How safe is the use of hyaluronic acid for ankle arthritis? Is it better to take the supplements in pill form or to have the injections directly into the joint?

Ankle osteoarthritis (OA) is not as common as hip or knee OA. But it affects enough people (especially young adults who injured their ankles during their teen years) that interest in treatment like hyaluronic acid (HA) has increased over time. Some of this interest may be because HA has been used successfully with hip and knee problems.

Hyaluronic acid is a normal part of the matrix that makes up cartilage. It has two distinct properties that make it so important for smooth joint motion. It is both viscous (slippery) and elastic.

The viscosity allows the tissue to release and spread out energy. The elasticity allows for temporary energy storage. Together, these two properties protect the joint, help provide joint gliding action (especially during slow movement), and act as a shock absorber during faster movements.

Hyaluronic acid (HA) injected into a joint has some additional benefits. The HA replaces unhealthy synovial fluid, reduces inflammation of the synovium (lubricating fluid inside the joint), and therefore has an analgesic (pain relieving) effect. It also has a direct effect on the pressure inside the joint to separate the joint capsule where it is stuck together. Hyaluronic acid may be protective of the joint cartilage and prevent the formation of adhesions that keep the capsule from the smooth gliding action needed for normal joint motion.

Studies comparing oral supplementation with injection therapy using hyaluronic acid have not been done. But a recent systematic review of studies from 1995 to 2012 on the use of the injected form offered the following observations and recommendations:

  • Significant pain reduction is possible using intra-articular hyaluronic acid injections for the treatment of ankle osteoarthritis.
  • There may be some minor, temporary adverse effects (e.g., increased ankle swelling, local itching at the injection site, lymph node enlargement in the groin area); 15 per cent of the patients in the studies included reported these kinds of after effects.
  • Increased pain relief was noted with more injections but not with more volume per dose. The ankle joint is fairly small and cannot accommodate large injection volumes. Too much fluid pushed into the joint can cause swelling and more pain instead of less.
  • Further studies are needed to identify appropriate and optimal dosing of injections.
  • The injection itself accounted for 87 per cent of the improvement in symptoms; this suggests that it isn’t the hyaluronic acid as much as it is the placebo effect of the injection procedure on pain. This phenomenon bears further study as well.

    A simple summary of this systematic review would say: hyaluronic acid injections for the treatment of painful ankle osteoarthritis may be most effective when given in the right dosage (volume and number of injections). Optimal values for dosage remain undetermined except to say that lower volume and higher number of injections seem to have the best results so far.