Shoulder Impingement Overview

Common Position for Subacromial Impingment

Shoulder impingement syndrome is often used as a “catch-all” term to describe pain in the shoulder that’s commonly associated with a “pinching” sensation. A shoulder impingement is normally classified as either an “Internal impingement”,  where pain is experienced in the back of the shoulder or a “subacromial impingement”, where the pain is experienced in the front of the shoulder. Typically, an internal impingement is felt when the arm is brought back into an overhead throwing position. In this position the arm is rotated outward and elevated laterally, away from the body. A subacromial impingement is most often felt when the arm is lifted in front of the body, rotated inward, and/or brought across the body. 

Numerous anatomical structures can be involved in a shoulder impingement diagnosis. Most often, a subacromial impingement is the result of the supraspinatus tendon (one of the four rotator cuff muscles) being compressed, while an internal impingement is most often associated with compression of the supraspinatus and infraspinatus tendons (two of the four rotator cuff muscles). Other anatomical structures that can be involved in a shoulder impingement diagnosis include: bursae, joint capsule, ligamants and bony growths. 

Common Position for Internal Impingement

Shoulder impingement syndrome is thought to be caused by repetitive stress associated with activities that involve frequent overhead shoulder movements. Activities like weightlifting, tennis, baseball and volleyball have higher incidences of shoulder impingement syndrome due to the necessity for overhead arm movements. This does not imply that these activities are “bad” for your shoulder. Though athletes that participate in overhead sports, and activities that involve repeated upper extremity use, will likely benefit from performance programs that focus on strength, mobility and control of the upper extremities. 

When assessing the factors that contribute to a specific case of shoulder impingement, it’s important to consider the subjects range of motion, strength and control of the involved arm. Shoulder impingement can develop from a joint that is either too stiff, or too “hypermobile” where the joint is flexible but lacks sufficient strength and control. It’s common that subjects with a diagnosis of shoulder impingement lack strength and control in the involved shoulder and shoulder blade musculature. 

The most common complaint associated with shoulder impingement syndrome 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 throughout larger portions of the shoulder range of motion.  Other common symptoms include: Pain when sleeping on the affected side, pain that radiates into the arm and forearm and/or Fatigue and weakness of muscles around the shoulder

Anatomy of the Shoulder Joint

The appropriate treatment strategy for shoulder impingement syndrome depends on a multitude of factors. Determining the correct stage of the condition is essential. If the pain is new and worsening, the best course of action likely includes a few days of rest/decreased activity, followed by exercises intended to improve shoulder strength, range of motion and control. If the pain has been occurring for a few weeks, or months, and the symptoms have been steady it’s likely ok to maintain a higher level of activity while you implement rehab exercises. If the condition has become chronic, has been active for >3 to 6 months and has not improved, exercises that emphasize eccentric contraction of the rotator cuff may be appropriate. The only way to determine the correct course of treatment is to understand the specific issues that are contributing to the shoulder impingement. 

The most appropriate strategy to combat a shoulder impingement is to undergo a comprehensive examination and receive an accurate diagnosis. When the most significant impairments are identified, developing an effective treatment solution is easy. 

Brendan Clarke, PT, DPT

Brendan is a Physical Therapist and Co-Owner of Kauno