IEEE Trans Biomed Eng. 2022 Jan;69(1):278-285. doi: 10.1109/TBME.2021.3092291. Epub 2021 Dec 23.
We describe a fluidic X-ray visualized strain indicator under applied load (X-VISUAL) to quantify orthopedic plate strain and inform rehabilitative care.
The sensor comprises a polymeric device with a fluidic reservoir filled with a radio-dense fluid (cesium acetate) and an adjoining capillary wherein the liquid level is measured. A stainless-steel lever attaches to the plate and presses upon the acrylic bulb with a displacement proportional to plate bending strain. The sensor was attached to a plate in a Sawbones composite tibia mimic and a human cadaveric tibia. An osteotomy model (5 mm gap) was used to simulate an unstable fracture, and allograft repair to simulate a stiffer healed fracture. The cadaveric and Sawbones tibia were cyclically loaded five times (0-400 N) using a mechanical test stand, and fluid displacement was measured from plain radiographs.
The sensor displayed reversible and repeatable behavior with a slope of 0.096 mm/kg and fluid level noise of 50-80 micrometer (equivalent to 5-10 N). The allograft-repaired composite fracture was 13 times stiffer than the unstable fracture.
An analysis of prior external fracture fixation studies and fatigue curves for internal plates indicates that the threshold for safe weight bearing should be 1/5-1/10 of the initial bending for an unstable fracture. The precision of our device (<2% body weight) should thus be sufficient to track fracture healing from unstable through safe weight bearing.
The X-VISUAL fluidic sensor enables orthopedic plate strain quantification to monitor facture healing via X-ray imaging.
我们描述了一种在受力下可视化的流体 X 射线应变指示器（X-VISUAL），用于量化骨科接骨板应变并为康复护理提供信息。
该传感器由一个聚合物装置组成，其中包含一个充满放射性高密度液体（醋酸铯）的流体储液器和一个相邻的毛细管，其中测量液体的液位。一个不锈钢杠杆连接到接骨板上，并通过与接骨板弯曲应变成比例的位移按压丙烯酸球。传感器被连接到一个在 Sawbones 复合材料胫骨模拟物和人体尸体胫骨上的接骨板。通过使用截骨术模型（5 毫米间隙）模拟不稳定骨折，以及同种异体骨修复模拟更硬的愈合骨折。尸体和 Sawbones 胫骨使用机械测试台进行五次循环加载（0-400 N），并从普通射线照片测量流体位移。
传感器显示出可重复的可逆行为，斜率为 0.096 mm/kg，液体水平噪声为 50-80 微米（相当于 5-10 N）。同种异体骨修复的复合骨折比不稳定骨折硬 13 倍。
对先前外部骨折固定研究和内部接骨板的疲劳曲线进行分析表明，安全承重的阈值应为不稳定骨折初始弯曲的 1/5-1/10。我们的设备（<2%体重）的精度应该足以通过 X 射线成像监测骨折愈合从不稳定到安全承重的过程。
X-VISUAL 流体传感器能够通过 X 射线成像量化骨科接骨板应变，以监测骨折愈合。
