人工全髖關(guān)節(jié)置換術(shù)后脫位發(fā)生率Theaverageincidenceofdislocationaftertotalhiparthroplastyisapproximately3%.

factorsahistoryofprevioushipsurgeryorrevisiontotalhipreplacement

（7.4%）aposteriorsurgicalapproach

（5.8%

vs

2.3%）faultypositioningofoneorbothcomponents

impingementofthefemuronthepelvisorresidualosteophytes

impingementoftheneckofthefemoralcomponentonthemarginofthesocket

inadequatesoft-tissuetension

insufficientorweakabductormuscles

avulsionornonunionofthegreatertrochanter

noncomplianceorextremesofpositioningintheperioperativeperiod

factorsAge,height,andweightdonotseemtobecausativefactors

inmanyseries,dislocationoccurredinwomenmoreoftenthaninmen.apreoperativediagnosisofosteonecrosis,proximalfemoralfractureornonunion,orinflammatoryarthritis.

Likelycontributingfactorsincludeextensivesoft-tissuerelease,muscularweakness,smallfemoralheadsize(22mm),andtrochantericnonunion.

后外側(cè)入路脫位高發(fā)的原因atendencytoretrovertthesocketnadequateanteriorretractionofthefemur,sotheacetabularpositioningdeviceisforcedposteriorlyduringcomponentinsertion

Divisionofalltheshortexternalrotators

防止發(fā)生脫位的策略fixingthecupintheproperposition

judgethepositionofthepatient'spelvisinthehorizontalandverticalplanes

womenwithbroadhipsandnarrowshoulders

menwithanarrowpelvisandbroadshoulders

truepositionofthepelvisalwaysmustbetakenintoaccount

防止發(fā)生脫位的策略Thefemoralcomponentshouldbefixedwiththeneckin5to10degreesofanteversion（

15degreesisacceptable

）developmentaldysplasiaorjuvenilerheumatoidarthritis,cancauseerrorinjudgingthecorrectposition

（anteversion）Retroversionofthefemoralneckmaybeencounteredwithslippedcapitalfemoralepiphysis,oriftheneckisresectedatanexcessivelylowlevel.

防止發(fā)生脫位的策略Boneorcementprotrudingbeyondtheflatsurfaceofthecupcancauseimpingementandmustberemovedafterthecuphasbeenfixedinplace.

ifthegreatertrochanterisenlargedordistorted,someboneoftenmustberemovedfromitsanteriororposteriormargintopreventimpingement.

bonyimpingementismuchmorelikelyiffemoraloffsethasnotbeenadequatelyrestored.Theuseofafemoralcomponentwithenhancedoffsetcanbeverybeneficialinthissituation

防止發(fā)生脫位的策略componentswithlargerdiameterheadswouldseemtobemoredesirablethanCharnley22-mmheadcomponents

therangeofprostheticmotionandultimatestabilityofthehipmaybediminishedifthelongerneckrequirestheadditionofaskirttotheheadcomponent

modularliners

isrotatedintoaninappropriateorientation.

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