From the Guidelines
Aspiration before injecting the final dose of hyaluronic acid into the knee is a crucial step to ensure safety and efficacy, as it helps prevent intravascular injection and confirms proper needle placement within the joint space. This safety practice involves pulling back on the syringe plunger after needle placement but before injection to check for blood return. If blood appears in the syringe during aspiration, it indicates the needle may be in a blood vessel rather than the intended intra-articular space. In this case, you should reposition the needle before proceeding with the injection. Proper aspiration helps prevent inadvertent intravascular injection of hyaluronic acid, which could potentially cause complications such as embolism or systemic reactions.
Key Considerations
- Aspiration before injection is a recommended step to decrease the risk of local anesthetic systemic toxicity, as outlined in guidelines for the use of local anesthesia in office-based dermatologic surgery 1.
- The technique of aspiration is important for confirming proper needle placement within the joint space, ensuring the hyaluronic acid will be delivered to its intended location for maximum therapeutic benefit.
- Intra-articular injections, such as those used for viscosupplementation with hyaluronic acid, require precise placement to achieve optimal effects, and aspiration helps verify that the needle is correctly positioned.
- The presence of blood vessels in the surrounding tissues of the knee joint underscores the importance of aspiration to avoid accidental intravascular injection.
Clinical Implications
- Aspiration is a simple yet critical step that can significantly enhance the safety and effectiveness of hyaluronic acid injections into the knee.
- By confirming proper needle placement and avoiding intravascular injection, aspiration contributes to minimizing potential complications and maximizing the therapeutic benefits of viscosupplementation.
- Clinicians should prioritize this safety measure as part of their standard protocol for administering hyaluronic acid injections, in line with best practices for minimizing risks associated with injections 1.
From the Research
Aspiration Before Hyaluronic Acid Injection
- The study 2 found that synovial fluid aspiration before injection of intra-articular hyaluronan significantly improved pain and function scores in patients with knee osteoarthritis.
- The improvement in pain and function scores was observed after 5 weekly injections of hyaluronan, with maximal aspiration performed before each injection.
- Another study 3 analyzed the effect of viscosupplementation and physiotherapy on the characteristics of synovial fluid, but did not specifically address the question of aspiration before injection.
Effectiveness of Hyaluronic Acid Injection
- Studies 4, 5, and 6 discuss the effectiveness of hyaluronic acid injection in reducing osteoarthritis symptoms and improving joint lubrication.
- These studies suggest that viscosupplementation with hyaluronic acid can be a useful treatment option for knee osteoarthritis, but do not provide direct evidence on the necessity of aspiration before injection.
Clinical Practice
- The study 2 provides evidence that aspiration before injection may be beneficial in improving treatment outcomes, but more research is needed to confirm this finding.
- The decision to aspirate before injecting hyaluronic acid should be based on individual patient needs and clinical judgment, taking into account the potential benefits and risks of the procedure 2, 3, 4, 5, 6.