Empty Can/Full Can Test
Jo Gibson, 2005
The Empty Can Test (ECT) was originally described by Jobe and Moynes to test integrity of the supraspinatus tendon. Kelly later proposed the Full Can Test (FCT) as an alternative as though EMG activity in the supraspinatus was similar in both positions the FCT was less provocative. It was therefore less likely to result in muscle weakness due to pain provocation.
Test
The patient is tested at 90° elevation in the scapula plane and full internal rotation (empty can) or 45°external rotation (full can). Patient resists downward pressure exerted by examiner at patients elbow or wrist.
With thanks to Kathleen Tatlow
Positive
FCT
- Pain
- Muscle weakness Pain/Muscle Weakness/Both
ECT
- Pain
- Muscle weakness Pain/Muscle Weakness/Both
- Pain located to subacromial region and/or weakness.
Research
In Itoi's study the two tests were performed in 143 shoulders of 136 consecutive patients. The tests were considered positive when there was pain, muscle weakness or both. Shoulders were then examined by high resolution MRI with 95% accuracy for full thickness tears of the supraspinatus tendon. There were 35 shoulders with full thickness tear of the supraspinatus tendon. The accuracy of the tests was the greatest when muscle weakness was interpreted as indicating a tom supraspinatus tendon in both the full can test (75% accurate) and the empty can test (70%) accurate).
Itoi suggests that as the empty can position is more likely to be pain provoking, the full can test may be more beneficial in the clinical setting.
Sensitivity | Specificity | Accuracy |
66% | 64% | 64% |
77% | 74% | 75% |
86% | 57% | 64% |
63% | 77% | 89% |
55% | 68% | 50% |
57% | 57% | 59% |
Kelly, Kadrmas & Speer (1996) showed the best position for maximal isolation of the supraspinatus muscle was best achieved with the test position of elevation at 90° of scapular elevation and +45° (external rotation) of humeral rotation ('full can'). Howver, Boettcher, Ginn & Carruthers (2009) demonstrated on EMG studies that the supraspinatus is not sufficiently isolated in the empty can postion of abduction, calling into question the validity of this test for the diagnosis of suprapinatus patholgy.