Study On The Degree Of Ligament Ossification And Sagittal Plane Morphology In Ankylosing Spondylitis

Chapter 1: The severity of syndesmophytes and its correlation with the spinopelvic and clinical outcomes in advanced ankylosing spondylitisObjective: This study aimed to evaluate the severity of syndesmophytes and its correlation with the spinopelvic and clinical outcomes in ankylosing spondylitis(AS)patients.Methods: 41 consecutive AS patients underwent pedicle subtraction osteotomy(PSO)surgery from our institution were reviewed.CT syndesmophyte score(CTSS),a novel method of evaluating the severity of syndesmophytes,was applied to assess the syndesmophytes of the whole,cervical,thoracic and lumbar spine.The measured spinopelvic parameters included global kyphosis(GK),sagittal vertical axis(SVA),lumbar lordosis(LL),pelvic incidence(PI),pelvic tilt(PT)and sacral slope(SS).The Oswestry disability index(ODI)questionnaire,C-reactive protein(CRP)and erythrocyte sedimentation rate(ESR)were administered to evaluate the clinical outcome.The Pearson correlation test was performed to identify the correlations between syndesmophytes,spinopelvic and clinical parameters.Results: Pearson analysis demonstrated that the whole CTSS(WCTSS),cervical CTSS(CCTSS),thoracic CTSS(TCTSS)and lumbar CTSS(LCTSS)were correlated with each other significantly(P<0.05).All the CTSSs were positively correlated with age,disease duration,and PT(P<0.05),respectively.Besides,both SVA and LL were significantly related to WCTSS,CCTSS,and LCTSS(P<0.05),respectively.ODI was negatively correlated with the WCTSS(r=-0.312,P<0.05),TCTSS(r=-0.314,P<0.05),and LCTSS(r=-0.343,P<0.05),respectively.Conclusion: In advanced AS,old age and long disease duration are risk factors for the progression of syndesmophytes.The progression of syndesmophytes may contribute to spinal sagittal malalignment.With the serious syndesmophytes,pelvic retroversion seems to be the major compensatory mechanism for spinal sagittal malalignment.Chapter 2: Comparison of sagittal alignment in patients with ankylosing spondylitis and diffuse idiopathic skeletal hyperostosisObjective: Ankylosing spinal disease(ASD)mainly includes ankylosing spondylitis(AS)and diffuse idiopathic skeletal hyperostosis(DISH).The aim of this study was to explore the differences of sagittal alignment in AS and DISH patients and to evaluate the characteristics of sagittal alignment,then to provide valuable clinical clues for the antidiastole.Methods: From February 2014 to December 2019,85 ASD patients(50 AS patients and 35 DISH patients)in our hospital were included in the retrospective study.The anteroposterior and lateral spinal radiographs were obtained in all patients.The sagittal parameters included global kyphosis(GK),C7 sagittal vertical axis(C7 SVA),lumbar lordosis(LL),thoracic kyphosis(TK),pelvic incidence(PI),pelvic tilt(PT),sacral slope(SS),C0-2 angle(C0-2 A),C2-7 lordosis(C2-7 L),C2-7 sagittal vertical axis(C2-7 SVA),spinosacral angle(SSA),spinopelvic angle(SPA)and T1 pelvic angle(TPA).The modified stoke AS spine score(m SASSS)was applied to assess the degree of ossification in both AS and DISH.The DISH group were divided into alignment-DISH and malalignment-DISH based on the C7 SVA of 50 mm.The independent t test was used for quantitative data between groups,chi-square test for classification data between groups,and Pearson correlation test for correlation study between m SASSS and sagittal parameters.Results: There were significant differences between AS group and DISH group in the age(32.8±9.6 years vs 66.0±9.4 years),GK(67.2°±18.2° vs 39.8°±12.0°),C7 SVA(144.7±50.7mm vs 31.5±61.5mm),LL(8.8°±22.4° vs 36.6°±14.1°),TK(46.3°±19.0° vs 28.8°±10.8°),PT(36.5°±9.5° vs 16.8°±8.5°),SS(8.8°±10.8° vs25.1°±7.6°),C2-7 L(28.2°±12.6° vs 19.3°±10.5°),C2-7 SVA(38.0±18.1mm vs 28.2±14.7mm),SSA(81.7°±13.5° vs112.8°±12.5°),SPA(124.9°±13.5° vs 158.9°±13.0°)and TPA(43.6°±11.7° vs 16.6°±10.2°).In AS patients,C2-7 SVA was positively correlated with m SASSS(r=0.400,P<0.05).In DISH patients,C7 SVA was significantly correlated with m SASSS(r=0.407,P<0.05).Compared with alignment-DISH group,malalignment-DISH group had significantly higher age,PI,PT,C2-7 L,TPA and m SASSS(P<0.05),whereas in terms of LL,SSA and TPA,M-DISH group had an obviously lower value(P<0.05).Conclusion: There were significant differences in sagittal alignment between AS and DISH group.AS patients showed worse sagittal malalignment and sagittal compensation.In both AS and DISH patients,the severity of osteophyte was associated with certain sagittal malalignment.Compared with alignment-DISH,malalignment-DISH patients might often have larger PI and more severe osteophyte.