Hyaluronic acid for joints: what it is, what it does and when it works

«I've been told to have hyaluronic acid in my knee, but I'm not really sure what that is.» It's one of the things I find myself explaining most often in clinic. Hyaluronic acid has become very popular, and it's worth understanding properly what it does and, above all, when it is worth it, so that you expect from it neither more nor less than it can give.

What hyaluronic acid is

Hyaluronic acid is a substance your body already makes naturally: it is the component that gives viscosity to the fluid that lubricates your joints (the synovial fluid). Think of the oil in an engine: when there is enough of it and it is of good quality, the parts glide without rubbing.

With osteoarthritis, that fluid loses quality and quantity: the joint becomes «dry», it rubs, it gets inflamed and it hurts. A hyaluronic acid injection replaces that lubricant, giving viscosity and cushioning back to the joint.

What it is for (and what you'll notice)

The aim of hyaluronic acid is threefold:

• To reduce pain by improving how the joint glides.
• To improve mobility and the feeling of stiffness, especially when you start moving.
• To gain quality of life: walking, going up stairs or standing with less discomfort.

It does not regenerate lost cartilage or «cure» osteoarthritis —no conservative treatment does— but it can keep the joint comfortable for months and delay the need for surgery.

Which joints it is used in

The most common is the knee, where it has the most evidence behind it. It is also used in the hip, the shoulder and other joints with osteoarthritis. In the hip, being a deep joint, it is essential to do it under ultrasound guidance in order to reach the exact spot.

Why I always do it under ultrasound guidance

An injection only works if the product reaches exactly where it needs to go. With musculoskeletal ultrasound I see the needle in real time and make sure I deposit the hyaluronic acid inside the joint, not in the surrounding tissues. That improves the result and reduces discomfort. Doing it «blind» is less accurate, especially in deep joints such as the hip.

Hyaluronic acid or PRP: how I decide

They are complementary treatments, not rivals. Broadly speaking: hyaluronic acid acts as a lubricant and works very well in established osteoarthritis; PRP (platelet-rich plasma) has a different, more biological and anti-inflammatory effect, which is of interest in mild to moderate osteoarthritis and in younger people. After assessing your case with ultrasound, I explain which one fits you better —or whether it is worth combining them.

And not just injections

Hyaluronic acid is one more tool, not the complete solution. Combined with therapeutic exercise and, if needed, weight control, the results are much better and longer-lasting. The muscle around the joint is its best shock absorber.