Finite Elements Analysis of Cervical Spine Simulating Ankylosing Spondylitis

Abstract

Ankylosing spondylitis (AS) is a systemic autoimmune disease mainly affects spine and sacroiliac joints In patients with AS there is new bone formation in entheses of the intervertebral discs (syndesmophyte) and the spine will finally become fused and deformed “bamboo spine” a characteristic image finding in AS The formation of bamboo spine will limit the range of motion and substantially fragile to minor injury which may cause major fracture and neurological deficit Some studies have reported the cervical spine fractures in AS mostly happened at the level of intervertebral disc in hyperextension injury But currently there is no literature mentioned about the relationship of disease progression and the response of spine to external force This study compare maximum principal strain and stress in the normal spine and AS spine model in different stages of AS by finite elements analysis The results in this study revealed that with the same external force applied on the models the maximum principal strain will extended from intervertebral discs to vertebral bodies with the progressing stages of syndesmophyte There is no obvious change of maximum principal stress in vertebral bodies compared different stages of syndesmophyte but in the intervertebral discs the maximum principal stress greatly increased especially near the entheses The greatest change happened mainly in C56 and C67 disc and the maximum principal stress increases up to 124 4% – 207 6% in C6-7 disc from normal disc to late stages of syndesmophyte formation The results are compatible to the clinical observation which means the progression of new bone formation of entheses is a key factor in cervical spine fracture in AS

Date of Award	2015 Feb 3
Original language	English
Supervisor	Chih-Han Chang (Supervisor)