Augat P, Merk J, Wolf S, Claes L
Institute of Orthopedic Research and Biomechanics, University of Ulm, Germany.
J Orthop Trauma. 2001 Jan;15(1):54-60. doi: 10.1097/00005131-200101000-00010.
To determine whether an externally induced interfragmentary movement enhances the healing process of a fracture under flexible fixation.
Randomized, prospective in vivo animal study with control group. Twenty-four skeletally mature Merino sheep were randomly assigned to six groups of four animals, which received cyclic interfragmentary movements of 0.2 and 0.8 millimeters and stimulation frequencies of 1, 5, and 10 Hertz, respectively. Twelve animals did not receive any externally applied stimulation and served as a control group.
Unrestricted stall activity with weight bearing reduced by tenotomy of the Achilles tendon.
Osteotomy of the tibial diaphysis with three-millimeter gap width fixed with a six-pin, monolateral, double-bar external fixator. Interfragmentary movement of the osteotomy gap was externally induced by a motor-driven actuator unit. Five hundred cycles inducing nonuniform tensile strains within the gap were performed each day.
Nine weeks after surgery, the animals were killed, and bone mineral density and callus cross-sectional area were measured with quantitative computed tomography. Callus projectional area was assessed by radiographs, and mechanical stability was determined with a three-point bending test.
External stimulation with nonuniform cyclic tensile strains did slightly affect but not significantly enhance the fracture healing process. Varying the stimulation frequency had no influence on the healing process. The stimulation with 0.8 millimeter displacement magnitude resulted in a larger periosteal callus, but a decreased bone mineral density compared with the 0.2-millimeter displacement magnitude. The stimulation had no significant influence on the mechanical properties of the healing bone.
Induced cyclic tensile strains did not produce a relevant enhancement of bone healing under flexible fixation.
确定外部诱导的骨折块间运动是否能增强弹性固定下骨折的愈合过程。
设有对照组的随机、前瞻性体内动物研究。24只骨骼成熟的美利奴绵羊被随机分为6组，每组4只，分别接受0.2毫米和0.8毫米的周期性骨折块间运动以及1赫兹、5赫兹和10赫兹的刺激频率。12只动物未接受任何外部施加的刺激，作为对照组。
通过跟腱切断术减少负重，在无限制的畜栏活动中进行。
在胫骨干进行截骨术，截骨间隙宽度为3毫米，用六针单侧双杆外固定器固定。截骨间隙的骨折块间运动由电动致动器单元外部诱导。每天进行500次在间隙内诱导不均匀拉伸应变的循环。
术后9周处死动物，用定量计算机断层扫描测量骨密度和骨痂横截面积。通过X线片评估骨痂投影面积，并用三点弯曲试验测定力学稳定性。
不均匀循环拉伸应变的外部刺激对骨折愈合过程有轻微影响，但未显著增强。改变刺激频率对愈合过程无影响。与0.2毫米的位移幅度相比，0.8毫米位移幅度的刺激导致更大的骨膜骨痂，但骨密度降低。刺激对愈合骨的力学性能无显著影响。
在弹性固定下，诱导的循环拉伸应变并未显著增强骨愈合。
