Spondylitis, AnkylosingSpondylitisArthritis, RheumatoidArthritisArthritis, ExperimentalArthritis, InfectiousHLA-B27 AntigenArthritis, PsoriaticArthritis, ReactiveSacroiliac JointArthritis, JuvenileSpondylarthritisSpineJointsAntirheumatic AgentsSeverity of Illness IndexBlood SedimentationSpondylarthropathiesSynovial MembraneSynovial FluidRheumatic DiseasesIritisRheumatoid FactorImmunoglobulin GTuberculosis, SpinalSynovitisSulfasalazineTumor Necrosis Factor-alphaUveitis, AnteriorArthritis, GoutyOsteoarthritisReceptors, Tumor Necrosis FactorAntibodies, MonoclonalBalneologyTreatment OutcomeRheumatologyMice, Inbred DBALumbar VertebraeHLA AntigensOsteitisKyphosisPsoriasisCollagen Type IIThoracic VertebraeMethotrexateCervical VertebraeSpinal DiseasesAutoantibodiesJoint DiseasesBack PainPseudarthrosisAnti-Inflammatory Agents, Non-SteroidalGenetic Predisposition to DiseaseSacroiliitisPhenylbutazoneDisability EvaluationAnkylosisCase-Control StudiesC-Reactive ProteinPsoas AbscessKlebsiellaImmunoglobulin A