Hyaluronic acid injections for the knee

What hyaluronic acid is

Hyaluronic acid is a long sugar chain that your body already makes. It is the reason healthy synovial fluid is thick and slippery rather than watery. Under load it stiffens and absorbs shock; under slow movement it thins and lubricates. That dual behaviour is called viscoelasticity, and it is what osteoarthritis takes away.

In an osteoarthritic knee the concentration of hyaluronic acid falls and the chains that remain are shorter. The fluid loses its cushioning. Injecting hyaluronic acid directly into the joint restores that cushioning for as long as the injected material survives in the joint.

Molecular weight is the number that matters

Products are not interchangeable. The single most useful thing to ask your doctor is the molecular weight of what they are about to inject.

• Low molecular weight, under 1 million daltons. Cheaper, usually given as three to five weekly injections, cleared from the joint fastest.
• High molecular weight, above 2 million daltons. Closer to native joint fluid, typically one or two injections, longer effect.
• Cross-linked. The chains are chemically tied together so the enzymes that normally break them down work more slowly. This is how a single injection can hold for the better part of a year.

Chondroplus, for example, uses cross-linked hyaluronic acid at 2.8 to 3.6 million daltons, produced by bacterial fermentation rather than from animal tissue.

How long it takes to work

Slower than people expect. Hyaluronic acid is not a painkiller and it does not shut down inflammation the way a steroid does. Most people notice a change between two and six weeks, and the improvement builds rather than arrives.

If your knee is acutely inflamed on the day, a doctor may drain it and settle it first, then give hyaluronic acid once the flare has passed.

How long the effect lasts

Conventional preparations are generally reported to give three to six months of relief.1 Cross-linked, high molecular weight products combined with collagen tripeptide are reported to hold considerably longer, and a 2024 study following such an injection in difficult knees found significant pain and function improvement still present at six months.2

Side effects and who should avoid it

The usual reaction is local: aching, warmth or mild swelling in the knee for a day or two. Ice and rest are enough. Serious adverse events are uncommon, and the 2024 cohort recorded no injection-related side effects and no post-injection flares.2

Injections are not given when there is infection in or around the joint. Tell your doctor if you are on anticoagulants, if you have had a reaction to a previous injection, or if you are pregnant or breastfeeding.

What it costs in Malaysia

Expect RM 450 to RM 1,500 per knee for the product and the procedure, with the range driven by molecular weight, cross-linking and whether the price covers one injection or a course. A five-injection course at RM 300 each is not cheaper than one injection at RM 1,200 once you add five consultation fees and five trips.