Shoulder pain is common. Pain can be due to intraarticular causes, periarticular causes and can be referred from other areas especially the cervical spine. For the purposes of this chapter it is important to be able to differentiate between a number of common problems outlined below.
Initially this will seem overwhelming, however, with an understanding of the anatomy the signs become easy to interpret. (diagram shoulder muscles and subacromial bursa).
Examination of the shoulder begins with exposing the area. Ask the patient to remove outer garments. This maybe difficult for the patient to do due to shoulder problems. Inspect from anterior, lateral and posterior aspects. Look for swelling and wasting. Wasting can be subtle and the shoulder should be compared to the opposite shoulder.
Begin palpation by standing behind the patient. Place your hand over the shoulder and feel for warmth. Palpate under the lateral end of the spine of the scapula with your thumb. This is the posterior aspect of the glenohumeral joint. Then palpate laterally under the acromion. Tenderness here is due to subacromial bursitis or supraspinatus tendonitis. Next palpate anterior with your index and middle fingers. Feel in the bicipital groove for bicipital tendonitis. Feel just medial to the coracoid process for anterior glenohumeral joint tenderness. Finally palpate the acromioclavicular joint. This is approximately 2 cm medial to the tip of the acromion.
Passive movements should be carried out from behind the patient. Stabilize the scapula by placing your fingers on the spine of the scapula and your thumb on the inferior angle of the scapula. With the elbow extended abduct the arm. A painful arc occurs when there is impingement of the supraspinatus tendon. Initially with abduction there is enough space for the supraspinatus tendon in the subacromial space but as the arm is abducted further the space narrows. This results in impingement and pain. This usually begins at approximately 70° abduction. Pain continues for another 120° abduction. At this point the pain is relieved, as once again there is space for the supraspinatus tendon. (Diagram)
The subacromial bursa and biceps tendon can also become impinged. With subacromial bursitis the painful arc tends to occur earlier than with supraspinatus tendonitis and there is no relief of pain above 120° abduction. In fact it is usually too painful to continue the abduction. With the biceps tendon the impingement occurs with abduction when the shoulder is flexed approximately 20° and then abducted.
Abduction is also painful with acromioclavicular joint disease. Causes of a monoarthritis of the acromioclavicular joint is the same as for peripheral joints. However, a tender joint without an effusion is usually due to osteoarthritis. With synovitis of the glenohumeral joint abduction as well as all other movements are painful.
Test for extension. With the arm by the side and elbow extended bring the arm back. Anterior shoulder pain occurs with biceps tendonitis.
Test for internal and external rotation. With the arm by the patient’s side and the elbow flexed to 90° rotate the arm towards the abdomen and then laterally. The hand should be able to touch the abdomen. Normal external rotation is 80-90°. Then ask the patient to put their hand behind their back and see how far they can move their thumb up their spine. The vertebral level should be noted. External rotation (as well as other movements) is severely limited in capsulitis.
Now move on to testing resisted movements. Again from behind check for resisted abduction. Ask the patient to abduct the arm against resistance. Immediate pain suggests supraspinatus tendonitis as the supraspinatus is the muscle used during the first 20° of abduction. Weakness implies a tear or partial tear of the supraspinatus tendon. Then ask the patient to raise the arm to 70° abduction and again test resistance. Weakness suggests deltoid weakness, which can be due to shoulder pathology or a sign of more global proximal weakness.
Then move to the front of the patient. Ask the patient to leave their arm by their side, flex the elbow to 90° and their wrist in a neutral position. Place your hand against the patient’s hand. Test resisted internal rotation by asking the patient to push against your hand. Pain suggests subscapularis tendonitis and weakness suggests a rupture or partial rupture of the tendon. (Diagram)
Test for resisted external rotation. Place your hand against the back of the patient’s hand. Ask the patient to push with the back of their hand against your hand. Pain suggests infraspinatus tendonitis and weakness suggests rupture or partial rupture of the infraspinatus tendon.
Some specialized tests.
Often when examining the shoulder the signs that are elicited are mixed. This is because often more than one structure is involved. For instance, in supraspinatus tendonitis there is often involvement of the subacromial bursa or biceps tendon. Consequently the signs will be somewhat mixed and difficult to interpret. Therefore if a particular lesion is suspected then further tests should be carried out to confirm the initial signs. These are more specialized clinical tests.