching shoulder pain, often linked to overhead activity and to a shoulder that's too stiff or lacks strength and control. The right treatment depends on the stage, and that starts with an accurate diagnosis.
Frequently asked questions
What is the difference between internal and subacromial impingement?
Internal impingement causes pain in the back of the shoulder, typically when the arm is brought back into an overhead throwing position. Subacromial impingement causes pain in the front of the shoulder, most often when the arm is lifted in front of the body, rotated inward, or brought across the body.
What causes shoulder impingement?
It's thought to be caused by repetitive stress from frequent overhead shoulder movement, which is why weightlifting, tennis, baseball, and volleyball have higher incidences. It can develop from a joint that is too stiff, or one that is flexible but lacks sufficient strength and control.
What are the symptoms of shoulder impingement?
The most common is a pinch when the arm moves into certain positions. Others include pain when sleeping on the affected side, pain that radiates into the arm and forearm, and fatigue and weakness of the muscles around the shoulder.
Should I rest a shoulder impingement?
If the pain is new and worsening, a few days of rest or decreased activity followed by strength, range-of-motion, and control exercises is likely best. If symptoms have been steady for weeks or months, it's likely OK to stay more active while you do rehab exercises.
Is overhead lifting bad for your shoulders?
No. Overhead activities aren't "bad" for your shoulder, but people who do them will likely benefit from training that focuses on strength, mobility, and control of the upper extremities.
