What is Impingement Syndrome?

Subacromial impingement is the pinching of the soft tissue in the subacromial space. In most basic terms, it's the compression of the rotator cuff tendons under the acromion of the scapula. This repeated compression leads to irritation of the tissue.

There are 2 kinds of impingement: primary and secondary.

Primary impingement is when the shape of the acromion is the cause of the compression. This is either congenital (genetic/ unknown origin) or acquired, such as bony formations due to inflammation or even maladaptive healing after a fracture.

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Secondary impingement is when the scapula moves abnormally (fancy terms: abnormal scapulothoracic kinematics or scapular dyskinesia or poor scapulohumeral rhythm) or there’s an imbalance of the humerus musculature causing the head of the humerus to jam up into the subacromial space. Usually, in secondary impingement, the site of compression is closer to the coracoid process rather than completely subacromial, as is most common with primary impingement. 

Image courtesy of Biodigital Human

How do you know it’s impingement?

Well… unless you cut someone open and peek inside, we don’t know for certain. However, there are a few assessments that are highly correlated with impingement syndrome. If someone comes to your clinic with pain in the middle of humeral abduction (also known as a painful arc), then there are a few more assessments you can conduct that are correlated with impingement. If a client presents pain with one or more of these assessments, it might be impingement and it’s probably a good idea to get them cleared by a physical therapist or doctor before working with them.

What can we do about it?

You can work on someone with impingement. If they have primary impingement (confirmed by x-ray), then the work you’ll do is more centered around flushing the area and keeping the muscles supple. If it's a secondary impingement, then we want to investigate what musculature is not functioning properly. 

In most cases, Pec Major and Pec Minor will be overactive and shortened, pulling the humerus forward and the scapula down. There may also be excessive tension in subscapularis (there are special release techniques for subscapularis since it’s located near an endangerment site, be sure to check out the techniques sections). Those are tissues we will want to release and soften. 

If we can see some scapular winging when the flexes the humerus to about 90 degrees, then the serratus anterior might be underworking. That makes it hard for the scapular to properly upwardly rotate during flexion and abduction. If the scapula does not upward rotate, the humerus encroaches into the subacromial space during these movements.

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The external rotators (infraspinatus and teres minor) are also worth checking in on. Strengthening exercises might be useful in balancing internal vs. external rotation of the humerus and creating more stability of the glenohumeral joint.

Traction and distractions of the glenohumeral joint can be a useful tool to desensitize pain and create more space in the joint complex. Always work to the client's tolerance levels. 

Important Reminders:

It’s always better to work integratively with other healthcare professionals. Have a PT you trust and can recommend clients to when they present with severe or troublesome pain. Soft tissue mobilizations can help, but they’ll work better with strengthening the proper structures and motor patterns.