Abstract
Shoulder impingement is a common source of gradual-onset shoulder pain, accounting for 44-65% of shoulder pain cases. It is mainly caused by repetitive overhead activities, osteophyte formation, or weakness of the stabilizing shoulder muscles. It can be confused with labral tears, rotator cuff tears, glenohumeral instability, or biceps pathology, without a proper history and physical exam. Imaging is usually limited to x-rays, magnetic resonance imaging (MRI), and ultrasound to rule out other pathology. Conservative management including activity modifications, rest, nonsteroidal antiinflammatory drugs (NSAIDs), corticosteroid injections, physical therapy, and home exercise programs are the mainstay of treatment to which most patients improve. Surgery is reserved for those who do not respond to conservative treatment more than 3 months. Overall, shoulder impingement is an insidious source of shoulder pain that has a favorable outcome with conservative management. Long-term prevention is aimed at avoiding repetitive overhead movements.
Key Concepts
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Subacromial impingement occurs in the subacromial space between the lateral aspect of the acromion and the humeral head
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Accounts for 44-65% of all shoulder pain
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May result in rotator cuff tendonitis/tendinopathy, subacromial bursitis, and degenerative rotator cuff tears ( Fig. 33.1 )
Fig 33.1
(A) Left, Subacromial bursitis; Right, Rotator cuff tendinitis. (B) Evaluation of the subacromial space with ultrasound and ultrasound guided steroid injection. MRI, Magnetic resonance imaging; NSAIDs , nonsteroidal antiinflammatory drugs.
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Congenital or degenerative changes involving the acromioclavicular joint may further contribute to the development of subacromial impingement syndrome.
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Symptoms typically resolve with conservative management such as activity modification, antiinflammatory medication, and/or physical therapy.
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Surgical management is acromioplasty (open or arthroscopic)/subacromial decompression
History
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Insidious onset of throbbing or aching pain of the anterolateral shoulder
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Typically no history of an acute injury
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Participation in repetitive overhead activities
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Painful range of motion, worse with forward flexion and abduction above the level of the shoulder (90 degrees)
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No radicular symptoms or sensory deficits
Physical Examination
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Inspection: Usually no visible shoulder abnormalities or asymmetry compared with opposite side, unless scapular winging or dyskinesia present (see Chapter 41 )
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Palpation: May have tenderness on palpation lateral to the acromion or upon compression of subacromial space
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Range of motion: Overall preserved, but pain reported on forward flexion and in mid-range of abduction (70 to 130 degrees, the “painful arc of abduction”)
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Strength testing: Usually equal to opposite side unless apparent strength loss due to pain from another cause, such as rotator cuff tendinitis
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Neurovascular testing intact
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Special tests positive for impingement: Neer (92% sensitivity, 26% sensitivity) and Hawkins ( Figs. 33.2 and 33.3 ;
Video 33.1 )
Fig 33.2
Neer sign. Pain with passive forward elevation of affected arm to 180 degrees with the arm externally rotated.
Fig 33.3
Hawkins sign. Pain is reproduced with passive flexion of the affected arm at 90 degrees and flexion of the elbow at 90 degrees. The arm is then internally rotated.
Impingement Tests
Imaging
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Radiographs
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Anteroposterior (AP) or posteroanterior (PA), lateral, axillary Y, and scapular outlet views to evaluate acromioclavicular and glenohumeral joints, acromion type, presence of osteoarthritis or osteophyte formation
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Magnetic resonance imaging (MRI) or ultrasound (see Fig. 33.1 )
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Useful if there are suspected rotator cuff or labral tears in acute injury
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Consider arthrogram to better evaluate labral pathology
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