Spondylitis, AnkylosingSpondylitisHLA-B27 AntigenSacroiliac JointSpineSpondylarthritisAntirheumatic AgentsSpondylarthropathiesBlood SedimentationArthritisIritisSeverity of Illness IndexTuberculosis, SpinalArthritis, ReactiveArthritis, PsoriaticRheumatic DiseasesBalneologyUveitis, AnteriorLumbar VertebraeKyphosisArthritis, RheumatoidThoracic VertebraeHLA AntigensCervical VertebraeImmunoglobulin GOsteitisSulfasalazineAnti-Inflammatory Agents, Non-SteroidalBack PainPseudarthrosisReceptors, Tumor Necrosis FactorSpinal DiseasesTreatment OutcomeSacroiliitisAntibodies, MonoclonalKlebsiellaPsoas Abscess