Empty Can Test: A Complete Guide for Shoulder Health

Shoulder pain is one of the most common musculoskeletal complaints worldwide, often caused by injuries, repetitive movements, or degenerative changes. For medical professionals, accurately diagnosing the cause of shoulder pain is essential to provide the right treatment. One clinical tool used in this process is the empty can test. This simple yet effective physical examination helps assess possible injuries to the rotator cuff, particularly the supraspinatus muscle and tendon.

In this comprehensive article, we will explore what the empty can test is, why it matters, how it is performed, and what its results can reveal about shoulder health.

Understanding the Rotator Cuff and Its Importance

Before diving into the details of the empty can test, it’s important to understand the anatomy of the rotator cuff.

The rotator cuff is a group of four muscles and their tendons that stabilize the shoulder joint. These muscles include:

• Supraspinatus

• Infraspinatus

• Teres minor

• Subscapularis

Among these, the supraspinatus muscle plays a key role in initiating arm elevation and providing strength during lifting. Because of its location and function, the supraspinatus tendon is highly vulnerable to overuse injuries, impingement, or tears. Detecting such injuries early is crucial to avoid long-term shoulder dysfunction.

What is the Empty Can Test?

The empty can test is a physical examination maneuver designed to evaluate the integrity of the supraspinatus tendon. It helps clinicians determine if shoulder pain or weakness is linked to a rotator cuff injury, particularly involving the supraspinatus.

The test gets its name from the position of the arm during the examination, which resembles a person holding an empty can and then pouring it out. By replicating this motion, the muscle and tendon are stressed in a way that highlights potential injury or dysfunction.

Why is the Empty Can Test Important?

Shoulder injuries are not always easy to diagnose through history alone. The empty can test provides a quick and reliable way to gather more clinical evidence. Here’s why it’s important:

• Identifies supraspinatus weakness – Indicates tendon tears or muscle impairment.

• Helps differentiate shoulder pain – Distinguishes between rotator cuff injuries and other conditions like bursitis or arthritis.

• Guides further testing – Positive results often lead to imaging studies such as MRI or ultrasound.

• Supports treatment planning – Helps physicians decide if physical therapy, rest, or surgical options may be necessary.

How to Perform the Empty Can Test

Performing the empty can test is straightforward, but it must be done with proper technique to ensure accuracy. Below is a step-by-step guide:

1. Patient Positioning

   • The patient stands or sits upright with arms relaxed at their sides.

2. Arm Placement

   • The examiner asks the patient to elevate both arms to about 90 degrees in the scapular plane (slightly in front of the body, not directly to the side).

3. Thumb Rotation

   • The patient then rotates their arms inward so that their thumbs point down, as if emptying a can.

4. Resistance Application

   • The examiner applies gentle downward pressure on the arms while the patient resists.

5. Observation

   • The examiner observes for pain, weakness, or an inability to maintain arm position.

Interpreting the Results

The results of the empty can test are based on how the patient responds during the maneuver:

• Positive Test:

  • Pain in the shoulder or noticeable weakness during resistance.

  • Suggests a supraspinatus tear, tendinopathy, or impingement.

• Negative Test:

  • No pain and the ability to resist downward pressure effectively.

  • Indicates the supraspinatus is likely intact and functioning well.

It’s important to note that while the empty can test is a valuable diagnostic tool, it should not be the sole determinant of a diagnosis. It is most effective when combined with other clinical tests, imaging, and medical history.

Empty Can Test vs. Full Can Test

Another variation often used in clinical practice is the full can test. In this version, the patient elevates the arm in the same scapular plane but with the thumb pointing upward (as if holding a full can).

• The full can test generally produces less pain and is thought to be more comfortable.

• Both tests target the supraspinatus but may stress it differently.

• Some clinicians prefer the full can test due to its reduced likelihood of impingement.

Comparing both tests helps ensure a more accurate assessment of shoulder function.

Accuracy and Limitations

Like any physical test, the empty can test has strengths and limitations:

• Strengths:

  • Quick, easy, and cost-effective.

  • Provides immediate feedback.

  • Useful for screening supraspinatus involvement.

• Limitations:

  • Not 100% specific or sensitive.

  • Pain from other conditions (bursitis, arthritis, labral tears) can mimic results.

  • Requires skill from the examiner to interpret correctly.

Studies suggest that while the empty can test is valuable, it should be combined with other special tests, such as the drop arm test, Hawkins-Kennedy test, or imaging for confirmation.

When Should the Empty Can Test Be Used?

The test is typically performed when patients present with:

• Shoulder pain during lifting or overhead activities.

• Weakness in raising the arm.

• Suspected rotator cuff injuries due to sports or trauma.

• Chronic shoulder discomfort without clear cause.

It is particularly useful for athletes, laborers, and older adults who are at higher risk of rotator cuff injuries.

Clinical Relevance in Sports and Daily Life

Shoulder injuries are common among athletes in sports like baseball, tennis, swimming, and weightlifting. The empty can test allows sports physicians and trainers to quickly assess potential injuries without requiring advanced equipment.

In everyday life, the test can help identify early signs of rotator cuff problems in people who perform repetitive overhead tasks, such as painters, mechanics, or construction workers. Early detection means quicker intervention, preventing long-term disability.

Treatment After a Positive Empty Can Test

If the empty can test indicates a possible supraspinatus injury, treatment may include:

1. Conservative Care

   • Rest and activity modification.

   • Ice or heat therapy.

   • Nonsteroidal anti-inflammatory drugs (NSAIDs).

2. Physical Therapy

   • Exercises to strengthen surrounding muscles.

   • Range of motion training.

   • Postural corrections.

3. Medical Interventions

   • Corticosteroid injections for inflammation.

   • Imaging to confirm the extent of injury.

4. Surgical Options

   • In severe cases, surgical repair of the tendon may be necessary.

Preventing Rotator Cuff Injuries

While tests like the empty can test are crucial for diagnosis, prevention is always better than cure. Steps to reduce the risk of rotator cuff injuries include:

• Regular shoulder-strengthening exercises.

• Proper warm-up before sports or heavy lifting.

• Avoiding repetitive overhead motions without breaks.

• Maintaining good posture during work and daily activities.

Conclusion

The empty can test is a simple, reliable, and widely used clinical tool for evaluating shoulder injuries, particularly those involving the supraspinatus muscle and tendon. Although it is not foolproof, when combined with other examinations and imaging techniques, it provides valuable insights into shoulder function and possible injuries.

Understanding this test empowers patients and professionals alike to recognize the early signs of rotator cuff problems, seek appropriate care, and prevent long-term complications.

Healthy shoulders are vital for both athletic performance and daily living—making diagnostic tools like the empty can test essential in modern healthcare.