What type of shoulder injection is recommended for a patient with suspected shoulder impingement or tendinitis, presenting with pain on abduction and external rotation of the shoulder?

Subacromial Corticosteroid Injection

For this patient with clinical features of subacromial impingement syndrome (pain on abduction beyond 90°, pain with external rotation, radiation to lower arm), a subacromial corticosteroid injection is the appropriate therapeutic injection. 1

Clinical Reasoning

The presentation strongly suggests subacromial impingement with rotator cuff tendinopathy/bursitis:

• Pain specifically during abduction beyond 90° indicates subacromial space narrowing 1
• Pain with external rotation is characteristic of rotator cuff involvement 1
• Pain only with movement (not at rest) suggests mechanical impingement rather than inflammatory arthropathy 1
• Radiation to lower arm during abduction is consistent with subacromial pathology 1

Injection Technique and Target

The subacromial space is the correct anatomic target because:

• The subacromial bursa and rotator cuff (particularly supraspinatus) are the primary pain generators in impingement syndrome 1
• Corticosteroid injections into the subacromial region are specifically recommended when pain is related to injury or inflammation of the rotator cuff or bursa 1
• This approach directly addresses the mechanical irritation occurring between the rotator cuff and coracoacromial arch during abduction 1, 2

Evidence-Based Support

The Canadian Stroke Best Practice Recommendations explicitly state that subacromial corticosteroid injections should be used when pain is thought to be related to injury or inflammation of the subacromial region (rotator cuff or bursa) 1. While this guideline addresses hemiplegic shoulder pain, the anatomic principles apply to all subacromial pathology.

The ACR Appropriateness Criteria note that ultrasound guidance may include injection of anesthetic and/or corticosteroid when clinically warranted for bursitis or tendinopathy 1.

Important Caveats

• Fluoroscopic or ultrasound guidance improves accuracy of subacromial injections, though blind technique is acceptable in experienced hands 1
• The injection should target the subacromial-subdeltoid bursa, not the glenohumeral joint itself 1
• Corticosteroid injection is adjunctive therapy - the patient still requires rehabilitation focusing on rotator cuff and scapular stabilizer strengthening 1
• If no improvement occurs after injection, consider alternative diagnoses including glenohumeral instability or labral pathology 1

Contraindications to Consider

Before proceeding, ensure there are no contraindications such as:

• Active infection (local or systemic) 1
• Allergy to corticosteroids or local anesthetics 1
• Complete rotator cuff tear requiring surgical repair (injection may delay necessary surgery) 1

Post-Injection Management

Following the subacromial injection 1:

• Relative rest for 48-72 hours
• Gradual return to activity as pain permits
• Physical therapy emphasizing rotator cuff strengthening and scapular stabilization 1
• Technique modification to avoid repetitive overhead activities during recovery 1