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Muscle contraction increases the in vivo structural strength to the same degree in osteopenic and normal rat tibiae

Nordsletten, L; Kaastad, T S; Obrant, Karl LU ; Skjeldal, S; Kirkeby, O J; Stokke, O and Ekeland, A (1994) In Journal of Bone and Mineral Research 9(5). p.679-685
Abstract
The increase in structural capacity due to muscle contraction in the lower leg was investigated in osteopenic and normal rats. Osteopenia was induced by ovariectomy combined with a low-calcium diet (0.01%). The control rats were sham operated and fed a diet containing 1.1% calcium. After 7 weeks the right lower leg of all animals were fractured in three-point ventral cantilever bending during muscle contraction induced by electrical stimulation of the ischiatic nerve. The left tibiae were resected and fractured as each animal's control. During muscle contraction in vivo, the ultimate bending moment, energy absorption, bending stiffness, and deflection were significantly lower in the osteopenic than in the sham-operated animals. However,... (More)
The increase in structural capacity due to muscle contraction in the lower leg was investigated in osteopenic and normal rats. Osteopenia was induced by ovariectomy combined with a low-calcium diet (0.01%). The control rats were sham operated and fed a diet containing 1.1% calcium. After 7 weeks the right lower leg of all animals were fractured in three-point ventral cantilever bending during muscle contraction induced by electrical stimulation of the ischiatic nerve. The left tibiae were resected and fractured as each animal's control. During muscle contraction in vivo, the ultimate bending moment, energy absorption, bending stiffness, and deflection were significantly lower in the osteopenic than in the sham-operated animals. However, the increase in mechanical parameters due to muscle contraction comparing the in vivo and resected tibiae in each animal were equally high in the osteopenic and sham-operated animals. Ultimate bending moment in the resected tibiae was 10% higher in the sham-operated animals compared with the ovariectomized, proving mechanically weaker tibiae in the osteopenic rats. In accordance with this, the medullary area of the osteopenic rats was 46% larger in the distal tibial diaphysis, and the ultimate stress the tibiae could withstand was 15% lower in the osteopenic compared with the sham-operated rats. The trabecular bone volume in the distal tibial metaphysis of the osteopenic rats was reduced by 70% compared with the sham operated. This study shows that muscle protection against fracture can be substantial in osteopenic tibia and that it is of the same magnitude as in rats with normal bone mass. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Bone and Mineral Research
volume
9
issue
5
pages
679 - 685
publisher
AMBMR
external identifiers
  • pmid:8053397
  • scopus:0028202806
ISSN
1523-4681
language
English
LU publication?
yes
id
c8d007a7-bd47-4988-b4ed-529d3a920b8e (old id 1108119)
date added to LUP
2008-07-23 14:19:12
date last changed
2017-01-01 04:42:43
@article{c8d007a7-bd47-4988-b4ed-529d3a920b8e,
  abstract     = {The increase in structural capacity due to muscle contraction in the lower leg was investigated in osteopenic and normal rats. Osteopenia was induced by ovariectomy combined with a low-calcium diet (0.01%). The control rats were sham operated and fed a diet containing 1.1% calcium. After 7 weeks the right lower leg of all animals were fractured in three-point ventral cantilever bending during muscle contraction induced by electrical stimulation of the ischiatic nerve. The left tibiae were resected and fractured as each animal's control. During muscle contraction in vivo, the ultimate bending moment, energy absorption, bending stiffness, and deflection were significantly lower in the osteopenic than in the sham-operated animals. However, the increase in mechanical parameters due to muscle contraction comparing the in vivo and resected tibiae in each animal were equally high in the osteopenic and sham-operated animals. Ultimate bending moment in the resected tibiae was 10% higher in the sham-operated animals compared with the ovariectomized, proving mechanically weaker tibiae in the osteopenic rats. In accordance with this, the medullary area of the osteopenic rats was 46% larger in the distal tibial diaphysis, and the ultimate stress the tibiae could withstand was 15% lower in the osteopenic compared with the sham-operated rats. The trabecular bone volume in the distal tibial metaphysis of the osteopenic rats was reduced by 70% compared with the sham operated. This study shows that muscle protection against fracture can be substantial in osteopenic tibia and that it is of the same magnitude as in rats with normal bone mass.},
  author       = {Nordsletten, L and Kaastad, T S and Obrant, Karl and Skjeldal, S and Kirkeby, O J and Stokke, O and Ekeland, A},
  issn         = {1523-4681},
  language     = {eng},
  number       = {5},
  pages        = {679--685},
  publisher    = {AMBMR},
  series       = {Journal of Bone and Mineral Research},
  title        = {Muscle contraction increases the in vivo structural strength to the same degree in osteopenic and normal rat tibiae},
  volume       = {9},
  year         = {1994},
}