Biomechanical analysis of spino-pelvic parameters in adolescent idiopathic scoliosis after spinal instrumentation and fusion: a case study.

: Posterior spinal fusion and instrumentation is used to correct the spinal deformities in scoliosis. However the effects of this intervention on the biomechanical loading of the distal unfused vertebrae particularly the sacrum are not well documented. The objective of this study was to develop the patient-specific models to simulate the biomechanical loading of the sacrum after operation in AIS subgroups. A detailed personalized finite element model of the spine, pelvis, and ribcage was developed. Biomechanical loading of the sacrum was simulated based on 9 scoliosis patients before surgical instrumentation and in average 16 months after operation, and compared to simulations of 12 controls. No significant difference was observed in the biomechanical loading of the sacrum between post-operative subjects and controls p>0.05 while the biomechanical loading of the sacrum was significantly different between the pre- and post-operative subjects and pre operative subjects and controls p<0.05. These simulations computed the possible effect of the spinal fusion on equilibrating the sacral loading in scoliotic subgroups.