Research On The Mechanism Of The Degeneration Of The Sacroiliac Joint--from The Nonlinear Biomechanical View

The sacroiliac joint's degeneration will cause some comman diseases, such as Low back pain(Lbp), which threatening the health of human body, serious impacting on people's normal life and work. So how to prevent or relief the sacroiliac joint's degeneration so as to prevent it from causing pain is becoming to be an unavoidable project. But until now, people havn't clearly understand the mechanism of sacroiliac joint's degeneration. Because of this , in the thesis I try to from an nonlinear biomechanical view to find out the degeneration -mechanism, so as to provide a basic theorical support for diagnosing and curing the relevant diseases.First, Basing on the frozen section color photos of human body, I constructed and validated a nonlinear three dimensional finite element model of human pelvis, which including ligaments,cartilage, cortical and cancellous bone tissues. The model beautifuly simulated the real geometry of structure, biomechanical characteristics of materials and bounding contitions.Second, I analysed the stress and displacement distribution of the model at double supporting,single left supporting and sitting posture, and compared the results to those in papers and experiments, so validated the model.At the same time, for clearly understand How do the behavior changes of soft tissue impact on sacroiliac joint degeneration , I tested the biomechanical characteristics of human patellar ligament, and disgned a new professional clamp for gripping soft tissues, such as ligament and tendon, it can support the tensile and viscoelastic properties test of soft tissue. At last, basing on the validated model and the undersanding of soft tissues'biomechanical behavior, I analysed the impation from properties changing of ligaments'to sacroiliac joint biomechanical behavior. Basing on the caculating results, I explained some degeneration phenomenon, and supplied some meaningful suggestion for diagnosing and treating the relevant clinical diseases.The nonlinear three-dimensional finite element model of human pelvis constructed in this thesis can also be a basic platform, for researching on the biomechanical characteristics of pelvis in all kinds behavior, the injury mechanism of pelvis, and the design and assessment of pelvis fixation device .