Finite Element Analysis Of Segment Selection In Osteotomy For Ankylosing Kyphosis

Objective: To explore the effect of choosing osteotomy segments on spinal stability in ankylosing spondylitis by using computer-aided software,and to calculate the distribution characteristics of biomechanics,and draw conclusions after comprehensive analysis,so as to provide theoretical basis for clinical operation.Methods: A patient with ankylosing spondylitis was selected from our hospital as the research object.The patients' spine was scanned by CT,ranging from cervical vertebra 1 to sacrococcyx.The scanned data were saved in DICOM format.The software Mimics 17.0 was opened to perform a series of operations,such as image importation,conversion,threshold setting,region growth and final calculation,and then a spine was established.Back convex three-dimensional model.Geomagic Studio software was used to fill the model,eliminate noise,optimize the model,and generate the geometric surface model of kyphosis after repair.NX 8.5 software was used to add tissue structures such as intervertebral disc and ligament,and sacrococcygeal tissue was removed.Pulmonary hilum-hip axis method was used to calculate the angle of single-segment and double-segment osteotomy.Two different osteotomy methods were simulated for osteotomy.The model was operated and fixed in NX 8.5 software.Finally,finite element analysis software ANSYS 15.0 was used to consult the relevant literature and to group the model.Structures such as weaves and ligaments set material parameters,load,calculated data,and statistical analysis of biomechanics after orthodontics.Result: Two finite element models of different osteotomy modes were established,one was L3 cancellous osteotomy and the other was L3 plus L1 double segmental cancellous osteotomy.The internal fixation stress of double-segmental cancellous osteotomy was higher than that of single-segmental osteotomy.The stress of nail rod was 49.83 Mpa,124.44 Mpa,495.64 Mpa,1194.7 Mpa,485.82 Mpa,146.89 Mpa and 733.84 Mpa,respectively.CONCLUSION: The internal fixation stress of double-segmental osteotomy is higher than that of single-segmental osteotomy,and the difference is obvious.The risk of internal fixation failure of double-segmental cancellous ossification osteotomy is higher than that of single-segmental cancellous ossification osteotomy.