What are the recommended doses of Kenalog (triamcinolone acetonide) and Decadron (dexamethasone) for injection into a knee joint, and how much Lidocaine should be used for local anesthesia?

Intra-Articular Knee Injection Dosing

For knee joint injections, use triamcinolone acetonide 20-40 mg (with 40 mg being the traditional dose) or dexamethasone 4-8 mg, combined with 1-2 mL of 1% lidocaine for local anesthesia. 1, 2

Corticosteroid Dosing

Kenalog (Triamcinolone Acetonide)

• Standard dose: 40 mg for large joints like the knee 1
• The FDA label specifies 5-15 mg for larger joints, with doses up to 40 mg having been sufficient for larger areas 1
• Recent evidence suggests 20 mg may be equally effective with potentially fewer adverse effects: A 2019 randomized trial found no difference in relapse rates at 6 months between 20 mg and 40 mg triamcinolone hexacetonide (30% vs 32%, p=0.822), leading investigators to recommend the lower 20 mg dose to reduce costs and metabolic side effects 3
• A 2023 non-inferiority trial demonstrated that 10 mg triamcinolone was non-inferior to 40 mg for pain reduction at 12 weeks in knee osteoarthritis 4

Important caveat: A 2017 JAMA trial showed that 40 mg triamcinolone every 3 months for 2 years resulted in significantly greater cartilage volume loss compared to saline (-0.21 mm vs -0.10 mm, p<0.05) without significant pain benefit, raising concerns about repeated high-dose injections 5

Decadron (Dexamethasone)

• Dose: 2-4 mg for large joints (knee) 2
• The FDA label specifies 2-4 mg for large joints via intrasynovial administration 2
• A 2016 comparative trial found 8 mg dexamethasone equivalent to 40 mg triamcinolone hexacetonide for knee arthritis in rheumatoid arthritis, with similar efficacy and safety profiles 6
• Dexamethasone offers faster pain relief: Average time to pain reduction was 2.3 days with dexamethasone versus 3.4 days with triamcinolone 6

Lidocaine Dosing

For Intra-Articular Use

• Use 1-2 mL of 1% lidocaine (10-20 mg total) 7
• The case report documenting a severe post-injection flare used 2 mL of 1% lidocaine mixed with triamcinolone 7
• Lidocaine can be infiltrated along the needle path or injected directly into the joint, alone or mixed with corticosteroid 8

Maximum Safe Dosing

• Maximum lidocaine dose without epinephrine: 4.5 mg/kg in adults 9
• With epinephrine, maximum increases to 7.0 mg/kg 9
• Critical safety rule: Do not use lidocaine within 4 hours of other local anesthetic interventions to prevent cumulative toxicity 9, 10

Administration Technique

• Warm the lidocaine to 37°C before injection to reduce infiltration pain, as demonstrated in high-quality systematic reviews 8
• Local anesthetics may be applied topically, infiltrated subcutaneously, along the needle path, or injected into the joint 8

Critical Safety Considerations

Aseptic Technique

• Always use strict aseptic technique: surgical gloves, skin preparation with alcohol/iodine/chlorhexidine, and change needles between drawing the drug and injecting 8
• Current infection risk is 0.035% (3 per 7,900 procedures), higher than historical estimates 8

Special Populations

• Diabetic patients: Warn about transient hyperglycemia (days 1-3 post-injection) and advise glucose monitoring 8
• Prosthetic joints: Avoid routine injections; infection rate is 0.6% in prosthetic knees 8
• Pre-surgical patients: Perform injections at least 3 months before joint replacement surgery to avoid increased infection risk (0.5% to 1.0% if injected within 3 months) 8

Post-Injection Care

• Advise patients to avoid overuse for 24 hours, but discourage complete immobilization 8
• Warn about post-injection flare: Though rare, severe crystal-induced inflammatory responses can occur 2 hours post-injection, mimicking septic arthritis with intense pain and swelling 7

Injection Frequency

• Limit to 3-4 injections per year in the same joint 8
• Frequent injections (every 2-3 weeks to every 3-5 days) may cause joint tissue damage 2

Practical Algorithm

1. Choose corticosteroid based on clinical context:

   • For routine osteoarthritis: Consider 20 mg triamcinolone (lower dose, equal efficacy) 3
   • For rheumatoid arthritis flare: Use 40 mg triamcinolone or 8 mg dexamethasone 6
   • For faster pain relief: Prefer dexamethasone 6

2. Add 1-2 mL of 1% lidocaine warmed to body temperature 8, 7

3. Use superolateral approach for knee (91% accuracy rate) 8

4. Aspirate synovial fluid if excessive before injection 1

5. Monitor diabetic patients' glucose for 3 days 8