Biomechanical modeling and assessment of patient positioning to facilitate spinal deformity instrumentation

Finite element models (FEM) were built based on clinical documentation of five AIS surgical cases to simulate patient positioning and spinal instrumentation. Various patient positioning and instrumentation configurations were simulated, and the associated corrections and screw pull-out forces were analyzed. Patient prone-positioning resulted in Cobb angle reduction of over 5°. Vertical, caudal, and cephalad displacement of thoracic cushions had significant impact on thoracic kyphosis. Pelvic rotation through lower-limb extension/flexion had significant effect on lumbar lordosis. The validated FEM enabled simulations of patient positioning and spinal instrumentation. Patient positioning configurations had significant effects on deformity correction and screw pull-out forces.