If you've ever experienced shoulder pain, you have probably scoured the internet for the cause and how to treat it. More than likely, you have read about rotator cuff injuries and how they are the most common shoulder ailment. However, the rotator cuff is made up of four muscles, one of which is the supraspinatus, and each muscle is responsible for different shoulder functions.
According to the Orthopaedic Journal of Sports Medicine, supraspinatus tears are the most common rotator cuff injuries, occurring 61.9% in men and 38.1% in women.
Overview of the Rotator Cuff and the Supraspinatus
The shoulder joint is a ball and socket joint, which means it is very mobile in all three planes of motion. Due to the shoulder joint being extremely mobile without a lot of ligamentous support, it is paramount that the rotator cuff is strong as they work as a dynamic stabilizer for the joint. The rotator cuff is comprised of the supraspinatus, infraspinatus, teres minor, and subscapularis, which are the four muscles that assist in stabilizing the joint. A very common tendon injury in the shoulder is supraspinatus tendinitis or tendinopathy. The supraspinatus lies on the top aspect of the scapula (shoulder blade) above the scapular spine and attaches to the humerus (upper arm bone) with the tendon passing underneath the acromion/“subacromial space” which is the space where other ligaments and tendons run under.
Types of Tendon Injuries
Tendon injuries fall on a spectrum: Tendinitis, Tendinosis, and tears. Tendinitis refers to a more acute injury and indicates there is inflammation along the tendon. Tendinosis refers to a chronic and recurring tendon injury. Tendons can also be partially or completely torn, which is often caused by a quick sudden movement, trauma like a fall, or even repetitive motion or activities. In some severe cases, a full tear may need surgical intervention to restore function.
Common Causes of Tendon Injuries
Impingement
The shoulder joint is composed of the glenoid (socket) of the scapula (shoulder blade) and the humeral head (ball) of the humerus (upper arm bone). A biomechanical fault or movement pattern dysfunction of the scapula can create impingement at the subacromial space and over time with repetitive use can lead to supraspinatus tendon injuries. Chronic impingement often leads to microtears of the tendon.
Weakness
Weakness of the rotator cuff can also lead to poor muscle activation patterns, muscle imbalances, and dysfunction, which then place abnormal loads onto the tendon causing injury.
Overloading
Tendon injuries can occur when muscles are loaded beyond their threshold causing damage to the tendon and muscle integrity. Example: Bodybuilders presenting with shoulder tendon injuries from lifting heavy weights or overtraining.
Instability
When a shoulder joint is hypermobile and unable to control motion, this can lead to poor joint approximation, which means the bones are not making good contact with the joint. This can increase the likelihood of dislocations which stress the tendons that support the shoulder joint, especially in high-demand activities.
Tightness
Suppose there is tightness in other muscles that attach to the shoulder girdle. In that case, this can change the relative posture of the shoulder joint where the ball of the shoulder sits too far away from the socket placing excessive stress and abnormal demands on the tendons.
Joint Restrictions
Other areas that contribute to tendon injuries are the thoracic spine and the scapulothoracic joint. The thoracic spine is the upper and middle part of the back and the scapulothoracic joint is the articulation of the shoulder blade and the ribcage. If there are restrictions in either area, this will limit the shoulder overhead range of motion. If the thoracic spine is not able to extend beyond neutral or if the scapulothoracic mobility is restricted this could lead to abnormal load to the supraspinatus tendon leading to poor global shoulder range of motion and pain. For example, give yourself a hunched-back posture and then raise your arm overhead, then try again with a straighter posture and note which feels better and which posture you get better range with.
Common Supraspinatus Tendinopathy Symptoms
Sharp pain when lifting your arm over your head, especially in the "painful arc" which is 60-120 degrees of abduction motion.
Sharp pain with reaching behind your back to reach in a back pocket or wash your back.
Weakness when exerting force with arms such as pulling, pushing, or lifting.
Pain when sleeping on the affected shoulder.
Weakness and fatigue after repetitive activities.
Supraspinatus Injuries in Athletes and Non-athletes
Overhead athletes such as tennis players, volleyball players, swimmers, or baseball pitchers, have a higher likelihood of injuries due to the demands of their sport. For example, baseball pitchers utilize an extreme amount of shoulder external rotation range and have to quickly reverse the direction to the internal range of motion from the cocking phase through the follow-through phases which creates a higher likelihood for shoulder injuries due to the amount of range, power, and speed that it takes to throw a ball. Supraspinatus tendon injuries can also happen to non-athletes as well, such as in people who work manual labor jobs that require lifting their arms overhead, especially with repetitive motion (for example: painters, construction workers, janitorial workers, housekeepers, and electricians). For more details on pain prevention while working a physical job, read our other blog post here! Older individuals can also develop tendon injuries as collagen production slows as we age, which weakens the tendons.
Goals with Rehab
Your physical therapist at Rehab United will perform a thorough evaluation; your posture, range of motion, strength, and functional movement mechanics (i.e., reaching, throwing/pitching) will be analyzed and assessed. Your physical therapist will then develop a comprehensive, individualized treatment plan that will focus on regaining proper shoulder mobility, strength, and mechanics in order to decrease the abnormal stress and demands on the supraspinatus tendon. These improvements allow for the normalization of functional shoulder strength and stability. If required, your therapist will then progress you to a higher level, sports-specific or job-specific training.
Interested in Physical Therapy?
Here at Rehab United, we care about our patients; we want to see you thrive and get back to the things you love. From the front desk to the physical therapists, our staff is full of wonderful and empathetic people dedicated to giving you the best care possible. We will support you throughout your entire recovery journey, don't wait, schedule an evaluation today!
Christine Kim, PT, DPT, is a physical therapist at our Escondido location. Christine graduated from the University of California, Los Angeles for her undergraduate studies with a degree in Anthropology in 2015 and earned her DPT at the University of St. Augustine for Health Sciences in 2021. She grew her passion for the healthcare field following several volunteering experiences at hospitals, nursing facilities, and pharmacies. After volunteering and being an aide at Rehab United, she decided to get her doctorate degree to become a physical therapist.