Effect of a hypergravity environment on cortical bone elasticity in rats |
| |
Authors: | S S Kohles J R Bowers A C Vailas R Vanderby |
| |
Institution: | (1) Division of Orthopedic Surgery, University of Wisconsin, Madison, Wisconsin, USA, US |
| |
Abstract: | There is considerable interest in determining whether hypergravity can be used as a countermeasure for microgravity-induced
bone loss. This study was conducted on 20 immature male rats in order to investigate possible elastic adaptations of cortical
bone in rapidly growing rats exposed to chronic hypergravity. Ten rats were continuously centrifuged for 14 days at twice
gravitational acceleration (2G) on a 12.75 foot radius centrifuge and 10 rats concurrently acted as stationary controls. The
effect of hypergravity on the elastic characteristics of cortical bone was quantified via ultrasonic wave propagation. Propagation
velocities of longitudinal and shear waves were measured through cubic cortical specimens from the posterior femoral diaphyses.
Density was measured with an Archimedes' technique. The orthotropic elastic properties were calculated and used to compare
the difference between groups. Results showed an average increase in both the Young's moduli (Eii, + 2.2%) and shear moduli (Gij, + 4.3%) with a statistically significant increase only in G12 (+15.7%, P= 0.046). The ratio of transverse to axial strain (Poisson's ratio, νij) demonstrated statistically significant changes in ν12, ν21, ν13, and ν31 (P < 0.05). These findings suggest that although slight elastic changes were incurred via a hypergravity environment, the treatment
level or duration in this study do not dramatically perturb the normal elastic behavior of cortical bone and that dramatic
biomechanical differences noted in previous studies were due more to structural changes than material elasticity changes.
Hypergravity applied post facto to a microgravity environment would offer further illucidation of this method as treatment for a degenerative spaceflight
experience.
Received: 12 August 1995 / Accepted: 23 February 1996 |
| |
Keywords: | : Cortical bone — Hypergravity — Elastic properties — Ultrasonic elasticity — Rats |
本文献已被 SpringerLink 等数据库收录! |
|