the use of platelet-rich plasma (prp) for the management of … · 2021. 1. 4. · keywords...

ORTHOPEDIC MANAGEMENT OF FRACTURES (M KACENA AND L GERSTENFELD, SECTION

EDITORS)

The Use of Platelet-Rich Plasma (PRP) for the Managementof Non-union Fractures

Christian Andersen1& Nicholas M. Wragg2,3

& Maryam Shariatzadeh2& Samantha Louise Wilson2

Accepted: 4 December 2020 /Published online: 4 January 2021# The Author(s) 2020

AbstractPurpose of Review The treatment of non-union fractures represents a significant challenge for orthopaedic surgeons. In recentyears, biologic agents have been investigated and utilised to support and improve bone healing. Among these agents, platelet-richplasma (PRP) is an emerging strategy that is gaining popularity. The aim of this review is to evaluate the current literatureregarding the application and clinical effectiveness of PRP injections, specifically for the treatment of non-union fractures.Recent Findings The majority of published studies reported that PRP accelerated fracture healing; however, this evidence waspredominantly level IV. The lack of randomised, clinical trials (level I–II evidence) is currently hampering the successful clinicaltranslation of PRP as a therapy for non-union fractures. This is despite the positive reports regarding its potential to heal non-union fractures, when used in isolation or in combination with other forms of treatment.Summary Future recommendations to facilitate clinical translation and acceptance of PRP as a therapy include the need toinvestigate the effects of administering higher volumes of PRP (i.e. 5–20 mL) along with the requirement for more prolonged(> 11 months) randomised clinical trials.

Keywords Bone healing . Fracture . Non-union . Platelet-rich plasma (PRP)

Introduction

The US Food and Drug Administration (FDA) defines a longbone non-union as a fracture that has failed to heal within thefirst 9 months following injury and has shown no signs ofhealing for at least 3 consecutive months [1]. However, there

is currently no standardised system to define a non-union, sofractures can also be classified as a non-union outside of theseparameters (Table 1). The diagnosis of non-union is depen-dent upon a number of factors including the location of injury,since healing times vary depending upon the type and locationof the bone; and weight-bearing bones, such as the femur andtibia, often require the longest healing times to achieve union[2]. A fracture can also be classified by a clinician as a ‘non-union’ when he/she believes the fracture has little or no po-tential to heal [3]. Specific examples of this arise when there isa persistent gap at the fracture site several months followingthe initial injury, and/or in instances whereby the patient suf-fers from persistent pain at the fracture site long after the initialpain of the break has occurred [4].

Impaired healing occurs in 10–15% of fracture patients,which ultimately can lead to a non-union [5]. Characteristicsof an impaired healing process include persistent pain, poorbridging of the fracture site by callus formation and a persis-tent radiolucent line at the fracture which can be visualised viaX-ray [6]. Risk factors associated with non-union include in-creasing age and alcohol consumption, smoking and deficien-cies in vitamin D, calcium or protein [4].

This article is part of the Topical Collection on Orthopedic Managementof Fractures

* Samantha Louise [email protected]

1 National Centre for Sport and Exercise Medicine, School of Sport,Exercise and Health Sciences, Loughborough University, EpinalWay, Loughborough, Leicestershire LE11 3TU, UK

2 Centre for Biological Engineering, Wolfson School of Mechanical,Electrical and Manufacturing Engineering, LoughboroughUniversity, Epinal Way, Loughborough, Leicestershire LE11 3TU,UK

3 School of Pharmacy and Bioengineering, Guy Hilton ResearchCentre, Thornburrow Drive, Hartshill, Keele University,Stoke-on-Trent, Staffordshire ST4 7QB, UK

Current Osteoporosis Reports (2021) 19:1–14https://doi.org/10.1007/s11914-020-00643-x

http://crossmark.crossref.org/dialog/?doi=10.1007/s11914-020-00643-x&domain=pdf

https://orcid.org/0000-0002-9152-9182

mailto:[email protected]

Non-union fractures provide a socioeconomic burden thatputs pressure on already strained healthcare systems [6]. In theUK, the average cost of long bone non-union treatment is£29,204 per patient; in Canada, 67–97% of the total costs oftibia fractures were specifically related to non-unions in 2014[7]. Within European healthcare systems, this range narrowedto 82.8–93.3% in the same year [7]. Non-unions are a signif-icant source of morbidity and have a serious impact on patientquality of life (QoL). This is because delayed healing requiresadditional hospitalisation and the requirement for extensive,often uncomfortable surgical treatments which take, on aver-age, a further 4–8 months to recover from (assuming no fur-ther issues arise during treatment and rehabilitation) [7]. Thecurrent ‘gold standard’ for treatment of non-union fractures isthe use of autologous cancellous bone grafts [8]. Bone fromanother part of the body is transplanted to the non-union sitewhere it can act as a scaffold on which new bone can grow.Bone grafts provide the non-union site with a fresh source ofbone cells to help ‘jump start’ the healing process [4].However, researchers are currently exploring alternative ther-apies and treatment options, largely due to the limited supplyand donor site morbidity associatedwith autologous grafts [8].One potential alternative, which is gaining popularity in theliterature, is the use of platelet-rich plasma (PRP).

The aim of this review is to use the current literature toevaluate the effectiveness of PRP in accelerating the healingof non-union fractures. This can be used to inform as towhether PRP may eventually have the potential to become aprimary treatment perceptive option.

Methods

As a part of the systematic literature search, the followinginclusion criteria were utilised: clinical reports of any levelof evidence, published in the last 20 years (2000–2020) usingPRP for the treatment of fractures, with a specific focus onnon-unions. Keyword strings of (((‘platelet rich plasma’ OR

‘PRP’))) AND ((‘bone fracture’ OR ‘non-union fracture’ OR‘delayed healing’)) AND (‘human’ OR ‘clinical’) were usedto identify relevant English language articles using the elec-tronic database, PubMed. Scopus, Google Scholar andSpringer were also utilised to search for additional resources.

Results

Using the search terms described returned 38 articles that wereeligible for inclusion. The removal of duplicate records result-ed in 29 records being screened for relevance (Fig. 1). Thetitles and abstracts were screened, and 7 articles were removedsince they were unrelated and/or review articles, book chap-ters or conference proceedings. Four articles were removedsince they referred to soft tissues. Eighteen studies were in-cluded in a qualitative synthesis. Due to the diversity of pro-tocols implemented and the significant variation in outcomemeasures that were reported, it is extremely difficult to directlyquantitatively compare the studies. Thus, a narrative critiquewas deemed to be most appropriate to review and present therelevant literature. The search revealed that the vast majorityof literature has reported benefits of PRP in accelerating boneregeneration. The optimum dose of PRP for treating non-unions is currently undetermined, and the lack ofstandardisation regarding the preparation and delivery ofPRP is retarding clinical translation. Therefore, this reviewalso aims to provide recommendations for successful clinicaltranslation, uptake and acceptance.

PRP and Its Role in Regeneration

The use of PRP in tissue regeneration is a rapidly evolvingarea for both clinicians and researchers and is being employedin various fields, including osteoarthritis [9], rotator cuff repair[10, 11] and bone regeneration [12]. This is because autolo-gous platelet concentrations offer an easy, cost-effectivemeth-od to obtain the high concentrations of specific growth factors

Table 1 Classification of non-union fractures adapted from Panagiotis et al. 2005 [5]

Classification Description/pathology

Hypertrophic (hypervascular,viable, vital)

Inadequate immobilisation, yet adequate blood supply. In radiographs, callus formation is decreased with anelephant-foot or horseshoe configuration observed.

Atrophic (avascular, non-viable,avital)

Poorly vascularised non-union, resulting in poor potential for forming bone cells and, therefore, delayed healing.There is little callus formation around the fibrous tissue–filled fracture gap.

Oligotrophic The body can initiate a healing response but is unable to complete the fracture formed between the two ends of thebone.

Septic A bacterial infection impedes the healing process. Typical bacterial strains that inflict non-union sites includecoagulase negative Staphylococcus spp. and Propionibacterium spp.

Pseudoarthrosis Persistent motion at fracture site causes formation of false joint (joint that develops at the site of a fracture), oftenproducing synovial fluid.

2 Curr Osteoporos Rep (2021) 19:1–14

including platelet-derived growth factor (PDGF), vascular en-dothelial growth factor (VEGF), transforming growth factor(TGF beta 1 and 2) and insulin-like growth factor (IGF-1)which are required for tissue healing and regeneration [9]. Ahealthy individual has a baseline platelet count between 1.5and 4.5 × 105/μL [12]; to be deemed as therapeutically bene-ficial, a platelet concentration of 4–5 times that of baselineshould be present. The preparation of PRP varies slightly inpublished literature. However, in general, blood is drawn intoa tubewhich is often treated with an anticoagulant [13]. This isfollowed by centrifugation and activation of the platelets via achemical agent [13]. Frequently used activators include calci-um chloride [13–19] and bovine [17, 20] or autologous throm-bin [15, 21, 22]. Thrombin forms a gel-like substance, fromwhich the PRP can be extracted and directly applied to thepatient intravenously [14, 17, 23].

Within platelets are granules, which contain numerousgrowth factors and cytokines that are important in the earlystages of bone repair [12]. On activation, following clotting,these platelets release these growth factors, which play a crit-ical role in the production of proteins required for regenerativeprocesses, such as cellular proliferation, matrix formation, os-teoid production and collagen synthesis [12].

Current Use of PRP in Non-union Fractures

Clinical trials have investigated the effect of PRP on non-union healing alone [14, 21, 24, 25] and in combination withother forms of treatment such as the use of mesenchymal stemcells (MSCs) [26, 27], internal fixation and/or nailing [16, 19,23, 28–30]. When using PRP in isolation to treat a non-union,the therapeutic benefit is divided; in some instances, PRP hasbeen deemed successful in achieving bony union at the frac-ture site [24, 25, 31] within 11 months of initial injury orsurgery [17]. In addition, PRP has been shown to enhancethe healing of non-unions when used in conjunction with otherforms of treatment such as the ‘gold standard’ autologousbone graft [32, 33], as well as MSCs [27, 34] and internalfixation [16, 28, 29]. Despite the majority of literaturereporting the success of PRP in accelerating healing, it hasbeen found to have less of an effect when compared to otherforms of treatment, most importantly the use of bone morpho-genetic proteins (BMPs), such as rhBMP-7 [35]. This is mostlikely due to the low concentration of growth factors whichcan be extracted with PRP in comparison to BMPs [36].

Among the literature concerning the use of PRP specifical-ly for the treatment of non-union fractures, there is currently a

Screenin

gIn

clu

de

dE

lig

ibility

Identification

Records excluded after

screening title and journal

abstract (n = 7)

- Unrelated

- Review articles, book

chapters, conference

abstracts/papers

Full-text articles

excluded, with reasons (n

= 4)

- not long-bone specific

- did not include PRP

Records identified through

database searching

(n = 38)

Records after duplicates removed

(n =29)

Records screened

(n = 29)

Full-text articles

assessed for eligibility

(n =22)

Studies included in

qualitative synthesis

(n = 18 )

Studies included in

quantitative synthesis

(meta-analysis)

(n = 0)

Fig. 1 Prisma flowchart of studyselection criteria

Curr Osteoporos Rep (2021) 19:1–14 3

lack of prospective randomised clinical trials (RCTs) and,therefore, a minimal amount of literature with level I–III evi-dence. Instead, studies are predominantly in the form of caseseries or preliminary studies (level IV evidence) [14–19, 22,24–27, 29, 31]. The advantage of case series is that they arerelatively easy to conduct whilst requiring less time and finan-cial resources in comparison to RCTs, cohort or case-controlstudies. However, the limitations include a lack of controlsubjects, which leaves the interpretation of results open tobias. Not only are the majority of published PRP studies caseseries, but the studies are also predominantly pre-clinical(Fig. 2). Fortunately, the most recent literature [14, 15, 22,31], summarised by Roffi et al. [37], demonstrated that studiesare moving towards a more clinical direction, which is vital forsuccessful translation of any therapy.

PRP Preparation and Administration

Despite PRP being widely used for several musculoskeletalpathologies [9–11], there is currently a lack of standardisationwith regard to the how PRP is prepared and delivered fortreatment of non-union fractures. In general, the PRP prepa-ration process involves the processes of collection, centrifuga-tion to separate out the platelets, extraction of platelet-richplasma from the red blood cells and platelet poor plasmaand activation using an anticoagulant agent (although this isnot always the case) followed by administration to the injurysite (Fig. 3).

During preparation, the process of centrifugation isutilised for concentrating platelets in all literature.However, the rates of centrifugation differ between stud-ies, ranging from 3200 up to 5200 rpm [15, 19, 21, 30],which leads to different relative forces depending on rotorlength, while other studies do not state the rate [7, 35].Furthermore, centrifugation can potentially lead to thefragmentation of the platelets and the early release ofgrowth factors which will ult imately reduce the

bioactivity of the PRP [15]. Thus, activation of the PRPcould be influenced by the relative centrifugal forces be-tween studies causing unwanted variation. Therefore, it isrecommended that future studies consider ultrafiltration,which potentially offers a more standardised process forPRP extraction [17].

Activation of PRP via the use of chemical anticoagulantagents is also a key component of the preparation process.Throughout the literature, this activator varies, with throm-bin, calcium chloride and calcium gluconate being themost common. Thrombin is often combined with calciumchloride (CaCl2) [19, 20] or calcium gluconate [15, 21] inan attempt to further increase activation of the platelets. Insome literature, details regarding activator use are absent[31], with some studies using none at all [24]. Differentreagents have differing half-lives [38], which also has animpact on the duration of the anticoagulant to clear thesystem. This in turn will have an impact on PRP activationand, therefore, have an impact on the rate of bone regen-eration and PRP efficacy. Furthermore, anticoagulant use,particularly those with prolonged half-lives, may limit thesuitability of PRP as a therapy for some patient groupsincluding those with anaemia and renal diseases [39].When analysing PRP delivery methods, it was noted thatthe volume of PRP delivered varies significantly betweenstudies, with the dose of a single injection varying from2.5 ml [14] up to 20 ml [24]. The total dose is usually givento a patient as a single dose [21, 24], but may also bedivided into multiple injections over consecutive weeks[14, 25] (Table 2). This will likely cause differing levelsof efficacy between methods of application as injecting asingle dose in comparison to the same dose being dividedover several weeks will impact upon the rate of bone re-generation. Dividing a set dose over a period of severalweeks will likely delay the intended effect of the injection,slowing the rate of non-union healing. Conversely, the ap-plication of multiple equivalent doses of PRP over a

Fig. 2 The current proportions ofpre-clinical and clinical studiesinvestigating the use of PRP forthe treatment of bone defects from2005 to 2016, reproduced fromRoffi et al. (2017) [37] withpermission from copyright owner(the authors)


prolonged period may increase healing rates, although it isimpossible to say for certain since rate of healing is patientspecific and RCTs would need to be performed to clarifythis.

The Impact of PRP Activation on Bone Regeneration

The majority of published studies currently fail to report keyaspects such as platelet concentrations, leukocyte componentsand activation modalities [37]. This is despite Chen et al. dem-onstrated how a medium concentration of PRP (2.65 ± 0.2 ×109/mL) induces oestrogenic differentiation of bone marrowstem cells (BMSCs/BM-MSCs), improving fracture healing,whereas a high concentrations of PRP (8.21 ± 0.4 × 109/mL)can inhibit osteogenic differentiation and delay callus remod-elling [40]. Labibzadeh et al. reported that leukocyte-rich PRPinduced higher proliferation of BMSCs [27], while other lit-eratures have found activation modality to influence the mol-ecules released by the PRP [41]. This highlights that differingconcentrations and ultimately levels of activation will affectthe efficacy of the therapy.

The Use of PRP in Isolation to Treat Non-unionFractures

Once PRP has been prepared, treated with an anticoagulant andactivated, it is often then applied alone as a form of treatment.Only one study reported PRP to be unsuccessful in achievingunion when used in isolation [14]. The study comprised 20 pa-tients, 12 of which were diagnosed with a non-union fracture.These subjects were treated weekly for 6months [14]. No patientachieved union up to 10 months following treatment. Therefore,the authors concluded that PRP was ineffective in treating non-unions [14]. However, the administration of the PRP was a lim-itation of the study. A total of 2.5 mL of PRP activated bycalcium chloride was injected each week for 3 weeks. A2.5 mL dose of PRP is relatively small in comparison to otherstudies; however, it is impossible to determine how the harvestblood and/or delivery volume used in any study compares to thenumber of platelets and/or leukocytes isolated, since this value is

very rarely stated in published studies (Table 2). Furthermore, thesize of non-union is widely varying when comparing patientswithin study groups and separate studies to each other.Moreover, the size/volume of the non-union is not always pre-scribed in published studies. PRP has been a reported successwith a dose of at least 5 mL per injection [28, 30], often appliedon at least three separate occasions [25, 31] In addition to this, thePRP was activated using calcium chloride. In the majority ofpublished literature where PRP has successfully induced union,bovine/autologous thrombin was utilised in the activation pro-cess [15, 17–19, 21, 22, 28], thus implying that activation usingcalcium chloride alone and the lower dose of PRP could poten-tially be key factors in the unsuccessful union of these patients’fractures.

Despite its common use, bovine thrombin as an activator hasbeen questioned in clinical application, since disease transmis-sion, possible carcinogenesis, availability and cost are all issuesrelated to bovine thrombin [20]. Furthermore, Malhotra claimedthat sufficient thrombin is produced via local trauma when thefracture site is infiltrated with a needle [24]. To test this hypoth-esis, a high volume of 20 mL of PRP was injected on one occa-sion without thrombin and with a high concentration of platelets(approximately 5 times normal values) [24]. Eighty-seven per-cent of patients achieved union at the end of the 4-month follow-up period. All of which had an average time of 9.1 months be-tween the injury and the PRP injection [24].

In 2008, Bielecki et al. concluded that PRP is a sufficientmethod to achieve union as long as the treatment occurs ≤11 months following initial surgery [17]. In Malhotra et al.’sstudy, the 13% of patients who had previously not achievedunion were treated with PRP over 12 months following initialdiagnosis. However, following the conclusions of Bielecki et al.,due to the delay in PRP treatment from diagnosis, the fracturegap most likely became too large for the PRP to have a regener-ative effect. Limitations that were acknowledged in the studywere that it was not a RCT and only involved non-unions whichhad more than 90% contact between the fracture fragments.Therefore, findings from this study may not be applicable tomore severe non-unions. A more recent study by Tawfik et al.had similar inclusion criteria (more than 90% contact between

Fig. 3 A generalised overview of the PRP process


Table2

Platelet-richplasmaforthetreatm

entand

managem

ento

fnon-unionfractures:comparisonof

studies

Author/study

Size

andtype

ofnon-union

Treatment

Harvestvolume

Plateletseparation/centrifugatio

nprotocol

PRPextractionbloodcount

Bieleckietal.

2008

[17]

Establisheddelayedunionand

non-unionfractures(n=32):

Delayed

uniongroup(n=12):tib

ia(n=9),fibula(n=3).

Non-union

group(n=20):tib

ia(n=11),fibula(n=1),

humorous(n=3),radius(n=2).

Percutaneousinjectionof

autologous

platelet-leukocyte-richgel

(PLRG),interventio

n>12

monthsfollo

winginjury.

ForPR

P:108mlo

fautologous

basilic

vein

with

12mL

anticoagulant

(sodium

citrate).

Centrifugation×1@

3200

rpm

12min.

Preoperativ

eplateletcount

<130×10

9/L

tomeetinclusion

criteria.

Meanplateletcountw

as241±64

×10

9/L

andmean

leukocytecountw

as7.6±2.57

×10

9/L

inblood.

Plateletcountswereincreasedby

720%

andleukocytecounts

wereincreasedby

760%

onaverage.

Calorietal.

2008

[35]

Persistent

atrophiclong

bone

non-unions

(n=120)

including

tibia(n=15),femur

(n=10),

humerus

(n=15),ulnar(n

=12)

andradius

(n=8)

inrhBMP-7

group.

Tibia(n=19),femur

(n=8),

humerus

(n=16),ulnar(n

=8),

radius

(n=9)

inPR

P-treated

group.

Com

parisonof

rhBMP-7mixed

with

abio-reabsorbablecarrier

(3.5

mgEptoterminalfa,+

1g

collagen,Osigraft,reconstituted

with

2–3mLphysiological

solutio

n(n=60),comparedto

PRP(n=60).

54-or

108-mLwholebloodinacid

acid-citrate-dextrose;2

0mL

PRPextractedin

total.

Centrifugation2×14

min

(no

rpm/×ginform

ationprovided)

Novalues

provided.

Centeno

etal.

2011

[26]

Stable,chronicnon-unionfractures

(n=6)

includingdistalhumerus

(n=1),sacralb

ase(n=1),1st

metatarsal(n=1),ischial

tuberosity

(n=1),tibia(n=1),

tibiaandfibula(n=1).

PRPcombinedwith

MSC

s,average

timeof

interventio

n8.75

months

post-fracture(range

4–18

months)

200mLof

heparinisedIV

venous

bloodwas

used

toharvest

plateletlysate(PL).MSC

isolated

using10

mLof

marrow

bloodfrom

rightp

osterior

iliac

spine(PSIS),and

10mLfrom

theleftPS

IS

Centrifugation@

200×

g(notim

e)~30.25×10

6±34.01MSC

sinjected

into

each

patient.

NoPL

countsprovided.

Chiangetal.

2007

[20]

Low

erextrem

itylong

bone

atrophic

non-unionfractures(n=12)of

tibia(n=8)

andfemur

(n=4),

both

septicandaseptic

patients

treated.

Bonegraftenrichedwith

autologous

plateletgel(APG

).APG

sprayed

onto

thebone

grafttoform

anAPG

/graftcomplex

which

was

cut/m

oulded

tobridge

thebony

defect.

Patientswith

smalld

efects(n=6)

cancellous

bone

autograftswere

harvestedfrom

theanterior

orposterioriliac

crest,dependent

upon

availability.

Forlarger

defects(n=6),the

graftconsisted

ofcancellous

autograftw

ithallograft(3patients)or

Osteoset

(3patients).45–55

mL

autologous

intravenousblood

used

toharvestp

latelets

Centrifugation@

3650

rpm,

follo

wed

by60

rpm

and

3000

rpm

(nospecifictim

ings

provided).

Novalues

provided.

Duram

azetal.

2018

[19]

PRPgroup:

long

bone

diaphysis

non-unions

(n=14);femur

(n=8),tibia(n=6)

Allpatientshadbeen

previously

treatedwith

intram

edullary

nailing

priorto

treatm

entw

ithpercutaneous

PRPinjectioninto

55mLvenous

blood.

Centrifugation×3@

3650

rpm,

follo

wed

by60

rpm

and

3000

rpm

(nospecifictim

ings

provided).

Novalues

provided.


Tab

le2

(contin

ued)

Control

group:

femur

(n=7)

and

tibia(n=8).

thenon-unionsiteunder

fluoroscopicguidance

(n=14)

vs.control:exchange

intram

edullary

nailing

(EIN

,n=15).

Galasso

etal.

2008

[16]

Atrophicdiaphyseallong

bone

non-unions

(n=22)of

tibia

(n=11),femur

(n=8)

and

humerus

(n=3).

Intram

edullary

nailing

andPRPgel

placed

inpseudoarthrosisrim

during

surgery.

50mLautologous

blood,6mL

PRPextracted.

‘Centrifugation’

(novalues/rates).

Preoperativ

eplateletcount

<100,000cells/m

Lto

meet

inclusioncriteria.

Ghaffarpasand

etal.2016

[30]

Longbone

non-unionfracture

(n=75):femur

(n=35),tib

ia(n=26),humerus

(n=11)and

ulna

(n=3).

Control:salineplacebo(n

=38)vs.

PRPcombinedwith

autologous

iliac

crestb

onegraftin

gand

intram

edullary

nailing

(fem

oral

factors)or

open

reductionand

internalfixatio

nusingsteelplates

andscrewsfor(hum

eral

fractures)(n=37).

54mLvenous

bloodfrom

right

cubitalv

ein,~5–6mLPRP

extracted

Centrifugation×1:

3200

rpm

15min

Preoperativ

ehaem

oglobin

(mg/dL

)13.5±1.8(PRP),

13.1±2.3(control);

Preoperativ

eplateletcount

(×10

6/μL):2.1±0.6(PRP),

2.2±0.8(control);PRPplatelet

count(×10

6/μL)9.3±2.6

Golos

etal.

2014

[31]

Delayed

unionof

long

bones

(n=132)

including:

humerus

(n=28),forearm

(n=4),fem

ur(n=9)

andtib

ia(n=33).

PRPinjectiontothefractureclefton

average4.05

monthsfollo

wing

diagnosisofdelayedunion(range

2–5.8months)with

open

reductionandplatefixatio

n.

50mLwholeblood(3–4

mLPRP)

or150mLwholeblood(7.8

mL

PRP)

dependentu

ponfracture

locatio

nandcleftsize.

Noinform

ation.

Novalues

provided.

Jiangetal.

2016

[25]

Tibianon-unionwith

breakage

oftheplate(n=1).

Autologousplateletlysate(A

PL)

percutaneous

injection

~9monthsfollo

wingfracture

diagnosis,6monthspost-failed

internalfixatio

nsurgery.

40mLperipheralvein

blood,

~20

mLPRPextracted.

Centrifugation200×

g20

min

@RT;followed

byovernight

cryopreservatio

n@

−80

°C,

resuscitatio

nat37

°Cand

repeated

free

thaw

s(‘morethan

twice’);follo

wed

by1.700×

gfor

6min.

Novalues

provided.

Labibzadeh

etal.2016

[27]

Asepticnon-union(n=7)

offemur

(n=4),tibia(n=1),fibula

(n=1),tibiaandfibula(n=1).

PRP(plateletlysates,P

L)combined

with

bone

marrow–derived

mesenchym

alstem

cells

(BM-M

SCs)MSCs(20–50

millioncells

perinjection).

Durationof

non-unionranging

from

8monthsto

11years.

Umbilicalcord

blood.BM

aspiratio

n:100–150mLfrom

iliac

crest

Centrifugation2000×g2min

or1000×g15

min

at20

°C;

follo

wed

by3000×g10

min

@10

°C;o

vernight

freezing

@−70

°Cfollo

wed

bythaw

ingat

37°C

andheatinactiv

ationat

56°C

for30

min.F

inally,900×g

30min.

Novalues.

Mahadik

etal.

2018

[29]

Longbone

non-union(n=30):

femur

(n=17),tib

ia(n=5),

humerus

(n=5),radiusandulna

(n=3).

PRPandinternalfixatio

n(open

reductionandinternalfixatio

n,screwingor

nailing

dependanton

type

offracture

follo

winginitial

failedtreatm

entu

sing

conservativ

e/surgerydependent

upon

fracture

type).

Novalues.

Noinform

ation.

Novalues.

Malhotraetal.

2015

[24]

Establishedlong

bone

non-union

(n=94):tib

ia(n=35),femur

(n=30),humerus

(n=11),

PRPintravenousinjection;

~9.1monthsbetweeninjury

and

100mLautologous

bloodfrom

cubitalv

ein.

‘Seriesofcentrifugatio

n’(nofurther

inform

ationprovided).

>2millionplatelets/μL.


Tab

le2

(contin

ued) radius

(n=4),ulna(n=12),

radius

andulna

(n=2).

>90%

contactb

etweenfracture

fragmentswith

suitableopen

reductionandinternalfixatio

n(n=71)or

stablereductionwith

plaster(n=23)im

mobilisatio

n.

PRPinterventio

n(range

7–24

months).

Mariconda

etal.2008

[15]

Longbone

aseptic

atrophic

non-union(n=20)locatedin

the

diaphysealtract(tib

ian=12,

humerus

n=6),forearm

(n=2)

comparedto

historicalcontrol

group(n=20)with

fracturesto

thetib

ia(n=12),humerus

(n=6)

andforearm

(n=2).

Externalfixationusingunilateral

externalfixatorsupportedin

compression

oflong

bone

non-unionsupplementedwith

plateletgel(PG

)comparedto

historicalcontrols

Average

duratio

nof

non-union

311±79

days

vs.333

±88

days

incontrolg

roup)

75mLvenous

bloodyielded

~14

mLPRP

Centrifugation×2:

1200×gfor

25min,followed

by1800×g

10min

Countsperformed

on5patients,

resulting

in~1,075,020

platelets/mL.

Meanplateletcountconcentratio

n4.1tim

esgreaterthan

the

baselin

eplateletcount.

Sanchezetal.

2009

[13]

Asepticnon-union(n=16):

diaphyseal(4

humerus,4

femur,

4tib

ia,n

=12),supracondylar

(n=4).

Surgicalfixatio

nwith

PRP

combinedwith

iliac

crest

autograft~

21monthsfollo

wing

priorsurgicaltreatm

ent(n=13);

PRPalone(n=3).

65mLperipheralvenous

blood.

Centrifugation×1:

640×

g8min.

Novalues.

Sayetal.2013

[14]

Tibia/fibulaaseptic

delayedunion

(n=8)

andnon-union(12)

follo

wingprevious

surgery

PRPmeantreatm

entp

ost-injury

~6–8monthsfollo

wingfracture

surgery.

30mLperipheralbloodfrom

antecubitalregion

Centrifugation×1:1800

rpm8min

PlateletcountP

RP/mLincreased

by400%

comparedto

thrombocytecount(no

values)

Tarallo

etal.

2012

[22]

Non-traum

aticulna

non-union

between1and5cm

PRPcombinedwith

iliac

crest

autograftand

compression

plate,

meantreatm

ent

post-injury=11.5

months

(n=10).Nocontrol.

450mLvenous

bloodcollected.

Centrifugation×2:

180×

g20

min

follo

wed

by580×

g15

min.

Novalues

Taw

fiketal.

2017

[21]

Nonhypertoniclong

bone

non-unions

with

90%

contact

betweenfracture

fragments

PRPalone,meandeliv

ery8months

post-injury.(n=20)Nocontrol.

5patientsreceived

additio

nal

injectionfollo

wing6weeks.

450mLwholebloodcollected,

~10%

used

forPR

PCentrifugation×2:

750×

g7min

follo

wed

by5300×g10

min.

Leukocytes0.15

±0.02

×10

3/μL.

Platelet(w

holeblood)

251±39

×10

3/μL.

Platelets(PRP)

989±265=10

3/μL.

Zhaoetal.

2017

[28]

Atrophicnon-unionof

femoralshaftControl

(conventionalinternal

fixatio

nsurgerywith

autologous/allo

geneicor

artificial

bone

graftn

=46)vs.P

RPand

conventio

nalsurgery

(n=46)

30mLcollected

from

elbowvein.

Centrifugation×2:

200×

g10

min

Novalues.

Author/study

Activation/useof

anticoagulant

Deliverymethod/volume

Outcomemeasure

Com

parison/benefito

fPRP

Typeof

study

Bieleckietal.

2008

[17]

12mLsodium

citratein

108mL

autologous

bloodused

asanticoagulant

forisolationof

PLRG.

Singlepercutaneous

injectionof

15mL

PLRG(12mLPL

RPwith

3mL

thrombinsolutio

n)directly

tositeof

delayed/non-unionunderfluoroscopic

guidance

Patientsfollo

wed

regularlyusing

clinicalexam

ination,

roentgenograms,dual-energyX-ray

absorptio

n(D

EXA)andfunctio

nal

Inthedelayeduniongroup,theaverage

hospitalstayperpatient

was

1.9days.

Union

was

observed

inallcases.T

heaveragetim

eto

unionwas

9.3weeks

Caseseries


Tab

le2

(contin

ued)

12mLPLRPmixed

with

3ml

1600

U/m

Lbovine

thrombinina10%

calcium

chloride

(CaC

l 2)solutio

n.

evaluations

atdays

3and3,5,8,12,

18and24

weeks

(range

5–12

weeks)afterPLRG

injection.

Inthenon-uniongroup,theaverage

hospitalstaywas

1.8days

perpatient.

Union

was

observed

in13

of20

cases.

The

averagetim

eto

unionwas

10.3

weeks

(range

8–18

weeks)after

PLRGinjection

Calorietal.

2008

[35]

Acid-citrate-dextrose

asan

anticoagulant

(0.163

mLper1mLof

blood)

used

asan

anticoagulant.

Localadministrationduring

revision

surgery.1×

vialrhBMP-7used

in58/60patientsinrhBMP-7group,and

×2vialsinremaining

twopatients(no

volumes

provided).

20mLPRPor

slightly

less

deliv

ered

topatientsassigned

toPRPgroup.

Fracture

healingviaclinicaland

radiologicalevaluatio

n(X

-ray

and

CTscanning

where

required)

performed

pre-treatm

ent,follo

wed

upatintervalsof

1,3,6,9and

12+months.

Functio

nalo

utcomes

evaluatedin

term

sof

presence

orabsenceof

pain

assessed

used

amodifiedVAS.

Rateof

unionin

PRPgroup(68.3%

)significantly

lower

comparedto

rhBMP-7group(86.7%

)Pain-freemovem

entw

asreported

byall

of35

patientswith

upperextrem

ityfracturestreatedwith

rhBMP-7atthe

9-month

prim

aryendpoint,compared

to30

outo

f33

patientstreatedwith

PRPwho

hadasatisfactoryfunctio

nal

outcom

e.The

percentage

ofreported

pain

with

and

with

outw

eightbearing

inpatientswith

lower

extrem

ityfracturestreatedwith

either

rhBMP-7

orPRPwas

comparable.Alower

medianclinical

andradiographichealingtim

ewas

observed

intherhBMP-7group

(3.5

monthsvs.4

monthsand

8monthsvs.9

months,respectiv

ely)

Prospectiv

eRCT

Centeno

etal.

2011

[26]

Heparin

used

asanticoagulant

for

isolationof

PL(novalues);1000

I.U.

heparin/mLused

forisolatio

nof

MSC

sfrom

marrowblood.

Percutaneous

injectionof

autologous

bone

marrow–derived

MSC

sand

plateletlysatedeliv

ered

to‘several

locatio

ns’atthefracture

siteunder

fluoroscopicguidance

Fracture

healingviaradiographic

evaluatio

n(high-resolutio

nX-ray

and/or

CTim

aging)

@1,3and

6+months

Adequatehealingandreturn

tofunctio

nal

recovery

seen

in66.7%

(4/6)of

patients

Caseseries

Chiangetal.

2007

[20]

5–7mLcitrate-basedanticoagulant

used

asan

anticoagulant

forisolationof

platelets.PR

PandPP

Pactiv

ated

using

5000

Upurified

bovine

thrombinor

autologous

thrombinand5mLof

10%

CaC

l 2.

Singleinjection(n=6)

ortwoinjections

(n=6)

Fracture

healingviaradiologic

evaluatio

nandbone

mineraldensity

(BMD)@

3days

aftertreatm

ent,

follo

wed

upat1,2,3,6and

12months.

Functio

nalo

utcomes

measuredusing

theshort-form

36health

survey

(SF-36).

11/12patients(91.7%

)healed

onaverage

19.7

weeks

follo

wingsingletreatm

ent,

1/12

patientshealed

at21

weeks

follo

wingasecond

treatm

ent.

AllSF

-36subscores

improved,w

ithSignificantimprovem

entsrecorded

regardingphysicalfunctio

n,role

physical,bodily

pain,vitality,social

functio

ning

andmentalh

ealth

.

Prelim

inary

case

study

Duram

azetal.

2018

[19]

500Ubovine

thrombincombinedwith

10%

CaC

l 2.

Singlepercutaneous

injectionof

10mL

PRPplus

1mLthrombinand1mL

CaC

l2injected

into

thenon-unionsite

underfluoroscopicguidance.

Clin

icalassessment:Absence

ofpain/tenderness

atsiteevery

2weeks

usingVAS.

Fracture

healingviaradiological

evaluatio

nevery4weeks

(X-ray

andCTscanning

performed

onall

Meanhealingduratio

nwas

shorterin

PRPgroupcomparedto

controls

(16.71

d±2.4weeks

vs.

19.07±3.67

weeks),although

the

difference

was

notsignificant.

Retrospectiv

ecase

study,

with

control

group.


Tab

le2

(contin

ued)

patients)foratleast2

4months,

meanfollo

w-up

34.97±8.78

months(PRPgroup)

and33.73±10.53months(control

group).

PRPtreatedpatientsachieved

92.8%

unionvs.80%

inthecontrolg

roup.

PostoperativeVASscores

werereduced

inboth

PRPandcontrolg

roups,

although

theresults

whencomparing

PRPto

controlswerenotsignificant.

Galasso

etal.

2008

[16]

Low

-molecular-w

eighth

eparin

used

asanticoagulant

(novalues).PR

Pactiv

ated

with

batroxobin

andCaC

l 2(novalues)to

obtain

agel

6mLPRPactiv

ated

with

batroxobinand

CaC

l 2(novalues)deliv

ered

asagelto

therim

ofthenon-unionsite.

Clin

icalassessment:absenceof

pain/tenderness

atsite.

Fracture


evaluatio

nperformed

every45

days

until

unionachieved.F

inal

follo

w-upat13

months.

AdditionalCTscansperformed

ifrequired.

91%

(n=20)of

patientsachieved

bony

unionat13-m

onth

follo

w-up,average

timeto

union:

2.5weeks

with

noinfection,complications

orlim

bshortening

observed.

Caseseries

Ghaffarpasand

etal.2016

[30]

PRPactiv

ated

with

acid-citrate-dextrose

containing

gravitatio

nalp

latelet

separatio

nsystem

reagent(GPS®)

priorto

centrifugatio

nfollo

wed

by1g

cefazolin

andlow-m

olecular-w

eight

heparinfollo

wingtheoperation.

5mLPRPvs.5

mLsalin

e(placebo

group)

injected

into

theperiosteum

.Clin


pain/tenderness

atsiteusingVAS.

SSracturehealingviaradiologic

evaluationevery45

days

for

270days

(9months).

Lim

blength

was

also

measuredand

comparedwith

postoperativelength

andincidenceof

infection;malunion

andnon-unionwerealso

recorded.

Healin

gratein

PRP-treated

patients

81.1%

(placebo

55.3%,p

=0.025)with

shorteradmission

(6.6±1.3vs.

7.7±1.4days;p

<0.001)

andhealing

duratio

n8.1±1.2vs.

8.5±10.7

months(p=0.003).N

ostatisticalsignificance

inpostoperative

infectionincidence.

Malunionwas

comparablebetween

groups

(10.8%

vs.15.8%

;p=0.136).

Lim

bshortening

lower

inPR

Pgroup

comparedto

control(p=0.030).

Postoperativepain

significantly

reducedinPR

Pgroupatday45

and90.

Randomised

doubled

blinded

placebo

controlled

clinicaltrial

Golos

etal.

2014

[31]

Noinform

ation.

PRPinjectionto

thefracture

cleftu

nder

radiographicguidance

×2.

Multip

ledosesdependentu

ponfracture

(predominantly

distaltib

ialand

forearm

shaftfracturepatients),i.e.3,

or4injections.

Radiologicevaluatio

nat6–8weeks

post-treatmentfollowed

bysubsequent

radiographsevery

6weeks

until

unionachieved.

Boneunionachieved

inin

81.8%

ofpatents(n=108),onaverage

3.5monthsfollo

wingadministration.

PRPmostsuccessfulinhealingof

forearm

fractures(92.8%

).Healin

grate82%

intib

ialfractures.

82.6%

infemoralfracturesand66.7%

inhumeralfractures.

Caseseries,

nocontrols

Jiangetal.

2016

[25]

PRPactiv

ated

with

1000

IUlow-m

olecular-w

eighth

eparin

sodium

follo

wed

by10

mg/mLdoxycycline,

ratio

1000:1

priorto

injection.

5mLAPL

injected

weeklydirectly

tofracture

siteunderfluoroscopic

guidance

×3

Fracture


evaluationatmonthly

intervalsuntil

unionachieved

Improved

clinicaloutcom

eandcallo

usform

ationat4-

and6-month

post-injectio

n;good

bony

unionat

8months.

Casestudy

Labibzadeh

etal.2016

[27]

Noinform

ation.

3mLPLwith

BM-M

SCsim

plantedinto

non-unionsiteusingfluoroscopic

guidance.

Radiologicalevaluationat1,3,6and

12monthspost-implantatio

n.57%

(4/7)successfulbony

unionwith

PL+BM-M

SCs:@

2months(n=1),

6months(n=2)

and12

months

(n=1)

Caseseries

clinical

trial,no

controls

Mahadik

etal.

2018

[29]

Noinform

ation.

~10

mLinjected

around

fracture

sitein

theperiosteum

Clin


pain/tenderness

atsite.V

ASand

radiologicalevaluatio

nat1,2and

Allfracturesshow

edradiological

evidence

with

in4months;65.25days

inclosed

fracturesand93.25days

in

Prospectiv

ecase

series,

nocontrols


Tab

le2

(contin

ued)

3months,follo

wed

byevery

45days

for12

months.

CTscan

incorporated

ifX-ray

findings

wereinconclusive

oram

biguous.

open

fractures.VASscores

reduced

from

11patientswith

VAS>6(severe

pain)at1-monthpost-interventionto5

patientsat1month.A

t6months

post-intervention,only

7patientshad

mild

pain,23patientshadno

pain

(VAS=0).

Malhotraetal.

2015

[24]

Noneused.

15–20mLdose

injected

once

via

intravenouscannulaunder

fluoroscopyguidance

(w/o

anticoagulant).

Clin


pain/tenderness

atsite.

Fracture


evaluatio

n@

1,2,3and4months.

87%

(n=82)patientsachieved

unionat

4months,36%

(n=34)show

edtrabecular

bridging

viaX-ray,44%

(n=41)trabecular

bridging

at3months,13%

(n=12)failedunion.

Caseseries,

lack

ofcontrols

Mariconda

etal.2008

[15]

Citrate/citricacid/dextroseused

asanticoagulant.

Autologousthrombin(0.2

mL/m

Lof

PRP)combinedwith

calcium

gluconate(0.2–0.5

mL/m

LPP

P)used

toactiv

atePRP,followed

bycalcium

glutam

ate(0.2

mL/m

L)drop

bydrop

toform

thePG

priorto

injection.

Duringsurgery,PG

was

percutaneously

injected

intheinterfragm

entary

space

underfluoroscopicguidance.

Clin


pain/tenderness

atsiteevery

2weeks.

FracturehealingviaX-ray

everymonth

The

studyfailedto

show

theclinical

usefulness

ofisolated

percutaneous

plateletgelsupplem

entatio

nin

long

bone

non-uniontreatedby

external

fixatio

n.The

healingrateof

non-unionwas

90%

(18/20)in

plateletgelcases

and85%

(17/20)in

controls,respectively

(p=0.633).T

hemeantim

euntil

radiographicconsolidationin

non-unionsupplementedwith

platelet

gel(147663

days)w

asnotdifferentto

theresultin

thecontrolg

roup

(153

661

days;p

=0.784).

Caseseries,

with

retrospec-

tive

(historical)

controls

Sanchezetal.

2009

[13]

PRPactiv

ated

with

3.8%

(wt/v

ol)sodium

citratepriorto

centrifugatio

nfollo

wed

by10%

(wt/v

ol)CaC

l 2priortomixing

with

bone

graft/adm

inistration.

PRPwith

bone

allograftb

iomaterial

injected

atexposedinjury

sitein

13patients(novalues),remaining

3patientswerepercutaneously

injected

with

6–8mLPRPaloneevery

2weeks

for6weeks

Clin


pain/tenderness

atsite.

Fracture

healingviaX-ray

at2weeks

follo

wed

by~monthly

intervals

until

unionachieved.

CTscan

incorporated

ifno

improvem

entfollowing

10–16weeks.

Union

ratein

surgicalfixatio

nwith

PRP

combinedwith

surgery=84.6%,w

ithaverageuniontim

eof

4.9months.

Dualcentre

retrospec-

tivecase

series

Sayetal.2013

[14]

PRPactiv

ated

with

3.2%

CaC

l 2priorto

centrifugatio

n,plus

5.5%

CaC

l 2(50μL/m

L)priorto

administration

2.5mLPR

Pplus

CaC

l 2activ

ator

injected

into

fracture

lineunder

fluoroscopyguidance

3tim

esover

aweek

Clin

icalassessment.Fracturehealing

viaradiologicevaluatio

nat

~15

weeks

Delayed

unionpatients:unionin

60%;

non-unionpatients:PRPunsuccessful

inachievingunionwhenused

inisolationfollo

wing12-m

onth

follo

w-up

Prospectiv

ecase

series

Tarallo

etal.

2012

[22]

PRPactiv

ated

with

citrate/citric

acid/dextrose(novalues)priorto

centrifugatio

n,plus

autologous

thrombinandcalcium

gluconateprior

toadministration.

Injectionatexposedinjury

site(no

values).

Clin


pain/tenderness

atsite.

Fracture


evaluatio

nat~21

months(range

7–14

months).

VASanddisabilityassessmentfor

shoulder

andhand

(DASH

).

Union

achieved

in90%

caseswith

averageuniontim

eof

4.11

months.

MeanVASscore=1atrest,V

AS=2

during

activ

ity.D

ASH=17

Single-centre

prospective

study


the fracture fragments) and dose of PRP (20 mL) and found verysimilar rates (85%) of union among patients [21] in comparisonto Malhotra et al. (87%).

PRP as a Hybrid Treatment

PRP can also be utilised in combination with other forms ofnon-union fracture treatment, including autografts, compres-sion plates and/or fixation devices [13, 15, 19, 27, 28, 30, 31].Some studies have investigated the effect of combining PRPwith an iliac crest autograft and concluded that the addition ofPRP has the potential to enhance healing [13, 22, 30]. However,in these studies, the authors could not attribute the healing of thefracture to the addition of PRP in isolation, due to the lack ofrandomised control groups. Therefore, no information could beprovided regarding the efficacy of one particular method. Thisis apparent in the case of Tarallo et al. where patients weretreated using a bone graft, dynamic compression plate andPRP [22]. Despite this, union was achieved in 90% of caseswith an average time to union of 4 months. Ghaffarpasand et al.conducted the only randomised double blinded placebo-controlled clinical trial investigating the effect of PRP on therate of healing of non-union fractures treated with an autolo-gous bone graft and internal fixation. Patients received either5 mL of PRP or 5 mL of saline (placebo) during surgery. Thehealing rate was significantly higher in the PRP group in com-parison to that in the control (81.1% vs. 55.3%, p = 0.025) [30].

Reports on the effectiveness of PRP and autograft fixation as anon-union fracture treatment are divided. Case series findingshave largely been positive in terms of improved rates of non-union healing [13, 17, 20, 26]. Though, the rate of healing cannotbe attributed to the use of PRP due to a lack of effective controls.However, in a unique case series byMariconda et al., the healingrate of union of patients treated with PRP and external fixation(90%) was compared to the healing rate of union of a historicalcontrol group (85%), with no significant clinical usefulness ofPRP being reported [15]. However, caution should be takenwhen interpreting this result, since the sample size was relativelysmall (n = 20), limiting the statistical power of the data. A recentrandomised, controlled clinical trial regarding the combined useof PRP and internal fixation [28] reported that the addition ofPRP to internal fixation significantly increased the rate of healing(94% vs. 78%, p< 0.05) whilst reducing healing time (91.6 ± 6.9vs. 115.2 ± 8.4 days, p < 0.05) in comparison to a control group[28]. The study had not only the primary measure of healing ratebut also secondary outcome measures assessed using a visualanalogue scale (VAS). The VASwas used to measure subjectivecharacteristics that cannot be directly measured such as painintensity, treatment costs and adverse reactions; all of which areimportant aspects in a method of treatment [28], particularlywhen considering clinical acceptance and translation. SincePRP elevated the healing rate, this shortened the treatment timewhilst reducing pain and costs.T

able

2(contin

ued)

Taw

fiketal.

2017

[21]

~20

mLPR

Pactiv

ated

with

5mL

autologous

thrombincombinedwith

2mLcalcium

gluconatepriorto

administration

25–30mLPR

Pplus

activ

ator

(throm

bin/calcium

gluconate)

percutaneously

injected

Clin


pain/tenderness

atsite.

Fracture

healingrateat6weeks

via

radiologicevaluatio

nfollo

wed

every

4weeks

until

union.

AdditionalCTscansperformed

at10–16weeks

ifsuboptim

aloutcom

esdetected.

85%

successful

unionam

ongpatients

receivingPR

Pat17

wks.75%

‘fair’

results

follo

wingsingleinjection

Single-centre

prospective

study

Zhaoetal.

2017

[28]

PRP(novalues)activ

ated

with

sodium

citrate(novalues

provided)priorto

centrifugatio

nplus

thrombinpriorto

administration(100

U/m

L)

5mLPRPplus

activ

ator

(throm

bin)

directly

injected

atexposedinjury

site

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pain/tenderness

atsite.

Fracture

healingrateat9monthsvia

radiologicevaluatio

n;VASat3,6,9

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months

PRPwith

internalfixatio

nsignificantly

increasedhealingrate(94%

vs.78%

comparedto

control).

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healingtim

e(91.6days

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incontrol).N

osignificant

difference

inVAS.

Randomised,

controlled

clinicaltrial

APG,autologous

platelet

gel;APL,

autologous

platelet

lysate;BM-M

SCs,bone

marrow–derived

mesenchym

alstem

cells;CaC

l 2,calcium

chloride;CT,

computerizedtomography;

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assessmentforshoulderandhand;E

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SCs,mesenchym

alstem

cells;P

G,plateletgel;P

LRG,platelet-leukocyte-rich

gel;PRP,platelet-rich

plasma;PSIS,posterioriliac

spine;rhBMP-7,recom

binant

human

bone

morphogeneticprotein-7;

RT,

room

temperature;S

F-36,short-form

36health

survey;V

AS,visualanalogue

score


Two case studies have been conducted investigating if thecombination of PRP and MSCs can facilitate healing of non-union fractures, both reporting success with the method [27,34]. Labibzadeh et al. stated that, when combined with MSCs,PRP is successful in patients who had previously failed toachieve union using the ‘gold standard’ iliac bone graft. Thishighlights how effective PRP could be in improving bone regen-eration in difficult cases of non-union [27]. However, Centenoet al. did reveal a limitation of the method, including the fact thatthe MSCs isolated from bone marrow aspirate obtained from theiliac crest required a second invasive surgical intervention. Thisincreased the potential risk of infection and causes further pain tothe patient [34]. Moving forward, double blinded, controlledtrials are still required to assess the clinical efficacy of thistreatment.

The Use of PRP vs. Alternative Treatments

In a well-documented, prospective RCT, it was suggested thatrhBMP-7 was a superior bone-stimulating agent compared toPRP. Rather than being injected into the site of the non-union,both PRP and rhBMP-7 were applied locally during revisionsurgery allowing both methods to be directly compared.Subjects (n= 120) in the PRP group had an average non-unionduration of 19.2 ± 2.86months [35]. As discussed above, Bieleckiet al. proposed that, for PRP to be a success, the treatment shouldbe made within 11 months of injury or initial surgery [17]. Thiswould suggest that, whilst the rate of union in the PRP group wassignificantly lower (68.3% PRP vs. 86.7% rhBMP-7), the find-ings of this study should be interpreted with caution. The authorsconcluded that administering PRP alone without a bone graftcould be deemed non-ideal in terms of exploiting PRP’s innatebone regeneration enhancement capabilities [35]. Since the study,PRP has demonstrated success alone in accelerating rate of union[7, 21, 29], with the majority of the literature investigating thepotential of PRP to enhance current treatment strategies [20, 28,30]. Thus, it is unlikely that PRP as a therapy will be used aloneon a large scale. However, PRP could potentially be applied as aminimally invasive method as a way of saving resources in med-ical care, with no significant difference being found between PRPand intramedullary nailing in achieving union [19]. Larger,randomised controlled studies under optimal treatment conditionsare needed to give more powerful and accurate results.

Conclusion

The consensus from the literature is that PRP is effective in accel-erating the healing of non-union fractures. The success it hasdemonstrated when used in isolation ranges in doses from 2.5 to20 mL, implying that it could potentially become a primary formof treatment.However, the non-unionwould have to be inherentlystable and PRP would ideally be administered within 11 months

of injury or initial surgery, although further investigation is neededto confirm this barrier. Moving forward, it is recommended thatRCTs should focus on the effect of injections of at least 5 mL ofPRP, since lower doses have not been reported as successful ininducing bone regeneration [14]. The study by Malhotra et al., amajor contribution to the research, suggested that the commonactivator bovine thrombin may not be a necessity [24] and thisshould be investigated further in future studies to determinewhether sufficient thrombin is produced via local trauma whenthe fracture site is infiltrated with a needle in order to activate theplatelets. Other major contributions include the work byGhaffarpasand et al. and Zhao et al., whereby they have demon-strated the success of PRP and internal fixation as a combinationtreatment [28, 30].However,moreRCTSareneeded to determineif PRP is a more effective bone-stimulating agent for augmentingunion in comparison to the likes ofMSCs and BMPs. Finally, themost effective method of PRP preparation (rate of centrifugation/ultrafiltration, activator, dose, etc.) and administration (single ormultiple injections) needs to be systematically investigated andstandardised in order for the therapy to develop further.

Compliance with Ethical Standards

Conflict of Interest The authors have no other relevant affiliations orfinancial involvement with any organisation or entity with a financialinterest in or financial conflict with the subject matter or materialsdiscussed in this manuscript.

Human and Animal Rights and Informed Consent This article does notcontain any studies with human or animal subjects performed by any ofthe authors.

Open Access This article is licensed under a Creative CommonsAttribution 4.0 International License, which permits use, sharing, adap-tation, distribution and reproduction in any medium or format, as long asyou give appropriate credit to the original author(s) and the source, pro-vide a link to the Creative Commons licence, and indicate if changes weremade. The images or other third party material in this article are includedin the article's Creative Commons licence, unless indicated otherwise in acredit line to the material. If material is not included in the article'sCreative Commons licence and your intended use is not permitted bystatutory regulation or exceeds the permitted use, you will need to obtainpermission directly from the copyright holder. To view a copy of thislicence, visit http://creativecommons.org/licenses/by/4.0/.

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