What medication is recommended for a knee injection?

Medication for Knee Injection in Osteoarthritis

Intra-articular corticosteroid injections are strongly recommended for knee osteoarthritis, with triamcinolone acetonide being the preferred agent at doses ranging from 10-40 mg. 1

Primary Recommendation: Corticosteroid Injections

• Intra-articular glucocorticoid injections are the medication of choice for knee injections in osteoarthritis, receiving a strong recommendation from the 2019 American College of Rheumatology/Arthritis Foundation guidelines 1

• Corticosteroid injections demonstrate short-term efficacy for pain relief and functional improvement in knee OA, though effects are time-limited 1

• Corticosteroid injections are conditionally recommended over other intra-articular options, including hyaluronic acid preparations, based on considerably higher quality evidence for efficacy 1

Specific Corticosteroid Dosing

Triamcinolone Acetonide Dosing Options:

• Standard dose: 5-15 mg for larger joints like the knee, with doses up to 40 mg having been used 2

• Lower doses (10 mg) are non-inferior to higher doses (40 mg) for pain improvement at 12 weeks, suggesting the lower dose should be preferred to minimize potential adverse effects 3

• Extended-release formulation (TA-ER 32 mg) provides prolonged pain relief with reduced systemic exposure compared to traditional crystalline suspension 4, 5

• For bilateral knee injections, total doses up to 80 mg have been given safely, though lower cumulative doses are preferable 2, 5

Important Safety Considerations

Cartilage Effects - Critical Caveat:

• Repeated high-dose triamcinolone (40 mg every 3 months for 2 years) results in significantly greater cartilage volume loss compared to saline (-0.21 mm vs -0.10 mm), without providing superior pain relief 6

• This finding raises concerns about frequent high-dose injections, though the clinical significance remains uncertain as cartilage loss was not associated with worsening pain or other radiographic features 1

• Corticosteroid injections should be avoided for 3 months preceding joint replacement surgery due to potential infection risk 1

Practical Administration:

• Ultrasound guidance is not required for knee injections (unlike hip injections where it is strongly recommended) 1

• Strict aseptic technique is mandatory, with deep injection into the joint space 2

• If excessive synovial fluid is present, some should be aspirated before injection 2

Alternative Intra-articular Options (Lower Priority)

Hyaluronic Acid (Viscosupplementation):

• The 2019 ACR guidelines made no recommendation regarding intra-articular hyaluronates, reflecting equivocal evidence 1

• May be considered for patients with inadequately controlled knee pain despite core treatments, though evidence quality is lower than for corticosteroids 1, 7

• The American Academy of Orthopaedic Surgeons could not make a definitive recommendation for or against hyaluronic acid injections 7

Clinical Algorithm for Knee Injection Selection

1. First-line intra-articular therapy: Corticosteroid injection

   • Use triamcinolone acetonide 10-20 mg (lower doses preferred) 3, 8
   • Consider extended-release formulation if available for prolonged effect 4

2. Limit injection frequency to avoid cartilage damage

   • Avoid injections more frequently than every 3 months 6
   • Consider maximum of 3-4 injections per year

3. Reserve hyaluronic acid for specific scenarios

   • Patients who have failed or cannot tolerate corticosteroids 7
   • Those seeking longer duration of effect despite weaker evidence

4. Avoid injection within 3 months of planned surgery 1

The evidence strongly favors corticosteroid injections as the medication of choice for knee injections, with the critical caveat that lower doses (10-20 mg) should be used and injection frequency should be limited to balance efficacy with potential cartilage effects.