Head-Neck Taper Corrosion in Hip Arthroplasty

Review ArticleHead-Neck Taper Corrosion in Hip Arthroplasty

S Hussenbocus1 D Kosuge1 L B Solomon2 D W Howie2 and R H Oskouei3

1Department of Orthopaedics and Trauma Royal Adelaide Hospital North Terrace Adelaide SA 5000 Australia2Department of Orthopaedics and Trauma Royal Adelaide Hospital and Centre for Orthopaedic and Trauma ResearchThe University of Adelaide North Terrace Adelaide SA 5000 Australia3School of Computer Science Engineering and Mathematics Flinders University Clovelly Park SA 5042 Australia

Correspondence should be addressed to R H Oskouei rezaoskoueiflinderseduau

Received 14 February 2015 Accepted 25 March 2015

Academic Editor Akihiro Sudo

Copyright copy 2015 S Hussenbocus et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Modularity at the head-neck junction of the femoral component in THA became popular as a design feature with advantagesof decreasing implant inventory and allowing adjustment of leg length offset and soft tissue balancing through different headoptions The introduction of a new modular interface to femoral stems that were previously monoblock or nonmodular comeswith the potential for corrosion at the taper junction throughmechanically assisted crevice corrosionThe incidence of revision hiparthroplasty is on the rise and along with improved wear properties of polyethylene and ceramic use of larger femoral head sizesis becoming increasingly popular Taper corrosion appears to be related to all of its geometric parameters material combinationsand femoral head size This review article discusses the pathogenesis risk factors clinical assessment and management of tapercorrosion at the head-neck junction

1 Introduction

Modularity at the head-neck junction of stems in total hiparthroplasty (THA) became popular in the 1980s [1] Thisdesign feature decreases implant inventory and simplifiessubsequent revision by offering the option of retaining thestem and performing a head exchange Head modularityallows adjustments of leg length and offset [1ndash3] and alsoallows the use of ceramic as a bearing option If the stem isto be retained at revision exposure may be improved by headremoval which also offers the opportunity to apply a newhead prior to closure This may be beneficial in terms of sub-sequent bearing surface wear Despite its potential benefitsan increase in the use of modular interfaces can lead to anincrease in fretting and crevice corrosion at the taper junction[3ndash6]

The confirmation of corrosion at the femoral head-neck junction is made at revision surgery The products oftaper corrosion may contribute to third-body wear of thearticulation Although taper corrosion is relatively rare inhips with metal-on-polyethylene articulations the corrosion

products can lead to adverse local tissue reactions (ALTRs)of the same type as that occurring with large diameter metal-on-metal (MoM) bearings [1] Head-neck taper corrosion iswell-described in large MoM bearing surfaces [7ndash9] but itsoccurrence with conventional metal or ceramic on polyethy-lene bearings is still relatively scarce Due to improved wearproperties of highly cross-linked polyethylene (HXLPE) [10ndash12] and ceramic [13] surgeons are more accepting of thinnerpolyethylene liners allowing the use of larger femoral headsto reduce the risk of dislocation [14 15] The number ofrevision THAs being performed is increasing and the higherdislocation rates in revision surgery also favour the use oflarger femoral heads [14ndash17] Factors affecting taper corrosioninclude taper design femoral head material and size use ofdissimilar metals at the head-neck junction lateral offsetvarus femoral stem position and time since implantation[2 5 6 18ndash21] This paper reviews the current literature ontaper corrosion at the head-neck junction and its clinicalimplications In this paper the term head-neck junctionrefers to the taper between the bore of the femoral head andthe trunnion of the femoral stem

Hindawi Publishing CorporationBioMed Research InternationalVolume 2015 Article ID 758123 9 pageshttpdxdoiorg1011552015758123

2 BioMed Research International

B

T

TL

CA

PCD

DCD

Figure 1 Diagrammatic representation of a femoral head-necktaper junction consisting of a female bore (B) andmale trunnion (T)The trunnion length (TL) proximal cone diameter (PCD) distalcone diameter (DCD) and cone angle (CA) are displayed

2 Definitions

The Oxford English Dictionary defines the word ldquotaperrdquo asldquoreduce in thickness towards one endrdquo [22] A more descrip-tive definition is the uniform change in diameter of a cylin-drical object measured along its axis The concept of a Morsetaper [23] is that of a cone within a conemdashthe trunnion(male portion) and the bore (female portion)mdashand thestresses created by the compression of the wall of the boreby the trunnion causes an interference fit (Figure 1) andcold-welding between the two components which increasesduring physiologic loading [2] The radial compressive stresscausing friction between the taper surfaces also providesresistance to separation at the head-neck junction The orig-inal Morse taper cone angle described was 2∘501015840 [23] butwithin Orthopaedics the termMorse taper is loosely used toencompass tapers of all angles that result in cold-welding ofone element upon another

3 Pathogenesis

Metal alloys traditionally used to manufacture THA implantsoffer good biocompatibility corrosion resistance andmecha-nical properties [24] The head-neck junctions of femoralstems are usually composed of titanium alloy (Ti-6Al-4V)or cobalt-chromium-molybdenum alloy (commonly knownas cobalt-chrome CoCr) both of which form a protectivesurface oxide layer through a process of self-passivationThisaids in resisting corrosion Cyclic loads through the hip jointmay induce small oscillatory motions between the head andneck at the taper This results in disruption of the passiveoxide layer by fretting [1 5 6] When the underlying metal isexposed repassivation occurs altering the passivation poten-tial and acidity of the local fluid environment Eventually theability to form a protective surface oxide layer is depleted andthis makes the exposed metal more susceptible to corrosion[2 25ndash27]

Taper corrosion includes a complex interaction of crevicecorrosion initiated by changes in local chemistry withincrevices and fretting which disrupts the protective oxidelayer on the taper [4 28 29] This process has also been

termed ldquomechanically assisted crevice corrosionrdquo (MACC)[30] In addition the presence in the body ofmixedmetal sys-tems such as Ti-6Al-4V stems with CoCr heads can inducegalvanic corrosion Corrosion appears to cause more loss ofmaterial from the bore of the head than from the trunnion[1 4ndash6]

MACC can potentially produce by-products at the head-neck junction primarily metal ions which can migratelocally and systemicallyThismay cause elevated serummetalion levels in extensively corroded tapers and is thought to ini-tiate a cascade of events leading toALTRs [1 2]These includemacrophage responses to particulate corrosion productswhich are more likely to be generated by fretting wear anda lymphocyte-dominated response to metal ion complexeswhich in some cases may lead to necrosis of periprosthetictissues local synovitis osteolysis component loosening andearly failure [2 31]

The histopathology is characterised by chronic inflam-mation and necrosis of periprosthetic soft tissues [1] Lym-phocytes plasmocytes and eosinophils may be found inviable areas of pseudocapsule and adjacent muscle [31] Bothtitanium oxide particles [31] and CoCr corrosion products[32 33] elicit a local macrophage-mediated inflammatoryresponse associated with increased release of inflammatorycytokines interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-120572) [34 35] This may lead to osteolysis and con-tribute to loosening [32]

4 Etiology

41 Taper Design Tapers exist in multiple sizes and anglesStudies have shown that larger diameter and longer taperswith circular necks result in a reduction of the range ofmotion compared to a smaller diameter and shorter taperwith a trapezoidal neck [36ndash38] With the former there isreduced arc of motion before impingement occurs and henceincreased risk of dislocation (Figure 2)

Trunnions are now manufactured shorter in order toreduce the dislocation risk with time 14mm16mm trun-nions have been replaced by narrower 12mm14mm trun-nions [18] An important concept to understand is that notall ldquo1214rdquo tapers have the same cone angle as the angle is alsodependent on the trunnion length (Figure 3)

It is not entirely clear what taper geometric parametersinfluence its corrosion This is evident by the numerousvarieties available from the different implant manufacturersShorter trunnions which tend to sit entirely within the boreare thought to increase edge loading at its base This mayincrease local stresses and cause increased damage to thetaper [18] Narrower trunnions provide less surface area forinterference fit and may increase micromotion at the head-neck junctionWhilst protecting against dislocations [39 40]maximizing the head-neck ratio with the use of shortersmaller tapers may also result in increased fretting and cor-rosion [2] In an in vitro study analysing tapers with differentsurface finishes and contact areas surface roughness on thehead taper was significantly increased after 107 loading cycleswhen the taper contact area was reduced and when necks

BioMed Research International 3

Arc of motion

(a)

Arc of motion

(b)

Figure 2 The effect of a long thin taper junction (a) and a short thick taper junction (b) on impingement and range of motion

TL1

TL2

12

12

14 14

CA1 CA2

Figure 3 Illustration to demonstrate the effect that trunnion lengthhas on cone angle with a constant proximal and distal diameter forexample in a ldquo1214rdquo taper With increasing trunnion length (TL1 gtTL2) the cone angle decreases (CA1 lt CA2) assuming the proximalcone diameter and distal cone diameter remain constant

with roughened trunnions were used [41] A recent retrievalstudy [19] of 40 femoral heads has suggested the contrarymdashshorter thinner tapers had lower fretting scores comparedto longer thicker tapers based on a previously describedscoring system [4] and on scans of negative molds of thefemale tapers The findings in that study [19] suggested thatthe larger the available surface area the greater the area overwhich fretting can occur

The taper cone angle varies according to the design in onestudy the taper angle was measured as 40∘ 60∘ and 56∘ intypes 1 1113 and 1214 tapers respectively [19] There wereno associations established between taper angles and corro-sion scores Another study looked at the effects of angularmismatch at the taper junction [42] by simulating a taperjunction on a computer model Micromotion at the taperwas independent of angular mismatches up to 0075∘ butincrease in micromotion was observed above this thresholdThe current industry accepted tolerance is 00167∘ [42] whichis lower than the threshold in the quoted study This area still

needs further investigation as there are theoretically increa-sed risks of corrosion with angular mismatch (Figures 4(a)and 4(b))

Most commercially available trunnions now have surfaceridges that can deform during impaction of the ceramic headproviding a close fit to the shape of the bore Some authorshave postulated that this leads to altered contact stresses andthus increased trunnion wear [18 41] In one study looking at161 failedMoMTHAs the authors suggested that these ridgesallow fluid to travel along the microthread of the trunnionand are ldquodetrimentalrdquo [30] Further investigation is requiredto determine whether different taper designs are required formetal and ceramic heads

42 Material

421 Head Ceramic is known for its inert and electricallyinsulating properties In an in vitro study analysing frettingcorrosion between zirconia ceramic heads and cobalt-alloystems compared to metal (cobalt-alloy) heads and cobalt-alloy stems there was less fretting corrosion in the ceramicgroup [43] Limitations of this study included its single stemhead design nature and the fact that the use of zirconia headshave generally been discontinued A more recent retrievalstudy [20] analysed fretting corrosion in matched groupsof 50 alumina ceramic heads and 50 CoCr heads on metaltapers The corrosion scores were lower for the stems inthe ceramic group suggesting that taper corrosion may bemitigated but not eliminated by using ceramic heads As thequality of ceramic has improved the risk of ceramic fractureshas decreased to between 002 and 01 [44] Howeverconcerns exist as to whether ceramic heads may safely bereimplanted onto femoral stems that are not being revisedThe concern is that the trunnion is likely to be damagedduring removal of the femoral head and damaged areas maylead to stress risers responsible for the initiation of a fracturein a newly implanted ceramic head [45 46] If the head isnot securely fixed onto the damaged taper there may bea risk of increased wear due to the abnormal movements


Mechanically assistedcrevice corrosion

120573

120572

(a)

120572

120573


Crevicecorrosion

(b)

Figure 4 Mechanically assisted crevice corrosion in different scenarios of angular mismatch (a) head angle 120572 greater than neck angle 120573and (b) head angle 120572 less than neck angle 120573 crevice corrosion can potentially occur in this design due to the corrosive fluid present at theinterface

at the head-neck junction In a study reporting 61 casesin which alumina heads were reimplanted onto well-fixedtitanium stems at revision of ceramic-on-ceramic prosthesesno fractures of the head had occurred at a mean of 88-monthfollow-up [47] Those authors suggested that this approachis acceptable so long as taper inspection revealed only minorscratches and the newly implanted ceramic head had a stablefit on the taper As this practice is against the manufacturersrsquorecommendations the surgeon should consider the potentiallegal implications in cases of subsequent head fracture

43 Head-Neck Couple Micromotion at the head-neck junc-tionmay induce fretting corrosion and contribute to the totalfailure of the implant [48] In a study where a Ti-6Al-4Vfemoral neck and a 316L stainless steel head were examinedunder axial fretting in ambient air and an artificial physiologicmedium [48] 316L steel showed fewer emitted wear particlesunder fretting corrosion conditions than the titanium alloyIn another study looking at how fretting corrosion is affectedby different material coupling combinations (Ti-6Al-4VTi-6Al-4V CoCrTi-6Al-4V and CoCrCoCr) [49] the Ti-6Al-4VTi-6Al-4V couple showed the most significant surfacedamage under axial loading However such in vitro studiesare limited as they cannot precisely duplicate all the in vivoconditions

In another retrieval study titanium-titanium interfacesdemonstrated the least amount of fretting when compared toCoCrCoCr and CoCrtitanium interfaces [19] The authorssuggest that this may reflect the ability of titanium-titaniuminterfaces to form a better interference fit via cold-weldingA better interference fit however may be a problem duringrevision surgery as multiple attempts at dislodging the femo-ral head from the stem may end up damaging the trunnionor the head may not disengage from the stem necessitating

revision of a (well-fixed) stem [50] Titanium alloy is nota commonly used material for femoral head manufacturingdue to its lower modulus of elasticity and inferior wearproperties compared to Co-Cr or ceramic so this may notbe so clinically relevant [51 52]

In another retrieval study examining 269 implants mildto moderate trunnion fretting and corrosion damage wasobserved in 38 (45118) of CoCr headtitanium-alloy stemcouple and 21 (32151) of CoCr headCoCr stem couple[53] In a large multicentre retrieval study moderate to severecorrosion was noted in 28 (65231) of heads of similar alloycouples compared to 42 (97231) of heads of mixed alloycouples [4] In both studies the differences were statisticallysignificant but no mention was made of what type of articu-lating surfaces was used Dissimilar alloy pairing between thehead and stemcausesmore damage at both the head and taperwhen compared to components with similar alloy pairing[4] as the former is more susceptible to galvanic corro-sion Interestingly several multicentre retrieval studies havereported higher rates and more severe corrosion and frettingin the head taper compared to the neck [4 54] In additiondifferent grades of metallic alloys with different chemicalcompositions such as Ti-6Al-4V and Ti-6Al-4V (ELI grade)possess different mechanical and surface properties andtherefore may have different levels of corrosion resistance

44 Femoral Head Size Larger heads have increased jumpdistance larger femoral head-neck ratio and a greater impin-gement-free range of motion [16 39 55] The Medicare data-base showed that the use of larger head sizes (32mm orgreater) over the course of a decade resulted in a decrease indislocation rate of about 50 [56] However the recent trendof using larger femoral heads to reduce risks of dislocationmay result in higher stresses at the femoral head-neck


(a) (b)

Figure 5 Fretting and corrosion damage on the (a) bore of a CoCr femoral head and (b) Ti-alloy trunnion from a retrieved failed metal-on-polyethylene THR

junction [18] In a retrieval study looking at CoCr alloy headand stem pairings featuring a 1214mm taper in metal-on-polyethylene articulations there was a significant increasein taper corrosion scores of 36mm heads compared with28mm heads [3] In another retrieval study looking at 90modular implants corrosion damage of the trunnion variedwith type of articulation and head size [57] In a retrievalanalysis of 100 taper junctions from metal-on-polyethylenearticulations 16 of the tapers had severe or moderatecorrosion [4] independent of femoral head size [54] Tapercorrosion was most strongly correlated to the severity of theabrasive wear affecting the surface of the CoCr head Femoralhead size only became an important cofactor in predictingcorrosion in the presence of abrasive wear of the surface ofthe headThe authors postulated that the abrasivewear seen issecondary to third-body damage which is common in manylarge diameter polyethylene liners and this would lead toincreases in frictional torques

The possible influence of head size on taper corrosion canbe speculated from the reported survival of MoM THAs inthe Australian Joint Replacement Registry An increased rateof revision was associated with the use of head sizes gt32mminMoMTHAs whereas the cumulative revision rates of thosewith head size lt32mm were comparable to their metal-on-polyethylene counterparts [15] The possible role of the taperjunction is also suggested by the higher revision rates of largeMoM THAs compared to their hip resurfacing counterpartsin the registry report For failed MoM THA material lossoccurs preponderantly fromwear of themetal bearing surfaceand retrieval analysis showed that the volumetric loss at thetaper junction represented only 61 of the material loss inthese cases [58]

45 Others Other factors that may affect taper corrosioninclude patient body mass index (BMI) lateral offset varusfemoral stem positioning longer necks time since implan-tation and inconsistency in assembly of modular headsincluding the force of impaction the vector of the appliedforce and contamination of the interface [4 8 21 54] It isinteresting to note that the observation of trunnion-relatedrevisions is relatively recent and has coincided with the more

widespread use of smaller incisions and operative approachesthat may make correct trunnion assembly more difficult

5 Clinical

The true incidence of clinically relevant taper corrosion isnot known but in one study 10 of 569 (18) revision THAsperformed were due to complications arising from corrosionat the head-neck taper inmetal-on-polyethylene articulations[1] Diagnosis is often difficult unless significant associatedALTRs occur A painful THA should have taper corrosion onits list of differential diagnoses even though more commoncauses such as aseptic loosening secondary to particulatedebris from the bearing surface and infection should behigher on the list

Taper corrosion may be suggested by elevated serumcobalt and chromium levels particularly a differential eleva-tion of serum cobalt levels with respect to chromium levels[1 17] As the clinical picture may be unclear elevation of theerythrocyte sedimentation rate (ESR) and C-reactive protein(CRP) may be a guide to hip aspiration to exclude infec-tion which provides the opportunity for joint fluid metalion analysis Ultrasound is an effective screening tool andmetal-artifact reduction magnetic resonance imaging (MRI)provides a visual assessment of the extent if any of synovitisosteolysis muscletendon destruction periprosthetic fluidcollections and pseudotumour formation [59]

6 Treatment

The surgeon has to weigh the potential benefits of revisinga well-fixed stem which has trunnion damage against thepotential morbidity associated with stem revision Avoidingstem revision reduces surgical time blood loss and compli-cations To avoid the difficult revision of a well-fixed stem thecommon practice is to place a new head on a retained stemThis should only be performed when trunnion corrosion ismacroscopically mild (visible but not palpable defects) andwhen an interference fit can be achieved with the new head(Figures 5(a) and 5(b)) Although the long-term consequenceof this practice is unknown an in vitro and retrieval study


favours this [60] In a study in which retrieved femoralheads assembled onto unimplanted Ti-6Al-4V trunnionswere mechanically tested the authors concluded that the tor-sional properties of the taper junctions were not significantlyinfluenced by mild or moderate grades of corrosion [60] Ifthe stem is to be retained we advocate intraoperative trunn-ion protection with the use of a cut-out suction tubing orplastic syringe [61] However given the lack of consensus onthe issue of how much taper damage warrants stem revisionand how much taper damage is acceptable the decision toretain or revise a stable stem which has taper damage shouldbe left to the judgment of the treating surgeon

The use of ceramic heads may reduce future problemswith taper corrosion but concerns exist in the revisionscenario of reimplantation of ceramic heads onto damagedtapers [1 20 62 63] It has been suggested that the use of atitanium alloy adaptor sleeve might help prevent the recur-rence of ALTRs by way of changing the material combinationat the head-neck junction to a Ti-6Al-4VTi-6Al-4V or Ti-6Al-4VCoCr pairing depending on the material of the stem[1 19] This has substantial added costs and may not be aviable option in every hospital

It is imperative to ensure that any femoral head implantedonto a trunnion should be compatible with the design ofthe trunnion as mismatch may contribute to taper corrosionfrom increased micromotion [42] It has been noted that1214 trunnions from different implants and companies differsubtly in dimensions and cone angles [23] Only one of theorthopaedic companies contacted by the authors requestingdetails of trunnion dimensions agreed to have the data madeavailable for clinicians through a forum like this journal Toillustrate the importance of such information we comparedthe 1214 taper of company A (trunnion length 1180mmproximal cone diameter 1260mm distal cone diameter1370mm) and company B (trunnion length 1120mmproximal cone diameter 1260mm distal cone diameter1365mm) The cone angles of these two implants are5∘4210158403010158401015840 and 5∘671015840 equaling a difference of 0412∘ or morethan five times the 0075∘ threshold mismatch above whichmicromotion is increased at the head-neck junction [42]Therefore tapers should never be mismatched even if theyare from the same manufacturer or if the taper design (eg1214) quoted is the same The process of applying a femoralhead onto a trunnion needs attention we advocate thecleaning and drying of the surfaces prior to application toavoid any fluid or tissue that may lodge between the twosurfaces preventing adequate interlocking of the taper [64]

7 Summary

Although modular hips were introduced in the 80s and tapercorrosion was reported in the early 90s the contribution offretting and corrosion at the taper junction [51 65] to implantfailure is now being increasingly recognised The severityof early corrosion-related failure of modular femoral stem-neck junction is a potential reason for concern [66] andthe surgeon should be aware of the potential drawbacks ofmodularity in THA Factors under the surgeonrsquos influence

include choice of femoral head material femoral head sizeengagement of the taper in an environment free from bloodor fat force and technique of impaction [64 67 68] andavoiding angular mismatch at the taper junction [69] Thesurgeonrsquos choice of stem will govern the taper design butdesign is under the control of the manufacturers

Data on taper corrosion are generated from in vitro andretrieval studies Given that in vitro studies cannot preciselyreproduce all the in vivo conditions these results should beinterpreted with caution Retrieval studies also have limi-tations as they involve analysis of clinically failed implantsand these findings may not necessarily reflect the well-functioning unrevised implants [20] In addition among theimplants in a given study there is often heterogeneity in thebearing surfaces used head size offset stem type stem alloyand implant manufacturer which may have implications ontaper corrosion

There is likely to be a wide spectrum when it comes totaper corrosion ranging from mild corrosion with no tissuereaction and little or no clinical implications to substantialALTRs with abductor deficiency metallosis and pseudotu-mour formation with significant clinical implications akin tothat seen in hips with MoM bearing surfaces

Although taper corrosion is a real entity onemust bewareof overdiagnosing this condition based on the recent increas-ing interest Although it was not well appreciated in the pastit is unlikely to pose a major clinical issue at present andpotential unnecessary changes in practice should be avoideduntil there is clear evidence to suggest the contrary

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors wish to acknowledge Mr Hamidreza FarhoudiSchool of Computer Science Engineering and MathematicsFlinders University for his help with creation of the figuresincluded in this paper

References

[1] H J Cooper C J Della Valle R A Berger et al ldquoCorrosion atthe head-neck taper as a cause for adverse local tissue reactionsafter total hip arthroplastyrdquo Journal of Bone and Joint SurgerymdashAmerican Volume vol 94 no 18 pp 1655ndash1661 2012

[2] A Srinivasan E Jung and B R Levine ldquoModularity of thefemoral component in total hip arthroplastyrdquo Journal of theAmerican Academy of Orthopaedic Surgeons vol 20 no 4 pp214ndash222 2012

[3] R M R Dyrkacz J-M Brandt O A Ojo T R Turgeon and UP Wyss ldquoThe influence of head size on corrosion and frettingbehaviour at the head-neck interface of artificial hip jointsrdquoJournal of Arthroplasty vol 28 no 6 pp 1036ndash1040 2013

[4] J R Goldberg J L Gilbert J J Jacobs TW BauerW Paproskyand S Leurgans ldquoA multicenter retrieval study of the taper


interfaces ofmodular hip prosthesesrdquoClinical Orthopaedics andRelated Research no 401 pp 149ndash161 2002

[5] G B Higgs J A Hanzlik DW MacDonald et al ldquoIs increasedmodularity associated with increased fretting and corrosiondamage in Metal-on-Metal Total Hip Arthroplasty devices Aretrieval studyrdquo Journal of Arthroplasty vol 28 supplement no8 pp 2ndash6 2013

[6] G B Higgs J A Hanzlik D W MacDonald et al ldquoMethodof characterizing fretting and corrosion at the various taperconnections of retrieved modular components from metal-on-metal total hip arthroplastyrdquo in Metal-on-Metal Total HipReplacement Devices S M Kurtz A S Greenwald W MMihalko and J Lemons Eds STP 1560 American Society forTesting and Materials Conshohocken Pa USA 2013

[7] J P Collier V A Surprenant R E Jensen and M B MayorldquoCorrosion at the interface of cobalt-alloy heads on titanium-alloy stemsrdquoClinical Orthopaedics andRelated Research no 271pp 305ndash312 1991

[8] J L Gilbert C A Buckley and J J Jacobs ldquoIn vivo corrosion ofmodular hip prosthesis components inmixed and similar metalcombinations The effect of crevice stress motion and alloycouplingrdquo Journal of Biomedical Materials Research vol 27 no12 pp 1533ndash1544 1993

[9] J S Kawalec S A Brown J H Payer and K Merritt ldquoMixed-metal fretting corrosion of Ti6Al4V and wrought cobalt alloyrdquoJournal of Biomedical Materials Research vol 29 no 7 pp 867ndash873 1995

[10] D D DrsquoLima J C Hermida P C Chen and C W Colwell JrldquoPolyethylene cross-linking by two different methods reducesacetabular liner wear in a hip joint wear simulatorrdquo Journal ofOrthopaedic Research vol 21 no 5 pp 761ndash766 2003

[11] G E R Thomas D J Simpson S Mehmood et al ldquoTheseven-year wear of highly cross-linked polyethylene in total hiparthroplasty a double-blind randomized controlled trial usingradiostereometric analysisrdquo Journal of Bone and Joint SurgerymdashAmerican Volume vol 93 no 8 pp 716ndash722 2011

[12] J Mutimer P A Devane K Adams and J G Horne ldquoHighlycrosslinked polyethylene reduces wear in total hip arthroplastyat 5 yearsrdquo Clinical Orthopaedics and Related Research vol 468no 12 pp 3228ndash3233 2010

[13] D Hannouche A Zaoui F Zadegan L Sedel and R NizardldquoThirty years of experience with alumina-on-alumina bearingsin total hip arthroplastyrdquo International Orthopaedics vol 35 no2 pp 207ndash213 2011

[14] Australian Orthopaedic Association National Joint Replace-ment Registry ldquoHip and knee arthroplastyrdquo Annual Report2013httpsaoanjrrdmacadelaideeduauannual-reports-2013

[15] Australian Orthopaedic Association National Joint Replace-ment Registry Hip and Knee Arthroplasty Annual Report 20122012 httpsaoanjrrdmacadelaideeduauannual-reports-2012

[16] D W Howie O T Holubowycz R Middleton et al ldquoLargefemoral heads decrease the incidence of dislocation after totalhip arthroplasty a randomized controlled trialrdquoThe Journal ofBone and Joint SurgerymdashAmerican Volume vol 94 no 12 pp1095ndash1102 2012

[17] D S Garbuz M Tanzer N V Greidanus B A Masri and C PDuncan ldquoThe john charnley award metal-on-metal hip resur-facing versus large-diameter head metal-on-metal total hiparthroplasty a randomized clinical trialrdquo Clinical Orthopaedicsand Related Research vol 468 no 2 pp 318ndash325 2010

[18] D J Langton R Sidaginamale J K Lord A V Nargol and T JJoyce ldquoTaper junction failure in large-diametermetal-on-metalbearingsrdquo Bone and Joint Research vol 1 no 4 pp 56ndash63 2012

[19] N A Nassif D H Nawabi K Stoner M Elpers T Wrightand D E Padgett ldquoTaper design affects failure of large-headmetal-on-metal total hip replacementsrdquo Clinical Orthopaedicsand Related Research vol 472 no 2 pp 564ndash571 2014

[20] S M Kurtz S B Kocagoz J A Hanzlik et al ldquoDo ceramicfemoral heads reduce taper fretting corrosion in hip arthro-plasty A retrieval studyrdquo Clinical Orthopaedics and RelatedResearch vol 471 no 10 pp 3270ndash3282 2013

[21] S A Brown C A C Flemming J S Kawalec et al ldquoFrettingcorrosion accelerates crevice corrosion of modular hip tapersrdquoJournal of Applied Biomaterials vol 6 no 1 pp 19ndash26 1995

[22] Oxford Dictionaries 2014 httpwwwoxforddictionariescom[23] P Hernigou S Queinnec and C H Flouzat Lachaniette

ldquoOne hundred and fifty years of history of the Morse taperfrom Stephen A Morse in 1864 to complications related tomodularity in hip arthroplastyrdquo International Orthopaedics vol37 no 10 pp 2081ndash2088 2013

[24] D W Hoeppner and V Chandrasekaran ldquoFretting in ortho-paedic implants a reviewrdquo Wear vol 173 no 1-2 pp 189ndash1971994

[25] B Sivakumar S Kumar and T S N Sankara NarayananldquoFretting corrosion behaviour of Tindash6Alndash4V alloy in artificialsaliva containing varying concentrations of fluoride ionsrdquoWearvol 270 no 3-4 pp 317ndash324 2011

[26] D C Rodrigues R M Urban J J Jacobs and J L GilbertldquoIn vivo severe corrosion and hydrogen embrittlement ofretrievedmodular body titanium alloy hip-implantsrdquo Journal ofBiomedical Materials Research Part B Applied Biomaterials vol88 no 1 pp 206ndash219 2009

[27] S Virtanen IMilosev EGomez-Barrena R Trebse J Salo andY T Konttinen ldquoSpecial modes of corrosion under physiologi-cal and simulated physiological conditionsrdquoActa Biomaterialiavol 4 no 3 pp 468ndash476 2008

[28] J J Jacobs J L Gilbert and R M Urban ldquoCorrosion of metalorthopaedic implantsrdquo The Journal of Bone amp Joint SurgerymdashAmerican Volume vol 80 no 2 pp 268ndash282 1998

[29] J L Gilbert and J J Jacobs ldquoThe mechanical and electrochem-ical processes associated with taper fretting crevice corrosiona reviewrdquo in Modularity of Orthopedic Implants ASTM STP1301 D Marlowe J Parr and M B Mayor Eds pp 45ndash59American Society for Testing andMaterials Conshohocken PaUSA 1997

[30] A Hexter A Panagiotidou J Singh J Skinner and A HartldquoMechanism of corrosion in large diameter head metal-on-metal total hip arthroplasty a retrieval analysis of 161 com-ponentsrdquo The Bone amp Joint JournalmdashBritish Volume vol 95supplement 12 p 4 2013

[31] R M Urban D J Hall H J Cooper C J D Valle J O Galanteand J J Jacobs ldquoLocal histological and systemic effects of metalcorrosion productsrdquo in Proceedings of the Hip Society MeetingChicago Ill USA 2013

[32] S-H Lee F R Brennan J J Jacobs R M Urban D R Ragasaand T T Glant ldquoHuman monocytemacrophage response tocobalt-chromium corrosion products and titanium particles inpatients with total joint replacementsrdquo Journal of OrthopaedicResearch vol 15 no 1 pp 40ndash49 1997

[33] D W Howie and B Vernon-Roberts ldquoThe synovial responseto intraarticular cobalt-chrome wear particlesrdquo Clinical Ortho-paedics and Related Research no 232 pp 244ndash254 1988


[34] M C D Trindade M Lind D Sun D J Schurman S BGoodman and R L Smith ldquoIn vitro reaction to orthopaedicbiomaterials by macrophages and lymphocytes isolated frompatients undergoing revision surgeryrdquo Biomaterials vol 22 no3 pp 253ndash259 2001

[35] S D Rogers D W Howie S E Graves M J Pearcy and D RHaynes ldquoIn vitro human monocyte response to wear particlesof titanium alloy containing vanadium or niobiumrdquo Journal ofBone and Joint SurgerymdashBritish Volume vol 79 no 2 pp 311ndash315 1997

[36] R L Barrack R A Butler D R Laster and P Andrews ldquoStemdesign and dislocation after revision total hip arthroplastyclinical results and computermodelingrdquo Journal of Arthroplastyvol 16 supplement 1 no 8 pp 8ndash12 2001

[37] D E Padgett J Lipman B Robie and B J Nestor ldquoInfluence oftotal hip design on dislocation a computer model and clinicalanalysisrdquo Clinical Orthopaedics and Related Research vol 447pp 48ndash52 2006

[38] A Malik A Maheshwari and L D Dorr ldquoImpingement withtotal hip replacementrdquo The Journal of Bone amp Joint SurgerymdashAmerican Volume vol 89 no 8 pp 1832ndash1842 2007

[39] J A Rodriguez and P A Rathod ldquoLarge diameter heads isbigger always betterrdquo The Journal of Bone and Joint SurgerymdashBritish Volume vol 94 no 11 pp 52ndash54 2012

[40] D J Berry M von Knoch C D Schleck and W S HarmsenldquoEffect of femoral head diameter and operative approach on riskof dislocation after primary total hip arthroplastyrdquoThe Journalof Bone amp Joint SurgerymdashAmerican Volume vol 87 no 11 pp2456ndash2463 2005

[41] A Panagiotidou J Meswania J Hua S Muirhead-Allwood AHart and G Blunn ldquoEnhanced wear and corrosion in modulartapers in total hip replacement is associated with the contactarea and surface topographyrdquo Journal of Orthopaedic Researchvol 31 no 12 pp 2032ndash2039 2013

[42] J Parekh H Jones N Chan and P Noble ldquoEffect of angularmismatch tolerance on trunnion micro-motion in metal-on-metal THA designsrdquoThe Bone amp Joint JournalmdashBritish Volumevol 95 supplement 34 p 261 2013

[43] N J Hallab C Messina A Skipor and J J Jacobs ldquoDiffer-ences in the fretting corrosion of metal-metal and ceramic-metal modular junctions of total hip replacementsrdquo Journal ofOrthopaedic Research vol 22 no 2 pp 250ndash259 2004

[44] D Hannouche C Nich P Bizot A Meunier R Nizard andL Sedel ldquoFractures of ceramic bearings history and presentstatusrdquo Clinical Orthopaedics and Related Research no 417 pp19ndash26 2003

[45] G Willmann ldquoCeramics for total hip replacementmdashwhat asurgeon should knowrdquo Orthopedics vol 21 no 2 pp 173ndash1771998

[46] G Willmann ldquoCerami femoral head retrieval datardquo ClinicalOrthopaedics and Related Research no 379 pp 22ndash28 2000

[47] D Hannouche J Delambre F Zadegan L Sedel and RNizard ldquoIs there a risk in placing a ceramic head on a pre-viously implanted trunionrdquo Clinical Orthopaedics and RelatedResearch vol 468 no 12 pp 3322ndash3327 2010

[48] L Duisabeau P Combrade and B Forest ldquoEnvironmentaleffect on fretting ofmetallicmaterials for orthopaedic implantsrdquoWear vol 256 no 7-8 pp 805ndash816 2004

[49] V Swaminathan and J L Gilbert ldquoFretting corrosion ofCoCrMo and Ti6Al4V interfacesrdquo Biomaterials vol 33 no 22pp 5487ndash5503 2012

[50] A M Kop C Keogh and E Swarts ldquoProximal componentmodularity in THAmdashat what cost An implant retrieval studyrdquoClinical Orthopaedics and Related Research vol 470 no 7 pp1885ndash1894 2012

[51] G Manivasagam D Dhinasekaran and A RajamanickamldquoBiomedical implants corrosion and its preventionmdasha reviewrdquoRecent Patents onCorrosion Science vol 2 no 1 pp 40ndash54 2010

[52] I K Brummitt C S Hardaker P J J McCullagh K JDrabu and R A Smith ldquoEffect of counterface material onthe characteristics of retrieved uncemented cobalt-chromiumand titanium alloy total hip replacementsrdquo Proceedings of theInstitution of Mechanical Engineers Part H vol 210 no 3 pp191ndash195 1996

[53] R M Urban D J Hall J L Gilbert et al ldquoAre frettingand corrosion reduced in contemporary headneck modularjunctionsrdquo in Proceedings of the ORS Annual Meeting PosterNo 1050 February 2012

[54] I Moga M A Harington and P C Noble ldquoVariables influ-encing tribo-corrosion of modular junctions in metal-on-polyethylene THRrdquo in Proceedings of the American Academyof Orthopedic Surgeons Annual Meeting Paper 614 2014

[55] D S Garbuz B A Masri C P Duncan et al ldquoThe FrankStinchfield award dislocation in revision THA do large heads(36 and 40 mm) result in reduced dislocation rates in arandomized clinical trialrdquo Clinical Orthopaedics and RelatedResearch vol 470 no 2 pp 351ndash356 2012

[56] A L Malkani K L Ong E Lau S M Kurtz B J Justiceand M T Manley ldquoEarly- and late-term dislocation risk afterprimary hip arthroplasty in the medicare populationrdquo Journalof Arthroplasty vol 25 no 6 supplement pp 21ndash25 2010

[57] I Moga M A Harrington S Ismaily and P Noble ldquoTrunnionsurface damage in THR MPE vsMOM articulationsrdquoThe Boneamp Joint JournalmdashBritish Volume vol 95 supplement 34 p 1402013

[58] A Matthies P J Bills R Racasan et al ldquoAnalysis of the tapersupports retention of a well-fixed stem in revision surgery ofmetal-on-metal hip replacementsrdquo in Proceedings of the AAOSAnnual Meeting Paper 613 2014

[59] A P Toms T J Marshall J Cahir et al ldquoMRI of early symp-tomatic metal-on-metal total hip arthroplasty a retrospectivereview of radiological findings in 20 hipsrdquo Clinical Radiologyvol 63 no 1 pp 49ndash58 2008

[60] J Alexander A Hexter S Ismaily A Hart and P Noble ldquoTheeffect of tribo-chemical damage on mechanical performanceof TIAlV-CoCr taper junctionsrdquo Poster 2556 InternationalSociety for Technology in Arthroplasty 2013

[61] T J S Puolakka P J Halonen J Oksa and K J J PajamakildquoProtection of femoral neck taper in revision of acetabularcomponentrdquo Journal of Arthroplasty vol 17 no 4 pp 497ndash4982002

[62] R M Meneghini N J Hallab and J J Jacobs ldquoEvaluation andtreatment of painful total hip arthroplasties withmodularmetaltaper junctionsrdquo Orthopedics vol 35 no 5 pp 386ndash391 2012

[63] F Traina E Tassinari M De Fine B Bordini and A TonildquoRevision of ceramic hip replacements for fracture of a ceramiccomponent AAOS exhibit selectionrdquo The Journal of Bone andJoint SurgerymdashAmerican Volume vol 93 no 24 article e1472011

[64] M L Mroczkowski J S Hertzler S M Humphrey T Johnsonand C R Blanchard ldquoEffect of impact assembly on the fret-ting corrosion of modular hip tapersrdquo Journal of OrthopaedicResearch vol 24 no 2 pp 271ndash279 2006


[65] C A Engh H Ho and D E Padgett ldquoThe surgical optionsand clinical evidence for treatment of wear or corrosionoccurringwith THAorTKArdquoClinical Orthopaedics andRelatedResearch vol 472 no 12 pp 3674ndash3686 2014

[66] M Meftah A M Haleem M B Burn K M Smith and SJ Incavo ldquoEarly corrosion-related failure of the Rejuvenatemodular total hip replacementrdquo Journal of Bone and JointSurgerymdashAmerican Volume vol 96 no 6 pp 481ndash487 2014

[67] T P Vail ldquoComplications metal-on-metal articulationsmdashdesign and technique related factorsrdquo in Proceedings of the HipSociety Meeting Chicago Ill USA 2013

[68] A Rehmer N E Bishop and M M Morlock ldquoInfluence ofassembly procedure and material combination on the strengthof the taper connection at the head-neck junction of modularhip endoprosthesesrdquoClinical Biomechanics vol 27 no 1 pp 77ndash83 2012

[69] L Milosev V Antolic A Minovic et al ldquoExtensive metallosisand necrosis in failed prostheses with cemented titanium-alloystems and ceramic headsrdquoThe Journal of Boneamp Joint SurgerymdashBritish Volume vol 82 no 3 pp 352ndash357 2000

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


B

T

TL

CA

PCD

DCD

Figure 1 Diagrammatic representation of a femoral head-necktaper junction consisting of a female bore (B) andmale trunnion (T)The trunnion length (TL) proximal cone diameter (PCD) distalcone diameter (DCD) and cone angle (CA) are displayed

2 Definitions

The Oxford English Dictionary defines the word ldquotaperrdquo asldquoreduce in thickness towards one endrdquo [22] A more descrip-tive definition is the uniform change in diameter of a cylin-drical object measured along its axis The concept of a Morsetaper [23] is that of a cone within a conemdashthe trunnion(male portion) and the bore (female portion)mdashand thestresses created by the compression of the wall of the boreby the trunnion causes an interference fit (Figure 1) andcold-welding between the two components which increasesduring physiologic loading [2] The radial compressive stresscausing friction between the taper surfaces also providesresistance to separation at the head-neck junction The orig-inal Morse taper cone angle described was 2∘501015840 [23] butwithin Orthopaedics the termMorse taper is loosely used toencompass tapers of all angles that result in cold-welding ofone element upon another

3 Pathogenesis

Metal alloys traditionally used to manufacture THA implantsoffer good biocompatibility corrosion resistance andmecha-nical properties [24] The head-neck junctions of femoralstems are usually composed of titanium alloy (Ti-6Al-4V)or cobalt-chromium-molybdenum alloy (commonly knownas cobalt-chrome CoCr) both of which form a protectivesurface oxide layer through a process of self-passivationThisaids in resisting corrosion Cyclic loads through the hip jointmay induce small oscillatory motions between the head andneck at the taper This results in disruption of the passiveoxide layer by fretting [1 5 6] When the underlying metal isexposed repassivation occurs altering the passivation poten-tial and acidity of the local fluid environment Eventually theability to form a protective surface oxide layer is depleted andthis makes the exposed metal more susceptible to corrosion[2 25ndash27]

Taper corrosion includes a complex interaction of crevicecorrosion initiated by changes in local chemistry withincrevices and fretting which disrupts the protective oxidelayer on the taper [4 28 29] This process has also been

termed ldquomechanically assisted crevice corrosionrdquo (MACC)[30] In addition the presence in the body ofmixedmetal sys-tems such as Ti-6Al-4V stems with CoCr heads can inducegalvanic corrosion Corrosion appears to cause more loss ofmaterial from the bore of the head than from the trunnion[1 4ndash6]

MACC can potentially produce by-products at the head-neck junction primarily metal ions which can migratelocally and systemicallyThismay cause elevated serummetalion levels in extensively corroded tapers and is thought to ini-tiate a cascade of events leading toALTRs [1 2]These includemacrophage responses to particulate corrosion productswhich are more likely to be generated by fretting wear anda lymphocyte-dominated response to metal ion complexeswhich in some cases may lead to necrosis of periprosthetictissues local synovitis osteolysis component loosening andearly failure [2 31]

The histopathology is characterised by chronic inflam-mation and necrosis of periprosthetic soft tissues [1] Lym-phocytes plasmocytes and eosinophils may be found inviable areas of pseudocapsule and adjacent muscle [31] Bothtitanium oxide particles [31] and CoCr corrosion products[32 33] elicit a local macrophage-mediated inflammatoryresponse associated with increased release of inflammatorycytokines interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-120572) [34 35] This may lead to osteolysis and con-tribute to loosening [32]

4 Etiology

41 Taper Design Tapers exist in multiple sizes and anglesStudies have shown that larger diameter and longer taperswith circular necks result in a reduction of the range ofmotion compared to a smaller diameter and shorter taperwith a trapezoidal neck [36ndash38] With the former there isreduced arc of motion before impingement occurs and henceincreased risk of dislocation (Figure 2)

Trunnions are now manufactured shorter in order toreduce the dislocation risk with time 14mm16mm trun-nions have been replaced by narrower 12mm14mm trun-nions [18] An important concept to understand is that notall ldquo1214rdquo tapers have the same cone angle as the angle is alsodependent on the trunnion length (Figure 3)

It is not entirely clear what taper geometric parametersinfluence its corrosion This is evident by the numerousvarieties available from the different implant manufacturersShorter trunnions which tend to sit entirely within the boreare thought to increase edge loading at its base This mayincrease local stresses and cause increased damage to thetaper [18] Narrower trunnions provide less surface area forinterference fit and may increase micromotion at the head-neck junctionWhilst protecting against dislocations [39 40]maximizing the head-neck ratio with the use of shortersmaller tapers may also result in increased fretting and cor-rosion [2] In an in vitro study analysing tapers with differentsurface finishes and contact areas surface roughness on thehead taper was significantly increased after 107 loading cycleswhen the taper contact area was reduced and when necks


Arc of motion

(a)

Arc of motion

(b)


TL1

TL2

12

12

14 14

CA1 CA2






42 Material




120573

120572

(a)

120572

120573


Crevicecorrosion

(b)









(a) (b)






5 Clinical



6 Treatment






7 Summary








Acknowledgment


References















































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Arc of motion

(a)

Arc of motion

(b)


TL1

TL2

12

12

14 14

CA1 CA2






42 Material




120573

120572

(a)

120572

120573


Crevicecorrosion

(b)









(a) (b)






5 Clinical



6 Treatment






7 Summary








Acknowledgment


References















































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















120573

120572

(a)

120572

120573


Crevicecorrosion

(b)









(a) (b)






5 Clinical



6 Treatment






7 Summary








Acknowledgment


References















































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















(a) (b)






5 Clinical



6 Treatment






7 Summary








Acknowledgment


References















































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of




















7 Summary








Acknowledgment


References















































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


























































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



























































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



























of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of





















of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















Documents

Head-Neck Taper Corrosion in Hip Arthroplasty