The Empty Can Test, often referred to as Jobe’s Test, is a standard clinical maneuver used by healthcare providers to assess the shoulder joint. This orthopedic assessment is a provocative test, designed to stress structures within the shoulder to elicit pain or weakness. The test evaluates the integrity and function of the muscle and tendon structures located in the upper portion of the rotator cuff. It is a preliminary diagnostic tool that helps narrow down potential sources of shoulder discomfort or reduced strength, guiding the need for further evaluation.
The Role of the Supraspinatus Muscle
The supraspinatus is a small muscle situated in the upper back, residing within the supraspinous fossa of the scapula. Its tendon passes underneath the acromion before attaching to the greater tubercle of the humerus. This muscle is one of the four muscles that form the rotator cuff, a group responsible for both movement and stability of the shoulder.
Its primary role is initiating arm abduction, the act of lifting the arm away from the body, particularly during the first 15 to 20 degrees of motion. It works in coordination with the larger deltoid muscle to lift the arm. The supraspinatus also plays a continuous role in securing the head of the humerus against the glenoid cavity of the scapula.
This compressive force counteracts the upward pull of the deltoid muscle during lifting, helping to keep the joint centered and stable. Due to its path, the supraspinatus tendon is prone to compression and injury as it passes through the narrow subacromial space.
Indication of Supraspinatus Pathology
A positive Empty Can Test result strongly suggests pathology within the supraspinatus tendon or muscle. The test is performed by positioning the arm in 90 degrees of elevation in the scapular plane, rotated fully inward so the thumb points toward the floor, simulating “emptying a can.” The examiner applies a downward force, and a positive result occurs if the patient experiences pain, demonstrable weakness, or both, when resisting this pressure.
If the patient reports only pain, it commonly suggests supraspinatus tendinopathy, which is irritation or inflammation of the tendon. This pain results from the tendon being compressed or strained in the test position.
If the patient demonstrates significant weakness against resistance, this increases suspicion for a structural tear in the tendon. The weakness suggests the muscle-tendon unit cannot generate sufficient force to counteract the downward pressure. This may indicate a partial-thickness tear, where a portion of the tendon fibers are damaged, or potentially a full-thickness tear. A positive Empty Can Test has a high sensitivity and a good positive predictive value for identifying a rotator cuff tendon tear.
Next Steps in Diagnosis and Management
The Empty Can Test is a useful clinical indicator but is not a definitive diagnosis and requires further investigation. A healthcare professional combines the positive result with information from other physical examination maneuvers to form a diagnostic cluster. For instance, the Full Can Test (thumb pointing up) or the Drop Arm Test provide additional context.
To confirm the diagnosis and determine injury severity, advanced imaging studies are typically ordered. High-resolution magnetic resonance imaging (MRI) or ultrasound are the most common tools used to visualize soft tissues. These images accurately assess the damage, distinguishing between tendinopathy, a small partial tear, or a larger full-thickness tear. An MRI can be up to 95% accurate in confirming a full-thickness tear.
Management is guided by the severity of the injury. For tendinopathy or small partial tears, the initial approach is usually conservative management. This involves relative rest, activity modification, and the use of non-steroidal anti-inflammatory drugs (NSAIDs) to manage pain and inflammation.
Physical therapy is a primary focus, concentrating on individualized exercises to strengthen the entire rotator cuff and improve scapular stabilization. If symptoms persist, a corticosteroid injection into the subacromial space may be considered to reduce localized inflammation.
If imaging reveals a significant tear, and conservative management has failed over three to six months, surgical intervention may be necessary. The most common procedure is arthroscopic repair, a minimally invasive surgery to reattach the torn tendon to the bone. The decision for surgery is made in consultation with an orthopedic specialist based on factors like the patient’s age, activity level, and the size of the tear.