Table 3.
Relative changes in metaphyseal trabecular bone morphology and diaphyseal cortical bone morphology during the first period of hindlimb unloading at 16–18 wk (3x-HLU), 22–24 wk (2x-HLU), or 28–30 wk (1x-HLU), during the first reambulation period at 18–20 wk (3x-HLU), 24–26 wk (2x-HLU), or 30–32 wk (1x-HLU), and during the entire first HLU/RA cycle
| Change Between Time Points, % |
|||
|---|---|---|---|
| 3x-HLU | 2x-HLU | 1x-HLU | |
| HLU Period | 16–18 wk | 22–24 wk | 28–30 wk |
| RA Period | 18–22 wk | 24–28 wk | 30–34 wk |
| HLU/RA Period | 16–22 wk | 22–28 wk | 28–34 wk |
| Metaphysis | |||
| BV/TV | |||
| HLU | −18 ± 9.0* | −13 ± 7.8* | −15 ± 8.3* |
| RA | −8.8 ± 7.5* | −8.7 ± 14* | 2.0 ± 9.1 |
| HLU/RA | −25 ± 11* | −21 ± 13* | −13 ± 15* |
| Tb.N | |||
| HLU | −6.4 ± 3.1*b,c | −3.8 ± 2.7* | −2.2 ± 1.8 |
| RA | −4.2 ± 2.1* | −4.1 ± 4.0* | −3.2 ± 3.3* |
| HLU/RA | −10.1 ± 4.0*b | −7.7 ± 5.0* | −5.3 ± 2.4* |
| Tb.Th | |||
| HLU | −2.9 ± 2.0b | −2.5 ± 2.5*b | −6.2 ± 2.7* |
| RA | 4.0 ± 2.8*b | 3.7 ± 2.8*b | 10 ± 5.7* |
| HLU/RA | 1.0 ± 3.2 | 1.0 ± 2.9 | 3.3 ± 5.3* |
| Tb.Sp | |||
| HLU | 7.0 ± 3.3*b,c | 4.1 ± 2.8* | 2.2 ± 2.0 |
| RA | 4.6 ± 2.0* | 4.8 ± 4.6* | 2.8 ± 4.2 |
| HLU/RA | 12 ± 4.5*b | 9.2 ± 5.9*b | 5.0 ± 3.1* |
| Conn.D | |||
| HLU | −40 ± 33* | −24 ± 30* | −54 ± 18* |
| RA | −6.8 ± 59 | −2.5 ± 96 | 25 ± 46 |
| HLU/RA | −47 ± 35* | −32 ± 50 | −42 ± 38 |
| Diaphysis | |||
| Ct.Ar | |||
| HLU | −7.8 ± 5.4*c | −2.7 ± 3.7b | −7.2 ± 3.9* |
| RA | 4.5 ± 4.8*b | 1.7 ± 3.2b | 9.2 ± 4.9* |
| HLU/RA | −3.6 ± 6.0*b | −1.5 ± 3.3 | 1.1 ± 2.8 |
| Ct.Th | |||
| HLU | −9.1 ± 6.0*c | −1.4 ± 5.3b | −7.5 ± 4.3* |
| RA | 5.3 ± 6.0c | −0.22 ± 2.8b | 9.0 ± 5.1* |
| HLU/RA | −4.5 ± 6.6b | −1.7 ± 3.4 | 0.64 ± 3.2 |
| Ma.Ar | |||
| HLU | 4.0 ± 3.1* | 3.3 ± 2.0*b | 6.0 ± 1.9* |
| RA | −3.5 ± 2.4*c | −1.1 ± 1.9b | −3.4 ± 2.5* |
| HLU/RA | 0.43 ± 3.8 | 2.1 ± 0.9* | 2.3 ± 2.1* |
| Tt.Ar | |||
| HLU | −1.1 ± 2.4 | 0.79 ± 1.0 | 0.25 ± 1.3 |
| RA | −0.32 ± 1.3 | −0.03 ± 1.25 | 1.5 ± 1.7 |
| HLU/RA | −1.4 ± 2.4b,c | 0.76 ± 1.6 | 1.8 ± 1.9 |
| Ct.Ip | |||
| HLU | −7.0 ± 6.4*c | −1.4 ± 4.0 | −5.7 ± 4.9* |
| RA | 3.3 ± 4.4c | 1.5 ± 3.4b | 9.7 ± 6.3* |
| HLU/RA | −4.1 ± 6.9b | 0.1 ± 4.7 | 3.2 ± 5.1 |
| Ct.TMD | |||
| HLU | −1.0 ± 2.0 | −0.40 ± 1.4 | −2.0 ± 1.5* |
| RA | 0.94 ± 1.2 | 0.93 ± 1.2 | 1.4 ± 1.9 |
| HLU/RA | −0.08 ± 1.9 | 0.36 ± 1.2 | −0.64 ± 0.8 |
| ICP | |||
| HLU | −0.04 ± 0.4 | −0.03 ± 0.23 | 0.01 ± 0.32 |
| RA | 0.01 ± 0.3 | 0.04 ± 0.23 | −0.00 ± 0.62 |
| HLU/RA | −0.03 ± 0.57 | 0.01 ± 0.20 | 0.00 ± 0.68 |
| BSI | |||
| HLU | −8.1 ± 8.4 | −0.42 ± 11 | −4.3 ± 11.5 |
| RA | 8.9 ± 10 | 2.7 ± 8.9 | 7.3 ± 9.5 |
| HLU/RA | −0.48 ± 7.1 | 1.7 ± 7.9 | 1.9 ± 9.0 |
Data are shown as means ± SD. The relative change during HLU was computed as the % change from the beginning to the end of the 2-wk HLU period; the relative change during RA is the % change from the beginning to the end of the 4-wk RA period; the relative change in HLU/RA is the % change from the beginning of the HLU period to the end of the RA period. Letters denote significant differences (P < 0.05) between groups. b2x- or 3x-HLU different from 1x-HLU; c3x-HLU different from 2x-HLU.
Significant within group change (P < 0.05) during the time period for which the relative % change is measured (HLU, RA, or HLU/RA) .