Raab-Cullen D M, Akhter M P, Kimmel D B, Recker R R
Center for Hard Tissue Research, Creighton University, Omaha, Nebraska.
J Bone Miner Res. 1994 Feb;9(2):203-11. doi: 10.1002/jbmr.5650090209.
Mechanical loading of the living skeleton influences bone formation, mass, and strength. The primary purpose of the present study was to examine the influence of different loading schedules (days/week) on the bone response to external loading using an in vivo rat tibia four-point bending model. Three studies were conducted to (1) characterize the loaded region, (2) examine the variation of the response within the loaded region, and (3) test the response to different loading schedules. In all studies adult female retired breeder Sprague-Dawley rats were used (6 months, 285 g). First, the location of the loaded region during four-point bending was determined by radiogrammetry of 7 rats. Second, 5 rats were externally loaded for 8 of 10 days at 31 N, 36 cycles, and 2 Hz (1349 +/- 244 mu epsilon). The extent of labeled (forming) periosteal and endocortical surface in the loaded region was compared both among four serial sections from the same tibia and between the loaded and the contralateral tibiae. Finally, 50 rats were randomized into five groups: two nonloaded, control and sham, and three loaded, alternate day, Monday, Wednesday, and Friday, and daily. The rats were externally loaded for 3 weeks at 35 N, 36 cycles, and 2 Hz (1533 +/- 308 mu epsilon). The tibia and fibula were studied for labeled surfaces and mineral apposition rate. For adult female rats with tibial length 39 mm, the loaded region was located 3.5-14 (+/- 0.7) mm proximal to the tibia-fibula junction (TFJ).(ABSTRACT TRUNCATED AT 250 WORDS)
活体骨骼的机械负荷会影响骨形成、骨量和骨强度。本研究的主要目的是使用体内大鼠胫骨四点弯曲模型，研究不同负荷时间表（每周天数）对骨骼对外在负荷反应的影响。进行了三项研究，以（1）确定负荷区域的特征，（2）研究负荷区域内反应的变化，以及（3）测试对不同负荷时间表的反应。在所有研究中，均使用成年雌性退休繁殖斯普拉格-道利大鼠（6个月，285克）。首先，通过对7只大鼠进行X线测量，确定四点弯曲过程中负荷区域的位置。其次，对5只大鼠在10天中的8天进行外部负荷，负荷为31牛、36次循环、2赫兹（1349±244微应变）。比较同一胫骨的四个连续切片之间以及负荷侧胫骨与对侧胫骨之间负荷区域内标记（正在形成）的骨膜和骨内膜表面范围。最后，将50只大鼠随机分为五组：两组非负荷组，即对照组和假手术组，以及三组负荷组，分别为隔日负荷组（周一、周三和周五）和每日负荷组。大鼠以35牛、36次循环、2赫兹（1533±308微应变）进行3周的外部负荷。对胫骨和腓骨进行标记表面和矿物质沉积率研究。对于胫骨长度为39毫米的成年雌性大鼠，负荷区域位于胫腓关节（TFJ）近端3.5 - 14（±0.7）毫米处。（摘要截断于250字）
