A patient presents with subacute right sided shoulder pain. Could this be rotator cuff disease?
The shoulder joint is shallow, making it the most mobile joint in the body. Much of its stability comes from muscles that traverse the glenohumeral joint. In addition to the rotator cuff, the long head of the biceps traverses this joint. Both are susceptible to degeneration as they rub against bone in a narrow space. Rotator cuff disease and bicipital tendinitis should be thought of together.
Although there are many specialized tests, the most important thing is knowing muscle function and how to test for it.
INFRASPINATUS/TERES MINOR -These serve external rotation. With the elbows at the side and flexed 90 degrees (airplane seat position), test external rotation against resistance. The best method is to tell the patient “don’t let me move you arm.”
SUBSCAPULARIS – The function of the subscapularis is internal rotation, and this could be tested in the same position. However, internal rotation is also supplied by the pectoralis major and the latissmus dorsi. To isolate the subscapularis, have the patient put the hand behind the small of the back and lift off against resistance (Gerber’s lift-off test).
SUPRASPINATUS – The supraspinatus serves abduction from 15-90 degrees. This is best tested in the scapular plane (not forward flexion, not pure lateral abduction, but about in between). Put the arm in this position, say “don’t let me move your arm,” and press against resistance. The biceps contributes to arm abduction and supination, so reduce its contribution by pronating the arm, thumb down (empty can test, aka Jobe’s test). This test is sensitive but not specific. Minor variations of this test are used to check for biceps tendinitis and labral tears, but these tests do not reliably discriminate between these diseases.
BICEPS TENDON – The biceps tendon serves arm abduction and forearm supination. Speed’s test is basically the empty can test but with the thumb up, in supination. Yergason’s test basically tests for resisted supination. Both are best performed with simultaneous bicipital tendon palpation. If these tests bring out bicipital tenderness, then they are considered positive.
Traditionally, it was believed that palpation of bicipital groove tenderness was pathognomonic for bicipital tendinitis. This has since been challenged. The hard part is finding the tendon. Here is how to do it. Put the patient in airplane seat position (elbows 90 degrees, at the side). Palpate just lateral to the coracoid. The bicipital groove runs between the lesser and greater tuberosity, so externally rotate the arm just a bit to expose the area. Drop down to the humeral head and feel the tendon roll as you move your thumb side to side. You can actually feel the tendon pulley as the patient flexes and extends the elbow (better palpated in internal rotation). Finally, you want to palpate the part of the tendon that is internal, getting frayed, so now extend (backward) the shoulder as much as possible as you palpate the tendon you have found. Your thumb should be as proximal as possible, right up against the acromion.
- Infraspinatus/teres minor – external rotation (airplane seat position)
- Subscapularis – internal rotation (lifting off from small of back)
- Supraspinatus – abduction in pronation from 15-90 degrees (nonspecific)
- Long head of the biceps – Arm abduction, forearm supination. The tests would be very nonspecific, but palpation of the tendon can improve specificity.