Bone-loading response varies with strain magnitude and cycle number
1 Osteoporosis Research Center, Creighton University, Omaha, Nebraska 68131; and 2 North Carolina Wesleyan College, Rocky Mount, North Carolina 27804 Mechanical loading stimulates bone formation and regulates bone size, shape, and strength. It is recognized that strain magnitude, strain rate, and...
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Published in | Journal of applied physiology (1985) Vol. 91; no. 5; pp. 1971 - 1976 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
Am Physiological Soc
01.11.2001
American Physiological Society |
Subjects | |
Online Access | Get full text |
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Summary: | 1 Osteoporosis Research Center, Creighton University, Omaha,
Nebraska 68131; and 2 North Carolina Wesleyan College, Rocky
Mount, North Carolina 27804
Mechanical loading stimulates bone formation and regulates bone
size, shape, and strength. It is recognized that strain magnitude, strain rate, and frequency are variables that explain bone stimulation. Early loading studies have shown that a low number (36) of
cycles/day (cyc) induced maximal bone formation when strains were high
(2,000 µ ) (Rubin CT and Lanyon LE. J Bone Joint Surg
Am 66: 397-402, 1984). This study examines whether cycle
number directly affects the bone response to loading and whether cycle
number for activation of formation varies with load magnitude at low
frequency. The adult rat tibiae were loaded in four-point bending at 25 ( 800 µ ) or 30 N ( 1,000 µ ) for 0, 40, 120, or 400 cyc at 2 Hz for 3 wk. Differences in periosteal and endocortical formation were examined by histomorphometry. Loading did not stimulate bone formation at 40 cyc. Compared with control tibiae, tibiae loaded at 800 µ
showed 2.8-fold greater periosteal bone formation rate at 400 cyc but
no differences in endocortical formation. Tibiae loaded at 1,000
µ and 120 or 400 cyc had 8- to 10-fold greater periosteal formation rate, 2- to 3-fold greater formation surface, and 1-fold greater endocortical formation surface than control. As applied load or
strain magnitude decreased, the number of cyc required for activation
of formation increased. We conclude that, at constant frequency, the
number of cyc required to activate formation is dependent on strain and
that, as number of cyc increases, the bone response increases.
tibia; adult rat; strain; histology; mechanical loading |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 8750-7587 1522-1601 |
DOI: | 10.1152/jappl.2001.91.5.1971 |