Clinical And Radiological Studies Of Ankylosing Spondylitis And The Expression Of MiR-155 During The Osteogenic Differentiation Of Bone Marrow-derived Mesenchymal Stem Cells From Ankylosing Spondylitis Patients

Chapter 2(section 1)When can one-level pedicle subtraction osteotomy obtain satisfied outcomes in ankylosing spondylitis patients with severe thoracolumbar kyphosis?Objective To make a comparison of clinical and radiographic outcomes between ankylosing spondylitis(AS)patients with severe thoracolumbar kyphosis(global kyphosis,GK≥80°)who underwent one-level or two-level pedicle subtraction osteotomy(PSO)and to determine the indication of one-level PSO for severe thoracolumbar kyphosis secondary to AS.Methods Fifty-five AS-related severe thoracolumbar kyphosis patients undergoing one-level or two-level PSO in our institution from January 2007 to November 2016 were retrospectively reviewed.The measured radiographic parameters included thoracic kyphosis,lumbar lordosis(LL),osteotomized vertebra angle(OVA),GK,pelvic tilt(PT),sacral slope(SS),pelvic incidence,sagittal vertical axis(SVA),and femoral obliquity angle(FOA).Clinical outcomes were evaluated by Oswestry Disability Index(ODI)and Visual Analogue Scale(VAS).The operative time,blood loss,and the number of fusion levels were recorded.The preoperative radiographic parameters,clinical scores,and postoperative improvement of radiographic parameters and clinical scores were compared between one-level and two-level PSO groups.Receiver operating characteristic curve analysis was used to determine the optimal cutoff points of preoperative radiographic parameters for the selection of one-level PSO.Results The follow-up period was 39.7±20.2 months(range,24-120 months).Thirty-four patients underwent one-level PSO and twenty-one patients underwent two-level PSO.The radiographic parameters including LL,OVA,GK,PT,SS,SVA,and FOA were all significantly improved postoperatively in both one-level and two-level PSO groups(P<0.05).Patients who underwent one-level PSO had significantly smaller preoperative GK,OVA,SVA,FOA,and larger preoperative LL and SS compared to those who underwent two-level PSO(P<0.05).The postoperative correction of LL,OVA,PT,SS,FOA,GK,and SVA was significantly larger in two-level PSO group(P<0.05).The optimal cutoff points of preoperative radiographic parameters for selecting one-level PSO were: GK<94°,SVA<18.0 cm,and LL<18°.Postoperatively,the VAS score was significantly improved in both groups(P<0.05)and the ODI score was significantly improved in one-level PSO group(P<0.05).No significant difference was observed between the two groups with regard to preoperative ODI and VAS(P>0.05),and the postoperative improvement of ODI and VAS(P>0.05).Significantly more operative time,blood loss,and fusion levels were observed in two-level PSO group(P<0.05).Conclusion Although two-level PSO had larger radiographic correction,it presented with more blood loss and operative time compared to one-level PSO.One-level PSO may be appropriate for selected AS-related severe thoracolumbar kyphosis patients with GK<94°,SVA<18.0 cm,and LL<18°.This finding may be beneficial for surgical decision-making in performing one-level PSO,a relatively less risky procedure,to treat the AS patients with severe thoracolumbar kyphosis.Chapter 2(section 2)The optimal postoperative sagittal alignment in ankylosing spondylitis patients with thoracolumbar kyphosis following one-level pedicle subtraction osteotomy Objective To investigate the correlation between postoperative radiographic parameters and clinical outcomes in ankylosing spondylitis(AS)patients with thoracolumbar kyphosis following one-level pedicle subtraction osteotomy(PSO)and to determine the optimal sagittal alignment at a minimum of two-year follow-up.Methods One hundred AS-related thoracolumbar kyphosis patients undergoing one-level PSO in our institution from March 2006 to August 2016 were retrospectively reviewed.The measured radiographic parameters included thoracic kyphosis,lumbar lordosis,osteotomized vertebra angle,pelvic tilt(PT),sacral slope(SS),pelvic incidence,C7-sagittal vertical axis(SVA),C2-SVA,spinosacral angle(SSA),T1 pelvic angle(TPA),spinopelvic angle(SPA),and global kyphosis.Clinical outcomes were evaluated by Oswestry Disability Index(ODI)and Bath Ankylosing Spondylitis Disease Activity Index(BASDAI).ODI<20 was regarded as good clinical outcome.The correlation between the postoperative radiographic parameters and clinical outcomes was investigated by Pearson correlation analysis.Linear regression analysis was performed to construct predictive models of the clinically-relevant radiographic parameters based on final follow-up ODI score and to determine the optimal postoperative sagittal alignment.Multiple stepwise regression analysis was applied to figure out the major radiographic contributor of the ODI score at the final follow-up.Results Ninety-two males and eight females were included.The age of the included patients was 34.7±9.5 years(range,17-63 years)and the follow-up period was38.6±17.5 months(range,24-120 months).At the final follow-up,both PT and TPA were positively correlated with ODI and BASDAI score(P<0.05);while SS,SSA,and SPA were negatively associated with the score of ODI(P<0.05),and BASDAI was negatively related to SPA(P<0.05).Predicting regression models of the clinically-relevant radiographic parameters were built based on the ODI score at the final follow-up as follows: PT=0.147×ODI+21.185,r2=0.061;SSA=-0.111×ODI+110.043,r2=0.041;TPA=0.145×ODI+18.562,r2=0.052;SPA=-0.177×ODI+155.520,r2=0.052.When ODI<20,PT was smaller than 24.1°,SSA was larger than 107.8°,TPA was smaller than 21.5°,SPA was larger than 152.0°.PT was the major radiographic contributor to the ODI score at the final follow-up.Conclusion The optimal sagittal alignment of AS-related thoracolumbar kyphosis patients who had underwent one-level PSO at a minimum of two-year follow-up was:PT<24°,SSA>108°,TPA<22°,and SPA>152°.Realizing the aforementioned realignment goals may be helpful for AS patients with thoracolumbar kyphosis to obtain favorable clinical outcome(ODI<20).Chapter 3(section 1)Occult Andersson lesions in patients with ankylosing spondylitis: undetectable destructive lesions on plain radiographs of the spine Objective Andersson lesions are not uncommon in ankylosing spondylitis(AS).Plain radiography is commonly used for the diagnosis of Andersson lesions.However,in clinical practice,we found that there were some Andersson lesions which could not be detected on plain radiographs.This study proposed the concept of occult Andersson lesions and investigated the incidence and radiographic characteristics of the occult Andersson lesions.Methods Four hundred and ninety-six AS patients admitted to our institution between April 2003 and November 2019 were retrospectively reviewed.The AS patients with Andersson lesions who met both of the following criteria were included for the investigation of occult Andersson lesions:(1)with preoperative plain radiographs of the whole-spine;(2)availability of preoperative CT and/or MRI of the whole-spine.The occult Andersson lesions were defined as the Andersson lesions which were undetectable on plain radiographs but could be detected by CT and/or MRI.The detectable Andersson lesions were defined as the Andersson lesions that could be detected on plain radiographs.The extensive Andersson lesions involved the whole discovertebral junction or manifested as the Andersson lesions throughout the vertebral body.Results Ninety-two AS patients with Andersson lesions(age: 44.4±10.11 years)were included for the investigation of occult Andersson lesions.Twenty-three patients had occult Andersson lesions.Fifteen extensive Andersson lesions were occult,and the proportion of extensive Andersson lesions was significantly higher in detectable Andersson lesions compared to that in occult Andersson lesions(P<0.001).As assessed by plain radiography,the proportions of osteolytic destruction with reactive sclerosis,angular kyphosis of the affected discovertebral units or vertebral body,formation of an osseous bridge at the intervertebral space adjacent to Andersson lesions caused by the ossification of the anterior longitudinal ligament,and an abnormal height of the affected intervertebral space were all significantly lower in occult Andersson lesions compared to that in detectable Andersson lesions(P<0.05).Conclusion In AS patients with Andersson lesions,the incidence of occult Andersson lesions was 25%.Occult Andersson lesions presented with more subtle radiographic changes.Occult Andersson lesions should not be neglected,especially in the case of extensive occult Andersson lesions,because the stability of the spine might be severely impaired by the extensive Andersson lesions.Chapter 4(section 1)The expression of mi R-155 during the osteogenic differentiation of bone marrow-derived mesenchymal stem cells from ankylosing spondylitis patients Objective To compare the expression of mi R-155 during the osteogenic differentiation of bone marrow-derived mesenchymal stem cells(BM-MSCs)between ankylosing spondylitis(AS)patients and spinal fracture patients and to investigate whether mi R-155 was abnormally expressed during the osteogenic differentiation of BM-MSCs from AS patients and whether mi R-155 was associated with the enhanced osteogenic differentiation capacity of BM-MSCs from AS patients.Methods Ten AS patients with thoracolumbar kyphosis and ten traumatic spinal fracture patients(control group)who underwent surgery in our institution were included.The bone marrow was obtained through the puncture of posterior superior iliac spine.The modified whole bone marrow adherent method was used for the isolation and culture of BM-MSCs.The BM-MSCs from AS patients and spinal fracture patients were induced for osteogenic differentiation.On day 21 of osteogenic induction,alizarin red staining was applied to detect the osteogenic differentiation capacity of BM-MSCs.The RNA was isolated from BM-MSCs and during the induced osteogenic differentiation of BM-MSCs.RT-q PCR was performed to detect the expression of alkaline phosphatase(ALP)and mi R-155.Results On day 7 of osteogenic induction,the expression of ALP was significantly higher in AS group than that in spinal fracture group(P<0.05).On day 21 of osteogenic induction,the area and intensity of alizarin red staining in BM-MSCs from AS patients were obviously larger than those from spinal fracture patients.There was no significant difference in the expression of mi R-155 between BM-MSCs from AS patients and those from spinal fracture patients on day 0,7,and 14 days of osteogenic induction(P>0.05).Conclusion Compared to the control group,the BM-MSCs from AS patients had stronger capacity of osteogenic differentiation.No significantly abnormal expression of mi R-155 was observed during the osteogenic differentiation of BM-MSCs from AS patients.The enhanced osteogenic differentiation capacity of BM-MSCs from AS patients may not be associated with mi R-155.