假体关节相关感染A62-year-oldwomanwithosteoarthritispresentswitha7-monthhistoryofprogressivelyworseninglefthippainradiatingtothegroin,8monthsafterundergoingtotalleft-hiparthroplasty.Thepainhasnotrespondedtononsteroidalanti-inflammatorydrugs.Physicalexaminationrevealsasinustractoverlyingherlefthip.Herleukocytecountis8000percubicmillimeter,andtheC-reactiveprotein(CRP)levelis15.5mgperliter.Aradiographshowslooseningoftheprosthesisatthebone–cementinterface.Synovial-fluidaspirateshows15×103cellspercubicmillimeter(89%neutrophils);culturesofanaspiratefromthehipgrowStaphylococcusepidermidis.Howshouldhercasebemanaged?1名62岁女性骨性关节炎患者，左侧THA术后8个月，左髋渐进性疼痛并向腹股沟放射7个月。服用非甾类抗炎药疼痛无缓解。查体示左髋有一窦道形成。白细胞计数为8000个/mm3，C-RP为15.5mg/L。放射线检查示假体和骨水泥界面有松动。关节液检查示15X103个细胞/mm3，中性粒细胞比例为89％；关节炎培养示为表皮葡萄球菌阳性。该如何对这一病例进行处理？TheClinicalProblemThenumbersofprimarytotalhipandtotalkneearthroplastieshavebeenincreasingoverthepastdecade,withnearly800,000suchproceduresperformedintheUnitedStatesin2006(Fig.1A).1Procedurestoreplacetheshoulder,elbow,wrist,ankle,temporomandibular,metacarpophalangeal,andinterphalangealjointsarelesscommonlyperformed.临床问题：过去10年间，行首次髋膝关节置换的病例数有了大幅的增长，到2006年美国约进行了800000例此类手术。而行肩、肘、腕、踝、颞下颌、掌指和指间关节置换则少见的多。Prostheticjointsimprovethequalityoflife,buttheymayfail,necessitatingrevisionorresectionarthroplasty.Causesoffailureincludeasepticloosening,infection,dislocation,andfractureoftheprosthesisorbone.Infection,althoughuncommon,isthemostseriouscomplication,occurringin0.8to1.9%ofkneearthroplasties3-5and0.3to1.7%ofhiparthroplasties.5-7Thefrequencyofinfectionisincreasingasthenumberofprimaryarthroplastiesincreases(Fig.1B).2Patient-relatedriskfactorsforinfectionincludepreviousrevisionarthroplastyorpreviousinfectionassociatedwithaprostheticjointatthesamesite,tobaccoabuse,obesity,rheumatoidarthritis,aneoplasm,immunosuppression,anddiabetesmellitus.Surgicalriskfactorsincludesimultaneousbilateralarthroplasty,alongoperativetime(>2.5hours),andallogeneicbloodtransfusion,andpostoperativeriskfactorsincludewoundhealingcomplications(e.g.,superficialinfection,hematoma,delayedhealing,woundnecrosis,anddehiscence),atrialfibrillation,myocardialinfarction,urinarytractinfection,prolongedhospitalstay,andS.aureusbacteremia.3-6,8-11假体关节能够提高患者的生活质量，但是一旦失败则必须进行翻修或是截骨矫形术。导致失败的原因包括了无菌性松动、感染、脱位和假体或是假体周围的骨折。感染虽不常见，但是却是最为严重的并发症，在膝关节置换中其发生率约为0.3-0.7％，在髋关节置换中约为0.3-1.7％。随着初次关节置换手术量的增加，术后感染的发生率也有所上升。与患者相关的感染危险因素包括同一关节已行翻修手术或是已发生过假体关节相关感染、吸烟、肥胖、类风湿性关节炎、有赘生物免疫抑制和未控制的糖尿病等。而手术相关的危险因素包括了同期行双侧置换、手术时间长（大于2.5小时）以及输血等。术后的感染危险因素包括伤口愈合相关并发症（表浅感染、血肿、延迟愈合、泌尿系感染、住院时间延长以及金葡菌菌血症等。Staphylococci(S.aureusandcoagulase-negativestaphylococcusspecies)accountformorethanhalfofcasesofprosthetic-hipandprosthetic-kneeinfection12(Fig.2).S.aureusinfectionisparticularlycommoninpatientswithrheumatoidarthritis.13Otherbacteriaandfungicausetheremainderofcases.1...
