Shoulder pain commonly impacts daily activities and quality of life. Understanding its cause often requires specific diagnostic assessments. The “empty can test” is a common maneuver used to evaluate the shoulder, offering insights into musculoskeletal problems.
The Rotator Cuff and Its Common Injuries
The rotator cuff is a group of four muscles and their tendons that surround the shoulder joint. These muscles, including the supraspinatus, infraspinatus, teres minor, and subscapularis, work together to stabilize the humerus within the shoulder socket. They also enable arm movements, such as lifting and rotating.
Common injuries to the rotator cuff include tears and impingement. Tears can range from partial to full thickness, often resulting from repetitive overhead activities, acute trauma, or age-related degeneration of the tendons. Impingement occurs when the tendons become compressed or irritated as they pass through a narrow space in the shoulder, causing pain and limiting movement.
Understanding the Empty Can Test
The empty can test is a physical examination maneuver used by healthcare professionals to assess the integrity of the supraspinatus muscle and its tendon. This muscle, located on the top of the shoulder blade, is often involved in rotator cuff injuries. The test aims to identify tears or impingement of the supraspinatus.
The name “empty can” derives from the arm position adopted during the test. When performed, the arm is positioned as if someone is emptying a beverage can, with the thumb pointing downward. This particular orientation helps isolate the supraspinatus muscle for evaluation.
Performing the Empty Can Test
During the empty can test, the patient stands or sits with their arm raised out to the side and slightly forward, at an angle of 90 degrees of abduction. The arm is then rotated internally so that the thumb points towards the floor. This position places stress on the supraspinatus tendon.
A trained healthcare professional applies a downward force to the patient’s arm, while the patient attempts to resist this pressure. The examiner observes for any signs of pain or weakness during this resistance. This test should only be performed by a medical professional, such as a doctor or physical therapist, and is not intended for self-diagnosis.
Interpreting Results and Seeking Professional Guidance
A “positive” empty can test result indicates pain or weakness in the supraspinatus muscle when resistance is applied. This finding suggests a supraspinatus tear or impingement, as the muscle is unable to effectively perform its function under load. Conversely, a “negative” result means the patient experiences no pain or weakness during the maneuver.
The empty can test is just one component of a comprehensive shoulder examination. A definitive diagnosis requires a thorough patient history, additional physical tests, and often imaging studies like magnetic resonance imaging (MRI) or ultrasound. Individuals experiencing persistent shoulder pain, weakness, or limited range of motion should seek medical attention. A healthcare professional can accurately diagnose the issue and recommend appropriate next steps, which may include physical therapy, medication, or surgical intervention.