What Is Shoulder Impingement?

Shoulder impingement is a very common phenomenon in the athletic population. It is often wrongly spoken of as a diagnosis but it is really a clinical sign (like jaundice is a clinical sign not a diagnosis). There are two types of shoulder impingement and the focus of this article is the most common type: Subacromial Impingement.

Subacromial impingement is most often felt as you raise your arm out to your side and can become quite severe. The source of pain is the tendons and/or bursa become crushed between two bones as you raise your arm. Your diagnosis will depend on which tendon/bursa becomes trapped. After time they become hypersensitive which means your pain is felt with smaller stimuli. This is particularly problematic because tendons have an important job to do. They are the fibrous cord that connect your muscles to the bones muscles pull on to create movement. When your tendons become damaged, it weakens these muscles and, consequently, weakens the movements they perform.

How does it happen?

The subacromial space is quite narrow but should have more than enough room for the subacromial bursa and the tendons that pass through the space. Impingement occurs when you raise your arm out to the side and the head of the humerus impacts the acromion crushing the structures between the two. This should not occur in a properly functioning shoulder.

What goes wrong for shoulder impingement to occur?

There are many causes and they often occur together in the one person to culminate in impingement.

• Tight chest muscles draws the scapula forward and the acromion down which narrows the subacromial space.

• Weak serratus muscles worsen this phenomenon.

• Weak middle and lower traps and rhomboids create aberrant scapular movement where the acromion does not rotate away from the humeral head as normal.

• Instability of the shoulder allows excessive gliding of the humeral head up into the subacromial space.

• Slumped thoracic spine posture further limits scapular rotation and acromial movement away from the humeral head.

Most subacromial impingement are created by some combination of these events.

What treatment can be done?

Treatment focuses first on reducing the sensitivity of the trapped tendons with massage and/or dry needling. Then we address any of the causes mentioned above as necessary each patient.

• Massage and stretching of the pectoralis (chest) muscles

• Mobilisations of the scapular encourage better positioning and movement.

• Adjustments of the thoracic spine to improve thoracic posture and scapular movement.

• Specific strengthening exercises are given to target the weak scapular and shoulder stabilising muscles

Most episodes of subacromial impingement improve greatly with sufficient treatment. It is expected, however, to take longer if you have inflammation of the bursa present. Please feel free to get in contact if you have any questions about the shoulder :).