Evaluation of effects of selected factors on inter-vertebral fusion-a simulation study.
This study simulated the effects of inter-vertebral disc degeneration and bone density distribution on the structural stiffness and strength provided by inter-vertebral fusion. Based on the original and redistributed bone density distributions, the effects of selected factors, including contact area between device/graft and vertebral endplates, endplate conditions, and bone growth capacity were evaluated using a factorial design of experiment. The simulation results suggested that the degeneration of inter-vertebral disc significantly affected the bone density and density distribution in adjacent vertebrae. The mechanical strength immediately after instrumentation is the worst case of device/graft subsidence. After that procedure, bone will adapt itself to the changed loading conditions and therefore reduce the risk of subsidence. A deficiency in structural stiffness immediately after instrumentation could be the "worst-case scenario" depending on the combinations of selected factors. The simulation results demonstrated that the contact area and initial bone density distribution should be considered jointly while estimating the risk of device/graft subsidence. The endplate condition is a secondary factor on the subsidence risk, compared with the contact area and initial bone density distribution.
Wang
Xiaobo
X
Department of Mechanical Engineering Queen's University, Kingston, Ont., Canada K7L 3N6. wangx4@netscape.net
Dumas
Geneviève A
GA
D015519:Bone Density; D016723:Bone Remodeling / Q000502:physiology; D019245:Compressive Strength; D003198:Computer Simulation; D017076:Computer-Aided Design; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D004548:Elasticity; D019544:Equipment Failure Analysis / Q000379:methods; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D008954:Models, Biological; D011379:Prognosis; D011474:Prosthesis Design / Q000379:methods; D020127:Recovery of Function / Q000502:physiology*; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013718:Tensile Strength; D016896:Treatment Outcome