The Full Can Shoulder Test is a common orthopedic assessment used by healthcare professionals to evaluate the health and function of the shoulder joint. This physical examination technique helps identify potential issues within the shoulder complex, serving as an initial step in understanding a patient’s condition.
Understanding the Full Can Test
The Full Can Test is a clinical assessment designed to investigate the integrity of the rotator cuff, focusing primarily on the supraspinatus muscle and its tendon. It is a valuable tool when a patient presents with shoulder pain or weakness, helping clinicians pinpoint the source of discomfort or dysfunction.
This test is often preferred over the “Empty Can Test” because it typically provokes less pain, making the assessment more comfortable. Despite arm rotation differences, electromyographic studies suggest the Full Can Test elicits similar supraspinatus muscle activity compared to the Empty Can Test. This makes it a practical option for assessing the supraspinatus while minimizing patient discomfort.
Performing the Full Can Test
The Full Can Test is performed by a trained healthcare professional to ensure accuracy and patient safety. The patient can either stand or sit upright, with arms positioned alongside their body. The examiner instructs the patient to elevate both arms forward and outward to 90 degrees.
This arm position is typically in the scapular plane, approximately 30 degrees anterior to the frontal plane, with thumbs pointing upwards, as if holding a full can. The examiner stabilizes the patient’s shoulder with one hand. They then apply a steady downward force to the patient’s arm, usually at the forearm or wrist, while the patient attempts to resist this pressure. This test should only be conducted by a professional for diagnostic purposes.
Interpreting the Results
Interpreting the results of the Full Can Test involves observing the patient’s response to applied resistance. A “positive” test result is indicated by pain, weakness, or an inability to maintain the arm’s position against the examiner’s downward pressure. Weakness during the test is often a more significant indicator than pain alone, as it may correlate more closely with actual structural damage.
A positive finding can suggest various conditions, including supraspinatus tendinopathy (inflammation of the tendon) or a tear in the supraspinatus muscle or tendon. It might also indicate a neuropathy of the suprascapular nerve, which innervates the supraspinatus muscle. Conversely, a “negative” test result means the patient experiences no pain or weakness when resisting the downward force. The Full Can Test is one component of a broader diagnostic evaluation and should be considered alongside patient history and other clinical findings.
The Supraspinatus Muscle and Test Limitations
The Full Can Test specifically targets the supraspinatus muscle because of its primary role in shoulder movement and stability. The supraspinatus is one of the four rotator cuff muscles, originating from the scapula (shoulder blade) and inserting onto the humerus (upper arm bone). Its main action is to initiate the first 0-15 degrees of arm abduction (lifting the arm away from the body) and to help stabilize the humeral head within the shoulder joint.
Despite its utility, the Full Can Test has certain limitations. It is not entirely specific or sensitive, meaning it can sometimes produce false positive or false negative results. Other shoulder muscles, such as the deltoid, are also activated during the test, which means the supraspinatus is not completely isolated. Pain during the test can also stem from other issues not directly related to the supraspinatus, such as subacromial impingement or problems in the cervical spine. Therefore, a definitive diagnosis often requires additional evaluations, including further clinical tests, medical imaging, and a thorough review of the patient’s overall clinical presentation.