The Empty Can Test, also known as Jobe’s Test, is a common physical examination maneuver used by clinicians to evaluate shoulder health. It is performed when a patient reports pain, weakness, or limited motion in the shoulder joint. This specialized test provides preliminary information that helps narrow down the potential causes of shoulder discomfort and assess the integrity of surrounding structures.
Purpose of the Empty Can Test
The purpose of the Empty Can Test is to evaluate the integrity of the supraspinatus muscle and its tendon. The supraspinatus is one of the four rotator cuff muscles responsible for stabilizing the shoulder joint and initiating the first 15 degrees of arm abduction (lifting the arm away from the body). This tendon is vulnerable to injury, such as a tear or tendinopathy, due to its location beneath the acromion. The test isolates the supraspinatus by forcing it to work against resistance, where resulting weakness or pain can indicate injury, inflammation, or impingement.
Executing the Physical Assessment
The Empty Can Test is performed with the patient either sitting or standing while the examiner stands behind them. The patient’s arm is raised to 90 degrees of abduction and forward flexed about 30 degrees, placing the arm in the scapular plane. This specific angle helps isolate the target muscle from other large shoulder muscles. The patient then internally rotates the arm so the thumb points toward the floor, simulating emptying a beverage can. The examiner stabilizes the shoulder blade and applies steady downward resistance to the patient’s forearm or wrist, and the patient is asked to resist this pressure.
The Meaning of a Negative Finding
A “negative” Empty Can Test result occurs when the patient is able to maintain the correct arm position and successfully resist the downward pressure without experiencing any pain. This finding suggests that the supraspinatus muscle and tendon are intact and strong enough to withstand the load applied. The ability to maintain full strength indicates there is likely no significant rupture or tear in the tendon. The absence of pain decreases the suspicion of severe tendinopathy or impingement.
A negative result reduces the likelihood that symptoms are caused by substantial supraspinatus pathology. By contrast, a positive result involves pain, weakness, or both, pointing toward a possible injury. However, a negative result does not completely exclude all possible shoulder issues, as the test is highly specific. While it is a strong indicator of a healthy supraspinatus, it does not provide information about other rotator cuff muscles or surrounding joint structures, meaning other causes must still be explored.
Limitations and Necessary Follow-Up
The Empty Can Test, like all physical examination maneuvers, is not a definitive diagnostic tool. Studies show varied results for sensitivity and specificity, meaning it can produce both false negatives and false positives. A false negative might occur if a patient has a small, partial tear but maintains enough strength to resist the pressure. Conversely, pain from other surrounding structures, like the subacromial bursa, can sometimes cause a false positive result.
Consequently, the test is rarely used in isolation to diagnose a condition. A negative result must be considered alongside the patient’s full medical history and the findings of other orthopedic tests. If shoulder symptoms persist despite a negative Empty Can Test, further investigation is warranted. Clinicians often use a combination of specialized tests, and medical imaging such as ultrasound or Magnetic Resonance Imaging (MRI) is utilized for a definitive diagnosis if a tear is suspected.