Shoulder impingement can be segmented into three categories based on severity.
What is shoulder impingement?
Shoulder impingement syndrome (SIS) is one of the most commonly occurring shoulder dysfunctions, making up between 44-65% of all shoulder pain complaints. This condition typically presents with pain around the shoulder joint, and restricted joint movement, especially overhead.
There are several risk factors for developing shoulder impingement, including but not limited to:
- Postural impairment
- Muscle weakness
- Presence of bursitis
- Presence of tendinitis
- History of rotator cuff tear
- Increased age
- Repetitive overhead movements
- Overuse in athletics
Shoulder impingement can be segmented into three categories based on severity. Stage 1, which is typically seen in patients under the age of 25 is commonly caused by edema within the rotator cuff.
Typically seen in those 25-40 years old, stage 2 is considered irreversible due to the structural changes seen in the joint such as the presence of tendinitis or fibrosis.
Stage 3, which is typically seen in those 40 years and older, is considered a chronic condition. It is typically paired with a rotator cuff tear.
Recommended course: The Shoulder Exam: An Evidence Based Approach
The shoulder impingement test
There are several tests which physicians, physical therapists and other medical professionals can use to identify the presence of SIS. Below is a brief description of each and what type of impingement they can identify.
Hawkins-Kennedy Test
This test can identify subacromial impingement, which is impingement occurring between the scapula (shoulder blade) and the head of the humerus. The testing position is with the affected arm placed at shoulder height with the elbow bent 90 degrees.
Gently rotate the arm so the hand moves down toward the ground. A positive test results if the patient experiences pain.
Neers Test
This test can also identify subacromial impingement. In this test, instruct the patient to hold the affected arm straight out in front of them with the palm facing away from the body and the pinky up toward the sky. The examiner then gently moves the arm up toward the sky. A positive test results if the patient experiences pain.
Painful Arc Test
This test can also identify subacromial impingement. In this test the patient will move the affected arm through the full arc of movement available, starting from their side and ending overhead.
A positive test results if the patient experiences pain in the middle 1/3 of the arc, or when the arm is between 60-120 degrees through the movement.
Empty Can Test
This test can identify a rotator cuff muscle tear, often seen in stage 3 SIS. The patient’s arm should hold their arm out and slightly to the side, like one side of a V, with the thumb pointing down.
The examiner gently applies force downward and cues the patient “Don’t let me move your arm.” A positive test results if the patient experiences pain.
Drop Arm Test
This test can identify a rotator cuff tear within the supraspinatus muscle, a muscle which runs along the top of the scapula. In this test, the examiner should support the affected arm and bring the patient’s arm 90 degrees out to the side with the palm facing up. The examiner then removes the support from the arm and observes whether the patient can maintain the starting position, or if their arm drops down to their side.
A positive test results when the arm drops suddenly, or if the lowering is painful. A negative test results if the patient can maintain the arm position and lower it in a controlled, pain free manner.
A comprehensive picture
Therapists have thoroughly researched each of the above tests. However, some have high reliability while others leave more room for interpretation. The best course of action when testing for SIS is to complete each of the tests above. This gives a comprehensive picture of the true level of dysfunction and impingement.