Forwood M R, Turner C H
Department of Anatomy, Indiana University Medical Center, Indianapolis.
Bone. 1994 Nov-Dec;15(6):603-9. doi: 10.1016/8756-3282(94)90307-7.
To investigate the minimum number of loading bouts necessary to produce new lamellar or woven bone formation, and the time required for its initiation, bone formation was measured in 32 retired breeder female Sprague-Dawley rats following one, two, three, or five bouts of applied loading. Bending forces of 54 N were applied to right tibiae using a four-point loading apparatus, and left tibiae served as contralateral controls. Loading was applied as a sine wave with a frequency of 2 Hz for 18 s (36 cycles) per loading bout. Rats were injected with alizarin on day 1 and calcein on days 5 and 12, and were killed on day 19. One bout of loading was sufficient to increase the periosteal woven bone surface (Wb.Pm/B.Pm) from 0% to 40% (p < 0.01), and to 80% after five bouts of loading (p < 0.01), with a dose-response relationship for increases in Wb.Pm/B.Pm (p < 0.0001), mineral apposition rate (Wb.AR; p = 0.002), and bone formation rate (Wb.BFR/BS; p = 0.0001). In the first labeling period (days 1-5), the endocortical lamellar bone forming surface (BSf/BS) was increased slightly (p < 0.05), but no significant differences were shown for BFR/BS or MAR. From days 5 to 19, right tibiae showed a dose-response increase in BFR/BS (p = 0.002) and BSf/BS (p = 0.008), but not MAR. These results are consistent with a "quantum" model of bone formation such that a "quantum" of bone cells is activated in response to the loading bout and the strain magnitude dictate the size or microstructural organization of a given packet of new bone. Conversely, the distributed nature of loading may define the recruitment, rather than size, of new packets of bone.
为了研究产生新的板层骨或编织骨形成所需的最小加载次数，以及其起始所需的时间，对32只退休的繁殖期雌性Sprague-Dawley大鼠在施加一次、两次、三次或五次加载后进行骨形成测量。使用四点加载装置对右胫骨施加54 N的弯曲力，左胫骨作为对侧对照。每次加载以2 Hz的频率施加正弦波，每次加载持续18 s（36个周期）。大鼠在第1天注射茜素，在第5天和第12天注射钙黄绿素，并在第19天处死。一次加载足以使骨膜编织骨表面（Wb.Pm/B.Pm）从0%增加到40%（p<0.01），五次加载后增加到80%（p<0.01），Wb.Pm/B.Pm的增加呈剂量反应关系（p<0.0001），矿物质沉积率（Wb.AR；p=0.002）和骨形成率（Wb.BFR/BS；p=0.0001）。在第一个标记期（第1 - 5天），内皮质板层骨形成表面（BSf/BS）略有增加（p<0.05），但BFR/BS或MAR无显著差异。从第5天到第19天，右胫骨的BFR/BS（p=0.002）和BSf/BS（p=0.008）呈剂量反应增加，但MAR无变化。这些结果与骨形成的“量子”模型一致，即响应加载一次激活“量子”的骨细胞，应变幅度决定给定新骨包的大小或微观结构组织。相反，加载的分布性质可能决定新骨包的募集，而不是大小。
