Injuries to the rotator cuff are one of the most common types of shoulder problems. They can arise from a traumatic episode to the area but are more often caused by repetitive movements of the glenohumeral joint. If there is any imbalance in the functioning of the rotator cuff muscles, an alteration in shoulder biomechanics will occur. This dysfunction of the cuff will cause the humeral head to shift or translate on the glenoid, eventually leading to problems in the shoulder. These underlying conditions can lead to impingement syndrome.
Subacromial impingement syndrome is defined as the “painful contact between the rotator cuff, subacromial bursa, and the undersurface of the anterior acromion”. It is a mechanical phenomenon in which there is weakness or imbalance in the strength of the rotator cuff that allows superior translation of the humerus, resulting in the repetitive compression of the supraspinatus tendon into the coracoacromial arch. Other factors can also contribute to this syndrome, such as:
- Instability patterns in the glenohumeral joint
- Anatomical concerns
- Glenohumeral capsular tightness
- Postural misalignments that change the position of the glenoid
- Dysfunctional scapular motion in which the acromion fails to rotate with the humerus
Initially, symptoms include deep pain in the shoulder that also occurs at night, crepitus, weakness, and pain over the subacromial space. Activity involving movements that are repetitive or are
above 90º of flexion or abduction will exacerbate the symptoms. A characteristic sign of shoulder impingement is the presence of a “painful arc.”
As the client abducts the arm, no pain occurs between 0º and 45 to 60º because the structures are not being compressed. Once the arm passes 60º, impingement of the structures begins, resulting in pain. This may prevent the client from abducting any further; however, if the client does abduct further, the pain will disappear after 120º. This is because the compressed structures have passed completely under the acromion and are no longer being impinged.
Repeated impingement of the rotator cuff structures will lead to tendon degeneration and the second rotator cuff injury: the eventual tearing of the supraspinatus tendon, or rotator cuff tear. The tears are almost always near the insertion and can be either partial or full thickness.
There are a few orthopedic assessments that a therapist can use to gather information about the client’s shoulder. We need to remember that we are NOT using these assessments to make a diagnosis or an evaluation but merely to help us make an informed treatment decision.
The first test is call the Neer Impingement sign.
- The client is in the seated position.
- Standing at the client’s side, use one hand to stabilize the posterior
shoulder and use the other hand to grasp the client’s arm at the elbow.
- Internally rotate the arm passively, and then flex it forcibly to its end
- Pain with motion, especially at the end of the range, indicates a positive test. It
also indicates a possible impingement of the supraspinatus or long head of the
The next test is called the Hawkins-Kennedy test:
- Client is in the seated position.
- Forward flex the shoulder to 90º, and bend the elbow to 90º.
- Keeping the shoulder at 90º of flexion, place one hand under the bent
elbow to support the arm and place the other at the wrist.
- Horizontally adduct the arm slightly across the chest, being careful not
to lower the arm and internally rotate the shoulder.
- Pain that occurs with this test may indicate shoulder impingement.
The last test is for tears in the rotator cuff, specifically the supraspinatus and is called the Empty Can Test:
- Client is standing. Have the client abduct the arms to 90º.
- Standing in front of the client, horizontally adduct the arms 30º and
internally rotate the arms so that the client’s thumbs point toward the floor (empty-can position).
- Place your hands on the proximal forearms of the client, and apply
downward force while the client resists.
- Weakness or pain in the shoulder indicates a positive test and a possible
tear of the supraspinatus tendon.
Watch this video for a demonstration of the tests and to see some treatment techniques: