Full Can Test

The Full Can Test is used to assess the function of the supraspinatus muscle and tendon in the shoulder complex. It is particularly relevant for identifying rotator cuff pathology, including supraspinatus tears and tendinopathy¹².

Test execution

Patient position

• The patient may sit or stand.

• The arm is positioned in 90° elevation in the scapular plane (30° anterior to the frontal plane).

• The shoulder is placed in full external rotation, so that the thumb points upward.

Procedure

• The examiner stabilizes the patient’s shoulder.

• A downward force is applied to the arm while the patient resists.

• A positive test is indicated by pain and/or weakness in the shoulder.

Interpretation

• Positive test:

  • Pain → may indicate irritation, tendinopathy, or other rotator cuff pathology.

  • Weakness → has stronger diagnostic value and correlates more closely with arthroscopic findings¹.

• Negative test:

  • Suggests that the supraspinatus is intact or not the primary cause of symptoms.

Diagnostic validity

• Sensitivity: 70% (95% CI: 59–82%)

• Specificity: 81% (95% CI: 74–88%)

Clinical application

Full Can vs. Empty Can Test

• Both tests produce similar EMG activation of the supraspinatus.

• The Full Can Test is less painful than the Empty Can Test and provides slightly better isolation of the supraspinatus⁴⁵.

Combination with other tests

• Combining the Empty Can Test, Full Can Test, and Zero-Degree Abduction Test provides the highest diagnostic accuracy for supraspinatus tears (AUC = 0.795)¹.

• The test correlates well with intraoperative findings, especially in tears ≥ 1 cm¹.

Limitations

• The Full Can Test does not isolate the supraspinatus completely, as up to 13 muscles may be simultaneously activated during the test⁷.

• Some studies suggest that shoulder special tests should primarily be viewed as pain provocation tests rather than stand-alone diagnostic tools⁸.

Conclusion

The Full Can Test is an effective assessment for supraspinatus function and is less painful than the Empty Can Test while providing comparable EMG activation.

• Weakness is more reliable than pain as a diagnostic criterion.

• The test demonstrates moderate sensitivity and specificity, but diagnostic accuracy is highest when combined with other supraspinatus tests.

• The Full Can Test should be used as part of a comprehensive shoulder evaluation to increase clinical certainty.

References

1. Sgroi M, Loitsch T, Reichel H, Kappe T. Diagnostic Value of Clinical Tests for Supraspinatus Tendon Tears. Arthroscopy. 2018;34(8):2326–33.

2. Timmons MK, Yesilyaprak SS, Ericksen J, Michener LA. Full can test: Mechanisms of a positive test in patients with shoulder pain. Clin Biomech [Internet]. 2017;42:9–13.

3. Ccedseminars. Full Can Test. Available from: https://www.youtube.com/watch?v=SGEIKmiP09s [last accessed 1/7/2024]

4. Kelly BT, Kadrmas WR, Speer KP. The manual muscle examination for rotator cuff strength: an electromyographic investigation. The American journal of sports medicine. 1996 Sep;24(5):581-8.

5. Lee CK, Itoi E, Kim SJ, Lee SC, Suh KT. Comparison of muscle activity in the empty-can and full-can testing positions using 18 F-FDG PET/CT. Journal of orthopaedic surgery and research. 2014 Dec;9(1):1-8.

6. Jain NB, Luz J, Higgins LD, Dong Y, Warner JJ, Matzkin E, Katz JN. The diagnostic accuracy of special tests for rotator cuff tear: the ROW cohort study. American journal of physical medicine & rehabilitation. 2017 Mar;96(3):176.

7. Boettcher, Craig E et al. “The 'empty can' and 'full can' tests do not selectively activate supraspinatus.” Journal of science and medicine in sport vol. 12,4 (2009): 435-9. doi:10.1016/j.jsams.2008.09.005

8. Salamh P, Lewis J. It is time to put special tests for rotator cuff-related shoulder pain out to pasture. The journal of orthopaedic and sports physical therapy. 2020;50(5):222–5.