Authors: Chris J McNeil Graydon H Raymer Timothy J Doherty Greg D Marsh Charles L Rice
Publish Date: 2009/06/17
Volume: 85, Issue: 1, Pages: 22-30
Abstract
Bone geometry is an important determinant of bone strength and is influenced by muscle pull and weightbearing Muscle mass and exposure to weightbearing decrease with age and thus the purpose of the study was to compare bone geometry of the weightbearing tibia and nonweightbearing fibula bones of the leg in different age groups Magnetic resonance images of the right leg were acquired in 13 young 26 yr 13 old 66 yr and 13 very old men 83 yr Cortical medullary and total crosssectional areas CSA of the bones were measured at approximately onethird and twothirds the length of the leg Muscle CSA of the anterior lateral and posterior compartments was measured at the proximal site Cortical CSA was ~14 to 22 smaller in the elderly in the tibia but similar across age in the fibula Medullary CSA was larger with age ~5 to 65 in both bones but ~15 to 440 greater in the tibia than fibula Total CSA was similar across age in both bones Muscle mass was similar between young and old but ~25 less in the very old and as a consequence the magnitude of differences in bone geometry at proximal and distal sites varied in the two elderly groups These findings indicate that there is a complex agedependent interaction between muscle pull and weightbearing The greater agerelated differences in bone geometry in the tibia suggest the weightbearing role of the tibia makes it more susceptible than the fibula to the reduced activity typically associated with aging
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