Clinical Analysis Of Vertebral Vertebral Osteotomy For Correction Of AS With Thoracolumbar Kyphosis

Chapter 1 Anatomical feature of Lumbar and SI Pedicle in patients with thoracolumbar kyphosis secondary to ankylosing spondylitisObjective:To analyze whether or not the anatomy parameters of pedicles differ between the patients with thoracolumbar kyphosis secondary to ankylosing spondylitis(AS)and disc degenerative disease(DDD).So as to assist selection and insertion of pedicle screw.Methods:30 male AS patients(AS group)with the mean age of 35.7 ± 9.5 years(range,23 to 51 years),and 30 male DDD patients(DDD group)with the mean age ’of 52.4 ± 8.9 years(range,39 to 64 years),who underwent surgery in our institution were recruited.The CT scans of lumbar and sacrum before surgery were performed.The parameters of pedicle from L1 to S1 were measured and compared,including pedicle width(PW),pedicle screw path length(PL),pedicle height(PH),transverse angle(EA),and inclined angle(FA).Paired sample t test was used to detect divergence in the above-mentioned data between left and right sides.In addition,results between two groups were compared using independent sample t test.Results:The study showed that a gradual increase in the average pedicle width both AS group and DDD group from L1 to S1.The average PW of AS group is bigger than DDD group from L5～S1,being(16.47±2.66)mm,(21.76±2.97)mm as compared to(14.51±2.11)mm,(18.87±2.14)mm respectively;The average PL of DDD group is smaller than AS group from L1～S1;The average EA of AS group is smaller than DDD group from L1～S1;The average FA of AS group is significantly smaller than DDD group from L3～S1,(P<0.05).Conclusion:To increase the strength of fixation,it is feasible to insert larger and bigger pedicle screws in low lumbar and S1 among AS patients.Chapter 2 Positional Brachial Plexus Injury Following Corrective Osteotomies for Thoracolumbar Kyphosis Secondary to Ankylosing Spondylitis:Incidence,Risk Factors and PrognosisSummary of Background Data:Postoperative brachial plexus injury(BPI)have been reported to occur in patients in the prone position after prolonged spinal surgery.However,the incidence,risk factors and prognosis of BPI following corrective osteotomies for thoracolumbar kyphosis in ankylosing spondylitis(AS)patients has not been well documented.Objective:To investigate the incidence,risk factors and prognosis of positional BPI following Smith-Peterson osteotomies(SPO)or pedicle subtraction osteotomy(PSO)in AS patients with thoracolumbar kyphosis.Methods:A retrospective review of AS patients undergoing SPO or PSO in our center from April 2000 to October 2013 was performed.The degree of global kyphosis,the surgical data,and the postoperative neurological function were reviewed.The incidence and risk factors of brachial plexus injuries were analyzed.Results:Six(2.6%)of the 228 patients experienced a postoperative BPI.Four risk factors of BPI were identified:(1)patients had global kyphosis greater than 100°;(2)long operative time(more than 4 hours);(3)with arms abducted more than 90°and(4)application of shoulder pad.All patients had complete both sensory and motor recovery,and the average duration of recovery was 5 weeks(range,2-16weeks).Conclusion:With good prognosis,the incidence of positional BPI following corrective surgery in AS patients is low.Long operation time and arm malpositioning are the key factors responsible for positional BPI.Thus,spine surgeons should be aware of and take some measures to prevent this neurological complication.In the prone position,the arms should be positioned to less than 90° abduction to reduce the tension on brachial plexus.Shortening operative time,intraoperative electrophysiological monitoring and adjusting the position of upper extremity regularly may prevent this iatrogenic complication.Chapter 3 The impact of ossified anterior longitudinal ligaments surrounding osteotomy vertebra on the lordosing capability of single-level pedicle subtraction osteotomy in kyphotic deformity secondary to ankylosing spondylitisObjective:To investigate if ossified anterior longitudinal ligaments(ALL)surrounding osteotomy vertebra impact the lordosing effect of pedicle subtraction osteotomy(PSO)in patients with thoracolumbar kyphosis secondary to Ankylosing spondylitis(AS).Methods:We retrospectively reviewed 71 AS patients with thoracolumbar kyphosis treated with single-level PSO at our institution between March 2006 and February 2014.Patients were stratified into either an ossified or a non-ossified group based on the presence of ALL ossification adjacent to osteotomy vertebra.Comparison of the contribution of adjacent disc wedging to total correction per PSO segment was made between the ossified and non-ossified groups.The long-term correction loss were also evaluated and compared between these two groups with a minimum 2-year follow-up.Results:71 AS patients were recruited,of whom 32 were stratified into the ossified group(OG).A significantly older age and larger pelvic incidence(PI)was observed in OG(p<0.05)..Solid bone healing and remodeling was exclusively observed during follow-up.The contribution of adjacent disc wedging to total lordosing effect per PSO segment was significantly larger in NG(8.10±6.19°,18.5%vs.1.09±2.88°,2.7%,p<0.001),yet endured larger loss of correction during follow-up(1.41±3.27°vs.0.22±1.49°,p<0.05).The spino-pelvic sagittal profile got deteriorated more significantly during follow-up in NG(p<0.05).Conclusion:Osteotomy vertebrae accompanied by unossified adjacent ALL in PSO of AS were prone to create more disc-originated lordosing effect immediately after surgery.However,a correction loss might occur more commonly for this subgroup during follow-up.