Microdamage in response to repetitive torsional loading in the rat tibia

Forwood M.R. and Parker A.W. (1989) Microdamage in response to repetitive torsional loading in the rat tibia. Calcified Tissue International, 45 1: 47-53. doi:10.1007/BF02556660


Author Forwood M.R.
Parker A.W.
Title Microdamage in response to repetitive torsional loading in the rat tibia
Journal name Calcified Tissue International   Check publisher's open access policy
ISSN 0171-967X
Publication date 1989
Sub-type Article (original research)
DOI 10.1007/BF02556660
Volume 45
Issue 1
Start page 47
End page 53
Total pages 7
Publisher Springer-Verlag
Subject 1310 Endocrinology
2732 Orthopedics and Sports Medicine
2712 Endocrinology, Diabetes and Metabolism
Abstract Tibiae from 60 male Wistar rats, aged 13 ±1 weeks, were divided into six groups for mechanical and histological testing. Bones were loaded repetitively in torsion at 90 deg.s-1. Group 1 was subjected to 5,000 loading cycles at a twist angle of 3.6°, groups 2-5 to 10,000 cycles at 3.6, 5.4, 7.2, and 9.0°, respectively, and group 6 was tested to failure. Six transverse sections from the middiaphysis were then cut, bulk-stained in basic fuchsin, and hand ground to 30-50 μm to examine the presence of microcracks. Cracks were classified as running parallel to lamellae, crossing lamellae, crossing the full thickness of the cortex, or invading vascular canals. Results for fatigue testing showed that the tibiae exhibited a gradual decrease in torque (P<0.05), average stress (P<0.01), stiffness (P<0.01) and energy absorbed (P<0.01) from the initial loading cycle. Analysis of microdamage showed an increase in the variety of cracks from groups, 1-5. Analysis of deviance demonstrated a strong dependence of crack probability on the level of loading for all crack types (P<0.05) except those crossing lamellae. This study reinforces the evidence that yielding of bone observed during repetitive loading is caused by diffuse structural damage such as microcracking or debonding.
Keyword Bone
Fatigue microdamage
Mechanical properties
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import
 
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