Total ruptures of the extensor apparatus of the knee

(1)

SOCIEDADE BRASILEIRA DE ORTOPEDIA E TRAUMATOLOGIA

w w w . r b o . o r g . b r

Original

Article

Total

ruptures

of

the

extensor

apparatus

of

the

knee

夽

Diogo

Moura

∗

,

Fernando

Fonseca

CentroHospitalareUniversitáriodeCoimbra,DepartamentodeOrtopedia,Coimbra,Portugal

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received12February2016 Accepted18March2016 Availableonline25October2016

Keywords:

Rupture Knee

Rangeofmotion,articular Patella

Tendons

a

b

s

t

r

a

c

t

Objective:Thiswasaretrospectivecase-controlstudyontotalrupturesoftheextensor appa-ratusoftheknee,aimedtocomparepatellafractureswithtendinousruptures.

Methods:Thesampleincluded190patientsand198totalrupturesofthekneeextensor apparatus.Allpatientswereevaluatedbythesameexaminerafteraminimumone-year follow-up.

Results:Tendinousrupturesoccurredmostfrequentlyinmen,inyoungerpatients,andhad betterclinicalandfunctionaloutcomeswhencomparedwithpatellafractures;however,the formerpresentedhigherlevelsofthighatrophy.Patellafracturesoccurredmostfrequently inwomenandinolderpatientsandcausedmostfrequentlycausedresidualpain,muscle weakness,andlimitationsindailyactivities.Comminutedfractureswererelatedto high-energytrauma,lowerclinicalandfunctionaloutcomes,andhigherlevelsofresidualpain andosteosynthesisfailure.Earlyremovalofosteosynthesismaterialwasrelatedtobetter outcomes.Regardingthetendinousruptures,overhalfofthepatientspresentedrisk con-ditionsfortendinousdegeneration;alongerdelayuntilsurgerywasrelatedtolowerKujala scores.

Conclusion:Thesurgicalrepairofbilateralrupturesofthekneeextensorapparatusresulted insatisfactoryclinicalandfunctionaloutcomes,whichwerebetterfortendinousruptures whencomparedwithpatellafractures.However,theselesionsareassociatedwith non-negligiblelevelsofresidualpain,muscleweakness,atrophy,andothercomplications.

Roturas

totais

do

aparelho

extensor

do

joelho

Palavras-chave:

Rotura Joelho

Amplitudedemovimentoarticular

r

e

s

u

m

o

Objetivo:Estudoretrospectivosobreroturastotaisdoaparelhoextensordojoelhoque com-paraasfraturasdapatelacomasroturastendinosas.

Métodos:Amostracom190pacientese198roturastotaisdoaparelhoextensordojoelho. Otempomínimodeseguimentoapósacirurgiafoideumanoetodosospacientesforam avaliadosclínicaeradiologicamentepelomesmomédico.

夽_Study_conducted_at_the_Department_of_Orthopedy,_Centro_Hospitalar_e_{Universitário}_de_Coimbra,_Coimbra,_Portugal. ∗ _{Corresponding}_author.

E-mail:dﬂ[email protected](D.Moura).

http://dx.doi.org/10.1016/j.rboe.2016.10.012

(2)

Patela Tendões

Resultados: Asroturastendinosasocorremmaisfrequentementeemhomens,empacientes maisnovoseestãoassociadasaníveisclínico-funcionaissuperioresemrelaçãoàsfraturas dapatela.Noentanto,comatrofiadacoxamaisfrequente.Asfraturaspatelaresocorrem maisfrequentementeemmulherescomidademaisavançadaeprovocammais frequente-mentedorresidual,déficitdeforçamuscularelimitaçãodasatividadesdavidadiária.A maiorcominuiçãodasfraturasdapatelaesteveassociadaaresultadosclínico-funcionais maisdesfavoráveis,aníveismaiselevadosdedorresidualededesmontagemdomaterial deosteossíntese.Aextraçãoprecocedomaterialdeosteossínteseesteveassociadaa mel-horesresultados.Nogrupodasroturastendinosas,maisdemetadeapresentavadoenças consideradasderiscoparadegeneraçãotendinosaeumtempodeesperamaisprolongado atéacirurgiademonstrouvaloresdeescoredeKujalasignificativamenteinferiores.

Conclusão: Otratamentocirúrgicodasroturastotaisdoaparelhoextensordojoelhogarante bonsresultadosfuncionais,quesãosuperioresparaasroturastendinosasemcomparação comasfraturasdapatela.Noentanto,estãoassociadasaníveisimportantesdedorresidual, fraquezamuscular,atrofiamusculareoutrascomplicações.

Introduction

Theextensorapparatusoftheknee consistsofthreebasic structures:twotendons,thequadricepsandpatellar;andone bone,thepatella.Thetotalruptureofthisapparatuscanoccur throughtheboneortendon,leadingtoaninabilitytoactively extendtheleg.Patellarfracturesaremorefrequentthan tendi-nousruptures,inratios rangingfrom17:1to43:1;ruptures ofthe quadricepstendonare more frequentthan those of thepatellartendon.1,2Theseinjuriesrequiresurgical recon-structionofthe extensorapparatusinorder torecoverthe extensionfunction.3_To_date,_only_one_study_has_directly

com-paredclinicalandfunctionalresultsofpatellarfracturesand tendinousruptureoftheextensorapparatusoftheknee.3

Material

and

methods

This was a retrospective study, comprising a mean of 5.1 years(range1–10);190patientswere retrieved, correspond-ingto198totalrupturesoftheextensorapparatusoftheknee thatweresurgicallytreated.Allpatientswithotherassociated traumaticinjuriesandthose whocould notbefollowed-up foraminimumofoneyearaftersurgerywereexcluded.The clinicalevaluationincludedfunctionalassessment, measure-mentofrangeofmotion,andtheapplicationofavalidated score for patellofemoral pathology, the Kujala score.4 _The

degreeof patientsatisfaction was also assessedina scale from 0to5, were 0–dissatisfied,and 5 –totally satisfied. Radiologically,patientswereassessedforfracture classifica-tion(AOclassification)5_;_presence_or_absence_of_{consolidation;}

patellofemoralarthrosis;patellarheight,usingtheInsalland Salvatiindex6_;_and_whether_or_not_the_{osteosynthesis}

mate-rial was extracted. The variables were treated statistically using SPSSv23, and a 0.05 signiﬁcance level was adopted.

Quantitativevalueswerepresentedasmean±standard devia-tion(minimum–maximum),andqualitativevaluesasnumber (n)or percentage(%).For comparisonsbetweentwogroups

with quantitative variables, Student’s t-test was used; the Mann–Whitney test was used when the values were very low. Tocompareamongthreeormoregroups,ANOVA was used.Forcomparisonsbetweentwogroupswithnominal vari-ables, the chi-squared test wasused; for ordinalvariables, the Mann–Whitney test. To study the association between quantitativevariables,Pearson’scorrelationwasused;forthe multivariate study,the generallinearmodel(GLM)analysis wasadopted.ThestudywasapprovedbytheEthics Commit-teeoftheCentroHospitalareUniversitáriodeCoimbraand all patientsortheir respectivefamilies signedaninformed consentform.

Results

Thesampleconsistedof190patientsor198ruptures,aseight werebilateral.Themeanagewas58.82±17.86years(range 18–90)and56.6%weremale.Ofthetotal,67.17%(n=133)was patellarfractures;tendinousrupturesoftheextensor appara-tusaccountedfortheremaining32.82%(n=65),whichwere dividedbetweenquadricepstendonruptures(56.9%)and rup-tureofthepatellartendon(43.1%;Table1).

In the analysisofthe groupwith patellarfractures, the mostcommonmechanismofinjurywaslowenergy(87.1%) direct trauma (86.4%). The predominant types of patellar fracturewereC1,C3,andA1consideringtheAOclassification (Fig. 1). Comminuted type C patellar fractures (C1 to C3) showedasignificantassociation(p=0.004)withhigh-energy trauma. Types of osteosynthesis used were figure-of-eight tension bandwithKirschner wires(74.2%),circular tension band withKirschner wires (9.8%), screws (3%), and double tension band withKirschner wires(1.5%). In 83% ofcases, twoKirschnerwireswereused.IntypeA1fractures, hemi-patellectomywasperformed,followedbytendonreinsertion. Thefunctional outcomesand complicationsofthesurgical treatmentofpatellarfracturesarepresentedinTable1. Statis-ticallysignificantdifferenceswereobservedbetweentypeC1 andC3fracturesregardingthemeanKujalascore(74.3±14.62

(3)

Table1–Comparativedatabetweenfracturesofthepatellaandtendonruptures.

Fracturesofthepatella Tendonruptures p

Lesions(n,%) 133(67.17%) 65(32.82%) – Age(years) 61.45±18.13 53.48±16.13 0.003a Prevailinggender 56.8%♀ 84.5%♂ <0.001a Flexion 99.81◦_±_20.75 _124.47◦_±_15.40 _<0.001a Kujalascore 71.89±16.11 89.94±9.75 <0.001a Satisfaction Grade3–33.3%; Grade5–30.3% Grade5–58.7%; Grade4–28.6% <0.001b

Limitationofdailyactivities 42.4% 6.90% <0.001a

Residualpain 74.20% 41.40% <0.001a

Deﬁcitinstrength 60.60% 20.70% <0.001a

Thighatrophy 21.20% 37.90% 0.007a

Patellofemoralarthrosis 37.90% 24.62% <0.001a

Changesinpatellarheight 9.10% 36.90% <0.001a

a _Chi-squared_test.

b _{Mann–Whitney}_test.

vs. 63.88±16.44; p=0.016) and ﬂexion (104.32±17.45 vs.

90.61±23.31; p=0.001). An extension deficit from 1◦ to 5◦ wasobservedin6.06%ofcases,andadeficitfrom5◦ to10◦, in 2.27%. Signs of patellofemoral arthrosis were observed in37.90%ofcases,andallchangesinpatellarheight corre-spondedtolowpatellae.Complicationsdirectlyrelatedtothe surgicaltreatmentoccurredin23.7%ofcasesandconsisted of painful material (19.7%), osteosynthesis removal (8.3%), infection(3%),non-consolidationofthe fracture(1.5%),and othersurgicalwoundproblems(3.8%).Comparedwithtype C1 fractures, type C3 comminuted patellar fractures pre-sentedhigherlevelsofosteosynthesisremoval(11.8%vs.3%) andresidualpain(84.8%vs.71%).Regardingosteosynthesis techniques,screwsledtocomplicationsin75%ofcaseswhile circular tension band, 38.5%. These techniques presented thehighestratesofcomplications,aswellashigherratesof osteosynthesisremoval,particularlyinthe25%ofthepatients whoreceivedscrewsandin15.4%ofthoseinwhomacircular tensionband wasperformed. Regarding theosteosynthesis material,screwswerethemostsymptomatic(50%ofcases), followedbycirculartension band(in 23.1%ofcases).Older individualshad asignificantlylower Kujalascore(r=−0.60;

p<.001),lowermeanﬂexion(r=−0.51;p<0.001),andalower degreeofsatisfaction (p<0.001; rho=−0.42).Moreover,they

AO classification 14.4% 0.8% 0.8% 50% 8.3% 25.8% A1 A2 B1 C1 C2 C3

Fig.1–Prevalenceoftypesofpatellarfracturesaccordingto theAOclassiﬁcation.

presentedhigherlevelsofresidualpain(p<0.001)andmore muscularstrengthdeficit(p<0.001).Inturn,younger individu-alspresentedsignificantlymoretightatrophy(p<0.001)anda trendforhigherratesofosteosynthesisremoval.Theremoval oftheosteosynthesismaterialoccurredin50.8%ofpatients withpatellarfractures;thesepatients,whencomparedwith thoseinwhomtheosteosynthesismaterialwasnotremoved, presentedasignificantlyhigherKujalascore(74.79±15.21vs.

64.84±15.49)(p=0.002)and meanﬂexion (104.66±19.40vs.

93.03±20.72)(p=0.006).Patients who underwentextraction ofosteosynthesismaterialpresentedlowerlevelsofresidual painwhencomparedwiththoseinwhomthematerialwas notremoved(69%vs.84.2%).

Regarding the group oftendon ruptures, falls were the causeofinjuryin70.69%ofcases,andindirecttraumawas themostfrequent(91.38%).Thepredominantmechanismsof injury wereknee torsion(67.92%),hyperﬂexion ofthe knee (15.1%), and counter-resistance with the knee in semiﬂex-ion(9.43%).Fivetendonrupturesoccurredbydirecttrauma andconsistedoffragmentswithdirecttendoncut.The col-lapseoccurredmorefrequentlyatthemidpointofthetendon (43.10%), followed bypatellar insertion (39.66%), myotendi-nous transition (13.79%), and insertion at the level of the anteriortibialtuberosity(3.45%).Recurrenceoftendon rup-turewasobservedin3.45%,rupturesinthecontextoftotal kneereplacementin3.45%,andbilateralrupturesin12.07%of casesoftendinousrupture.Halfofthepatientswithtendinous rupture wereconsidered tobeatriskfordegeneration and tendinousruptureoftheextensorapparatus,and2.07% pre-sentedriskdrugintakes(Fig.2).7–9_Only_12.07%_of_the_patients

withtendinous rupturewere healthy.Agewassigniﬁcantly higher(p<0.001)incasesofruptureofthequadricepstendon (61.31±13.47years)whencomparedwiththoseofthe patel-lartendon(44.33±4.08years).Rupturesofthepatellartendon were10.65times(oddsratio)morerelatedtothe consump-tionofrisksubstanceswhencomparedwithrupturesofthe quadricepstendon(23.4%ofpatellartendonrupturesoccurred inpatientswithriskconsumption,comparedwithonly2.8%of thosewithruptureofthequadriceps;p=0.019)andatrendfor theformertooccuratthemidpointlevelofthetendon. Surgi-caltreatmentoptionswereend-to-endtenorrhaphy(51.72%),

(4)

Dyslipidemia Risk factors 5.17% 27.59% 5.17% 5.17% 6.90% 5.17% 1.72% 1.72% 6.90% 5.17% Hyperuricemia Tendinopathy Diabetes mellitus type II Chronic renal failure hemodialysis Rheumatoid arthritis Collagenosis Corticosteroid therapy Anabolic steroids

Fig.2–Prevalenceofriskfactorsinthegroupoftendinous ruptures.

followedbytenorrhaphywithtrans-bonepoints(24.14%), ten-odesiswithanchors(17.24%),andotherreconstructivegraft optionsforcircumstantialcases(6.90%).Protectivewiringwas usedin64%ofcasesofpatellartendonrupture;themeantime foritsremovalwas6.38months.Themeandurationof postop-erativeimmobilizationwas45.43days(range41–66days).The functionaloutcomesandcomplicationsofsurgicaltreatment oftendinousruptures oftheextensorapparatusareshown inTable1.Oftheindividualsinthisgroup,13.85%presented extensiondeficit,alwaysless than 5◦. Radiologicalsigns of patellofemoral arthrosis were identified in 36.90% of the knees;highpatella,in15.81%;andlowpatella,in21.09%.The waitingtimeuntilsurgerypresentedastatisticallysignificant inversecorrelation(r=−0.03;p=0.008)withtheKujalascore. Thebest resultswere observedin repairs withtrans-bone points,whichshowedastatisticallysignificantdifferencein themeanrangeofflexion(126.14±13.88;p=0.031)andmean Kujalascore(88.46±9.33;p=0.006)whencomparedwiththe results of reconstruction with tendon grafts (respectively, 107.50±22.17 and 77. 25±10.50). Recurrent ruptures and thosethatoccurredinthecontextoftotalkneereplacement presented a significantly lower Kujala score (respectively, 80.25±8.62and 91.08±9.83;p=0.031)whencomparedwith otherdisruptions.Residualpainwas1.75times(oddsratio) morepresentinrupturesofthepatellartendonwhen com-paredwiththoseofthequadricepstendon(50%inpatellar tendonrupturevs.36.1%intheruptureofthequadriceps ten-don)andwasassociatedwithmorerupturesatthelevelof thesiteoftendoninsertioninthebones(100%intheanterior tibialtuberosityand 44.1%inthe patellarinsert, compared to36.7%inthetendinousbody).Patientswithresidualpain hadsignificantlylowerflexionamplitudes(119.46±17.60vs.

128.16±12.54;p=0.031)andlower Kujalascore(83.43±9.32

vs.95±6.62;p<0.001)when comparedwiththose who did nothaveresidualpain.Othercomplications,observedless fre-quently,includedre-ruptureofthetendon(3.08%),knee stiff-ness(3.08%),andwounddehiscence(3.08%),amongothers.

Discussion

Thepresentstudydemonstratedthatthegradeof comminu-tionofpatellarfractureswasassociatedwithhigher-energy traumaandwithlessfavorableclinicalandfunctionalresults. The comminution, a difﬁculty to achieve anatomic reduc-tion andstability ofosteosynthesis,aswell astheneed to use circular and doubletension bands,likelycontribute to thefactthatC3fracturesandthesetypesofosteosynthesis

present higher levels of osteosynthesis removaland resid-ualpain,whichleadstoaworseprognosisofthesefractures. Althoughconsolidationisachievedinmostcases,allowing forreasonableclinicalandfunctional outcome,thesurgical treatmentofpatellarfracturesleadstohighlevelsofresidual pain, atrophy,muscle strength deﬁcit,and other complica-tions,whichisinagreementwiththe literature.10–13 _In_the

present study,osteosynthesisremovalandthighatrophyin patellarfracturesweremorecommoninyoungerindividuals, probablyduetothehigherfunctionallevelofthisagegroup and moreintensivedemandonthe extensorapparatus.As thisisanosteosynthesisofaprominentbone,whichisvery mobileandsubjecttohighandrepeatedforces,togetherwith theneedforearlyjointmobilization,impliesthatthe mate-rialoftendesintegrates,migrates,orbecomesprolapsedand painful,delayingfunctionalrecovery.13_Early_extraction_of_the

osteosynthesismaterialshouldbeperformedwhenever pos-sible,asthisprocedureisassociatedwithsuperiorclinicaland functionalresults.

Tendonrupturesoccurredmorefrequentlyatthe midsec-tionofthetendonandpatellarinsertion.Thisisinagreement with the fact that almost all tendon ruptures ofthe knee extensor apparatus occur after adegenerative and inﬂam-matoryprocess,whichismorepronouncedinthetendinous midsection and in osteotendinous junction in which the tendonresistanceissigniﬁcantlyreducedandtheriskof rup-ture,increased.7–9 _The_older_age_range_observed_in_patients

with rupture of the quadriceps tendon is consistent with theliterature.3_A_longer_waiting_time_until_surgery_presented

signiﬁcantly lower Kujala scores, which is consistent with results obtained by other authors.2,14–16 _Clinical _and

func-tionalresultsinthetendontearswerealsosatisfactory,with near normalmobility and Kujala score; nonetheless,these were less favorable inrecurrent ruptures, inpatients with knee prostheses,and whentherewas aneedforatendon graft, probably due to the weakening and changes in the patellofemoralbiomechanics.14–16_Furthermore,_nearly_half_of

patients with tendon ruptures had residual pain; this was morepresentinpatellartendonrupturesandinthoseatthe levelofboneinserts.

When comparinggroupsofpatellar fracturesand tendi-nous ruptures (Table 1), there were statistically significant differences in age, flexion amplitude (Fig. 3), Kujala score (Fig. 4), degree of satisfaction, limitation of activities of daily life, residual pain, thigh atrophy, muscle strength deficit,andpatellofemoralarthrosis(Table1).Tendonruptures occurred morefrequently inmenand inyounger patients, andwereassociatedwithhigherclinicalandfunctionallevels (Figs. 3 and 4); nonetheless, tightatrophy was more com-mon. Patellarfracturesoccurred moreofteninwomenand inolderpatients;theypresentedlowerclinicalandfunctional levelsandmoreoftencausedresidualpain,musclestrength deficit,andlimitationintheactivitiesofdailyliving.Despite thesignificantdifferenceinagebetweenGroupswithpatellar fracturesandtendonruptures,thisdifferenceoccurredmainly inpatellartendonruptures(44.33±14.08years),asthemean age ofpatientswithfractures (61.45±18.13)was similarto thatofpatientswithquadricepstendonruptures(61.31±13.47 years). Thepresenceofradiologicalsigns ofpatellofemoral arthrosis was substantial in both groups. However, it was

(5)

Patellar fractures 125.0 100.0 75.0 Flexion 50.0 25.0 125.0 100.0 75.0 Flexion 50.0 25.0 50.0 40.0 30.0 n n 20.0 10.0 0.0 10.0 20.0 30.0 40.0 50.0 Tendinous ruptures

Fig.3–Amplitudesofﬂexion:comparisonofpatellar fractureswithtendinousruptures.

predictablyhigherinpatellarfractures,notonlyduetothe advanced age, but also because these fractures have joint involvement.Inamultivariateanalysis,whencomparing flex-ionandKujalascorebetweenpatellarfracturesandtendinous ruptures,adjustingforageandthepresenceofpatellofemoral arthrosis,theseparameterswerestillfoundtobesignificantly higherintendinousruptures;theestimatedmeanflexionwas 98.92◦ in fractures and 116.62◦ in tendinous ruptures, and the Kujalascorewas 70.86in fractures and82.59 in tendi-nousruptures.Theonlypreviousstudythatdirectlycompared resultsofsurgicaltreatmentofpatellarfractures(n=50)with rupture ofthe quadriceps tendon (n=36) and patellar ten-don(n=13) didnotidentifysignificant differencesinrange ofmotion,radiographicsignsofarthrosis,andfunctional Teg-ner,Lysholm,andSF-36scoresamongthedifferenttypesof rupture.3

Limitations of this study are related to the fact that it was anobservationalretrospective study with asubjective clinical assessment and tothe difﬁculty ofcontrolling the variablesthatdetermineclinicalandfunctionalresults,and complications.Thestrengthsofthepresentstudyincludethe largenumberofpatientsineachgroup,aswellastheuseof

Tendinous ruptures Patellar fractures 120 100 80 60 Kujala score 40 20 120 100 80 60 Kujala score 40 20 20.0 15.0 10.0 n n 5.0 0.0 5.0 10.0 15.0 20.0

Fig.4–Kujalascore:comparisonofpatellarfractureswith tendonruptures.

objectiveandvalidatedmeasuresforclinicalandfunctional assessmentofrangeofmotionandtheKujalascore.

Conclusion

Surgicaltreatmentoftotalrupturesoftheextensor appara-tusofthekneeprovidedgoodfunctionalresults,whichwere superior fortendonruptureswhen comparedwithpatellar fractures,probablyduetohigherage ofthe latterpatients. Nonetheless,ruptureoftheextensorapparatusisassociated withhighlevelsofresidualpain,muscleweakness,muscle atrophy,andothercomplications,whichisprobablyduetoa lossofdynamicbalanceofthepatellofemoraljoint.

Conﬂicts

of

interest

Theauthorsdeclarenoconﬂictsofinterest.

Acknowledgement

ToDr.MargaridaMarques,fromtheStatisticsDepartmentof theHospitalandUniversityofCoimbra,forhercollaboration.

r

e

f

e

r

e

n

c

e

s

1.KellersmannR,BlattertTR,WeckbachA.Bilateralpatellar tendonrupturewithoutpredisposingsystemicdiseaseor steroiduse:acasereportandreviewoftheliterature.Arch OrthopTraumaSurg.2005;125(2):127–33.

2.SiwekCW,RaoJP.Rupturesoftheextensormechanismofthe kneejoint.JBoneJointSurgAm.1981;63(6):932–7.

3.TejwaniNC,LekicN,BechtelC,MonteroN,EgolKA. Outcomesafterkneejointextensormechanismdisruptions: isitbettertofracturethepatellaorrupturethetendon?J OrthopTrauma.2012;26(11):648–51.

4.KujalaUM,JaakkolaLH,KoskinenSK,TaimelaS,HurmeM, NelimarkkaO.Scoringofpatellofemoraldisorders. Arthroscopy.1993;9(2):159–63.

5.Classiﬁcac¸ãoAOdaPatela;2016.Disponívelem:

https://www2.aofoundation.org/wps/portal/surgery? showPage=diagnosis&bone=Knee&segment=Patella[acesso em07jan2016].

6.InsallJ,SalvatiE.Patellapositioninthenormalkneejoint. Radiology.1971;101(1):101–4.

7.KellyDW,CarterVS,JobeFW,KerlanRK.Patellarand quadricepstendonruptures–Jumper’sknee.AmJSports Med.1984;12(5):375–80.

8.ZernickeRF,GarhammerJ,JobeFW.Humanpatellartendon rupture:akineticanalysis.JBoneJointSurgAm.

1977;59(2):179–83.

9.KannusP,JozsaL.Histopathologicalchangespreceding spontaneousruptureofatendon.Acontrolledstudyof891 patients.JBoneJointSurgAm.1991;73(10):1507–25.

10.LazaroLE,WellmanDS,SauroG,PardeeNC,BerkesMB,Little MT,etal.Outcomesafteroperativeﬁxationofcomplete articularpatellarfractures:assessmentoffunctional impairment.JBoneJointSurgAm.2013;95(14):e961–8.

11.LeBrunCT,LangfordJR,SagiHC.Functionaloutcomesafter operativelytreatedpatellafractures.JOrthopTrauma. 2012;26(7):422–6.

(6)

12.KumarG,MereddyPK,HakkalamaniS,DonnachieNJ.Implant removalfollowingsurgicalstabilizationofpatellafracture. Orthopedics.2010;33(5):301.

13.DyCJ,LittleMT,BerkesMB,MaY,RobertsTR,HelfetDL,etal. Meta-analysisofre-operation,nonunion,andinfection afteropenreductionandinternalﬁxationofpatella fractures.JTraumaAcuteCareSurg.2012;73(4):928–32.

14.KovacevN,Anti ćJ,Gvozdenovi ćN,Obradovi ćM,VranjeˇsM, MilankovM.Patellartendonrupture–treatmentresults.Med Pregl.2015;68(1–2):22–8.

15.BoudissaM,RoudetA,Rubens-DuvalB,ChaussardC, SaragagliaD.Acutequadricepstendonruptures:aseriesof50 kneeswithanaveragefollow-upofmorethan6years.Orthop TraumatolSurgRes.2014;100(2):213–6.

16.RougraffBT,ReeckCC,EssenmacherJ.Completequadriceps tendonruptures.Orthopedics.1996;19(6):509–14.