Most common causes of pain: rotator cuff tendinopathy, impingement, acromioclavicular joint disease, adhesive capsulitis, referred pain.
Usually pain related to progression of subacromial bursitis to tendinitis to partial/full thickness tears. Usually due to activity involving putting arm above shoulder.
Rotator Cuff Tendons: 4 muscles, all originate on scapula, go thru glenohumeral joint and insert onto proximal humerus.
Supraspinatus: back/top of scapula. Arm elevation/abduction. Isolate by doing ’empty beer can’ movement with arm abducted 90 degrees with 30 degrees of forward flexion and resist upward movement.
Infraspinatus: back/middle scapula. Arm external rotation. Isolate with teres minor with arm adducted at waist with elbow bent at 90 degrees and resist external rotation.
Teres Minor: lateral scapula. Similar function to infraspinatus with external rotation.
Subscapularis: Anterior scapula. Isolate with arm adducted, elbow flexed to 90 degrees and resist internal rotation.
Coracoacromial Arch: space that rotator cuff functions. Coracoid posteriorly, acromion anteriorly, humeral head inferiorly.
Subacromial bursa: main bursa for shoulder/rotator cuff.
Impingement Syndrome: repetitive overuse of arm causes changes to bursa, rotator cuff, biceps tendon. Edema/hemorrhage of tendon (pain with activity, resolved with rest) leads to tendinitis/fibrosis (aching pain, night pain) leads to tears/tendon rupture/spurs (likely needing surgical decompression). Pain usually in anterior/lateral shoulder radiating into mid humerus. Pain at night. pain with resisted motions.
Neer maneuver: prevent scapular rotation and raise straight hand in forward flexion. Causes impingement at 70-120 degrees.
Hawkins impingement test: abducted 90 degrees, elbow at 90 degrees and internally rotate with resistance.
Tx: minimize all overhead activity. Immobilization not recommended. NSAIDs as always. Cryotherapy (ice) 3-4x/day. Exercises: pendulum swings in clockwise/counterclockwise to level of pain. Also walk fingers up wall. Steroid injections can be effective though can cause muscular atrophy/weakness.
Rotator Cuff Tears: acute injury rare (10%); majority related to chronic injury/use. Glenohumeral dislocation is common cause of tear. If dislocation with age> 40, 60% have tear. If still having weakness > 3 weeks after injury, likely tear involved. Partial thickness 2x more common than full tear – conservative treatment where as full tear usually requires surgery. Supraspinatus most common tendon injured.
Rent test: patient has relaxed flexed elbow. Palpate rotator cuff (anterior to acromion thru deltoid). Soft tissue defect are palpated as arm is brought into full extension with internal/external rotation.
Drop arm test: patient unable to keep arm abducted 90 degrees when let go or falls with light push.
Xray: non helpful usually, narrowing of acromiohumeral space <7mm very specific for large tear.
Tx: slight for acute pain, prolonged immobilization should be avoided. NSAIDs, ROM, f/u with ortho/sports medicine.
Calcific Tendonitis: calcium deposits within the tendon. Females > males, age 40-60. Supraspinatus most likely involved. Calcium near proximal humerus. Catchy sensation on movement. Sometimes warm/tender shoulder. During resorptive phase, increase in pain can occur. Usually self-limited, lasting 1-2 weeks. Adhesive capsulitis most common complication. Worse at night, resorptive usually spontaneous. Tx: Same as above, keep arm abducted slightly either on back of chair or pillow in armpit at night. Can get ‘needle lavage’ to break up tension within tendon.
Adhesive capsulitis: ‘frozen shoulder’ syndrome. can be caused by post-menopause, DM, thyroid, pulmonary neoplasm, autoimmune. Usually women 40-60 yo, non dominant hand. Limited active and passive ROM.
Stage I: synvoial inflammation with limited shoulder movement (2-3 months). Stage II: freezing stage – decrease in shoulder motion with capsular thickening/scarring/chroinc pain (3-9 months). Stage III: frozen stage – less pain but more fibrosis (9-15 months). Stage IV: thawing stage – improvement with minimal pain (>15 months).
Tx: avoid sling, physical therapy at stage II. Consider oral steroids. Injection help as well.
Bicipital Tendonitis: acute pain at anterior aspect of shoulder. Biceps tendon rupture is always proximal tendon. Palpate bicipital groove in anterior humeral head with arm externally rotated. Muscle isolated mainly with forearm supination.
Ferguson test: shoulder adducted, elbow at 90 degrees – resist supination.
Bicep tendon rupture: ‘popeye’ deformity caused by distal contraction of muscle belly. Tx: sling – usually surgery in younger adults.
Osteoarthritis: rare due to joint not weight bearing, though can occur.
Acute thrombosis of axillary artery: due to repetitive mechanical trauma or explosive stress from lifting objects.
Tintinalli, Chapter 277: Shoulder Pain
Rosen, Chapter 46: Shoulder