How should I perform a systematic physical examination of the right shoulder in a 30‑year‑old woman who has difficulty lifting her infant and cannot reach behind her back?

Systematic Physical Examination of the Right Shoulder

In a 30-year-old woman with difficulty lifting her infant and inability to reach behind her back, perform a focused examination targeting rotator cuff pathology (particularly supraspinatus and infraspinatus tears), biceps tendon pathology, and internal rotation deficits, as these findings directly correlate with her functional limitations.

Initial Assessment Framework

Begin with the patient's torso completely exposed to visualize both shoulders for comparison. Examine from both anterior and posterior views 1, 2.

Inspection

• Posterior view: Look for scapular winging (suggests serratus anterior or trapezius palsy), muscle atrophy (particularly supraspinatus and infraspinatus fossae indicating chronic rotator cuff tears), and asymmetry 1, 3
• Anterior view: Assess for deltoid contour abnormalities, anterior shoulder swelling, and visible deformity
• Note: Muscle atrophy and fatty infiltration are critical findings that influence surgical decision-making and prognosis 4

Range of Motion Assessment

Active range of motion first (patient moves shoulder independently):

• Forward flexion: Normal is 180°; inability suggests rotator cuff pathology
• Abduction: Normal is 180°; painful arc between 60-120° indicates subacromial impingement (80% specificity) 5
• Internal rotation: Have patient reach behind back—document vertebral level reached (her inability to do this is a key finding suggesting subscapularis or posterior capsule pathology)
• External rotation: Test at side and at 90° abduction

Passive range of motion (examiner moves shoulder):

• If passive ROM exceeds active ROM, this suggests rotator cuff weakness rather than adhesive capsulitis
• If passive ROM is also restricted, consider adhesive capsulitis 6

Strength Testing (Critical for Rotator Cuff Assessment)

Supraspinatus (most commonly torn):

• Jobe test (empty can test): Arm at 90° abduction, 30° forward flexion, thumb down; resist downward pressure
  • Sensitivity 52.6%, specificity 82.4% for full-thickness tears 5
  • Weakness or pain with lifting infant directly correlates with this pathology

Infraspinatus/Teres Minor:

• External rotation lag sign: Arm at side, elbow flexed 90°, passively externally rotate shoulder maximally, then release
  • If arm drops >10° when released, indicates full-thickness tear
  • Combined supraspinatus and infraspinatus tears: 97% sensitivity, 93% specificity 5
• Hornblower's sign: Arm at 90° abduction, elbow flexed 90°; patient attempts to externally rotate against resistance
  • Inability indicates teres minor involvement

Subscapularis (affects internal rotation):

• Lift-off test: Hand behind back at waist level, lift hand away from back against resistance
  • Directly relevant to her inability to reach behind back
• Belly-press test: Hand on abdomen, press against resistance while maintaining elbow forward
  • If elbow drops back, indicates subscapularis weakness

Impingement Testing

Neer sign: Passively forward flex arm overhead while stabilizing scapula

• 75% sensitivity for subacromial impingement 5

Hawkins-Kennedy test: Arm at 90° forward flexion, forcibly internally rotate

• 80% sensitivity for subacromial impingement 5

Biceps Tendon Assessment

Speed test: Arm forward flexed 60°, elbow extended, forearm supinated; resist forward flexion

• 54% sensitivity, 81% specificity for biceps pathology 5
• Relevant given her lifting difficulties

Instability Testing (Less Likely but Important to Rule Out)

Apprehension test: Arm at 90° abduction and maximal external rotation; apply anterior force

• Hazard ratio 2.96 for anterior instability 5
• Less likely in her age group without trauma history, but MR arthrography would be indicated if positive (age <35 years) 4

Neurovascular Examination

• Axillary nerve: Test deltoid strength and sensation over lateral shoulder
• Suprascapular nerve: Already assessed via infraspinatus/supraspinatus testing
• Radial pulse: Ensure vascular integrity

Clinical Interpretation for This Patient

Her specific presentation (difficulty lifting infant + inability to reach behind back) most strongly suggests:

1. Supraspinatus tear (explains lifting difficulty)
2. Possible infraspinatus involvement (if external rotation is weak)
3. Subscapularis pathology or posterior capsule tightness (explains internal rotation deficit)

Critical Pitfall: Ten percent of rotator cuff tears are asymptomatic and present only with morphologic changes 4. However, her functional limitations make symptomatic pathology highly likely.

Next Steps Based on Examination Findings

If rotator cuff pathology is suspected clinically:

• MRI shoulder without contrast is the appropriate next imaging study (rating 9/9) 4
• Ultrasound is equivalent to MRI if local expertise available (rating 9/9) 4
• These modalities excel at detecting tendinosis, partial-thickness tears, and full-thickness tears with associated muscle atrophy and fatty infiltration 4

If labral pathology suspected (less likely given age and presentation):

• MR arthrography would be preferred for patients <35 years 4

The examination findings of weakness in specific rotator cuff muscles combined with her functional deficits provide the clinical diagnosis that guides imaging selection and subsequent management decisions 7, 1.