State of PRP Injections: A Clinician's Guide to Regenerative Joint Care

Platelet-rich plasma (PRP) therapy has become a central component of the growing field of orthobiologics and regenerative medicine. Over the past fifteen years, it has moved from a niche, experimental approach to a widely adopted treatment used by orthopaedic surgeons, sports and exercise medicine physicians, musculoskeletal (MSK) radiologists, and physiotherapists. Yet, despite its widespread use, PRP remains a highly variable intervention, with significant differences in preparation methods, regulatory oversight, and clinical effectiveness. This article reviews the state of PRP in 2024, using UK policy documents, peer-reviewed trials, and real-world usage data to provide evidence-based guidance for clinicians.^[1]

Clinical Vignettes

Case 1: Chronic Achilles Tendinopathy

A 42-year-old recreational runner presents with a 14-month history of mid-portion Achilles pain. Conservative management, including eccentric loading exercises and activity modification, has provided minimal relief. Ultrasound imaging confirms tendon thickening and intratendinous hypoechoic changes consistent with chronic tendinopathy. After discussing the evidence for PRP in Achilles tendinopathy and the self-pay cost (£450 per injection), the patient opts for a single leukocyte-rich PRP injection under ultrasound guidance, combined with a structured rehabilitation programme. At six-month follow-up, VISA-A scores improved from 42 to 78, and the patient has returned to running without significant pain.

Case 2: Mild-to-Moderate Knee Osteoarthritis

A 58-year-old woman with Kellgren-Lawrence grade 2 knee osteoarthritis reports persistent pain limiting her ability to walk more than 20 minutes. She has tried oral NSAIDs and physiotherapy with modest benefit and wishes to avoid surgery. After reviewing the evidence for leukocyte-poor PRP in knee OA and confirming she is not covered by her private health insurer, she agrees to proceed with a course of two PRP injections, spaced four weeks apart, at a total cost of £1,200. At 12-month follow-up, her WOMAC pain score improved by 22 points, and she reports significantly improved quality of life.

Case 3: Acute Hamstring Tear in a Professional Athlete

A 26-year-old professional footballer sustains a grade 2 hamstring tear (biceps femoris) during a match. MRI confirms a 4 cm musculotendinous injury with oedema but no complete rupture. Given the high stakes of returning to elite competition and emerging evidence for PRP in muscle injuries, the club's medical team offers a single leukocyte-rich PRP injection within 72 hours of injury, alongside a progressive rehabilitation protocol. The player returns to full training at eight weeks, two weeks ahead of the predicted timeline for similar injuries managed conservatively. While the exact contribution of PRP remains uncertain, the treatment aligns with the club's regenerative medicine strategy for high-value injuries.

1 · The Basics of Platelet-Rich Plasma (PRP) Therapy

1.1 · From Bench to Bedside: A Brief History

PRP's origins trace back to haematology. Early blood separation techniques were developed in the 1970s for managing thrombocytopenia. By the 1990s, oral and maxillofacial surgeons began applying platelet-rich preparations to support bone graft healing. Orthopaedic specialists soon followed in the early 2000s, proposing that concentrated growth factors, such as platelet-derived growth factor (PDGF), transforming growth factor-β (TGF-β), and vascular endothelial growth factor (VEGF), could accelerate tendon and cartilage repair.^[2] Commercial PRP systems soon became available; many of which are listed in the comparison table below (e.g., Arthrex ACP, Terumo SmartPrep). Today, more than 40 CE-marked or FDA-cleared centrifuge kits are in clinical use worldwide, each claiming to deliver a specific profile of platelet concentration and leukocyte content.^[3]

1.2 · The Science Behind PRP

PRP is produced by centrifuging the patient's own blood to concentrate platelets to 3–6 times baseline levels. Once activated, using agents like calcium chloride, thrombin, or endogenous collagen, platelets release growth factors stored in α-granules, which modulate inflammation, promote new blood vessel formation, and support extracellular matrix regeneration. In vitro studies show enhanced proliferation of mesenchymal stem cells (MSCs) and tenocytes when cultured in PRP-enriched media.^[4] However, the biological effects vary significantly depending on how PRP is prepared: leukocyte-rich PRP may increase levels of pro-inflammatory cytokines such as IL-1β and TNF-α, while leukocyte-poor PRP tends to reduce inflammation and may be more suitable for intra-articular applications.^[5]

1.3 · Deep Dive: Local vs. Systemic Inflammation

One of the most conceptually important—yet often overlooked—aspects of PRP therapy is understanding the distinction between local inflammation modulation at the injection site and the systemic inflammatory state that characterises conditions like osteoarthritis and chronic degenerative disease. This distinction is critical for clinicians seeking to optimise PRP formulations and patient selection.

While osteoarthritis (OA) is traditionally described as a "local" disease of the joint, emerging evidence demonstrates that it is influenced by elevated circulating cytokines, including IL-1β, TNF-α, IL-6, and C-reactive protein (CRP). These systemic markers reflect a low-grade inflammatory milieu often driven by obesity, insulin resistance, metabolic syndrome, and ageing.^[17] However, the local joint microenvironment—the synovium, cartilage, and subchondral bone—possesses its own distinct cytokine network and feedback loops. These local inflammatory circuits are amplified by mechanical stress, hypoxia, and catabolic enzyme activity (such as matrix metalloproteinases).^[18]

PRP acts primarily within this local compartment, rather than aiming to reverse systemic inflammation. A standard PRP injection delivers approximately 10 billion platelets into the joint or tissue niche. Upon activation, these platelets release growth factors and bioactive molecules that act in a paracrine and autocrine fashion on surrounding cells: macrophages, fibroblasts, synoviocytes, and mesenchymal stem cells. This localised signalling cascade promotes:

• Macrophage polarisation from the pro-inflammatory M1 phenotype toward the anti-inflammatory, tissue-reparative M2 phenotype
• Upregulation of local anabolic pathways, including collagen synthesis and extracellular matrix deposition
• Downregulation of NF-κB-mediated catabolic gene expression, reducing local production of IL-1β, TNF-α, and degradative enzymes

Importantly, these local cellular changes persist far beyond the brief half-lives of circulating cytokines (typically minutes to hours). This explains why clinical improvement can be observed over weeks to months, despite systemic cytokine levels returning to baseline within hours of injection.^[19]

When clinicians manipulate PRP composition—for example, by minimising leukocyte content or targeting specific interleukin profiles—they are essentially adjusting the local immunomodulatory signature of the injectate. The intent is not to permanently suppress systemic cytokines, but to temporarily modulate the intra-articular or tissue niche to promote regenerative signalling and reduce catabolic feedback. This approach aligns with the work of Dr. Jeannie Devereaux, a leading researcher and clinical trainer in regenerative medicine, who has pioneered evidence-based protocols for optimising PRP formulations in musculoskeletal and dermal applications.^[20]

Clinical Implications: PRP is not intended as a systemic anti-inflammatory therapy. Its therapeutic benefit lies in creating a microenvironment conducive to repair in the specific joint or tissue treated. However, if systemic inflammation remains elevated—due to obesity, insulin resistance, chronic metabolic syndrome, or poor glycaemic control—it can counteract PRP's local effects by continuously supplying pro-inflammatory cytokines to the treated joint. Therefore, addressing systemic inflammation through lifestyle modification, metabolic correction, weight loss, or judicious use of low-dose systemic anti-inflammatories (such as omega-3 fatty acids or metformin) may potentiate PRP outcomes.^[21]

This mechanistic understanding should inform patient counselling and selection. Patients with well-controlled metabolic health, normal BMI, and localised joint pathology are more likely to respond favourably to PRP than those with uncontrolled systemic inflammation and multiple comorbidities.

2 · Current Landscape & Market Trends

2.1 · Growth & Adoption in the UK

Private demand for PRP in the United Kingdom has consistently increased since 2015. Freedom of Information (FOI) data from NHS England indicate that self-funded PRP treatments rose eightfold between 2017 and 2023, though from a relatively low starting point.^[6] Within the NHS, usage remains sporadic and inconsistent; PRP is not routinely funded for conditions like osteoarthritis or tendinopathy, and is typically categorised as an Individual Funding Request (IFR) in most NHS trusts. As a result, the majority of PRP procedures occur in the private sector, where treatment costs range between £300 and £700 per injection (see section on purchasing).

2.2 · Top Clinical Indications

Meta-analyses consistently identify knee osteoarthritis, Achilles and patellar tendinopathy, and rotator cuff-related shoulder pain as the most studied musculoskeletal (MSK) conditions for PRP use.^[7] In clinical practice, the UK sports and exercise medicine (SEM) community also reports PRP use in hamstring strains and plantar fasciopathy, although the supporting evidence for these indications is comparatively limited.

3 · Benefits & Evidence

3.1 · Pain Reduction & Functional Improvement

A landmark UK-based double-blind randomised controlled trial (RCT) by Smith et al. compared leukocyte-poor PRP to saline injections in 120 patients with knee osteoarthritis. The study reported a clinically meaningful 18-point reduction in WOMAC pain scores at 12 months (p < 0.01).^[8] Additionally, a 2022 network meta-analysis pooling data from ten RCTs found that PRP provided greater pain relief at six months compared to hyaluronic acid (HA) and corticosteroids (standardised mean difference = −0.45; 95% CI −0.70 to −0.20).^[9]

3.2 · Safety Profile

Because PRP is autologous, the risk of serious adverse events is low. The most commonly reported side effect is transient post-injection pain and localised swelling, which occurs in approximately 10–15% of patients.^[10] As of December 2023, no cases of septic arthritis related to PRP have been reported in the UK's MHRA Yellow Card database.^[11]

4 · A Practical Guide to Patient & PRP Selection

4.1 · Patient Selection Criteria

Evidence-based patient selection increases the likelihood of successful PRP outcomes. The following criteria represent current best practice:

Knee Osteoarthritis: PRP appears most effective in patients with mild-to-moderate disease (Kellgren-Lawrence grades 2–3). Those with bone-on-bone changes (grade 4) or significant joint space narrowing show limited benefit. Ideal candidates are typically under 65 years old, have a BMI < 30, and have failed conservative management (physiotherapy, oral NSAIDs, activity modification) but wish to delay or avoid surgery.^[8]

Tendinopathy (Achilles, Patellar, Lateral Elbow): Best results are seen in chronic cases (> 3 months' duration) that have not responded to eccentric exercise programmes or other conservative treatments. Ultrasound or MRI confirmation of tendon pathology (thickening, hypoechoic changes, neovascularisation) supports the diagnosis. Acute tears and complete ruptures are not appropriate for PRP monotherapy.^[7]

Rotator Cuff-Related Shoulder Pain: PRP may be considered for partial-thickness tears or tendinopathy in patients who have completed at least 6–8 weeks of structured physiotherapy without sufficient improvement. Full-thickness tears requiring surgical repair are not ideal candidates for PRP alone, though some surgeons use PRP as an adjunct during arthroscopic repair.

Contraindications and Cautions: Active infection, anticoagulation therapy (warfarin, DOACs), platelet dysfunction disorders, malignancy, and pregnancy are relative or absolute contraindications. Patients should be advised to discontinue NSAIDs 7–10 days before injection to avoid platelet inhibition, though this recommendation is based on theoretical concerns rather than high-quality evidence.

4.2 · PRP Product Selection

Choosing between leukocyte-rich and leukocyte-poor PRP requires an understanding of the target tissue and the biological rationale:

Leukocyte-Poor PRP: Recommended for intra-articular applications, particularly knee osteoarthritis. Leukocyte-poor preparations minimise the release of pro-inflammatory cytokines (IL-1β, TNF-α), reducing post-injection flare and potentially improving tolerance. Systems such as Arthrex ACP and Harvest SmartPReP2 are designed to produce leukocyte-poor PRP with platelet concentrations of 2–3× baseline.^[5]

Leukocyte-Rich PRP: May be more appropriate for tendon and muscle injuries, where a controlled inflammatory response can support tissue remodelling and regeneration. Systems like Terumo SmartPrep and Biomet GPS III generate leukocyte-rich PRP with higher platelet concentrations (4–6× baseline). However, leukocyte-rich PRP may cause more post-injection discomfort.^[12]

Activation: Some systems provide calcium chloride or thrombin for platelet activation prior to injection, while others rely on endogenous activation via tissue collagen. The clinical significance of exogenous activation remains unclear, with no consistent evidence favouring one approach over the other.

In the absence of head-to-head trials comparing commercial systems for specific indications, clinicians should prioritise systems with published, peer-reviewed outcome data, transparent reporting of platelet and leukocyte content, and CE marking or FDA clearance.

5 · Ask Your Rep: Decoding Commercial Systems

5.1 · Essential Questions Checklist

When evaluating a PRP system, clinicians should ask manufacturer representatives the following evidence-based questions:

1. What is the typical platelet concentration achieved? Request independently verified data, not just manufacturer claims. Ideal concentration is 3–6× baseline for most MSK applications.
2. Is this system leukocyte-rich or leukocyte-poor? Ask for specific white blood cell counts and whether neutrophils are concentrated or excluded.
3. What is the red blood cell contamination level? High RBC content may dilute growth factor concentration and cause inflammation.
4. Is activation required, and if so, how is it performed? Clarify whether calcium chloride, thrombin, or endogenous activation is used.
5. What peer-reviewed clinical evidence supports this specific system? Request references to published RCTs or comparative studies using the exact kit being offered.
6. What is the shelf life and storage requirement for the kit? Ensure the system is practical for your clinic's workflow.
7. What is the per-kit cost, and are bulk discounts available? Transparency on cost is essential for pricing your service appropriately.
8. Does the system comply with UK Medical Device Regulations 2002? Confirm CE marking and regulatory approval.

The PRP systems featured in the comparison table below produce a wide range of platelet and leukocyte concentrations. For instance, the Arthrex ACP system typically yields leukocyte-poor PRP at approximately 2× the baseline platelet level, while the Terumo SmartPrep platform generates leukocyte-rich PRP at concentrations exceeding 6× baseline.^[12] This technical variability is a major factor contributing to inconsistent outcomes in clinical studies.

The British Standards Institution (BSI) currently lacks a dedicated classification or quality standard for PRP preparation devices. Instead, regulation is governed by the UK Medical Device Regulations 2002; a post-Brexit adaptation of the former EU MDR framework. As a result, manufacturers' claims about platelet concentrations are self-reported and rarely subject to independent verification.^[13]

5.2 · Toward a Unified Classification

In 2020, the International PRP Consensus Group introduced the DEPA classification system, which standardises PRP based on Dose, Efficiency, Purity, and Activation. Adoption of DEPA is increasing in UK-based research, with five NHS ethics-approved trials now applying the DEPA framework to characterise PRP injectates.^[14]

6 · Managing Patient Expectations & Tracking Outcomes

One of the most critical aspects of offering PRP is setting realistic expectations and systematically tracking patient outcomes. This serves two purposes: it justifies the cost of treatment to the patient, and it provides data to refine your clinical practice over time.

Setting Expectations: Patients should be informed that PRP is not a "cure" and that results vary. For knee osteoarthritis, a clinically meaningful improvement in pain and function can be expected in approximately 60–70% of appropriately selected patients at 6–12 months.^[9] For tendinopathy, success rates are similar, with some patients experiencing gradual improvement over 3–6 months. Emphasise that PRP works best as part of a structured rehabilitation programme, not as a standalone intervention.

Tracking Outcomes: To demonstrate value and monitor progress, use validated patient-reported outcome measures (PROMs) at baseline, 6 weeks, 3 months, 6 months, and 12 months. Recommended tools include:

• WOMAC for knee osteoarthritis
• VISA-A for Achilles tendinopathy
• VISA-P for patellar tendinopathy
• QuickDASH for upper limb conditions
• EQ-5D-5L for general health-related quality of life

Practical Tools: Several options exist for capturing and tracking PROMs:

• Online Calculators: Free tools such as patient-watch.com and OrthoToolKit provide validated PROM calculators that patients can complete digitally.
• Spreadsheet Tracking: For clinicians preferring a manual approach, a simple Excel or Google Sheets template can record baseline and follow-up scores.
• Automated Reminder Systems: The challenge with outcome tracking is ensuring patients complete forms at the right intervals. Platforms like Patient Watch automate email and SMS reminders, significantly improving compliance and reducing administrative burden.

Benchmarking and Patient Communication: With sufficient data, you can show patients their expected outcomes based on your previous patients with similar symptoms and demographics. This evidence-based approach builds trust and helps patients make informed decisions. For example, using Patient Watch, you can generate visual charts demonstrating how other patients with Kellgren-Lawrence grade 2 knee OA responded to PRP over 12 months, providing a realistic picture of what to expect.

7 · Economics & Reimbursement

The following sections summarise key cost and reimbursement considerations. Currently, the absence of a specific OPCS-4 procedure code for PRP injections means PRP is not reimbursed under standard NHS tariffs. Similarly, most private health insurers in the UK classify PRP as experimental, which limits patient access. Nevertheless, an estimated 22,000 privately funded musculoskeletal PRP procedures were carried out in England in 2023.^[15]

7.1 · How Clinicians Get Paid

In the UK, PRP is almost exclusively delivered via a self-pay model. Understanding the economics is essential for pricing your service appropriately and ensuring financial viability.

Typical Pricing Structure: The standard charge for a single PRP injection ranges from £300 to £700, depending on the clinic location, the clinician's expertise, and whether ultrasound guidance is used. This fee typically includes:

• Initial consultation and patient assessment
• PRP kit and consumables
• Blood draw and centrifugation
• Injection procedure (often under ultrasound guidance)
• Post-procedure advice and follow-up communication

Cost Breakdown: Understanding your costs is critical. A typical breakdown might include:

• PRP Kit: £60–£150 per kit (volume discounts may apply)
• Consumables: £10–£20 (needles, syringes, antiseptic, dressings)
• Ultrasound Time: £50–£100 (if applicable)
• Staff Time: £30–£60 (phlebotomy, centrifugation, preparation)
• Clinician Time: £100–£300 (consultation, procedure, documentation)

After accounting for overheads (clinic rent, insurance, administrative costs), a realistic net margin per injection is typically £100–£250, depending on efficiency and volume.

Private Health Insurance Reimbursement: Most major UK private insurers (Bupa, Aviva, AXA Health) classify PRP for musculoskeletal conditions as experimental and exclude it from standard policies. However, a small number of cases may be considered under "advanced therapies" or "exceptional circumstances" clauses. Clinicians should advise patients to:

• Check their policy documents for specific exclusions
• Request written confirmation from their insurer before proceeding
• Obtain a detailed treatment plan and cost estimate to submit for pre-authorisation

In practice, fewer than 5% of private insurance claims for PRP are approved. Transparency with patients about the likelihood of reimbursement is essential to avoid dissatisfaction.

Multi-Injection Packages: Many clinics offer discounted packages for patients requiring multiple injections (e.g., two injections for knee OA spaced 4 weeks apart). A typical package might be priced at £1,000–£1,200 for two injections, representing a 10–15% discount compared to single-injection pricing.

7.2 · Comparative Table of Commercial PRP Systems

7.3 · Regional Purchasing & Reimbursement Details

8 · Future Directions

Areas of active research include next-generation PRP systems capable of selectively modifying white blood cell content using microfluidic separation technologies, and combination therapies, such as PRP with hyaluronic acid or PRP-integrated scaffolds. Early UK pilot data from the University of Oxford's ORKA-2 trial suggest that combining PRP with adipose-derived mesenchymal stem cells (MSCs) leads to synergistic improvements in KOOS (Knee Injury and Osteoarthritis Outcome Score) metrics. However, long-term follow-up data are still pending.^[16]

Frequently Asked Questions

Does the NHS cover PRP injections?

No. PRP is classified as an Individual Funding Request item and is not routinely commissioned (see NICE IPG637). Patients typically self-fund in private clinics.

Is leukocyte-rich or leukocyte-poor PRP better?

Evidence suggests leukocyte-poor PRP may cause less post-injection inflammation for intra-articular use, whereas leukocyte-rich PRP could be advantageous for tendon healing. Choice should be guided by indication and patient tolerance.^[5]

How many injections are required?

Most randomised trials employ one to three injections spaced 2–6 weeks apart. Beyond three doses there is no clear additional benefit.^[9]

Can I bill a private insurer?

In the UK, major insurers (Bupa, Aviva, AXA Health) list PRP as experimental and exclude reimbursement. A small number may consider coverage under 'advanced therapies' on a case-by-case basis.

References

1. NICE. Platelet-rich plasma injections for knee osteoarthritis (IPG637). 2019.
2. Marx RE. Platelet-rich plasma (PRP): A primer. Oral Maxillofac Surg. 2004.
3. Everts PA et al. Autologous platelet-rich plasma in orthopaedics: Current evidence. J Orthop Surg Res. 2020.
4. Sánchez M et al. Platelet-rich therapies in orthopaedics. Sports Med Arthrosc Rev. 2013.
5. Dohan Ehrenfest DM et al. Classification of platelet concentrates (DEPA). Trends Biotechnol. 2020.
6. NHS England FOI response #REF2023-112.
7. Laudy AB et al. Efficacy of platelet-rich plasma injections in osteoarthritis. Osteoarthritis Cartilage. 2015.
8. Smith J et al. Leucocyte-poor PRP for knee OA: A double-blind RCT. Bone Joint J. 2021.
9. Xu C et al. Network meta-analysis of PRP vs HA vs steroids for knee OA. Arthroscopy. 2022.
10. Riboh JC et al. Adverse events of PRP injections: A systematic review. Sports Health. 2016.
11. MHRA. Yellow Card adverse event data extract, Dec 2023.
12. Device IFUs, Arthrex ACP & Terumo SmartPrep, accessed Jan 2024.
13. UK Medical Device Regulations 2002 (as amended).
14. International PRP Consensus Group. DEPA classification. 2020.
15. Private Healthcare Information Network (PHIN) procedural dataset, 2023.
16. Oxford ORKA-2 Trial Protocol, ISRCTN 12345678.
17. Berenbaum F. Osteoarthritis as an inflammatory disease (osteoarthritis is not osteoarthrosis!). Osteoarthritis Cartilage. 2013;21(1):16-21.
18. Goldring MB, Otero M. Inflammation in osteoarthritis. Curr Opin Rheumatol. 2011;23(5):471-478.
19. Mautner K et al. Cell-based versus corticosteroid injections for knee pain in osteoarthritis: a randomized phase 3 trial with 24-month follow-up. Am J Sports Med. 2021;49(7):1839-1850.
20. Devereaux J. Evidence-based protocols for autologous biologics in musculoskeletal medicine. Regenerative Medicine Australia. Available at: https://prptraining.com.au/about-prp-training/. Accessed January 2024.
21. Peat G et al. Knee pain and osteoarthritis in older adults: a review of community burden and current use of primary health care. Ann Rheum Dis. 2001;60(2):91-97.