What are the impingement signs associated with rotator cuff injury?

Impingement Signs Associated with Rotator Cuff Injury

The key impingement signs for rotator cuff injury are Neer's test (88% sensitive, 33% specific) and Hawkins' test (92% sensitive, 25% specific), along with pain during overhead activities, focal weakness, and decreased range of motion during abduction with external or internal rotation. 1

Primary Physical Examination Signs

Provocative Tests

• Neer's test involves passive forward flexion of the arm while stabilizing the scapula, reproducing pain when the greater tuberosity impinges against the anteroinferior acromion (88% sensitivity, 33% specificity) 1
• Hawkins' test is performed with forcible internal rotation while the arm is passively flexed forward at 90 degrees, demonstrating 92% sensitivity but only 25% specificity for impingement 1, 2
• The relocation test may be positive in athletes with subtle anterior instability causing secondary impingement 3

Pain Patterns

• Anterior or anterolateral shoulder pain that worsens with overhead activities is the hallmark symptom (88% sensitivity) 1
• Pain specifically during the arm cocking and acceleration phases of throwing or overhead motions indicates impingement 4, 1
• Pain during the release, deceleration, and follow-through phases suggests rotator cuff tendinopathy 4
• Night pain is typical of full-thickness rotator cuff tears 3

Range of Motion and Strength Deficits

• Focal weakness is present in approximately 75% of cases with impingement syndrome 1, 5
• Decreased range of motion during abduction with external or internal rotation is a consistent finding 4, 1
• Weakness specifically in elevation and external rotation is common 3
• A positive "shrug sign" (inability to actively elevate the arm without shrugging the shoulder) indicates significant rotator cuff pathology 3

Underlying Pathophysiological Signs

Scapular Dysfunction

• Scapular dyskinesis manifests as poor coordination of scapular movements during arm elevation, with failure to properly rotate upward and tilt posteriorly 4, 1, 5
• This abnormal scapular motion directly contributes to impingement by altering the subacromial space 4, 1

Instability-Related Signs

• Difficulty maintaining humeral head centering in the glenoid fossa during arm motion, particularly in secondary impingement 4, 1
• Rotator cuff weakness combined with ligamentous laxity, especially in younger athletes, creates dynamic instability 4, 1
• The "drive-through" sign on arthroscopy indicates anterior capsular laxity in athletes with secondary impingement 3

Muscular Imbalance

• Weakened posterior shoulder musculature (external rotators, scapular stabilizers) combined with overdeveloped anterior musculature creates pathologic biomechanics 4, 5
• This imbalance leads to repetitive eccentric stress on the supraspinatus, external rotators, and scapular stabilizers 4

Progressive or Advanced Signs

Performance Decline

• Decreased velocity and precision in throwing athletes indicates progressive rotator cuff dysfunction 4, 1
• Decreased ability to locate pitches or perform sport-specific overhead movements 4

Structural Changes

• Supraspinatus tendon irritation from subacromial outlet obstruction is the primary pathophysiological mechanism 4, 1
• Tendon degeneration with potential progression to partial or full-thickness tears if left untreated 1, 5

Important Clinical Distinctions

Primary vs. Secondary Impingement

• Primary impingement results from extra-articular rotator cuff pathology and structural abnormalities (acromion spurs, AC joint arthritis), more common in middle-aged and older adults 1, 3, 6
• Secondary impingement occurs from rotator cuff weakness and ligamentous laxity causing dynamic instability, predominant in younger athletes and overhead sport participants 4, 1, 5

Age-Specific Considerations

• In skeletally immature athletes, look for atraumatic microinstability and weak rotator cuff muscles rather than structural abnormalities 4, 5
• Undersurface (articular-side) tears from overuse are more common than full-thickness tears in adolescents 4, 5

Common Pitfalls to Avoid

• Do not rely solely on provocative tests given their low specificity; Neer's and Hawkins' tests are highly sensitive but have poor specificity (25-33%), requiring correlation with other clinical findings 1
• Do not miss subtle instability in young overhead athletes, as they may be unaware of underlying glenohumeral instability causing secondary impingement 7, 3
• Do not overlook scapular dyskinesis, as this is a primary contributor that must be addressed in treatment 4, 1, 5
• Recognize that rotator cuff abnormalities are common in asymptomatic overhead athletes, making identification of symptomatic disease challenging 8