What are the recommended materials and procedures for knee injections?

Knee Injection Materials and Procedures

Intraarticular glucocorticoid injections are strongly recommended for patients with knee osteoarthritis, with triamcinolone hexacetonide being the preferred corticosteroid choice when available. 1, 2

Recommended Materials

Corticosteroid Options

• First choice: Triamcinolone hexacetonide (provides longer duration of effect compared to triamcinolone acetonide) 2
• Alternative: Triamcinolone acetonide (commonly used)
  • Dosage: 5-40 mg for knee joints 3
  • Lower dose (10 mg) is non-inferior to higher dose (40 mg) for pain relief 4

Equipment Needed

• Sterile gloves
• Antiseptic solution (e.g., chlorhexidine or povidone-iodine)
• Sterile gauze
• Adhesive bandage
• 5-10 mL syringe
• 21-25 gauge needle
• Local anesthetic (optional but often desirable) 3

Injection Procedure

Patient Positioning

• Patient should be in supine position with knee slightly flexed (20-30 degrees)
• Place a small pillow or rolled towel under the knee for support

Anatomical Approaches

1. Anterolateral approach (most common)

   • Entry point: 1 cm above and 1 cm lateral to the superior lateral border of the patella
   • Direct needle toward the intercondylar notch

2. Anteromedial approach

   • Entry point: 1 cm above and 1 cm medial to the superior medial border of the patella
   • Direct needle toward the intercondylar notch

3. Superolateral approach

   • Entry point: 1 cm above and 1 cm lateral to the superolateral corner of the patella
   • Direct needle behind the patella toward the center of the joint

Procedure Steps

1. Identify and mark the injection site
2. Prepare the skin with antiseptic solution
3. If using local anesthetic, infiltrate the skin and subcutaneous tissue
4. Insert the needle into the joint space
5. Aspirate to ensure the needle is not in a blood vessel and to remove any excess synovial fluid if present 3
6. Inject the corticosteroid slowly
7. Apply pressure with sterile gauze after removing the needle
8. Apply adhesive bandage
9. Instruct patient to rest the joint for 24 hours

Clinical Considerations

Accuracy and Efficacy

• Intra-articular placement is not achieved in up to 20% of knee injections 5
• No evidence that a medial approach is more accurate than other approaches 5
• Ultrasound guidance is not required for knee injections but may improve accuracy 1

Efficacy

• Provides short-term pain relief (typically 1-6 weeks) 2, 6
• Improves function and quality of life in the short term 7
• More effective in patients with:
  • Clinical evidence of joint effusion 6
  • Successful aspiration of synovial fluid during injection 6

Safety Considerations

• Risk of infection is estimated at approximately 1 in 3,000 injections 5
• Avoid injection if there is:
  • Local skin infection
  • Bacteremia
  • Joint prosthesis at the injection site
• Corticosteroid injection should be avoided for 3 months preceding joint replacement surgery 1
• Use lowest effective dose to minimize potential cartilage loss with repeated injections 1
• Long-term studies (up to 2 years) have not shown deleterious effects on knee structure with repeated injections every 3 months 7

Common Pitfalls to Avoid

• Injecting into surrounding tissues rather than the joint space
• Using excessive force during injection
• Failing to aspirate before injection
• Injecting when there is local infection
• Overuse of repeated injections without considering other treatment modalities

By following these recommendations and procedures, knee injections can be performed safely and effectively for the management of knee osteoarthritis pain.