Why can tests suck | Proper Supra- & Infraspinatus Assessment

most probably every one of us learned the empty and full can tests as special tests for the supraspinatus muscle. However, an EMG study done by Boettcher et al. (2009a) has shown that the empty can and the full can test both activate 9, respectively 8 other muscles around the shoulder complex to the same degree.

It is impossible to completely isolate the cuff from other shoulder muscles, but we have to find positions that reduce the other muscles’ activity better.
Another study by Boettcher et al. (2009b) has shown that external rotation in the zero position is better at reducing deltoid activity, but we’re going to show you the best position now:

Having your patient in prone position allows him to relax the deltoid and trapezius muscles and to activate the supraspinatus and infraspinatus even more. Abduct the shoulder to 90° and flex the elbow to 90° and apply resistance at the wrist This also means that it is impossible to isolate the supraspinatus from the infraspinatus.

21 OF THE MOST USEFUL ORTHOPAEDIC TESTS IN CLINICAL PRACTICE

• • Name*
• • Email*

Δ

Other common tests to assess for subacromial impingement syndrome are:

• Hawkins-Kennedy Test
• Neer Test
• Full Can Test
• Painful Arc Sign

References

Boettcher, C. E., Ginn, K. A., & Cathers, I. (2009). The ‘empty can’and ‘full can’tests do not selectively activate supraspinatus. Journal of Science and Medicine in Sport, 12(4), 435-439.

Boettcher, C. E., Ginn, K. A., & Cathers, I. A. N. (2009). Which is the optimal exercise to strengthen supraspinatus?. Medicine and science in sports and exercise, 41(11), 1979-1983.