Modeling and remodeling responses to normal loading in the human lower limb.
Limb bones are designed to be strong enough to support the body and yet be energetically conservative during locomotion. Bones of the distal segment, which are relatively costly to move, are often more slender than bones of the proximal segments, even though they must sustain proportionally greater loads. As a result, they are expected to experience a higher incidence of microdamage. With this constraint in mind, Lieberman and Crompton (1998 Principles of Animal Design, Cambridge: Cambridge University Press, p. 78-86) proposed that bones response to strain varies along the proximo-distal axis of the limb. In order to avoid fatigue fractures due to the accumulation of microdamage, the distal segment, in comparison to the proximal segment, will have an increase in remodeling events to replace damaged bone. In this paper, we test the hypothesis of Lieberman and Crompton (1998) with respect to the human lower limb. With a sample of adult individuals, we compare tibiae and femora for mid-diaphyseal cross-sectional geometry and Haversian remodeling differences. Our results indicate that the human limb is not designed like that of quadrupedal cursorial animals. The tibia is not less resistant in bending and torsion, and does not remodel more than the femur. Our findings fail to support the hypothesis of Lieberman and Crompton (1998) and suggest, instead, that the human lower limb is not designed like a cursorial animal limb. In addition, our results support previous observations that remodeling is not uniform within the cross section of a bone, probably a reflection of different loading histories within the different regions of the cross section.
Drapeau
Michelle S M
MS
Département d'anthropologie, Université de Montréal, Montréal, Québec, Canada. m.drapeau@umontreal.ca
Streeter
Margaret A
MA
D001696:Biomechanical Phenomena; D001837:Body Weights and Measures; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D013977:Tibia / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology