Kaneps A J, Stover S M, Lane N E
Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, USA.
Bone. 1997 Nov;21(5):419-23. doi: 10.1016/s8756-3282(97)00167-1.
The purpose of this study was to assess cortical and cancellous bone responses to unilateral limb immobilization and, subsequently, to remobilization with exercise, in a young adult canine model. Right forelimbs of 14 1-2-year old mongrel dogs were immobilized in a non-weight-bearing position by a bandage for 16 weeks. Six control dogs were untreated. At 16 weeks, seven immobilized and three control dogs were euthanized. The remaining seven immobilized dogs began a recovery protocol consisting of 16 weeks of kennel confinement (without the right forelimb bandaged) followed by 16 weeks of treadmill exercise conducted three times per week. These seven dogs and three control dogs were euthanized at 48 weeks. Bone mineral density of the proximal radii was determined with dual-energy X-ray absorptiometry and humeral middiaphyseal cross-sectional areas were determined with computed tomography. Humeri were tested in cranio-caudal three-point bending to failure. Cancellous bone cores from the lateral humeral condyles had wet apparent density determined and were tested to failure in compression. Mechanical properties, bone density, and cross-sectional areas were compared between immobilized (right forelimb), contralateral weight bearing (left forelimb), and control forelimbs with Kruskal-Wallis and post hoc tests. At 16 weeks, bone mineral density, cortical load, yield, and stiffness as well as cancellous bone failure stress, yield stress, and modulus were significantly lower (p < 0.02) for immobilized limbs than control limbs. Immobilized limb cancellous bone mechanical properties were 28%-74% of control values, and cortical bone mechanical properties were 71%-98% of control values. After 32 weeks of remobilization, cortical and cancellous bone mechanical properties were not different from control values except that cortical bone failure stress and modulus were significantly higher (p < 0.01) between remobilized and control limbs. In summary, 16 weeks of forelimb immobilization was associated with significantly lower mechanical properties, and with greater differences in cancellous than cortical bone properties. Mechanical properties were not different from control values after 32 weeks of recovery that included 16 weeks of treadmill exercise.
本研究的目的是评估在一个年轻成年犬模型中，皮质骨和松质骨对单侧肢体固定以及随后运动再动员的反应。14只1 - 2岁的杂种犬的右前肢通过绷带固定在非负重位置16周。6只对照犬未接受治疗。在16周时，对7只固定肢体的犬和3只对照犬实施安乐死。其余7只固定肢体的犬开始恢复方案，包括16周的犬舍禁闭（右前肢不包扎绷带），随后是每周3次、持续16周的跑步机运动。在48周时，对这7只犬和3只对照犬实施安乐死。用双能X线吸收法测定近端桡骨的骨密度，用计算机断层扫描测定肱骨中段骨干的横截面积。对肱骨进行颅尾向三点弯曲试验直至破坏。测定肱骨外侧髁的松质骨芯的湿表观密度，并进行压缩破坏试验。用Kruskal - Wallis检验和事后检验比较固定肢体（右前肢）、对侧负重肢体（左前肢）和对照前肢之间的力学性能、骨密度和横截面积。在16周时，固定肢体的骨密度、皮质骨负荷、屈服强度和刚度以及松质骨破坏应力、屈服应力和模量均显著低于对照肢体（p < 0.02）。固定肢体的松质骨力学性能为对照值的28% - 74%，皮质骨力学性能为对照值的71% - 98%。再动员32周后，皮质骨和松质骨的力学性能与对照值无差异，只是再动员肢体与对照肢体之间的皮质骨破坏应力和模量显著更高（p < 0.01）。总之，前肢固定16周与力学性能显著降低相关，且松质骨性能的差异大于皮质骨性能。在包括16周跑步机运动的32周恢复后，力学性能与对照值无差异。
