Shoulder pain is a VERY common problem, especially among individuals over 40 years old. Experts estimate that between 16-30% of the population has experienced shoulder pain in the last month, with subacromial impingement syndrome (SIS) being one of most likely diagnoses made by clinicians.
Why is SIS so common? The short answer is because the ball and socket part of the shoulder joint is shallow to allows for a wide range of motion but at a cost of reduced stability. Factors that can increase one’s risk for SIS include increasing age, overhead work, repetitive microtrauma, hypoxia (lack of oxygen), type III acromion shape (a hooked-shaped “roof” over the ball and socket joint), spurs off the acromioclavicular joint and/or front part of the acromion (the roof of the joint), and ligaments becoming calcified.
These risk factors can cause wear-and-tear of the rotator cuff muscle tendon, which can lead to a muscle tendon rupture (partial or complete) over time. In turn, this results in a high position of the humeral head (the ball part of the joint), which when it shifts upwards, causes pinching of the subacromial bursa, especially when the arm is raised, resulting in bursitis. Lying on the affected shoulder is often uncomfortable and a common complaint of SIS. In fact, finding ANY comfortable position in bed can be a challenge! Overhead work is often prohibited due to pain.
The diagnosis of SIS is made using a combination of a thorough history, physical examination, and imaging studies (x-ray, MRI, CT, diagnostic ultrasound). Imaging facilitates the differential diagnosis, which includes spurs, tears, assessing the acromion shape, and more.
Interestingly, a 2019 review of previously published studies concluded that surgery has little benefit for impingement (SIS) in the middle-aged patient. Instead, it’s advised that patients seek a multi-modal, non-surgical treatment approach often utilized by doctors of chiropractic that may include:
- Patient education with respect to the cause of their pain, the realization that progress may be gradual and take three to six months or longer, and the importance of performing a home exercise program.
- Exercises to reduce the high position humeral head (ball), regain range of motion without impingement, strengthen the rotator cuff and surrounding muscles, restore scapular and clavicular function and stability, and reduce pain to regain function.
- Manual therapies (manipulation and mobilization) to the shoulder’s multiple joints.
- Physical therapy modalities (ice, electrical stim, ultrasound, laser, pulsed magnetic field) to facilitate healing and reduce pain and inflammation.