Beals Caitlyn J, Wong Gabriella A S, Dupont Kenneth M, Safranski David L
Engineering Student, Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA.
Engineering Student, Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA.
J Foot Ankle Surg. 2023 Jan-Feb;62(1):7-13. doi: 10.1053/j.jfas.2022.03.001. Epub 2022 Mar 10.
Midfoot and subtalar arthrodesis surgeries are performed to correct foot deformities and relieve arthritic pain. These procedures often employ intramedullary (IM) devices. The aim of the present study was to evaluate the biomechanical performance of a sustained dynamic compression (SDC) IM device compared to mechanically static devices in withstanding the effects of simulated bone resorption. Mechanically static and SDC IM devices were implanted in simulated bone blocks (n = 5/device). Compressive loads were measured with a custom-made mechanism to simulate bone resorption. The construct bending stiffness was determined from a 4-point bend test. Resorption was simulated by cutting a 1 mm or 2 mm gap in the midpoint of each construct and repeating the loading (n = 6/device). Initial compressive loads after device insertion were greater in the SDC IM devices when compared to the static devices (p < .01). The SDC device was able to sustain compression from 2 mm to 5.5 mm of simulated resorption depending upon device length, while the static devices lost compression within 1 mm of simulated resorption regardless of implant length (p < .001). In the 4-point bend test, the SDC device maintained its bending stiffness during simulated resorption whereas the static device displayed a significant loss in bending stiffness after 1 mm of simulated resorption (p < .001). The SDC device exhibited a significantly higher bending stiffness than the static device (p < .001). The SDC IM device demonstrated superior biomechanical performance during simulated resorption compared to static devices (p < .001). In conclusion, the ability of SDC IM devices to maintain construct stability and sustain compression across the fusion site while adapting to bone resorption may lead to greater fusion rates and overall quicker times to fusion than static IM devices. Surgeons who perform midfoot and subtalar arthrodesis procedures should be aware of a device's ability to sustain compression, especially in cases where bone resorption and joint settling are prevalent postoperatively.
中足和距下关节融合手术用于矫正足部畸形并缓解关节炎疼痛。这些手术通常使用髓内（IM）装置。本研究的目的是评估一种持续动态加压（SDC）IM装置与机械静态装置相比，在承受模拟骨吸收影响时的生物力学性能。将机械静态和SDC IM装置植入模拟骨块中（每个装置n = 5）。使用定制装置测量压缩载荷以模拟骨吸收。通过四点弯曲试验确定结构弯曲刚度。通过在每个结构的中点切割1毫米或2毫米的间隙并重复加载来模拟吸收（每个装置n = 6）。与静态装置相比，SDC IM装置在装置插入后的初始压缩载荷更大（p <.01）。SDC装置能够根据装置长度维持2毫米至5.5毫米模拟吸收的压缩，而静态装置无论植入长度如何，在模拟吸收1毫米内就失去了压缩（p <.001）。在四点弯曲试验中，SDC装置在模拟吸收期间保持其弯曲刚度，而静态装置在模拟吸收1毫米后弯曲刚度显著降低（p <.001）。SDC装置的弯曲刚度明显高于静态装置（p <.001）。与静态装置相比，SDC IM装置在模拟吸收期间表现出优异的生物力学性能（p <.001）。总之，SDC IM装置在适应骨吸收的同时保持结构稳定性并维持融合部位压缩的能力，可能导致比静态IM装置更高的融合率和总体更快达到融合的时间。进行中足和距下关节融合手术的外科医生应了解装置维持压缩的能力，特别是在术后骨吸收和关节沉降普遍的情况下。
