Quantification of bone stresses during remodeling

Abstract

An experiment to quantitate the effect of compressive stress upon bone remodeling rate was devised. Remodeling herein is described as the renewal process of bone separate from initial formation. A finite element mathematical model of the rabbit calvarium was devised. Actual rabbit calvaria were stressed utilizing a load cell monitored lever type loading device. They were periodically stained with fluorescing bone seeking dyes. Upon necropsy, histologic sections were prepared and the growth rate at known locations in the stressed area was measured by planimetry. Observed bone formation was subdivided into lamellar and fibrous. Lamellar bone formation (remodeling) rate remained above control levels until stresses of approximately 360 psi were reached; above this level remodeling rate fell to or below control. Fibrous bone exhibited higher formation rates which decreased with increasing stress but remained above control. At stresses approaching 1000 psi the technique could not measure formation rates due to the confused fibrous bone formation.