Korean J Aerosp Environ Med.
2005 Aug;15(2):64-72.
Effect of Hindlimb Unloading of the Mechanical Properties of Bone in Mature Adult Male Rats: with Emphasis on the Bone Strength
- Affiliations
-
- 1Korea National Sports University, Korea.
- 2Department of Rehabilitation, Eulji University Hospital, Daejeon, Korea.
- 3Department of Food and Nutrition, Keimyung University, Daegu, Korea.
- 4Department of Anesthesiology and Pain Medicine, College of Medicine, Hanyang University, Seoul, Korea.
- 5Department of Physiology and Biophysics, Antiageing Research Center, School of Medicine, Eulji University, Daejeon, Korea. ckim@eulji.ac.kr
Abstract
- BACKGROUND
The purpose of this study was to examine site-specific bone strength changes induced by hindlimb unloading in mature adult male rats.
METHODS
Eight month old (390-410 g) 26 male Sprague-Dawley rats were weight-mated assigned to either a Ground control (CON) or a Hindlimb Unloading (HU) for 24 days. Daily body weight was watched for status of animal. Weight, BMD, strength, geometry of femur, tibia and humerus were examined in both groups.
RESULTS
The 24-day hindlimb unloading of HU showed no significant change of body weight, total bone mineral, and bone geometry compared to CON. HU showed that the upper limb had maintained total bone mineral, bone geometry, and bone mechanical strength compared to CON. The hindlimb of HU had significantly decreased bone strength and ultimate stress (F/B) compared to CON. DEXA analysis of BMD and BMC in HU showed inconsistent changes at femur and tibia, although a relatively constant increase was shown in humerus. In HU rats, mechanical stress testing of compulsive fracture showed that more significant decreases in UL (ultimate load) and ultimate stress (F/B) was seen in femur than in tibia.
CONCLUSION
These results support the theory that hindlimb unloading contribute to deleterious effects in femur rather than in tibia. It induced higher loss of mechanical bone strength in femur. In testing for BMD, pQCT, 2D, or 3D is recommended. DEXA is not recommended because it has inconsistent results and limitation with respect to the characteristics of area BMD (g/cm2) as a surrogate of volume BMD (g/cm3).
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