What is the diagnosis and management of a positive painful arc test?

Painful Arc Test: Diagnosis and Management of Shoulder Impingement Syndrome

A positive painful arc test indicates subacromial impingement syndrome (SAIS), which should be managed with a combination of conservative treatment initially, followed by surgical intervention if conservative measures fail.

What is the Painful Arc Test?

The painful arc test is a physical examination maneuver used to diagnose subacromial impingement syndrome (SAIS). It is performed by having the patient actively abduct their arm from a neutral position to full elevation.

• Positive Test: Pain occurs between 70-120° of abduction but diminishes above and below this range
• Mechanism: Pain results from compression of the rotator cuff tendons (particularly supraspinatus) between the humeral head and the acromion during this specific arc of motion
• Diagnostic Value: The painful arc test has moderate to substantial reliability (kappa=0.45-0.67) and good diagnostic accuracy with:
  • Sensitivity: High (able to rule out SAIS when negative)
  • Specificity: Moderate (helpful in confirming SAIS when positive)
  • Positive likelihood ratio: 2.25 1

Diagnostic Approach

1. Physical Examination Combination:

   • The painful arc test should not be used in isolation
   • Combine with other special tests for higher accuracy:
     • External rotation resistance test
     • Empty can (Jobe) test
     • Neer impingement test
     • Hawkins-Kennedy test

2. Diagnostic Algorithm:

   • If 3 or more of these 5 tests are positive → High probability of SAIS 1, 2
   • Best combination for confirming SAIS: painful arc + empty can + external rotation resistance (when 2+ are positive) 2
   • Best combination for ruling out SAIS: painful arc + external rotation resistance (when both negative) 2

3. Imaging:

   • Radiography: First-line imaging for all patients with shoulder pain to rule out fractures, dislocations, and bony abnormalities 3
   • MRI: Indicated when radiographs are normal or equivocal to assess for rotator cuff tears and other soft tissue pathology 3

Management Approach

Conservative Management (First-line treatment)

1. Rest and Activity Modification:

   • Avoid painful overhead activities
   • Modify work or sports activities that provoke symptoms

2. Physical Therapy:

   • Rotator cuff and scapular stabilizer strengthening
   • Range of motion exercises
   • Posture correction

3. Medications:

   • NSAIDs for pain and inflammation
   • Analgesics as needed for pain control

4. Corticosteroid Injections:

   • Consider subacromial corticosteroid injection if symptoms persist despite other conservative measures
   • May provide temporary relief to facilitate physical therapy

Surgical Management

If conservative treatment fails after 3-6 months, surgical intervention should be considered:

1. Arthroscopic Subacromial Decompression:

   • Acromioplasty (reshaping of the acromion)
   • Excision of the coracoacromial ligament
   • Removal of subacromial bursa

2. Additional Procedures (based on intraoperative findings):

   • Rotator cuff repair if tear is present
   • Distal clavicle excision if acromioclavicular joint arthritis is present
   • Biceps tenodesis if biceps pathology is present

Prognosis

• Conservative Treatment: Approximately 60-70% of patients improve with conservative management alone
• Surgical Outcomes: 80-90% success rate with appropriate patient selection 4, 5
• Recovery Timeline:
  • Shorter recovery (3-4 months) with isolated subacromial bursitis or minor impingement
  • Longer recovery (6-12 months) with associated rotator cuff tears, especially larger tears 4

Common Pitfalls to Avoid

1. Misdiagnosis: Painful arc can also be present in other conditions:

   • Rotator cuff tears
   • Acromioclavicular joint arthritis
   • Glenohumeral instability
   • Biceps tendinopathy

2. Incomplete Evaluation: Never rely on a single test; always perform a comprehensive shoulder examination

3. Delayed Referral: Failure to refer for surgical consultation after 3-6 months of failed conservative treatment can lead to progression of rotator cuff damage

4. Overlooking Associated Pathologies: SAIS often coexists with other shoulder conditions that may require specific treatment approaches

The painful arc test is a valuable clinical tool when used as part of a comprehensive shoulder examination. When positive, it strongly suggests subacromial impingement syndrome, which should be managed with a structured approach beginning with conservative measures and progressing to surgical intervention when necessary.