Table 3.
Endocortical Bone-Formation Indices From Mice Subjected to Axial Tibial Compression (Mean ± SD)
| 7 Months | 22 Months | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 8 N | 10 N | 12 N | 8 N | 10 N | 12 N | |||||||
| Outcome | Control (n = 11) | Loaded (n = 12) | Control (n = 13) | Loaded (n = 12) | Control (n = 7) | Loaded (n = 8) | Control (n =11) | Loaded (n = 10) | Control (n = 8) | Loaded (n = 9) | Control (n = 9) | Loaded (n = 9) |
| Ec.sLS/BS (%) | 28.9 ± 9.7 | 29.0 ± 11.1 | 25.4 ± 8.0 | 31.8a ± 9.2 | 29.2 ± 6.9 | 39.0 ± 23.6 | 34.8 ± 12.4 | 50.4d ± 15.1 | 33.0 ± 12.8 | 48.8a,d ± 13.2 | 39.3d ± 7.7 | 46.2 ± 18.1 |
| Ec.dLS/BS (%) | 0.1 ± 0.3 | 0.9 ± 1.9 | 0.2 ± 0.6 | 1.0 ± 1.7 | 0.0 ± 0.0 | 4.5a,b,c ± 4.2 | 0.2 ± 0.5 | 4.4a,d ± 4.4 | 0.1 ± 0.2 | 13.9 a,b,d ± 11.1 | 0.0 ± 0.0 | 17.3a,b,d ± 14.7 |
| Ec.MS/BS (%) | 14.2 ± 5.6 | 15.4 ± 5.9 | 12.9 ± 3.8 | 16.9a ± 5.6 | 14.6 ± 3.4 | 24.0 a,b,c ±10.7 | 17.6 ± 6.2 | 29.6a,d ± 9.2 | 16.6 ± 6.6 | 38.2a,d ± 12.3 | 19.7d ± 3.9 | 40.4a,d ± 15.4 |
| Ec.MAR (µm/day) | 0.75 (n = 1) | 1.29 ± 0.33 (n = 4) | 1.63 (n = 1) | 1.41 ± 0.64 (n = 5) | ND | 1.42 ± 0.60 (n = 6) | 1.13 (n = 2) | 1.52 ± 0.36 (n = 8) | 1.03 (n = 1) | 1.71 ± 0.52 (n = 9) | ND | 1.92 ± 0.52 (n = 9) |
| Ec.BFR/BS (µm/day) | 0.13 (n = 1) | 0.22 ± 0.03 (n = 4) | 0.21 (n = 1) | 0.30 ± 0.11 (n = 5) | ND | 0.32 ± 0.21 (n = 6) | 0.27 (n = 2) | 0.49 ± 0.25 (n = 8) | 0.26 (n = 1) | 0.70d ± 0.33 (n = 9) | ND | 0.82d ± 0.44 (n = 9) |
a
Loaded (right) different from control (nonloaded, left); p < .05, paired t test.
b
Different from 8-N group of same age.
c
Different from 10-N group of same age; p < .05, ANOVA.
d
Different from 7-month-old group at same force level; p < .05, ANOVA.
ND = no detectable double label; owingue to the low incidence of double labels in control tibias, statistical comparisons of MAR and BFR between loaded and control bones were not performed.