Do you always aspirate effusions in patients with knee osteoarthritis prior to injecting hyaluronic acid?

There is strong biologic plausibility that one should always aspirate an effusion before injecting hyaluronic acid. Even a mildly inflammatory effusion will have an excess of white cells. White cells produce hyaluronidase. Hyaluronidase catalyzes the degradation of hyaluronic acid and renders it inactive. As an aside, this biologic fact is the basis for the string test in synovial fluid analysis. Synovial fluid viscosity proportionately depends on the concentration of hyaluronic acid. The more i...

Yes, I routinely aspirate an OA knee effusion when one is there just before injecting HA. Most all of my knee interventions are performed under ultrasound, even if informally, to minimize pain and maximize fluid identification, so it is easy to aspirate and then change the syringe onto the same needle to inject HA. While I am not aware of literature to support this technique, I was taught this way during the fellowship.