Knee osteoarthritis: what to try before an injection, and where PRP fits

Reviewed by The Wellness Team. Last reviewed October 2026.

Short answer: for knee osteoarthritis, the NHS and NICE put exercise, weight management and topical anti-inflammatory gel first. A steroid injection comes later and only helps for a while. The best trial of PRP for knee osteoarthritis found it no better than a saline injection. So the honest order is: core treatments first, injections second, and PRP only after a proper conversation about the evidence.

What the NHS says comes first

The NHS says there is no cure for osteoarthritis, but the condition does not necessarily get worse over time. It names exercise as one of the most important treatments, whatever your age or fitness, and says regular exercise that builds muscle and strengthens the joints usually helps symptoms. If you are overweight, it says extra weight puts strain on weight-bearing joints and losing it helps.

For pain, the NHS lists paracetamol, anti-inflammatory painkillers (NSAIDs) and capsaicin cream. It says topical NSAIDs, which you rub on the joint, can be particularly effective for knees and hands.

What NICE says

NICE guideline NG226 (osteoarthritis in over 16s) recommends:

• Therapeutic exercise for everyone with osteoarthritis, tailored to the person, and warns that joint pain may rise a little when you start.
• A topical NSAID for people with knee osteoarthritis.
• Weight loss support where relevant. NICE says any loss helps and about 10% of body weight is likely to be better than 5%.
• Not to offer glucosamine, because there is no strong evidence of benefit.
• Not to offer intra-articular hyaluronan injections.
• To consider an intra-articular corticosteroid injection when other medicines have not worked or cannot be used, or to support exercise. NICE says to explain that it gives short-term relief only, around 2 to 10 weeks.

The NG226 recommendations do not list PRP as an option.

Where PRP fits

The largest placebo-controlled trial is the RESTORE trial, published in JAMA in 2021. It enrolled 288 adults aged 50 or over with mild to moderate knee osteoarthritis (Kellgren and Lawrence grade 2 or 3). Half had three weekly injections of leukocyte-poor PRP and half had saline.

At 12 months, knee pain fell by 2.1 points on an 11-point scale with PRP and 1.8 with saline. The difference was not statistically significant. Cartilage volume on MRI also did not differ. The authors concluded the findings do not support PRP for knee osteoarthritis.

We think people should hear that before they pay for anything. It does not mean no one improves. In the trial both groups improved, which is a reminder of how strong the placebo effect is in knee pain. It does mean PRP should not be sold as a way to rebuild cartilage.

A sensible order to try things

1. A proper diagnosis. Knee pain has many causes. An examination, and imaging if needed, tells you whether osteoarthritis is the problem.
2. Strength and activity plan, ideally guided by a physiotherapist.
3. Weight management if relevant, and topical NSAID gel.
4. A steroid injection if pain stops you doing your exercises, knowing it may last weeks, not months.
5. If you still want to consider PRP, discuss what the evidence does and does not show, what it costs, and what you will measure to decide whether it worked.

When to see a doctor sooner

See a GP promptly if your knee is hot, red and swollen, you cannot put weight on it, or you have a fever. These can mean infection or another problem that needs urgent care.

Talk to us

If you are weighing up injections for your knee, we will tell you plainly where the evidence stands and which options fit your situation. Message us on WhatsApp

Sources: NHS, Osteoarthritis treatment and support (nhs.uk/conditions/osteoarthritis/treatment). NICE NG226, Osteoarthritis in over 16s: diagnosis and management, recommendations (nice.org.uk/guidance/ng226). Bennell KL et al., JAMA 2021;326(20):2021-2030, RESTORE trial (jamanetwork.com/journals/jama/fullarticle/2786501).

This article is general information and not a substitute for medical advice.