The Effects of Hind Limb Suspension and Cast Mediated Immobilization on Bone Strength Properties

Astronauts and patients on bedrest are subject to a combination of bone strength losses and muscle atrophy due to microgravity and unloading. In this study, mice were subject to both hind limb suspension and cast mediated immobilization. Pre-treatment and post-treatment microCT scans were utilized to create finite element models. Both pre-treatment and posttreatment scans were then cropped, rotated and threedimensional image registration was performed to eliminate inconsistency in alignment. A hexahedral finite element mesh was then generated from this 3D data. Finite element analysis was conducted to perform simulated physiological loading of the femoral neck to assess bone strength through bone structural morphology. Hind limb suspension combined with Cast Mediated Immobilization caused a 7.9% decrease in bone FEA stiffness compared to the in-vivo pre-treatment control. No differences were found in bone volume or structural efficiency.