title: Mechanical variables affecting balloon kyphoplasty outcome--a finite element study.
abstract: It is still unclear how a vertebral fracture should be stabilised and strengthened without endangering the remaining intact bone of the augmented vertebra or the adjacent vertebrae. Numerical modelling may provide insight. To date, however, few finite element (FE) spine models have been developed which are both multi-segmental and capture a more complete anatomy of the vertebrae.   A 3-D, two-functional unit, CT-based, lumbar spine, FE model was developed and used to predict load transfer and likelihood of fracture following balloon kyphoplasty. The fractured anterior wall and injected cement were modelled in a two-functional spinal unit model with osteoporotic bone properties. Parameters investigated included: cement stiffness, cement volume and height restoration. Models were assessed based on stresses and a user-defined fracture-predicting field.   Augmentation altered the stress distribution; shielding was dependent on positioning of the cement; and fracture algorithm found incomplete height restoration to increase the likelihood of fracture, particularly in adjacent vertebrae.
authors.affiliation: Medical Device Research, Macquarie University Private Hospital, Sydney, Australia. dane.d@mdresearch.com.au
authors.forename: Danè
authors.initials: D
authors.lastname: Dabirrahmani
authors.forename: Stephan
authors.initials: S
authors.lastname: Becker
authors.forename: Michael
authors.initials: M
authors.lastname: Hogg
authors.forename: Richard
authors.initials: R
authors.lastname: Appleyard
authors.forename: Gamal
authors.initials: G
authors.lastname: Baroud
authors.forename: Mark
authors.initials: M
authors.lastname: Gillies
mesh_terms: D000268:Adhesiveness; D003198:Computer Simulation; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D058498:Kyphoplasty / Q000379:methods*; D008159:Lumbar Vertebrae / Q000293:injuries* / Q000503:physiopathology*; D008954:Models, Biological; D033081:Shear Strength; D016103:Spinal Fractures / Q000503:physiopathology* / Q000628:therapy*; D013813:Therapy, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome