Rittweger Jörn, Winwood Keith, Seynnes Olivier, de Boer Maarten, Wilks Desirée, Lea Rosalind, Rennie Michael, Narici Marco
Manchester Metropolitan University, IRM, Hassall Road, Alsager ST7 2HL, UK.
J Physiol. 2006 Nov 15;577(Pt 1):331-7. doi: 10.1113/jphysiol.2006.115782. Epub 2006 Oct 5.
Bone loss during immobilization is well documented. Currently, the only means of studying this in human beings is bed rest, which is resource intensive and inconvenient for the subjects. Unilateral lower limb suspension (ULLS) has been suggested as an alternative, but has not previously been demonstrated to cause bone loss. The main aim of our study was to test the hypothesis that ULLS would cause bone loss determined by peripheral quantitative computed tomography (pQCT). We investigated eight young healthy volunteers (19.1 +/- 0.7 years; body mass index, 22.4 +/- 2.6 kg m(-2)), who underwent ULLS for 24 days; their right foot was suspended with a strap attached to the shoulder so the knee angle was 10 deg and they wore a left shoe with a 7.5 cm sole to allow clearance of the right foot and used bilateral crutches to perambulate. Bone scans were obtained by pQCT from the distal epiphyses and from the diaphyses of the tibia in each leg twice before suspension, at days 7, 14 and 21 of the ULLS, and at days 4, 9, 35 and 90 of recovery. After 21 days of ULLS, bone mineral content of the peripheral portion of the epiphysis of the suspended tibia was reduced by 0.89 +/- 0.48% (from 280.9 +/- 34.5 to 278.4 +/- 34.2 mg mm(-1), P < 0.001) but no changes were observed in its central portion or in the unsuspended tibia. In the peripheral epiphyseal portion, significant bone loss (by 0.32 +/- 0.54%, P = 0.045) occurred as early as day 7 of ULLS. We have demonstrated, for the first time, that in humans bone is lost during ULLS at rates comparable to those seen with bed rest, without alteration in limb fluid volumes thus validating the technique and raising important questions about the mechanisms involved.
固定期间的骨质流失已有充分记录。目前，在人体中研究这一现象的唯一方法是卧床休息，这对资源要求很高，且给受试者带来不便。有人提出单侧下肢悬吊（ULLS）作为一种替代方法，但此前尚未证明其会导致骨质流失。我们研究的主要目的是验证ULLS会导致骨质流失这一假设，该骨质流失通过外周定量计算机断层扫描（pQCT）来确定。我们调查了8名年轻健康志愿者（19.1±0.7岁；体重指数，22.4±2.6 kg m⁻²），他们接受了24天的ULLS；他们的右脚用一条系在肩部的带子悬吊起来，使膝关节角度为10度，并且他们穿着一只鞋底厚7.5厘米的左脚鞋，以便右脚能够悬空，并用双侧拐杖行走。在悬吊前、ULLS的第7天、第14天和第21天以及恢复的第4天、第9天、第35天和第90天，通过pQCT对每条腿胫骨的远端骨骺和骨干进行了骨扫描。ULLS 21天后，悬吊侧胫骨骨骺外周部分的骨矿物质含量降低了0.89±0.48%（从280.9±34.5降至278.4±34.2 mg mm⁻¹；P<0.001），但其中心部分和未悬吊侧胫骨未观察到变化。在外周骨骺部分，早在ULLS第7天就出现了显著的骨质流失（降低了0.32±0.54%，P = 0.045）。我们首次证明，在人类中，ULLS期间骨质流失的速率与卧床休息时相当，且肢体液体量无变化，从而验证了该技术，并引发了有关所涉及机制的重要问题。
