Hyaluronic acid is a natural component of synovial fluid, which is the fluid within all your joints. Hyaluronic acid injections help to lubricate the joints; this gives you temporary pain relief. They are used in osteoarthritis of the joints in anyone wanting to avoid or delay surgery to their arthritic joints.
Hyaluronic injections are most useful in osteoarthritis when the smooth, highly polished surfaces of the joint have become roughened but there’s no significant inflammation. The knee joint is most often injected but you can also have injections in your shoulder, elbow, ankle or toe joints. You’re less likely to be prescribed hyaluronic acid injections if there’s already inflammation in the joint, or if the damage has been caused by a condition such as rheumatoid arthritis.
Hyaluronic acid helps to restore the normal joint homeostasis. It improves lubrication and shock absorbency in the joint. It has been suggested that it also protects the chondrocytes (cartilage cells), increases collagen synthesis and that it has both an anti-inflammatory and analgesic effect that could change the disease process, but more research is needed to confirm this.
How often you have the injections depends on the type of hyaluronic acid preparation used. You can be given a course of 3, each separated by 1–3 weeks. I give the first two injections close together and then extend the period between those remaining.
The particles in hyaluronic acid are quite large, so they’ll stay in your joint for some time before they’re absorbed into your blood stream.
Some of the hyaluronic acid preparations available contain significantly larger particles than others – these injections only need to be given as a single injection and can last even longer than the smaller particular injections but there is an increased risk of mild allergic reactions.
The injections should work within days if they’re effective and they’ll probably last for a few months usually between 3 and 6 months depending on the preparation used. If the injection is successful you can have repeat courses.
Hyaluronic acid injections have very few side effects, although some people have a slight allergic reaction, which causes temporary pain and swelling in their joint after the injection. There’s also a small risk of infection and bleeding or bruising – this is the same risk whenever a needle is used to pierce the skin. Sterile precautions are used to help prevent an infection. If the injection is done in slightly the wrong place, it won’t damage your skin or muscle but is less effective so ultrasound guidance is very useful to ensure that the injection is accurately placed within the joint.
The main alternative is Platelet Rich Plasma (PRP) or a steroid injection into the joint. Steroid injections have anti-inflammatory rather than lubricating properties, so it makes sense to have a steroid injection if the joint is inflamed. If you have osteoarthritis, hyaluronic injections may last longer than steroid injections. There is some evidence that mixing hyaluronic acid and corticosteroid in one injection prolongs the effect of both of these injections and this option may be offered to you.
PRP has been shown to be more effective than hyaluronic acid alone at 12 months after the injection, however PRP injections are more expensive and may not be covered by your insurance.
There’s no known reason to avoid other medication while you’re having hyaluronic acid injections, but you should always check with your doctor. Warfarin or other anticoagulants can increase your chance of bleeding with any injection so make sure that you discus this with the doctor.
Do not drive immediately after the injection. Gentle activity is advised for the first 48 hours following the injection. It is then important to gradually increase your activity as your pain allows. Pain from osteoarthritis is improved by weight loss and exercise. It is therefore recommended to start an exercise programme under the supervision of our therapists if required, to keep the muscles surrounding the joint strong and maintain the movement of the joint. All joints especially osteoarthritic ones need to keep moving as they will stiffen and be more painful with inactivity.