Clinical Outcomes Of Surgical Treatment Of Ankylosing Spondylitis Related Thoracolumbar Kyphosis And The Investigation Of Osteogenic Differentiation Of Bone Marrow Mesenchymal Stem Cells

Chapter 2(Section 1)Does the preoperative lumbar sagittal profile affect the selection of osteotomy level in pedicle subtraction osteotomy for thoracolumbar kyphosis secondary to ankylosing spondylitis?Objective To investigate the different preoperative lumbar sagittal profiles of ankylosing spondylitis(AS)patients and the selection of osteotomy level for one-level pedicle subtraction osteotomy(PSO)for the correction of thoracolumbar kyphosisPatients and methods Seventy-one consecutive AS patients with an average age of 35.3 years and a mean follow-up time of 35.9 months who underwent one-level PSO for thoracolumbar kyphosis were divided into 2 groups based on their preoperative lumbar sagittal profiles as follows:group A,lordotic lumbar sagittal profiles;and group B,kyphotic lumbar sagittal profiles.The following radiological parameters were measured and compared:chin-brow vertical angle(CBVA),global kyphosis(GK),thoracic kyphosis(TK),lumbar lordosis(LL),sagittal vertical axis(SVA),pelvic incidence(PI),pelvic tilt(PT)and sacral slope(SS).Clinical evaluation included Oswestry Disability Index(ODI)and Visual Analogue Scale(VAS).Perioperative and mid-term complications were reviewedResults There were 28 patients in group A and 43 in group B.The preoperative LL was-21.0°in group A and 2.3°in group B(P<0.05).The preoperative SVA was 122.5mm in group A and 184.3mm in group B(P<0.05).All the patients in group A(100%)underwent PSO at L1/L2,while 90%of group B patients underwent PSO at L2/L3,with no significant difference of postoperative GK,LL and SVA between the 2 groups(P>0.05).No obvious loss of correction was observed in either group at the final follow-up.The correction of LL and SVA showed a strong but not statistically significant increasing trend as the PSO level descended from L1 to L3(P>0.05).The postoperative ODI was significantly lower in patients underwent PSO at L1 or L2(P<0.05)Conclusions Patients in group B had significantly worse preoperative sagittal alignments compared to group A.The distribution of osteotomy levels varied between the 2 groups due to the different lumbar profiles;however,satisfactory correction was achieved in both groups.The preoperative lumbar profiles need to be considered in selecting the optimal osteotomy level.Patients with kyphotic lumbar profiles are suitable candidates for PSO at L2/L3,while L1/L2 PSO is appropriate for patients with lordotic lumbar profiles.Chapter 2(Section 2)Does the bilateral S1 screw-based instrumentation sustain in pedicle subtraction osteotomy in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis?Objective To investigate the mid-term results of S1 screw-based instrumentation after pedicle subtraction osteotomy(PSO)for ankylosing spondylitis(AS)related thoracolumbar kyphosis.Methods A retrospective review of 94 consecutive AS patients who underwent PSO from May 2006 to April 2015 with a minimum of 2-year follow-up was performed.Patients were divided into 2 groups according to the lowest instrumentation vertebra(LIV)(25 patients in group S1 and 69 patients in group Non-S1).The compared radiologic measurements included global kyphosis(GK),thoracic kyphosis(TK),lumbar lordosis(LL),sagittal vertical axis(SVA),pelvic incidence(PI),pelvic tilt(PT),sacrum slope(SS)and angle of fused segments(AFS).Clinical data including Body Mass Index(BMI),Oswestry Disability Index(ODI)and Visual Analogue Scale(VAS)were recorded.Mid-term complications were reviewedResults All of the 94 patients(84 males and 10 females)had the mean age of 35.3 years(range,19-59 years).The average follow-up period was 36.2 months(range,24-96 months).The average GK,LL,SS and SVA were corrected from 73.3°,-5.1°,8.9°and 168.1mm to 37.1°,-46.9°,22.5°and 47.4mm,respectively(P<0.05).The mean ODI and VAS changed from 20.1 and 4.3 to 6.4 and 2.1 postoperatively(P<0.05).One S1 screw loosening was observed in group S1(4.0%)and 1 rod fracture was observed in group Non-S1(1.4%)during the follow-up.Loss of correction at the final follow-up was 2.2°in group S1 and 2.0°in group Non-S1(P>0.05)Conclusions Long instrumentation to sacrum with bilateral S1 screw-based instrumentation sustained in PSO in AS patients with thoracolumbar kyphosis during 2-year follow-up.Low mid-term complication rates and mild loss of correction were observed in both groupsChapter 3 The investigation of osteogenic differentiation of bone marrow mesenchymal stem cells in ankylosing spondylitis Objective To investigate the osteogenic differentiation capacity of bone marrow mesenchymal stem cells(BM-MSCs)in ASMethods A total of 10 AS patients and 10 healthy controls were included.Bone marrow was acquired through bone marrow aspiration.MSCs were then isolated and cultured for 21 days in osteogenic differentiation medium.Alizarin red S(ARS)staining and quantification were used to test and compare the osteogenic differentiation abilities between the 2 groupsResults No significant differences were observed between the 2 groups resarding cell morphology and phenotype.ARS quantification showed that the calcium incidence of AS-MSCs and Con-MSCs was 61.1%and 15.7%,respectivelyConclusion AS-MSCs have greater osteogenic differentiation ability than Con-MSCs,and further studies are needed to explain the difference.