Table 5.
Effects of diabetes (DM) and/or estrogen deficiency on the mechanical properties of cancellous (the proximal tibial metaphysis) and compact (the femoral diaphysis) bone in rats.
| Parameter/group | Nonovariectomized (NOVX) rats | Ovariectomized (OVX) rats | Two-way ANOVA | |||||
|---|---|---|---|---|---|---|---|---|
| Control | DM | Control | DM | OVX | DM | OVXx DM | ||
| Tibia | Young's modulus (MPa) | 4063 ± 430 | 3269 ± 390 | 2713 ± 248∗∗ | 3169 ± 182 | p < 0.05 | NS | NS |
| Fracture point load (N) | 89.5 ± 7.5 | 54.5 ± 5.0∗∗∗ | 60.0 ± 2.8∗∗∗ | 43.6 ± 2.2∗∗∗X | p < 0.001 | p < 0.001 | NS | |
| Displacement for fracture point load (mm) | 1.068 ± 0.054 | 1.004 ± 0.088 | 1.208 ± 0.074 | 0.953 ± 0.087 | NS | p < 0.05 | NS | |
| Energy for fracture point load (mJ) | 80.8 ± 5.7 | 49.9 ± 7.0∗∗∗ | 63.9 ± 5.0∗ | 40.7 ± 3.9∗∗∗XX | p < 0.05 | p < 0.001 | NS | |
| Stress for fracture point load (MPa) | 74.1 ± 7.8 | 47.3 ± 4.8∗∗∗ | 47.4 ± 4.2∗∗∗ | 35.6 ± 1.3∗∗∗ | p < 0.001 | p < 0.001 | NS | |
|
| ||||||||
| Femur | Young's modulus (MPa) | 8929 ± 242 | 10886 ± 373∗∗∗ | 8957 ± 418 | 9955 ± 333∗X | NS | p < 0.001 | NS |
| Maximum load (N) | 124.8 ± 4.3 | 125.8 ± 3.8 | 130.1 ± 3.7 | 119.3 ± 5.3 | NS | NS | NS | |
| Displacement for maximum load (mm) | 0.502 ± 0.021 | 0.493 ± 0.019 | 0.516 ± 0.034 | 0.487 ± 0.016 | NS | NS | NS | |
| Energy for maximum load (mJ) | 38.0 ± 2.8 | 38.2 ± 2.4 | 41.0 ± 3.7 | 35.7 ± 2.6 | NS | NS | NS | |
| Stress for maximum load (MPa) | 168.9 ± 4.2 | 189.7 ± 4.9∗∗ | 171.2 ± 4.3 | 174.6 ± 5.7a | NS | p < 0.05 | NS | |
| Fracture point load (N) | 123.3 ± 4.4 | 124.8 ± 3.6 | 129.4 ± 3.8 | 118.3 ± 5.2 | NS | NS | NS | |
| Displacement for fracture point load (mm) | 0.517 ± 0.021 | 0.505 ± 0.021 | 0.524 ± 0.034 | 0.501 ± 0.019 | NS | NS | NS | |
| Energy for fracture point load (mJ) | 39.8 ± 2.9 | 39.8 ± 2.6 | 42.0 ± 3.8 | 37.5 ± 3.2 | NS | NS | NS | |
| Stress for fracture point load (MPa) | 166.8 ± 4.6 | 188.1 ± 4.6∗∗ | 170.3 ± 4.4 | 173.1 ± 5.7a | NS | p < 0.05 | NS | |
Bilateral ovariectomy was performed 5 weeks before the end of the experiment. Diabetes was induced 3 days after the ovariectomy by a single administration of streptozotocin (60 mg/kg i.p.). Results are presented as means ± SEM (n = 9 − 10). Two-way ANOVA followed by Fisher's LSD test was used for evaluation of the significance of the results. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001—significantly different from the NOVX control rats; Xp < 0.05, XXp < 0.01—significantly different from the OVX control rats; ap < 0.05—significantly different from the DM-NOVX rats.