Recommended Injection Sites for the Left Knee
For intra-articular injections in the left knee, the superolateral approach is recommended as the most accurate site when performing blind injections, with a reported accuracy of approximately 87%. 1
Anatomical Approaches for Knee Injection
Preferred Approach
- Superolateral patellar approach: Insert the needle 1 cm above and 1 cm lateral to the superior lateral aspect of the patella at a 45-degree angle, advancing 1 to 1½ inches deep 2
- This approach provides the highest accuracy rate (87%) for blind injections 1
Alternative Approaches
- Medial midpatellar approach: Less accurate (64%) when performed without imaging guidance 1
- Anterolateral joint line approach: Also less accurate (70%) without imaging guidance 1
Technique Considerations
Imaging Guidance
- Ultrasound guidance improves accuracy by 9-19% compared to blind injections 1
- While ultrasound guidance is strongly recommended for hip injections, it is not required for knee injections 3, 4
- Consider ultrasound guidance for difficult cases or when previous blind injections have failed
Procedural Steps
- Position the patient supine with the knee slightly flexed (20-30°)
- Prepare the site with proper antiseptic technique
- Insert the needle at the superolateral approach
- Aspirate any effusion if present before injecting medication
- Inject the medication slowly
- Apply gentle pressure after needle withdrawal
Medication Considerations
Corticosteroid Selection and Dosing
- For knee injections (large joint): 20-40 mg of triamcinolone acetonide or 20-80 mg of methylprednisolone 4
- Recent evidence suggests that 10 mg of triamcinolone acetonide is non-inferior to 40 mg for pain relief in knee osteoarthritis 5
- Lower doses are preferred when effective to minimize systemic effects 4
Injection Frequency
- No more than once every 6 weeks in the same joint 4
- Limit to 3-4 injections per year in the same joint 4
- Avoid overuse of the injected joint for 24 hours following injection, but complete immobilization is not recommended 3
Clinical Pearls and Pitfalls
Pearls
- Experience of the injector improves accuracy for blind injections 1
- Local compression after needle insertion can aid in aspiration of fluid 2
- Intra-articular corticosteroid injections provide short-term pain relief (few weeks to months) 4
Pitfalls to Avoid
- Injecting through infected skin or into an infected joint
- Excessive frequency of injections (risk of cartilage damage)
- Failure to warn diabetic patients about potential transient hyperglycemia (particularly days 1-3 post-injection) 3
- Injecting when there are contraindications such as bacteremia or overlying soft tissue infection 2
By following these recommendations, clinicians can optimize the effectiveness of intra-articular injections in the left knee while minimizing potential complications.