Injection Therapy

Platelet-Rich Plasma (PRP)

A biological injection prepared from the patient's own blood, designed to support joint health in selected cases.

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What is a Platelet-Rich Plasma (PRP)?

Platelet-Rich Plasma (PRP) therapy is a biological treatment that utilizes components of the patient's own blood. A sample of blood is drawn and processed in a centrifuge to separate and concentrate the platelets, which are rich in growth factors and signaling proteins. This concentrated plasma is then injected directly into the knee joint or surrounding tendon structures.

Procedure & Aftercare Details

Platelet-Rich Plasma (PRP) Explanation

1. Joint Anatomy Target

AnatomyClinical Approved

Platelet-Rich Plasma (PRP) Injection Target

Concentrated platelets and growth factors targeted to the intra-articular space.

2. Injection Needle Path

Needle PathClinical Approved

Platelet-Rich Plasma (PRP) Needle Access Path

Infographic of the PRP preparation process and targeted joint delivery.

This outpatient procedure is conducted under strict sterile conditions:

1Clinical consultation and review of diagnostic imaging to confirm suitability.

2Drawing a small sample of blood from a vein in the patient's arm, similar to a standard blood test.

3Processing the blood sample in a centrifuge to separate and concentrate the platelet-rich fraction.

4Sterile preparation of the knee injection site.

5Injecting the concentrated platelet-rich plasma into the targeted joint or tendon, potentially under ultrasound guidance.

6Applying a clean dressing and providing post-procedure instructions.

Clinical AccuracyUltrasound-Guided Injections

We highly recommend executing injections under real-time ultrasound guidance to ensure precise placement within the joint space, maximizing therapeutic safety and efficacy.

Learn About Guidance →

Clinical Characteristics Summary

Onset of Action4-6 weeks

Typical Duration6-12 months

Primary MechanismGrowth factor cell signaling

Main IndicationMild osteoarthritis or chronic tendinopathy

This information is for general patient education and does not replace an individual clinical assessment.

How does it work?

PRP aims to deliver a high concentration of platelets to the affected area. Platelets contain biological molecules that play a role in natural cell signaling and tissue responses. In degenerative joints or tendon issues, this concentration is intended to modulate the local environment. Clinical evidence for PRP continues to evolve, and its use is considered for select patients.

Who is this suitable for?

Patients Who May Be Considered

Selected patients with chronic knee tendinopathies (such as patellar tendinopathy) who have not responded to active physical therapy.
Individuals with early-to-moderate knee osteoarthritis looking for biological treatment options.
Patients who prefer an autologous option (using their own blood components) over synthetic alternatives.
Selected cases where traditional measures have not provided sufficient symptom management.

Who May Not Be Suitable

Active infection at the injection site or systemic blood infections.
Underlying haematological disorders, low platelet counts, or severe anaemia.
Patients taking anticoagulant medications where a blood draw or joint injection carries increased bleeding risk.
Advanced, severe bone-on-bone knee arthritis (where structural restoration is required).

Potential Benefits & Risks

Potential Benefits

Uses the patient's own blood components, minimizing risk of allergic reaction to synthetic substances.
Delivers concentrated growth factors directly to the targeted joint or tendon tissue.
May assist in managing discomfort and supporting joint function in selected patients.
Provides an autologous option for conservative clinical management.

Risks & Limitations

Clinical evidence is still developing, and individual responses to PRP therapy vary significantly.
There is no clinical guarantee that PRP will heal damaged tissues or restore worn cartilage.
Requires a blood draw, which carries standard minor risks like bruising or localized soreness.
Potential for temporary post-injection pain, stiffness, or localized swelling.
Standard minor risks associated with any joint injection, including infection.

What happens during the procedure?

Knee injections are outpatient procedures completed in our sterile clinical rooms. The step-by-step process is detailed in the interactive guide above, including:

1. Preparation & CleaningJoint positioning, skin disinfection, and local anaesthetic.

2. Needle InsertionPrecise injection, often under ultrasound guidance.

3. Dressing & MonitoringSterile dressing applied and post-procedure check.

Needle placement may be performed under real-time imaging guidance depending on clinical indication.Learn about ultrasound-guided knee injections →

After the injection

Aftercare is focused on protecting the joint and monitoring for rare complications. Guidelines are outlined in the interactive tabs above. Remember to rest the joint for the first 48 hours and avoid unaccustomed heavy loads.

Frequently Asked Questions

No. Clinical evidence does not support the claim that PRP injections can regenerate, regrow, or heal severely worn knee cartilage. PRP is used to modulate the local joint environment and manage symptoms in select cases.

The appointment typically takes 30 to 45 minutes. This extended time is necessary to perform the blood draw, process the sample in the centrifuge, prepare the sterile injection area, and administer the treatment.

It is generally recommended to arrange for someone to drive you home. The procedure involves both a blood draw and a joint injection, which can leave you feeling temporarily lightheaded, stiff, or uncomfortable.

You should rest the knee and avoid strenuous or high-impact exercise for at least 48 to 72 hours. Light daily movements are acceptable as comfort permits, followed by a gradual return to active rehabilitation.

Treatment protocols vary. Some patients receive a single injection, while others may be considered for a series of two to three injections spaced a few weeks apart, depending on clinical assessment and response.

You will feel a standard needle prick during the blood draw, followed by a pressure sensation during the joint injection. Some temporary localized soreness is common for a few days after the procedure.

Yes. An up-to-date X-ray or MRI scan is required to confirm the diagnosis, locate the specific tissue pathology (such as tendinopathy), and ensure PRP is an appropriate consideration.

In selected patients with early-stage osteoarthritis or chronic tendon issues, PRP may help manage symptoms and support rehabilitation, which may temporarily defer surgery. It is not a permanent alternative to joint replacement in advanced arthritis.

Which injection may be appropriate?

Choosing an injection therapy requires an individualized clinical assessment. The choice depends upon several factors, including:

Verified clinical diagnosis
Type and severity of symptoms
Diagnostic imaging findings (X-ray, MRI, Ultrasound)
Patient activity levels and functional goals
Previous conservative treatments attempted
Individual medical history, medications, and allergies
Potential clinical risks versus patient-specific benefits
Available non-injection treatment alternatives

⚠️ Only an individual consultation with our consultant orthopaedic surgeon can determine whether a knee injection is clinically appropriate for your condition.

Schedule a Clinical Consultation

To evaluate your knee symptoms and discuss whether an injection therapy is indicated, arrange a specialist consultation.

Call Clinic Book Assessment

Clinically Reviewed

Mr Ricardo J Pacheco (GMC 4145976)Consultant Trauma & Orthopaedic Surgeon

Last reviewed: 29 July 2026

Evidence & References

NICE guidelines on PRP for osteoarthritis and tendinopathies (highlighting safety and efficacy review).
Consensus statements on orthobiologics in sports medicine.
Clinical literature on processing protocols and clinical trials of PRP in knee pathology.
A Systematic Review of Current Clinical Practice Guidelines on Intra ... (pmc.ncbi.nlm.nih.gov)
Platelet-rich plasma injections for knee osteoarthritis (nice.org.uk)
Choosing between platelet-rich plasma (PRP) and hyaluronic acid ... (sciencedirect.com)
Platelet-Rich Plasma (PRP) for Knee Osteoarthritis Technology Overview (aaos.org)
HTG497 Platelet-rich plasma injections for knee osteoarthritis (nice.org.uk)

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Medical Disclaimer

This website provides educational and general information about knee symptoms, conditions, and treatments. The content is for informational purposes only and does not constitute medical advice, diagnosis, or a treatment plan. It should not be used as a substitute for a professional consultation, examination, or clinical decision-making by a qualified orthopaedic specialist.

If you are experiencing symptoms or are concerned about a knee problem, please arrange a clinical consultation. If you have urgent symptoms, severe pain, or are unable to put weight on your leg, please read our urgent advice guidance or contact emergency services immediately (dial 999 or NHS 111).