Arthroscopy: The Journal of Arthroscopic & Related Surgery
Level V EvidencePlatelet-Rich Plasma: The PAW Classification System
Section snippets
Identifying Content of PRP
Several essential factors exist that need to be identified to adequately determine the effects of PRP treatment.
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The most essential factor is to ensure accurate and definitive concentration measurements of platelets. Without precise quantification of the cellular components, validation and accurate comparison of studies will remain extremely difficult, ultimately impeding discovery of optimum dosing. Many studies published in the recent literature lack this most basic requirement.
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The presence
Understanding PRP Methods and Systems
PRP can be manufactured in 2 basic formats: plasma-based and buffy-coat preparations. Both begin with whole blood but differ in the centrifugation process, which isolates and concentrates different blood-cell components.12
Plasma-based methods work to isolate only plasma and platelet components and remove WBCs. Protocols for these preparations leave some platelets behind and focus on intentionally excluding leukocytes, which are thought to be detrimental to the healing process.2, 3, 4, 5, 6, 7, 8
Platelet Concentration
Few studies have compared the healing effects of different PRP platelet concentrations for the same indication.14, 41 This may prove to be the most significant aspect in identifying the true effectiveness of PRP and in choosing the proper protocol.
Activation Methods
Platelets can be activated endogenously or through the addition of an exogenous clotting factor to any commercially available system. Each type of activator may produce varying effects and significantly influence growth factor kinetics. Accurately documenting the delivery method and activation scheme used is another key to a successful classification system.
PAW Classification System
With all of the previous information being taken into consideration, the PAW classification system of PRP is based on 3 components: (1) the absolute number of Platelets, (2) the manner in which platelet Activation occurs, and (3) the presence or absence of White cells. By analyzing these 3 variables, we are able to accurately compare publications (Table 3, Table 4).
Conclusions
PRP continues to occupy both orthopaedic literature and the lay press, and more funding is being dedicated to unraveling its mysteries; a simple method for comparing published data based on the content of PRP needs to be established. Our system offers a simple, effective method for quickly documenting the cellular components and activation method used. The acronym PAW serves as a pneumonic for Platelets, Activation, and White cells, and the subcategories are thoughtfully organized to enhance
Acknowledgment
The following individuals are acknowledged for their substantial contribution in the development of the classification system: Bryan T. Hanypsiak, M.D., David O. Shepard, M.B.A., C.T.B.S., and Brandon L. Roller, M.D. All are employees of Arthrex, Naples, Florida.
References (97)
- et al.
Inflammatory cells during wound repair: The good, the bad and the ugly
Trends Cell Biol
(2005) - et al.
Poor standardization in platelet-rich therapies hampers advancement
Arthroscopy
(2010) - et al.
Autologous preparations rich in growth factors promote proliferation and induce VEGF and HGF production by human tendon cells in culture
J Orthop Res
(2005) - et al.
Ligamentization of tendon grafts treated with an endogenous preparation rich in growth factors: Gross morphology and histology
Arthroscopy
(2010) - et al.
Effect of platelet concentration in platelet-rich plasma on peri-implant bone regeneration
Bone
(2004) - et al.
Effect of platelet-rich plasma (PRP) concentration on the viability and proliferation of alveolar bone cells: An in vitro study
Int J Oral Maxillofac Surg
(2005) - et al.
Classification of platelet concentrates: From pure platelet-rich plasma (P-PRP) to leucocyte- and platelet-rich fibrin (L-PRF)
Trends Biotechnol
(2009) - et al.
Wound healing in the PU.1 null mouse—Tissue repair is not dependent on inflammatory cells
Curr Biol
(2003) - et al.
Treatment of tendon and muscle using platelet-rich plasma
Clin Sports Med
(2009) - et al.
Platelet-rich fibrin (PRF): A second-generation platelet concentratePart I: Technological concepts and evolution
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
(2006)
Angiogenic properties of sustained release platelet-rich plasma: Characterization in-vitro and in the ischemic hind limb of the mouse
J Vasc Surg
Activation of platelet-rich plasma using soluble type I collagen
J Oral Maxillofac Surg
Does a single application of PRP alter the expression of IGF-I in the early phase of tendon healing?
J Foot Ankle Surg
Platelet-rich plasma: New clinical application: A pilot study for treatment of jumper's knee
Injury
Platelet rich plasma in arthroscopic rotator cuff repair: A prospective RCT study, 2-year follow-up
J Shoulder Elbow Surg
Rotator cuff repair healing influenced by platelet-rich plasma construct augmentation
Arthroscopy
Platelet-rich plasma intra-articular injection versus hyaluronic acid viscosupplementation as treatments for cartilage pathology: From early degeneration to osteoarthritis
Arthroscopy
Producing accurate platelet counts for platelet rich plasma: Validation of a hematology analyzer and preparation techniques for counting
J Craniofac Surg
M1/70 attenuates blood-borne neutrophil oxidants, activation, and myofiber damage following stretch injury
J Appl Physiol
Role of neutrophil-endothelial adhesion in skeletal muscle reperfusion injury
Br J Surg
Wound healing: An overview of acute, fibrotic and delayed healing
Front Biosci
Accelerated wound closure in neutrophil-depleted mice
J Leukoc Biol
The polymorphonuclear leukocyte: Has it a role in fracture healing?
Arch Orthop Trauma Surg
Neutrophil infiltration in exercise-injured skeletal muscle: How do we resolve the controversy?
Sports Med
The neutrophilic leukocyte in wound repairA study with antineutrophil serum
J Clin Invest
The inflammatory response: Friend or enemy for muscle injury?
Br J Sports Med
Inflammatory processes in muscle injury and repair
Am J Physiol Regul Integr Comp Physiol
Platelet-rich plasma therapy: A systematic literature review and evidence for clinical use
Phys Sports Med
Comparison of growth factor and platelet concentration from commercial platelet-rich plasma separation systems
Am J Sports Med
Platelet-rich plasma (PRP) to treat sports injuries: Evidence to support its use
Knee Surg Sports Traumatol Arthrosc
Variation of pH in lysed platelet concentrates influence proliferation and alkaline phosphatase activity in human osteoblast-like cells
Platelets
Potential anti-thrombotic effects of local anesthetics due to their inhibition of platelet aggregation
Acta Anaesthesiol Scand
Platelet-rich plasma differs according to preparation method and human variability
J Bone Joint Surg Am
In vitro short-term platelet adhesion on various metals
J Artif Organs
Platelets
Decrease in platelet surface charge during phagocytosis of polystyrene latex particles or thorium dioxide
Scand J Haematol
ACP: Autologous conditioned plasma double syringe systemBrochure LB0810F
Releasing the power of growth factor healingBrochure 408-5M 506TC4
Platelet content and growth factor release in platelet-rich plasma: A comparison of four different systems
Vox Sang
Not every PRP-gel is born equalEvaluation of growth factor availability for tissues through four PRP-gel preparations: Fibrinet, RegenPRP-Kit, Plateltex, and one manual procedure
Vox Sang
Effectiveness of autologous preparation rich in growth factors for the treatment of chronic cutaneous ulcers
J Biomed Mater Res B Appl Biomater
Intra-articular injection of an autologous preparation rich in growth factors for the treatment of knee OA: A retrospective cohort study
Clin Exp Rheumatol
Comparison of surgically repaired Achilles tendon tears using platelet-rich fibrin matrices
Am J Sports Med
GPS III platelet separation system process stepsBrochure BB10001.0
GPS III platelet separation systemBrochure BB10003.0
Platelet quantification and growth factor analysis from platelet-rich plasma: Implications for wound healing
Plast Reconstr Surg
Comparison of methods for point of care preparation of autologous platelet gel
J Extra Corpor Technol
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The authors report the following conflict of interest in relation to this article: A.D.M. received research support and is a consultant for Arthrex, Inc., Naples, Florida.