The skeleton is continuously being renewed in the bone remodeling process. This prevents accumulation ofdamage and adapts the architecture to external loads. A side effect is a gradual decrease of bone mass,strength, and stiffness with age. We investigated the effects of bone loss on the load distribution andmechanical properties of cancellous bone using three-dimensional (3D) computer models. Several bone lossscenarios were simulated. Bone matrix was removed at locations of high strain, of low strain, and randomthroughout the architecture. Furthermore, resorption cavities and thinning of trabeculae were simulated.Removal of 7% of the bone mass at highly strained locations had deleterious effects on the mechanicalproperties, while up to 50% of the bone volume could be removed at locations of low strain. Thus, ifremodeling would be initiated only at highly strained locations, where repair is likely needed, cancellous bonewould be continuously at risk of fracture. Thinning of trabeculae resulted in relatively small decreases instiffness; the same bone loss caused by resorption cavities caused large decreases in stiffness and high strainpeaks at the bottom of the cavities. This explains that a reduction in the number and size of resorption cavitiesin antiresorptive drug treatment can result in large reductions in fracture risk, with small increases in bonemass. Strains in trabeculae surrounding a cavity increased by up to 1000 microstrains, which could lead tobone apposition. These results give insight in the mechanical effects of bone remodeling and resorption attrabecular level.
Keywords: bone remodeling; computer simulation; trabecular bone; bone loss; bone mineral density