What are the physical examination (PE) findings and patient symptoms that indicate the need for a shoulder steroid injection, and what is the proper technique for administration?

Shoulder Steroid Injection: Indications and Technique

Clinical Indications for Shoulder Corticosteroid Injection

Shoulder corticosteroid injections are indicated when patients present with shoulder pain lasting more than one month that has failed conservative therapy (over-the-counter medications and physical therapy), particularly when pain intensity exceeds 4/10 or causes functional limitation. 1, 2

Key Physical Examination Findings

• Positive impingement signs: Neer impingement sign and Hawkins impingement sign indicate subacromial pathology requiring injection 3
• Painful arc of motion: Pain during active abduction between 60-120 degrees suggests subacromial impingement 3
• Limited range of motion: Restricted forward elevation, abduction, internal rotation, or external rotation compared to contralateral side 3
• Painful tendon signs: Tenderness over rotator cuff insertion points on the greater tuberosity 3
• Absence of complete rotator cuff tear: Patients should maintain some active elevation capability; inability to actively elevate suggests full-thickness tear requiring surgical evaluation 3

Patient Symptoms Warranting Injection

• Pain duration: Symptoms present for 1-12 months that have not responded to NSAIDs, rest, or initial physical therapy 3
• Pain pattern: Pain with overhead activities, reaching behind back, or lying on affected shoulder 4
• Functional impairment: Difficulty with activities of daily living despite conservative measures 1, 2
• Night pain: Persistent nocturnal pain disrupting sleep 4

Contraindications to Assess

• Active infection: Local or systemic infection is an absolute contraindication 5
• Complete rotator cuff tear: If suspected based on inability to actively elevate arm or positive drop arm test, imaging should precede injection as surgery may be needed 3
• Allergy to corticosteroids or local anesthetics: Document any prior reactions 5

Proper Injection Technique

Subacromial Injection Approach (Preferred for Impingement)

The subacromial space should be accessed via a posterior or lateral approach, with the injection containing both corticosteroid and local anesthetic for immediate pain relief and diagnostic confirmation. 3

Preparation

• Strict aseptic technique is mandatory 5
• Shake the corticosteroid vial to ensure uniform suspension and inspect for clumping or granular appearance (agglomeration); discard if present 5
• Prepare injectate: 1 ml triamcinolone acetonide 40 mg (or methylprednisolone 40 mg) mixed with 1 ml lidocaine 1-2% 3, 6

Posterior Approach Technique

• Position patient sitting with arm relaxed at side 3
• Identify the posterolateral corner of the acromion 3
• Insert needle approximately 1-2 cm below the posterior acromion edge, directing anteriorly and slightly superiorly into the subacromial space 5, 3
• Aspirate to ensure no blood vessel entry 5
• Inject without delay after withdrawal to prevent settling in syringe 5
• Total injection volume: 2 ml (1 ml corticosteroid + 1 ml local anesthetic) 3

Lateral Approach Alternative

• Patient positioned with arm at side 3
• Palpate lateral edge of acromion 3
• Insert needle horizontally just beneath the lateral acromion edge, advancing medially into subacromial space 5

Glenohumeral Joint Injection (For Intra-articular Pathology)

For glenohumeral osteoarthritis or intra-articular pathology, direct intra-articular injection may be considered, though evidence for efficacy is limited. 1

Dosing for Intra-articular Injection

• Larger joints (glenohumeral): 5-15 mg triamcinolone acetonide, with doses up to 40 mg used for larger areas 5
• Smaller joints: 2.5-5 mg triamcinolone acetonide 5

Post-Injection Protocol

• Immediate assessment: Pain should decrease within 10-15 minutes if local anesthetic included, confirming correct placement 3
• Activity modification: Avoid strenuous shoulder activities for 48 hours 3
• Rehabilitation: Initiate home exercise program focusing on rotator cuff stretching and strengthening after 48 hours 3
• Avoid overhead pulley exercises: These promote uncontrolled abduction and can worsen pathology 7, 2

Expected Outcomes and Follow-Up

• Short-term efficacy: 91% of patients show satisfactory improvement in pain and range of motion at 4 weeks, with mean improvements of 56° forward elevation, 48° abduction, 18° internal rotation, and 22° external rotation 3
• Long-term efficacy: 88% maintain improvement at 1 year, though 8% experience recurrence after average of 5.4 months 3
• Repeat injection criteria: Consider repeat injection if patient had ≥50% pain relief lasting at least 2 months from first injection 7
• Surgical referral: If no improvement after 1-2 injections, suspect rotator cuff tear and obtain MRI; 9% of non-responders have partial or complete tears requiring surgery 3

Critical Pitfalls to Avoid

• Missing rotator cuff tears: Failure to improve after injection should prompt imaging for rotator cuff tear, not repeated injections 3
• Improper injection technique: Ensure deep injection into subacromial space or joint; subcutaneous injection causes fat atrophy without therapeutic benefit 5
• Agglomerated product: Never use corticosteroid suspension that appears clumped or granular 5
• Delayed injection: Inject immediately after drawing up suspension to prevent settling 5
• Overhead pulley exercises: These are contraindicated and can worsen shoulder pathology 7, 2

Adverse Events

• Common: Injection site soreness (most common), transient pain flare, facial flushing/sweating (corticosteroid-specific), vasovagal reaction (2.5% incidence) 7
• Rare: Joint infection, though extremely uncommon with proper aseptic technique 7
• Bleeding risk: Low; most guidelines recommend continuing anticoagulation 7