Responders to Platelet-Rich Plasma in Osteoarthritis: A Technical Analysis

Aspirin Does Not Inhibit Platelet-Rich Plasma Releasate Efficacy in a Murine Model of Rotator Cuff Tendinopathy

Background

Platelet-rich plasma (PRP) has been shown to be a promising treatment for subacromial impingement, and although its interaction with aspirin (ASA) is controversial, many providers ask patients to stop non-steroidal anti-inflammatory drug use before PRP administration.

Purpose

This studied aimed to identify the effect of PRP in a murine model of subacromial impingement and to explore the effect of ASA on PRP treatment.

Methods

A murine model of subacromial impingement was used, incorporating 48 wild-type C57BL/6 mice. After impingement surgery, mice received either human PRP activated via calcium chloride or saline injected into the subacromial space. The mice received either drinking water with ASA or standard drinking water, creating 4 groups: saline injection, saline injection + ASA, PRP injection, and PRP injection + ASA. All injections occurred at 3 weeks after impingement surgery, and mice were evaluated at 6 weeks. Each mouse underwent gait analysis, biomechanical analysis (N = 10 shoulders), histological analysis (N = 6), and gene expression analysis (N = 8).

Results

Biomechanical testing showed increased load to failure in the PRP group compared to the ASA group, and increased stiffness in PRP vs saline, PRP vs ASA, and PRP vs ASA + PRP. Gene expression analysis identified 17 downregulated genes between the ASA + PRP and saline groups. Eight of these differentially expressed genes contribute to collagen biosynthesis and modification, 4 to extracellular matrix (ECM) synthesis, and 4 to ECM degradation.

Conclusions

In this preliminary analysis, PRP injections in a murine model of subacromial impingement demonstrated mixed effects on tendon quality and pain, and ASA did not have a consistent effect on the response to PRP.

Most Publications Regarding Platelet-Rich Plasma Use in the Knee Are From Asia, Investigate Injection for Osteoarthritis, and Show Outcome Improvement: A Scoping Review

PURPOSE

To evaluate and synthesize the available literature related to platelet-rich plasma (PRP) treatment of knee pathologies and to provide recommendations to inform future research in the field.

METHODS

PubMed, CINAHL, and Scopus databases were queried on October 6, 2023. All identified citations were collated and uploaded into Covidence for screening and data extraction. Studies were included if they were human studies published in English with adult cohorts that received PRP as a procedural injection or surgical augmentation for knee pathologies with patient-reported outcome measures (PROMs) and level of evidence Levels I-IV.

RESULTS

Our search yielded 2,615 studies, of which 155 studies from 2006 to 2023 met the inclusion criteria. Median follow-up was 9 months (±11.2 months). Most studies (75.5%) characterized the leukocyte content of PRP, although most studies (86%) did not use a comprehensive classification scheme. In addition, most studies were from Asia (50%) and Europe (32%) and were from a single center (96%). In terms of treatment, 74% of studies examined PRP as a procedural injection, whereas 26% examined PRP as an augmentation. Most studies (68%) examined treatment of knee osteoarthritis. Many studies (83%) documented significant improvements in PROMs, including 93% of Level III/IV evidence studies and 72% of Level I/II evidence studies, although most studies (70%) failed to include minimal clinically important difference values. The visual analog scale was the most-used PROM (58% of studies), whereas the Short Form Health Survey 36-item was the least-used PROM (5% of studies).

CONCLUSIONS

Most published investigations of knee PRP are performed in Asia, investigate procedural injection for osteoarthritis, and show significant outcome improvements. In addition, this review highlights the need for better classification of PRP formulations.

LEVEL OF EVIDENCE

Level IV, scoping review of Level I-IV studies.

Platelet-Rich Plasma Injections in Chronic Lateral Ankle Instability: A Case Series

The platelet-rich plasma (PRP) approach may be an effective treatment for joint and cartilage pathologies. However, the rationale for its effectiveness on joint instability is limited. This study aimed to assess the safety and effectiveness of PRP injections in patients with chronic lateral ankle instability (CLAI). This retrospective study was performed at a single-center outpatient clinic between January 2015 and February 2023 and included pre-intervention assessment and short-term follow-up. Patients were excluded if they had received previous surgical treatment or had constitutional hyperlaxity, systemic diseases, or grade II or III osteoarthritis. The clinical and functional evaluation consisted of the Karlsson score, the Cumberland Ankle Instability Tool (CAIT), Good's grading system, the patient's subjective satisfaction level, and the time required to return to exercise. The entire PRP therapy regime consisted of three PRP administrations at 7-day intervals and follow-up appointments. PRP was administered both intraarticularly and into talofibular ligaments. A total of 47 consecutive patients with CLAI were included, 11 were female (23.4%), with a mean age at intervention of 31.19 ± 9.74 years. A statistically significant improvement was found in the CAIT and Karlsson scores at 3 months (27.74 ± 1.68 and 96.45 ± 4.28, respectively) relative to the pre-intervention status (10.26 ± 4.33 and 42.26 ± 14.9, respectively, p < 0.000). The mean follow-up of patients with CLAI was 17.94 ± 3.25 weeks. This study represents successful short-term functional and clinical outcomes in patients with CLAI after PRP treatment, with no adverse effects. It demonstrates the feasibility of a randomized controlled trial to further assess this therapy.

Efficacy and safety of platelet-rich plasma injections for the treatment of osteoarthritis: a systematic review and meta-analysis of randomized controlled trials

Background

In recent years, platelet-rich plasma (PRP) injections for osteoarthritis (OA) have been widely promoted in clinical practice, but their effectiveness is controversial. Therefore, we conducted a meta-analysis of relevant randomized controlled trials (RCTs) to determine the efficacy and safety of PRP injections for the treatment of OA.

Methods

We searched databases including Embase, Web of Science, Medline, PubMed, and the Cochrane Library for relevant studies. Two researchers (YQX and CG) performed literature screening, baseline data extraction, literature quality assessment, and heterogeneity analysis of RCTs from the retrieved studies. Based on the magnitude of heterogeneity I², random-effects or fixed-effects models were selected for the meta-analysis.

Results

We included 24 RCTs comprising 1344 patients with OA who met the inclusion criteria, with the main types of morbidity being knee osteoarthritis (KOA), hip osteoarthritis (HOA), ankle osteoarthritis (AOA), and temporomandibular joint osteoarthritis (TMJOA). Our results indicate that PRP injections were effective in improving Visual Analog Scale (VAS) pain scores in patients with KOA, HOA, and AOA compared to controls (AOA, MD = -1.15, CI = 95% [-1.74, -0.56], I² = 40%, P < 0.05; KOA, MD = -1.03, CI = 95% [-1.16, -0.9], I² = 87%, P < 0.05; TMJOA, MD = -1.35, CI = 95% [-1.74, -0.97], I² = 92%, P < 0.05) but showed no significant efficacy in patients with HOA (MD = -0.27, CI = 95% [-0.8, 0.26], I² = 56%, P>0.05). Compared to controls, PRP injections were effective in improving Knee Injury and Osteoarthritis Outcome Score (KOOS), including the patient's pain symptoms, activities of daily living (ADL), and adhesion symptomatology, but not for that of sports function (KOOS-pain, MD = 2.77, CI = 95% [0, 5.53], I² = 0%, P < 0.05; KOOS-symptoms, MD = 3.73, CI = 95% [0.76, 6.71], I² = 0%, P < 0.05; KOOS-ADL, MD = 3.61, CI = 95% [0.79, 6.43], I² = 0%, P < 0.05; KOOS-QOL, MD = 4.66, CI = 95% [0.98, 8.35], I² = 29%, P < 0.05, KOOS-sport, MD = 0.48, CI = 95% [-3.02, 3.98], I² = 0%, P > 0.05). PRP injections were effective in improving Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores, including pain, stiffness, and functional joint motion, in patients with OA compared with the control group (WOMAC-pain, MD = -1.08, CI = 95% [-1.62, -0.53], I² = 87%, P < 0.05; WOMAC-stiffness, MD = -1.17, CI = 88% [-1.72, -0.63], I² = 87%, P < 0.05; WOMAC-function, MD = -1.12, CI = 95% [-1.65, -0.58], I² = 87%, P < 0.05). In addition, subgroup analysis showed that leukocyte-poor (LP) PRP injections were more effective than leukocyte-rich (LR) PRP injections in improving pain symptoms in patients with OA (VAS, LR-PRP, MD = -0.81, CI = 95% [-1.65, -0.03], I² = 83%, P = 0.06 > 0.05; LP-PRP, MD = -1.62, CI = 95% [-2.36, -0.88], I² = 92%, P < 0.05). A subgroup analysis based on injection sites showed that no statistical difference in efficacy between intra-articular (IA) combined with intra-osseous (IO) simultaneous PRP injections. IA PRP injections only improved VAS pain scores in patients with OA (IA+IO PRP injections, MD = -0.74, CI =95% [-1.29, -0.18], I² = 61%, P < 0.05; IA PRP injections, MD = -1.43, CI = 95% [-2.18, -0.68], I² = 87%, P < 0.05, test for subgroup differences, P > 0.05, I² = 52.7%).

Conclusion

PRP injection therapy can safely and effectively improve functional activity in patients with OA and produce positive analgesic effects in patients with KOA, TMJOA, and AOA. However, PRP injection therapy did not significantly reduce pain symptoms in patients with HOA. In addition, the analgesic effect of LP-PRP was greater than that of LR-PRP.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022362066.

Platelet-Rich Plasma for Knee Osteoarthritis: What Does the Evidence Say?

The utilization of platelet-rich-plasma as a therapeutic intervention for knee osteoarthritis has gained immense attention since 2008. The increase in the number of scientific publications dedicated to this area can be attributed to the majority of favorable results reported in clinical trials and basic science studies. However, despite the growing evidence, the use of platelet-rich plasma in clinical practice still poses controversial aspects. The potential mechanisms of action described for platelet-rich-plasma so far indicate that it could serve as a disease-modifying drug, acting to counteract important aspects of knee osteoarthritis pathophysiology (cartilage breakdown, inflammation, and bone remodeling). Nevertheless, its efficacy in slowing down the progression of knee osteoarthritis remains unproven. While inconsistencies have been noted, the majority of controlled clinical trials and meta-analyses advocate for the utilization of platelet-rich-plasma in treating knee osteoarthritis, as it has demonstrated greater efficacy than hyaluronic acid and placebo, with a follow-up of at least 1 year. Despite advancements made in certain areas, significant diversity persists regarding the formulations used, therapeutic regimen, extended follow-up periods, patient selection, and assessment of clinically relevant outcomes. Consequently, the leading clinical practice guidelines do not recommend its use. In light of the emerging evidence, this narrative review aims to provide an objective evaluation of the recent available scientific literature (last 5 years) focused on randomized clinical trials and meta-analyses to present a current overview of the topic.

Prognostic Factors Related to Clinical Response in 210 Knees Treated by Platelet-Rich Plasma for Osteoarthritis

Many studies have shown the effectiveness of platelet-rich plasma (PRP) in the treatment of knee osteoarthritis. We aimed to determine the factors associated with good or poor response to PRP injections in knee osteoarthritis. This was a prospective observational study. Patients with knee osteoarthritis were recruited from a university hospital. PRP was injected twice at a one-month interval. Pain was assessed on a visual analog scale (VAS) and function was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Radiographic stage was collected and defined according to the Kellgren-Lawrence classification. Patients were classified as responders if they met the OMERACT-OARSI criteria at 7 months. We included 210 knees. At 7 months, 43.8% were classified as responders. Total WOMAC and VAS were significantly improved between M0 and M7. Physical therapy and a heel-buttock distance >35 cm were the two criteria associated with poor response at M7 by multivariate analysis. Pain VAS at M7 appeared to be lower in patients with osteoarthritis for less than 24 months. No adverse effects were reported. PRP treatment in knee osteoarthritis appears to be well-tolerated and effective, even in patients who reacted poorly to hyaluronic acid. Response was not associated with radiographic stage.

Comparison between the effects of ultrasound guided intra-articular injections of platelet-rich plasma (PRP), high molecular weight hyaluronic acid, and their combination in hip osteoarthritis: a randomized clinical trial

Background

Intra articular (IA) injection of platelet-rich plasma (PRP) and hyaluronic acid (HA) are of the new methods in the management of hip osteoarthritis (OA). The aim of this study was to compare the effectiveness of IA injections of PRP, HA and their combination in patients with hip OA. HA and PRP are two IA interventions that can be used in OA in the preoperative stages. Due to the different mechanisms of action, these two are proposed to have a synergistic effect by combining.

Methods

This is a randomized clinical trial with three parallel groups. In this study, patients with grade 2 and 3 hip OA were included, and were randomly divided into three injection groups: PRP, HA and PRP + HA. In either group, two injections with 2 weeks’ interval were performed into the hip joint under ultrasound guidance. Patients were assessed before the intervention, 2 months and 6 months after the second injection, using the visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Lequesne questionnaires.

Results

One hundred five patients were enrolled randomly in HA, PRP and PRP + HA groups. All three groups showed significant improvement in WOMAC, VAS, and Lequesne at 2 months and 6 months compared with baseline. Comparison of the 3 groups demonstrated significant differences regarding WOMAC and Lequesne total scores and the activities of daily living (ADL) subscale of Lequesne (P = 0.041, 0.001 and 0.002, respectively), in which the observed improvement at 6th month was significantly higher in the PRP + HA and PRP groups compared to the HA group.

Conclusion

Although all 3 interventions were associated with improvement of pain and function in patients with hip OA, the therapeutic effects of PRP and PRP + HA injections lasted longer (6 months), and the effects of these two interventions on patients’ performance, disability, and ADL were superior to HA in the long run. Moreover, the addition of HA to PRP was not associated with a significant increase in the therapeutic results.

Trial registration

The study was registered at Iranian Registry of Clinical Trials (IRCT) website http://www.irct.ir/, a WHO Primary Register setup, with the registration number of IRCT20130523013442N30 on 29/11/2019.

Relative Efficacy of Intra-articular Injections in the Treatment of Knee Osteoarthritis: A Systematic Review and Network Meta-analysis

BACKGROUND

In younger patients and those without severe degenerative changes, the efficacy of intra-articular (IA) injections as a nonoperative modality for treating symptomatic knee osteoarthritis (OA)-related pain while maintaining function has become a subject of increasing interest.

PURPOSE

To assess and compare the efficacy of different IA injections used for the treatment of knee OA, including hyaluronic acid (HA), corticosteroids (CS), platelet-rich plasma (PRP), and plasma rich in growth factors (PRGF), with a minimum 6-month patient follow-up.

STUDY DESIGN

Meta-analysis of randomized controlled trials; Level of evidence, 1.

METHODS

A systematic review was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using the following databases: PubMed/MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Google Scholar. Mean or mean change from baseline and standard deviation for outcome scores regarding pain and function were recorded at the 6-month follow-up and converted to either a 0 to 100 visual analog scale score for pain or a 0 to 100 Western Ontario and McMaster Universities Osteoarthritis Index score for function. A frequentist network meta-analysis model was developed to compare the effects of HA, CS, PRP, PRGF, and placebo on patient-reported outcomes.

RESULTS

All IA treatments except CS were found to result in a statistically significant improvement in outcomes when compared with placebo. PRP demonstrated a clinically meaningful difference in function-related improvement when compared with CS and placebo due to large effect sizes. Studies evaluating outcomes of PRGF reported significant improvement when compared with placebo due to large effect sizes, whereas a potential clinically significant difference was detected in the same comparison parameters in pain evaluation. With regard to improvements in pain, function, and both combined, PRP was found to possess the highest probability of efficacy, followed by PRGF, HA, CS, and placebo.

CONCLUSION

PRP yielded improved outcomes when compared with PRGF, HA, CS, and placebo for the treatment of symptomatic knee OA at a minimum 6-month follow-up. Further investigations evaluating different IA and other nonoperative treatment options for patients with knee OA are warranted to better understand the true clinical efficacy and long-term outcomes of nonsurgical OA management.

Platelet-Rich Plasma as an Orthobiologic: Clinically Relevant Considerations

Platelet-rich plasma (PRP) is an autologous blood-derived product processed to concentrate platelets and the associated growth factors. PRP has been shown to be relatively well-tolerated and safe to use for a number of conditions in humans, equines, and canines. There are multiple commercial systems that have been validated for canine use. These systems use a variety of methodologies to produce a PRP product. However, PRP products have been shown to differ greatly between systems. Further study is needed to fully elucidate optimal component concentrations for various indications.

The application of platelet-rich plasma in the treatment of knee osteoarthritis: A literature review

BACKGROUND

Primary knee osteoarthritis remains a difficult-to-control degenerative disease. With the rise in average life expectancy and the incidence of obesity, osteoarthritis has brought an increasing economic and physical burden on people. This article summarizes the latest understanding of platelet-rich plasma in the treatment of knee osteoarthritis, and reviews the economic issues of PRP.

METHODS

The literatures in Pubmed, Embase, Cochrane library, Web-science and other databases were searched, and literature inclusion and exclusion criteria were formulated. According to the Cochrane systematic reviewer's manual, the included literatures were grouped, and qualitative descriptions and quantitative meta-analysis were performed. Continuous statistical methods were used to compare the effects and adverse effects of PRP before and after treatment, as well as between PRP and other conservative treatments.

RESULTS

A total of 12 randomized controlled trials were included in this study. A total of 959 KOA patients (1070 knees) were enrolled and followed for 3-12 months. PRP total knee scores were significantly better than baseline at 1, 2, 3, 6 and 12 months after treatment (1 month: SMD = 0.60, P < 0.01; 2 months: SMD = 0.98, P < 0.01; 3 months: SMD = 1.16, P < 0.01; 6 months: SMD = 1.49, P < 0.01; 12 months: SMD = 1.47, P < 0.01). In terms of adverse reactions, PRP did not increase the risk of adverse events compared with HA (OR = 0.96, P = 0.85).

CONCLUSIONS

Compared with many other treatment methods, intra-articular injection of PRP has been proven to be safe and effective to improve the quality of life of patients with KOA.

Safety and efficacy of a single intra-articular injection of a novel enhanced protein solution (JTA-004) compared to hylan G-F 20 in symptomatic knee osteoarthritis: a randomized, double-blind, controlled phase II/III study

Background

New minimally invasive treatments are vital to delay joint replacement surgery in patients with knee osteoarthritis. This study was designed to select the most effective among three formulations of an enhanced protein solution containing clonidine, hyaluronic acid, and human plasma (JTA-004), and compare the safety and efficacy of intra-articular administration of the selected formulation with a reference treatment (hyaluronic acid) in symptomatic knee osteoarthritis patients.

Methods

In this two-stage, double-blind, phase II/III study conducted in 12 Belgian centers, 50–79-year-old patients with primary knee osteoarthritis were randomized (1:1:1:1) to receive one dose of one of three JTA-004 formulations (differing in clonidine concentration [50 or 100 μg/ml] and volume [2 or 4 ml]) or the reference treatment (hylan G-F 20). Patients were evaluated using Western Ontario McMaster Universities (WOMAC®) Scores and the Short-Form health survey up to 6 months post-injection (Month 6). Drug consumption and safety were evaluated.

Results

Among 164 treated patients, 147 completed the study. The JTA-004 formulation containing 200 μg clonidine and 20 mg hyaluronic acid in 2 ml (JTA-200/2) was selected based on interim results at Month 6. The difference in adjusted mean change in WOMAC Pain Subscale Score from baseline (JTA-200/2 minus reference group) at Month 6 was − 9.49 mm; statistical superiority of JTA-200/2 over the reference was not demonstrated. No statistically significant differences in adjusted mean changes from baseline between JTA-200/2 and reference groups were observed for Pain, Physical Function and Stiffness Subscales WOMAC Scores, Total WOMAC Score, and Well-being Score at any timepoint, although JTA-200/2 induced larger improvements in WOMAC Scores than the reference. Statistically significantly larger improvements in WOMAC Pain Subscale Scores for JTA-004 versus the reference were observed in post-hoc analyses on pooled data from all JTA-004 formulations at Month 6 (p = 0.030) and Month 3 (p = 0.014). All JTA-004 formulations had clinically acceptable safety profiles.

Conclusions

This study provided preliminary evidence of the safety of intra-articular injection of JTA-004 in knee osteoarthritis patients. Phase III randomized controlled trials with larger sample sizes are needed to evaluate the efficacy of JTA-004 in knee osteoarthritis.

Trial registration

Clinicaltrials.gov/identifier NCT02740231;  clinicaltrialsregister.eu/identifier 2015–002117-30. Retrospectively registered 13/4/2016.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04750-3.

Novel assessment of leukocyte-rich platelet-rich plasma on functional and patient-reported outcomes in knee osteoarthritis: a pilot study

Background: Leukocyte-rich platelet-rich plasma (LR-PRP) has demonstrated to be beneficial for patients with knee osteoarthritis (KOA); however, reliable objective end points to accurately assess its therapeutic effects is lacking. Aim: To investigate the efficacy of LR-PRP as assessed by functional and patient-reported outcomes at early time points (6 weeks). Materials & methods: We conducted a prospective cohort study in 12 patients with diagnosed KOA (Kellgren Lawrence score of II-III), who underwent a single ultrasound-guided LR-PRP injection. Results: There was significant improvement in timed up and go, pain and quality of life scales and balance parameters. There were nonsignificant improvements in range of motion and gait parameters. Conclusion: LR-PRP demonstrates efficacy in meaningful end points for functional and patient-reported outcomes at early time points in patients with KOA.

The immature platelet fraction affects the efficacy of platelet rich plasma therapy for knee osteoarthritis

Introduction

Platelet-rich plasma (PRP) therapy is used to treat pathological conditions such as degenerative inflammatory diseases including osteoarthritis (OA) by enhancing tissue repair and promoting anti-inflammatory effects. Although PRP therapy for patients with knee OA improved pain and functional scores, the association of clinical outcomes and quality of PRP including cell composition and concentration is unclear.

Methods

Therefore, this study analyzed blood cell counts, including the immature platelet fraction (IPF), in peripheral blood and PRP of 144 patients with knee OA who underwent PRP therapy. The mean leukocyte and platelet concentrations in whole blood and PRP were analyzed using an XN-1000 automated hematology analyzer. Visual analogue scale (VAS) scores and knee injury and osteoarthritis outcome scores (KOOS) before and 1 month after a single PRP injection were also determined.

Results

Higher platelet and lower leukocyte concentration rates were observed in PRP compared with whole blood. The platelet concentration in whole blood was negatively correlated with VAS improvement. The percentage of IPF (IPF%) in whole blood was positively correlated with VAS improvement and KOOS (pain) improvement, whereas the IPF% in PRP tended to correlate with VAS improvement. Furthermore, multivariate logistic regression demonstrated the high IPF% in whole blood was significantly associated with VAS improvement. The low percentage of neutrophil (neutrophil%) in PRP was significantly associated with the VAS improvement and KOOS (ADL) improvement.

Conclusions

Therefore, PRP efficacy for OA might depend on the patient's biological status.

•

High percentage of IPF (IPF%) in whole blood was significantly associated with VAS improvement.

•

Low neutrophil% in PRP was significantly associated with VAS improvement and KOOS (ADL) improvement.

•

The PRP efficacy for knee OA might depend on the patient's biological status.

Intra-Articular Injections in Knee Osteoarthritis: A Review of Literature

Knee osteoarthritis (OA) is a chronic, degenerative, and progressive disease of articular cartilage, producing discomfort and physical disability in older adults. Thirteen percent of elderly people complain of knee OA. Management options for knee OA could be divided into the following categories: conservative, pharmacological, procedural, and surgical. Joint replacement is the gold standard, reserved for severe grades of knee OA, due to its complications rate and increased risk of joint revision. A nonsurgical approach is the first choice in the adult population with cartilage damage and knee OA. Yearly, more than 10% of knee OA-affected patients undergo intra-articular injections of different drugs, especially within three months after OA diagnosis. Several molecules, such as corticosteroids injection, hyaluronic acid (HA), and platelet-rich plasma (PRP), are managed to reduce the symptoms of patients with knee OA. The aim of this review was to offer an overview of intra-articular injections used for the treatment of OA and report the conventional pharmacological products used.

Intra-articular injections of platelet-rich plasma in symptomatic knee osteoarthritis: a consensus statement from French-speaking experts

PURPOSE

There has been much debate regarding the use of intra-articular injections of platelet-rich plasma (PRP) as symptomatic treatment for knee osteoarthritis. The objective of this consensus was to develop guidelines for PRP injections in knee osteoarthritis according to the French National Authority for Health recommendations.

METHODS

Fifteen physicians from different French-speaking countries (10 rheumatologists, 4 specialists in rehabilitation and sports medicine and 1 radiologist) were selected for their expertise in the areas of PRP and osteoarthritis. A comprehensive literature review was conducted on Medline including all published therapeutic trials, open studies, meta-analysis and systematic reviews focusing on the effects of PRP in knee OA, as well as fundamental studies concerning the characteristics of the various types of PRP and their mechanisms, indexed before April 2019. Using the method recommended by the French National Authority for Health inspired by the Delphi consensus process, 25 recommendations were finally retained and evaluated. The recommendations were classified as appropriate or not appropriate, with strong or relative agreement, or uncertain if a consensus was not achieved.

RESULTS

Among the 25 recommendations selected, the main ones are the following: (1) Intra-articular injections of PRP are an effective symptomatic treatment for early to moderate knee osteoarthritis. This recommendation was considered appropriate with a relative agreement (Median = 8; rank = 6-9). Level of evidence 1A. (2) A PRP treatment sequence in knee osteoarthritis may include 1-3 injections. This recommendation was considered appropriate with a strong agreement (Median = 9; rank = 7-9). Level of evidence 1A. (3) Leucocytes-poor PRP should be preferred in knee osteoarthritis. This recommendation was considered appropriate with a relative agreement (Median = 8; rank = 5-9). Level of evidence 5. (4) Intra-articular PRP knee injections should be performed under ultrasound or fluoroscopic guidance. This recommendation was considered uncertain with no consensus (Median = 8; rank = 3-9). Level of evidence 5. (5) PRP should not be mixed with an anesthetic or intra-articular corticosteroid. This recommendation was considered appropriate with a relative agreement (Median = 9; rank = 6-9). Level of evidence 5 CONCLUSION: Those 25 recommendations should standardize and facilitate the use of IA PRP injections, which are considered by experts as an effective treatment especially in early or moderate knee OA. Although a strong or relative agreement from the experts was obtained for most of the recommendations, many of them had a very low level of evidence (Level 5) and were principally based on the clinical experience of the experts.

Hyaluronic acid and platelet-rich plasma for the management of knee osteoarthritis

PURPOSE

Symptomatic knee osteoarthritis (OA) remains a substantial cause of pain and disability worldwide and effective management in young patients without indications for total knee arthroplasty remains challenging. Intra-articular injections represent a viable option in the non-operative treatment of knee OA. Hyaluronic acid (HA) and platelet-rich plasma (PRP) are two commonly utilized intra-articular treatment modalities that are of particular clinical interest in the current literature. The purpose of this manuscript is to provide a concise review of the current literature on the use of HA, PRP, and HA-PRP conjugates for the treatment of symptomatic knee OA.

METHODS

A review of the literature utilizing PubMed, OVID/Medline, and Cochrane databases on basic science and clinical literature pertaining to preparation, composition, and outcomes of HA, PRP, and HA-PRP conjugates in patients with symptomatic knee OA.

RESULTS

Both HA and PRP have been shown to be efficacious for the treatment of symptomatic knee OA, with HA injections providing limited short-term improvement, while PRP may provide greater therapeutic relief, particularly with the use of leukocyte-poor (LP-PRP) formulations. Despite limited data, the combination of different formulations of HA-PRP conjugates may provide a synergistic effect, resulting in a clinically significant improvement in both pain and function.

CONCLUSION

In patients with symptomatic knee OA, intra-articular HA and PRP provide short-term improvement in pain and function, while the efficacy of HA-PRP conjugates warrants further study.

Intraosseous infiltrations of Platelet-Rich Plasma for severe hip osteoarthritis: A pilot study

OBJECTIVE

Addressing the subchondral bone through intraosseous infiltrations of Platelet-Rich Plasma (PRP) may improve the effectiveness of this technique for severe hip osteoarthritis (HOA).

METHODS

Forty patients with HOA degree 2 and 3 according to the Tönnis scale were recruited for this study. They were susceptible to a total hip arthroplasty, without response to previous treatment based on intraarticular infiltrations of PRP. Patients received a combination of intraosseous injections into the acetabulum and the femoral head, as well as intraarticular PRP infiltrations. The clinical outcome was evaluated at 2, 6 and 12 months using the Hip Osteoarthritis Outcome Score (HOOS) and the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index.

RESULTS

At 2, 6 and 12 months, patients had significant pain improvement according to HOOS pain, WOMAC pain, and VAS scores. After the treatment, the percentage of patients with minimal clinically important improvement was 40% (16 over 40 patients) at 2 months, 37.5% (15 over 40) at 6 months, and 40% (16 over 40) at 12 months. Conclusion: The combination of intra-articular and intra-osseous infiltrations of PRP showed a pain reduction and improvement in hip joint functionality up to 12 months in patients with severe HOA, with no severe adverse effects.

Concentrated Growth Factor Matrices Prepared Using Silica-Coated Plastic Tubes Are Distinguishable From Those Prepared Using Glass Tubes in Platelet Distribution: Application of a Novel Near-Infrared Imaging-Based, Quantitative Technique

Platelet-rich fibrin (PRF) matrices were originally prepared using plain glass tubes without the aid of coagulation factors because coagulation factor XII is activated by glass surfaces. Recently, the use of silica-coated plastic tubes as a substitute of glass tubes has been recommended for PRF preparation. This recommendation is owing not only to the shortage of glass tubes for medical use in the market, but also the higher coagulation activity of silica-coated plastic tubes and equal quality of PRF. However, these matrices are not the same. To evaluate the differences, we compared glass- and silica-coated plastic tubes in terms of platelet distribution and quantity in concentrated growth factors (CGF). CGF matrices were immediately prepared from freshly collected blood samples, fixed after red thrombus removal, and divided into two equal pieces sagittally. One piece was used for CD41 detection and the other was applied as an isotype control. Platelet distribution in CGF matrices was examined, without embedding or sectioning, by a novel method using invisible near-infrared imaging. The dehydrated membranous CGF matrix was more transparent. Thus, the fluorescence signal was clearly detectable with less scattering. Platelets were distributed mainly in the distal side of the glass-prepared CGF matrix, but homogeneously in the silica-prepared CGF matrix. Platelet count was positively correlated with fluorescence intensity. Although not yet fully developed, this imaging technique enabled us to recognize the differences in platelet distribution and quantity in CGF matrices by excluding bias caused by the technical limitations of scanning electron microscopy and conventional immunohistochemical methods.

Alternative and complementary therapies in osteoarthritis and cartilage repair

Osteoarthritis (OA) is the most common joint condition and, with a burgeoning ageing population, is due to increase in prevalence. Beyond conventional medical and surgical interventions, there are an increasing number of ‘alternative’ therapies. These alternative therapies may have a limited evidence base and, for this reason, are often only afforded brief reference (or completely excluded) from current OA guidelines. Thus, the aim of this review was to synthesize the current evidence regarding autologous chondrocyte implantation (ACI), mesenchymal stem cell (MSC) therapy, platelet-rich plasma (PRP), vitamin D and other alternative therapies. The majority of studies were in knee OA or chondral defects. Matrix-assisted ACI has demonstrated exceedingly limited, symptomatic improvements in the treatment of cartilage defects of the knee and is not supported for the treatment of knee OA. There is some evidence to suggest symptomatic improvement with MSC injection in knee OA, with the suggestion of minimal structural improvement demonstrated on MRI and there are positive signals that PRP may also lead to symptomatic improvement, though variation in preparation makes inter-study comparison difficult. There is variability in findings with vitamin D supplementation in OA, and the only recommendation which can be made, at this time, is for replacement when vitamin D is deplete. Other alternative therapies reviewed have some evidence (though from small, poor-quality studies) to support improvement in symptoms and again there is often a wide variation in dosage and regimens. For all these therapeutic modalities, although controlled studies have been undertaken to evaluate effectiveness in OA, these have often been of small size, limited statistical power, uncertain blindness and using various methodologies. These deficiencies must leave the question as to whether they have been validated as effective therapies in OA (or chondral defects). The conclusions of this review are that all alternative interventions definitely require clinical trials with robust methodology, to assess their efficacy and safety in the treatment of OA beyond contextual and placebo effects.

A Comparative Study of The Effects of Anticoagulants on Pure Platelet-Rich Plasma Quality and Potency

It is generally accepted that citrate or the A-form of acid-citrate-dextrose (ACD-A) are suitable for preparing platelet-rich plasma (PRP) for regenerative therapy. However, this is based on evidence from blood transfusions and not from regenerative medicine. Thus, we examined the effects of anticoagulants, such as ACD-A, ethylenediaminetetraacetic acid (EDTA), and heparin, on the regenerative quality of PRP to address this gap. The blood samples were collected in the presence of anticoagulants and were processed to prepare pure-PRP. Platelet size, activation status, and intra-platelet free Ca²⁺ concentration were determined while using a hematology analyzer and flow cytometer. Platelet-derived growth factor-BB (PDGF-BB) was quantified while using an ELISA. In pure-PRP samples, EDTA caused platelet swelling and activation, but yielded the highest number of platelets. Heparin aggregated platelets and disturbed the overall counting of blood cells. However, no significant differences in PDGF-BB levels were observed among the anticoagulants tested. Moreover, when considering the easy preparation of platelet suspensions, without the need for high-level pipetting skills, these findings suggest the comparable potency of EDTA-derived pure-PRP in tissue regeneration and support the use of EDTA in the preparation of pure-PRP. Further in vivo studies are required in animal models to exclude the possible negative effects of including EDTA in pure-PRP preparations.

Clinical outcomes following injections of leukocyte-rich platelet-rich plasma in osteoarthritis patients

Background

Scientists are trying to discover how to repair cartilage defects in knee osteoarthritis (KOA). In our previous study, we found a fibrocartilage-rich cover over the defective portions of cartilage after administering leukocyte-rich platelet-rich plasma (LR-PRP). This study aimed to investigate the efficacy of multiple injections of LR-PRP for the treatment of KOA and determine an LR-PRP treatment protocol for KOA in actual clinical practice.

Hypothesis

We hypothesized that using abundant LR-PRP would improve outcomes in patients with KOA.

Study design

Prospective, cross-sectional, interventional, randomized trial.

Methods

Intra-articular LR-PRP injections were administered to 50 knees. Patients received six injections of LR-PRP in total, which were administered at 4-week intervals. Patients were evaluated based on clinical outcomes, including visual analog scale (VAS) scores, Knee injury and Osteoarthritis Outcome Scores (KOOS), and magnetic resonance images (MRI) and radiographic findings before treatment and at 3 and 6 months after treatment. We investigated the recurrence of pain and presence/absence of MRI changes. Furthermore, we examined the Outcome Measures In Rheumatology-Osteoarthritis Research Society International (OMERACT-OARSI) responder criteria.

Results

The mean improvement rate, as assessed by VAS, was 61.6% (P < .0001). Concerning OMERACT-OARSI, 37 of 50 knees (74%) were considered responders. There was a significant difference in the follow-up MRI findings, as assessed by the MRI Osteoarthritis Knee Score for bone marrow lesions (P < .007). No significant difference in osteoarthritis grade was observed.

Conclusion

Our LR-PRP procedure resulted in 74% of knees being classified as responders, regardless of the degree of knee deformation. Multiple injections of LR-PRP was effective for advanced grades of KOA. Thus, based on the results of our study, we believe that LR-PRP should be implemented as an additional conservative treatment option for non-operative management of OA.

Trial registration

Japan Medical Association Center for Clinical Trials (JMA-XXX).

Optimizing the safety of intradiscal platelet-rich plasma: an in vitro study with Cutibacterium acnes

Aim: The most common risk associated with intradiscal injection of platelet-rich plasma (PRP) is discitis with Cutibacterium acnes. It is hypothesized that antimicrobial activity of PRP can be enhanced through inclusion of leukocytes or antibiotics in the injectate. Materials & methods: Multiple PRP preparations of varying platelet and leukocyte counts were co-cultured with C. acnes with or without cefazolin, with viable bacterial colony counts being recovered at 0, 4, 24 and 48 hours post-inoculation. Results: A direct correlation between C. acnes recovery and granulocyte counts were observed. Conclusion: We observed the greatest antimicrobial activity with the leukocyte-rich, high platelet PRP preparation combined with an antibiotic in the injectate. However, cefazolin did not completely clear the bacteria in this assay.

Intra-articular and extra-articular platelet-rich plasma injections for knee osteoarthritis: A 26-week, single-arm, pilot feasibility study

AIM

Platelet Rich Plasma (PRP) is an emerging therapy for knee osteoarthritis (KOA). Studies have evaluated the effectiveness of intra-articular PRP, which ignores extra-articular tissue dysfunction and may provide incomplete treatment of KOA. The study aimed to pilot test a leukocyte-rich (mononuclear cells) PRP injection protocol for primary KOA, which consisted of single intra-articular injection and extra-articular injections on the medial coronary and medial collateral ligaments.

METHODS

A prospective 26-week single-arm uncontrolled feasibility pilot study. Patients (N = 12) with primary KOA as defined by the American Rheumatology Association, with moderate to severe medial knee pain which failed conservative management, were recruited in a university primary care clinic and received a single session of PRP injection in week 1. The primary outcome was the feasibility of the protocol at 26 weeks as defined by rates of recruitment, compliance, retention, dropout, side effects or adverse events; and treatment satisfaction. Secondary outcomes included the Western Ontario McMaster University Osteoarthritis Index, the Intermittent and Constant Osteoarthritis Pain total and subscales, objective physical function tests and EuroQol-5D.

RESULTS

Twelve of 40 potential patients were recruited in 3 months period (recruitment rate 30%, x2 = 3.33, P = 0.068). All participants adhered to the protocol and completed the follow up assessment with no dropouts (dropout rate 0%, X2= 2.67, P = 0.103). Satisfaction was high; no related adverse events were reported. Most secondary outcomes showed statistically significant improvement.

CONCLUSIONS

Concomitant intra-articular and extra-articular PRP injections were feasible and produced preliminary favourable outcomes.

Efficiency of platelet-rich plasma therapy in knee osteoarthritis does not depend on level of cartilage damage

OBJECTIVES

Osteoarthritis of the knee is common and often leads to significant physical disability. While classic conservative therapeutic approaches aim for symptoms like pain and inflammation, procedures like the intraarticular application of hyaluronic acids (HA) or platelet-rich plasma (PRP) are thought to stimulate the endogenous HA production, stop catabolism of cartilage tissue, and promote tissue regeneration. To analyse whether the positive effects of PRP injections are associated with the level of cartilage damage, patient satisfaction with the treatment was correlated with the level of knee joint osteoarthritis quantified by MRI.

METHODS

PRP was performed with a low-leukocyte autologous conditioned plasma (ACP) system in 59 patients. A pre-treatment MRI was performed and a Whole-Organ MRI Score (WORMS) was used to score the level of knee osteoarthritis by 14 features: integrity of the cartilage, affection of the bone marrow, subcortical cysts, bone attrition, osteophytes, integrity of the menisci and ligaments, presence of synovitis, loose bodies, and periarticular cysts. A multivariate analysis with ordinary least squares regressions was used.

RESULTS

Although pain symptoms and severity of clinical osteoarthritis symptoms decreased, regression analysis could not detect a correlation between the degree of cartilage damage measured by the WORMS score and a positive response to PRP therapy.

CONCLUSION

This study suggests that intraarticular injection of PRP might improve osteoarthritis symptoms and reduces the pain in patients suffering from osteoarthritis of the knee joint independent from the level of cartilage damages quantified by the whole-organ MRI scoring method WORMS.

Review of concentration yields in commercially available platelet-rich plasma (PRP) systems: a call for PRP standardization

Platelet-rich plasma (PRP) has become increasingly popular in pain medicine with hopes of becoming a safe, effective alternative to routine treatments. However, given its autologous nature, PRP injectate may differ depending on the specific manufacturer and protocol. Currently, there is no standardization of reporting protocol. This systematic review compiles and standardizes values on PRP preparation and final product composition of platelets, white cell count, and growth factors for ease of comparison. On review of 876 studies, 13 studies were selected according to our inclusion criteria. Data from 33 PRP systems and protocols were extracted and standardized. Overall, PRP final product concentrations as well as PRP preparation protocols varied widely between systems. However, platelet concentration was directly correlated with both volume of blood collected and device centrifugal force. In conclusion, there is a large heterogeneity between PRP separation systems that must be resolved for proper study of this promising treatment.

Treating Severe Knee Osteoarthritis with Combination of Intra-Osseous and Intra-Articular Infiltrations of Platelet-Rich Plasma: An Observational Study

OBJECTIVE

Assessing the therapeutic effects of a combination of intra-articular and intra-osseous infiltrations of platelet-rich plasma (PRP) to treat severe knee osteoarthritis (KOA) using intra-articular injections of PRP as the control group.

DESIGN

In this observational study, 60 patients suffering from severe KOA were treated with intra-articular infiltrations of PRP (IA group) or with a combination of intra-osseous and intra-articular infiltrations of PRP (IO group). Both groups were matched for sex, age, body mass index, and radiographic severity (III and IV degree according to Ahlbäck scale). Clinical outcome was evaluated at 2, 6, and 12 months, using the Knee injury and Osteoarthritis Outcome Score (KOOS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires.

RESULTS

At 2, 6 and 12 months after treatment, IO group had a significant improvement in all KOOS and WOMAC subscales ( P < 0.05). On the contrary, patients of the IA group did not improve in any of the scores. Sixteen out of 30 IO group patients showed minimal clinically important improvement (MCII) whereas 8 out of 30 IA group patients showed this response at 6 months (26.7%; 95% CI -0.4 to 49.9; P = 0.037). At 12 months, 14 patients of IO group and 5 patients of the IA group showed MCII (30%; 95% CI 4.3 to 51.9; P = 0.013). No differences between groups were observed at 2 months.

CONCLUSIONS

PRP intra-articular injections in severe KOA were not effective and did not provide any benefit. Combination of intra-articular and intra-osseous infiltrations of PRP was not clinically superior at 2 months, but it showed superior clinical outcomes at 6 and 12 months when compared with intra-articular injections of PRP.

Platelet-leukocyte rich gel application in the prevention of deep sternal wound problems after cardiac surgery in obese diabetic patients

Background

Deep sternal wound problems (DSWP) are a rare, but serious complication following cardiac surgery requiring extensive medical treatment and resulting in increased mortality. Cardiac surgery patients presenting with both obesity and diabetes mellitus type 2 (DM 2) showed an increased incidence of DSWP in our clinic. As platelets upon activation have been shown to excrete growth factors and attractants for tissue stem cells, thus potentially promoting tissue healing, we investigated whether activated platelets could reduce the incidence of DSWP.

Methods

We applied activated autologous platelet rich plasma (PRP), forming a gel (PLG), between the sternal halves immediately prior to closure in obese [body mass index (BMI) >30] DM 2 cardiac surgery patients. The reference group constituted of all elective patients with a BMI >30 and DM 2 operated upon in the 2-year period before the application of PLG.

Results

The PLG treated group (n=144) showed a significant decrease in DSWP compared to the reference group (n=118), 6 DSWP vs. 13 DSWP respectively, P=0.03. In these groups the application of PLG was associated with a risk reduction for DSWP from 11% to 4.2%.

Conclusions

These results suggest PLG application could be beneficial to prevent DSWP following cardiac surgery in a high-risk population.

Platelet-rich plasma vs. steroid injections for hamstring injury-is there really a choice?

OBJECTIVE

To assess the effectiveness of pain relief in patients with grade 2 proximal hamstring injury, treated with platelet-rich plasma (PRP) or corticosteroid injection, by using the primary outcome of visual analog scale (VAS) at 1 week and 4 weeks of follow-up.

MATERIALS AND METHODS

A single institution retrospective study was performed for image-guided PRP or steroid injections between 12/1/2015 and 10/30/2017 for proximal hamstring injuries. VAS was measured at 1 week and 4 weeks post-injection via telephone interviews and the pain response was recorded into two groups (negative/no change vs. positive). A comparison of pain responses between PRP and steroid was conducted by generalized estimating equation.

RESULTS

Among 56 patients, 32 received PRP and 24 received steroid injections with ages from 13 to 75 years old. At 1 week post-injection follow-up, 23 patients (71.9%) from the PRP group and 11 patients (45.8%) from the steroid group showed positive response. After controlling for age, pre-procedure pain level, and gender, the positive response rate in the PRP group was higher than the steroid group (aOR: 4.04, 95% CI: 1.04-15.63, p value = 0.04). At 4 weeks post-injection, 23 patients (71.9%) from the PRP group and 13 patients (54.2%) from the steroid group showed positive response with no statistical significance (aOR: 2.48, 95% CI: 0.63-9.79, p value = 0.19).

CONCLUSIONS

The PRP group had shown more favorable response compared to steroid group at 1 week post-injection, which suggests that PRP therapy can be considered as a conservative treatment choice for grade 2 proximal hamstring injuries with better short-term pain relief based on limited pilot data.

Biologic Therapies for the Treatment of Knee Osteoarthritis

BACKGROUND

The use of biologic therapies for the management of knee osteoarthritis has increased, despite insufficient evidence of efficacy. Our aim was to complete a systematic review and analysis of reports utilizing the highest level-of-evidence evaluating: (1) platelet-rich plasma injections (PRPs); (2) bone marrow-derived mesenchymal stem cells (BMSCs); (3) adipose-derived mesenchymal stem cells (ADSCs); and (4) amnion-derived mesenchymal stem cells (AMSCs).

METHODS

PubMed, Embase, and Cochrane Library databases were queried for studies evaluating PRP injections, BMSCs, ADSCs, and AMSCs in patients with knee osteoarthritis. Of 1009 studies identified within the last 5 years, 123 met inclusion criteria. A comprehensive analysis of all levels-of-evidence was performed, as well as separate analysis on level-of-evidence I studies. Level-of-evidence was determined by the American Academy of Orthopedic Surgeons classification system.

RESULTS

Although the majority of PRP reports demonstrated improvements in pain and/or function, others revealed no substantial improvements. Similar findings were noted for BMSCs, ADSCs, and AMSCs. Assessments of BMSC studies yielded majority with positive clinical results, although short-lived. Studies on ADSCs revealed improved clinical outcomes, but equivocal radiographic outcomes. Studies evaluating AMSCs demonstrated improvements in pain and function, and decreased radiographic evidence of osteoarthritis.

CONCLUSION

Despite some promising early results for PRP, BMSC, ADSC, and AMSC therapies, the majority of level-of-evidence I studies have multiple problems: small sample sizes, potentially inappropriate control cohorts, short-term follow-up, and so on. Despite the limitations, there still appears to be evidence justifying their use for knee osteoarthritis management. More high-level, larger human studies utilizing standardized protocols are needed.

Current concepts in intraosseous Platelet-Rich Plasma injections for knee osteoarthritis

Knee osteoarthritis (OA) is a degenerative process that slowly destroys the joints producing pain and loss of function, and diminishes the quality of life. Current treatments alleviate this symptomatology but do not stop the disease, being total knee arthroplasty the only definitive solution. Among the emerging treatments, Platelet-Rich Plasma (PRP) has shown promising results in the treatment of OA. However, to improve its effectiveness, it is necessary to approach this pathology targeting the whole joint, not only the cartilage, but including other tissues such as subchondral bone. The pathological processes that occur in the subchondral bone have influence of the cartilage loss, aggravating the disease. The combination of intraarticular infiltrations with intraosseous infiltrations regulates the biological processes of the tissues, reducing the inflammatory environment and modulating the overexpression of biomolecules that generate an aberrant cellular behavior. Although the first clinical results using this technique are promising, further research and developing adequate protocols are necessary to achieve good clinical results.

Use of platelet-rich plasma in regenerative medicine: technical tools for correct quality control

Background/aims

Platelet-rich plasma (PRP) injections are used in sports medicine and have been the subject of increased clinical interest. However, there have been very few reports of the composition of initial whole blood and the final PRP product. The objective of this study was to provide technical tools to perform a correct characterisation of platelets, leucocytes and red blood cells (RBCs) from whole blood and PRP.

Methods

Blood and PRP were obtained from 26 healthy volunteers and prepared according to the varying parameters encountered within PRP process preparation and quantification (harvesting method, anticoagulant used, sampling method, counting method). Concentrations were measured at t=0, t=1, t=6 and t=24 hours.

Results

Sampling of blood in Eppendorf tubes significantly decreased platelet concentration over time, whereas sampling in Microvette EDTA-coated tube kept platelet concentration stable until 24 hours. A non-significant difference was observed in platelet counts in PRP with impedance (median (IQR): 521.8 G/L (505.3–524.7)) and fluorescence (591.5 G/L (581.5–595.8)) methods. Other studied parameters did not influence platelet concentrations in blood or PRP samples. Leucocytes and RBC counts were similar whatever the anticoagulant, sampling, harvesting and counting methods used for both blood and PRP samples.

Conclusions

Systematic sampling of blood and PRP in EDTA-coated tubes for quality control is recommended. The use of a validated counter for PRP sample should also be taken into account.