Intermittent vibrations accelerate fracture healing in sheep

Abstract Purpose: To investigate the effect of intermittent vibration at different intervals on bone fracture healing and optimize the vibration interval. Methods: Ninety sheep were randomized to receive no treatment (the control group), incision only (the sham control group), internal fixation with or without metatarsal fracture (the internal fixation group), and continuous vibration in addition to internal fixation of metatarsal fracture, or intermittent vibration at 1, 2, 3, 5, 7 and 17-day interval in addition to internal fixation of metatarsal fracture (the vibration group). Vibration was done at frequency F=35 Hz, acceleration a=0.25g, 15 min each time 2 weeks after bone fracture. Bone healing was evaluated by micro-CT scan, bone microstructure and mechanical compression of finite element simulation. Results: Intermittent vibration at 7-day interval significantly improved bone fracture healing grade. However, no significant changes on microstructure parameters and mechanical properties were observed among sheep receiving vibration at different intervals. Conclusions: Clinical healing effects should be the top concern. Quantitative analyses of bone microstructure and of finite element mechanics on the process of fracture healing need to be further investigated.

摘要 目的：探讨不同间歇时长的间歇性振动对骨折愈合的影响，优化振动间歇周期。方法：将90只绵羊随机分为5组：未接受任何干预的空白对照组、仅行皮肤切口操作的假手术对照组（sham control group）、行内固定术（伴或不伴跖骨骨折）的内固定组（internal fixation group）、跖骨骨折内固定术后联合持续振动干预组，以及跖骨骨折内固定术后分别联合1、2、3、5、7、17天间歇时长的间歇性振动干预的振动组（vibration group）。于骨折术后2周开始施加振动刺激，振动参数为频率35 Hz、加速度0.25g，每次干预15分钟。采用显微CT（micro-CT）扫描、骨微结构分析以及有限元模拟（finite element simulation）的力学压缩实验评估骨折愈合情况。结果：采用7天间歇时长的间歇性振动可显著提升骨折愈合等级。但接受不同间歇时长振动干预的绵羊，其骨微结构参数与力学性能均未出现显著差异。结论：临床愈合效果应作为首要考量指标。骨折愈合过程中骨微结构与有限元力学的定量分析仍有待进一步研究。