2009年现代疾病诊断与治疗骨关节炎章

Note:Largeimagesandtablesonthispagemaynecessitateprintinginlandscapemode.Copyright©TheMcGraw-HillCompanies.Allrightsreserved.CURRENTMedicalDx&TxChapter20.Musculoskeletal&ImmunologicDisordersDiagnosis&EvaluationofMusculoskeletalDisordersExaminationofthePatientInthepatientwitharthritis,thetwoclinicalcluesmosthelpfulfordiagnosisarethejointpatternandthepresenceorabsenceofextra-articularmanifestations.Thejointpatternisdefinedbytheanswerstothreequestions:(1)Isinflammationpresent?(2)Howmanyjointsareinvolved?and(3)Whatjointsareaffected?Jointinflammationismanifestedbyredness,warmth,swelling,andmorningstiffnessofatleast30minutes'duration.Boththenumberofaffectedjointsandthespecificsitesofinvolvementaffectthedifferentialdiagnosis(Table20–1).Somediseases—gout,forexample—arecharacteristicallymonarticular,whereasotherdiseases,suchasrheumatoidarthritis,arechieflypolyarticular.Thelocationofjointinvolvementcanalsobedistinctive.Onlytwodiseasesfrequentlycauseprominentinvolvementofthedistalinterphalangeal(DIP)joint:osteoarthritisandpsoriaticarthritis.Extra-articularmanifestationssuchasfever(eg,gout,Stilldisease,endocarditis),rash(eg,systemiclupuserythematosus,psoriaticarthritis,Stilldisease),nodules(eg,rheumatoidarthritis,gout),orneuropathy(eg,polyarteritisnodosa,Wegenergranulomatosis)narrowthedifferentialdiagnosisfurther.Table20–1.Diagnosticvalueofthejointpattern.CharacteristicStatusRepresentativeDiseaseInflammationPresentRheumatoidarthritis,systemiclupuserythematosus,goutAbsentOsteoarthritisNumberofinvolvedjointsMonarticularGout,trauma,septicarthritis,Lymedisease,osteoarthritisOligoarticular(2–4joints)Reiterdisease,psoriaticarthritis,inflammatoryboweldiseasePolyarticular(5joints)Rheumatoidarthritis,systemiclupuserythematosusSiteofjointinvolvementDistalinterphalangealOsteoarthritis,psoriaticarthritis(notrheumatoidarthritis)Metacarpophalangeal,wristsRheumatoidarthritis,systemiclupuserythematosus(notosteoarthritis)FirstmetatarsalphalangealGout,osteoarthritisArthrocentesisandExaminationofJointFluidIfthediagnosisisuncertain,synovialfluidshouldbeexaminedwheneverpossible(Table20–2).Mostlargejointsareeasilyaspirated,andcontraindicationstoarthrocentesisarefew.Theaspiratingneedleshouldneverbepassedthroughanoverlyingcellulitisorpsoriaticplaquebecauseoftheriskofintroducinginfection.Forpatientswhoarereceivinglong-termanticoagulationtherapywithwarfarin,jointscanbeaspiratedwithasmall-gaugeneedle(eg,22F)iftheinternationalnormalizedratio(INR)islessthan3.0(seeillustration).Table20–2.Examinationofjointfluid.Measure(Normal)GroupI(Noninflammatory)GroupII(Inflammatory)GroupIII(Purulent)Volume(mL)(knee)3.5Often3.5Often3.5Often3.5ClarityTransparentTransparentTranslucenttoopaqueOpaqueColorClearYellowYellowtoopalescentYellowtogreenWBC(permcL)200200–3002000–75,000100,0001Polymorphonuclearleukocytes25%25%50%ormore75%ormore1CultureNegativeNegativeNegativeUsuallypositive1Gout,rheumatoidarthritis,andotherinflammatoryconditionsoccasionallyhavesynovialfluidWBCcounts75,000/mcLand100,000/mcL.2Mostpurulenteffusionsareduetosepticarthritis.Septicarthritis,however,canpresentwithgroupIIsynovialfluid,particularlyifinfectioniscausedbyorganismsoflowvirulence(eg,Neisseriagonorrhoeae)orifantibiotictherapyhasbeenstarted.WBC,whitebloodcellcount.Fig.Aspirationroutesforsynovialjoints.(Reproduced,withpermission,fromPettyW,FajgenbaumMC:Infectionofsynovialjoints.In:SurgeryoftheMusculoskeletalSystem.Vol5.EvartsCM[editor].ChurchillLivingstone,1983.)TypesofStudiesGrossexaminationClarityisanapproximateguidetothedegreeofinflammation.Noninflammatoryfluidistransparent,mildinflammationproducestranslucentfluid,andpurulenteffusionsareopaque.Bleedingdisorders,trauma,andtraumatictapsarethemostcommoncausesofbloodyeffusions.CellcountThesynovialfluidwhitecellcountdiscriminatesbetweennoninflammatory(2000whitecells/mcL),inflammatory(2000–75,000whitecells/mcL),andpurulent(100,000whitecells/mcL)jointeffusions.Synovialfluidglucoseandproteinlevelsaddlittleinformationandshouldnotbeordered.MicroscopicexaminationCompensatedpolarizedlightmicroscopyidentifiesanddistinguishesmonosodiumurate(gout,negativelybirefringent)andcalciumpyrophosphate(pseudogout,positivebirefringent)crystals.Gramstainhasspecificitybutlimitedsensitivity(50%)forsepticarthritis.CultureBacterialculturesaswellasspecialstudiesforgonococci,tuberclebacilli,orfungiareorderedasappropriate.InterpretationSynovialfluidanalysisisdiagnosticininfectiousormicrocrystallinearthritis.Althoughtheseverityofinflammationinsynovialfluidcanoverlapamongvariousconditions,thesynovialfluidwhitecellcountisahelpfulguidetodiagnosis(Table20–3).Table20–3.Differentialdiagnosisbyjointfluidgroups.GroupI(Noninflammatory)(2000whitecells/mcL)GroupII(Inflammatory)(2000–75,000whitecells/mcL)GroupIII(Purulent)(100,000whitecells/mcL)HemorrhagicDegenerativejointdiseaseRheumatoidarthritisPyogenicbacterialinfectionsHemophiliaorotherhemorrhagicdiathesisAcutecrystal-inducedsynovitis(goutandpseudogout)ReitersyndromeTraumawithorwithoutfractureTrauma1Ankylosingspond