PRP for Knee Pain and Osteoarthritis: The Non-Surgical Treatment Changing How We Manage Arthritic Knees

Medically reviewed by a GMC-registered doctor at The PRP Clinic | Last updated: February 2026

Knee osteoarthritis affects over 8 million people in the UK alone. For decades, the management pathway has been frustratingly limited: paracetamol and anti-inflammatories for mild symptoms, cortisone injections for flare-ups, physiotherapy to maintain strength, and ultimately — when the pain becomes unbearable — knee replacement surgery. The gap between "manage the pain" and "replace the joint" has been vast, with few effective options in between.

PRP therapy is changing this. A substantial and growing evidence base now demonstrates that PRP injections for knee osteoarthritis produce clinically meaningful improvements in pain and function that are superior to both placebo and hyaluronic acid injections, and that these benefits last 12 months or longer. For patients with early to moderate osteoarthritis, PRP represents a genuinely effective treatment that can reduce pain, improve mobility, and potentially delay or avoid surgical intervention.

This guide explains the evidence, who benefits most, how PRP compares to other injections, and what treatment involves at The PRP Clinic.

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How PRP works in an osteoarthritic knee

Osteoarthritis is characterised by progressive cartilage degradation, chronic low-grade inflammation within the joint, and changes to the bone and synovial membrane. Traditional treatments address symptoms (pain relief) but do not influence the underlying disease process.

PRP works differently. When injected into the knee joint, the concentrated growth factors in PRP exert multiple beneficial effects. They modulate the inflammatory environment within the joint, reducing the catabolic (destructive) processes that drive cartilage breakdown. They stimulate chondrocyte (cartilage cell) activity, promoting some degree of cartilage repair and maintenance. They improve the quality of synovial fluid, enhancing lubrication and nutrient delivery within the joint. And they reduce pain through both anti-inflammatory effects and modulation of pain signalling.

The net result is reduced pain, improved joint function, and a biological environment that is more favourable to cartilage preservation — outcomes that no other non-surgical injection has been shown to achieve as effectively or as durably.

What the evidence shows

The evidence for PRP in knee osteoarthritis is now robust. Multiple systematic reviews and meta-analyses — the highest level of clinical evidence — have confirmed its effectiveness.

PRP produces statistically and clinically significant improvements in pain scores compared to placebo. PRP is superior to hyaluronic acid injections at both 6 and 12 months — an important finding because hyaluronic acid (viscosupplementation) has been the standard injectable treatment for knee osteoarthritis. PRP produces longer-lasting benefits than cortisone, which typically provides relief for only weeks to months. The benefits of PRP last 12 months or longer from a single treatment course, with some studies reporting sustained improvement at 18-24 months.

PRP is most effective in patients with early to moderate osteoarthritis (Kellgren-Lawrence radiographic grades 1-3). Patients with severe, end-stage disease (grade 4, bone-on-bone) may experience less benefit, though many still report meaningful pain reduction.

PRP vs cortisone vs hyaluronic acid

Cortisone provides the fastest pain relief (within days) by powerfully suppressing inflammation. However, it does not promote healing, its effects typically last only weeks to months, and repeated injections have been shown to accelerate cartilage degeneration. Current guidelines are increasingly cautious about the frequency of cortisone injections into weight-bearing joints.

Hyaluronic acid (viscosupplementation) acts as a lubricant and mild anti-inflammatory within the joint. It provides moderate pain relief lasting several months. It is generally safe but produces less durable and less substantial improvement than PRP.

PRP takes longer to work (typically 2-6 weeks for initial improvement) but produces superior outcomes at 6 and 12 months compared to both cortisone and hyaluronic acid. It is the only injectable option that promotes biological repair within the joint rather than simply suppressing symptoms or providing temporary lubrication.

Who benefits most

PRP for knee osteoarthritis is most effective in patients with mild to moderate disease who still have some cartilage remaining (Kellgren-Lawrence grades 1-3). Ideal candidates include patients whose pain is limiting activity or quality of life but who are not yet candidates for or ready for knee replacement, patients who have found cortisone provides only temporary relief, patients who want to avoid or delay surgery, active individuals who need better knee function for sport or exercise, and patients who prefer a regenerative approach over repeated symptom management.

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What treatment involves

Assessment. Your doctor takes a detailed history, examines your knee, and reviews any imaging (X-rays or MRI). We assess the severity of your osteoarthritis, identify other contributing factors (muscle weakness, alignment, body weight), and determine whether PRP is appropriate.

Treatment. A blood sample is drawn and processed to prepare your PRP using medical-grade centrifugation. The PRP is injected into the knee joint under sterile conditions. The procedure takes approximately 30 minutes and is performed in our clinic with no hospital admission required.

After treatment. Mild discomfort or swelling at the injection site is common for 24-48 hours. We advise avoiding anti-inflammatory medications for 1-2 weeks (as they can interfere with PRP's mechanism). Light walking is encouraged from day one. Progressive return to full activity over 2-4 weeks.

Results. Most patients begin noticing improvement within 2-6 weeks, with progressive benefit over 3-6 months. Peak results typically develop at 2-3 months post-treatment.

Your knees do not have to dictate your life. PRP offers genuine, lasting improvement for arthritic knee pain.

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Frequently asked questions

Does PRP work for knee osteoarthritis?

Yes. Meta-analyses confirm PRP produces superior outcomes to placebo and hyaluronic acid, lasting 12+ months.

Is PRP better than cortisone?

For long-term outcomes, yes. Cortisone is faster but temporary and can damage cartilage. PRP promotes repair and lasts longer.

How many sessions do I need?

Usually 1-3 injections spaced 2-4 weeks apart. Many patients improve significantly after a single injection.

Can PRP avoid knee replacement?

For early-to-moderate osteoarthritis, PRP can significantly delay or potentially avoid the need for surgery.

How long do results last?

12 months or longer. Annual maintenance treatments can sustain benefit.

This article is for informational purposes only. Always consult a qualified healthcare professional.