Rankin Kathryn, Steer Joshua, Paton Joshua, Mavrogordato Mark, Marter Alexander, Worsley Peter, Browne Martin, Dickinson Alexander
Bioengineering Science Research Group, School of Engineering, University of Southampton, Southampton SO17 1BJ, UK.
µ-VIS X-Ray Imaging Centre, University of Southampton, Southampton SO17 1BJ, UK.
Materials (Basel). 2020 Sep 7;13(18):3955. doi: 10.3390/ma13183955.
Personalised prosthetic sockets are fabricated by expert clinicians in a skill- and experience-based process, with research providing tools to support evidence-based practice. We propose that digital volume correlation (DVC) may offer a deeper understanding of load transfer from prosthetic sockets into the residual limb, and tissue injury risk. This study's aim was to develop a transtibial amputated limb analogue for volumetric strain estimation using DVC, evaluating its ability to distinguish between socket designs. A soft tissue analogue material was developed, comprising silicone elastomer and sand particles as fiducial markers for image correlation. The material was cast to form an analogue residual limb informed by an MRI scan of a person with transtibial amputation, for whom two polymer check sockets were produced by an expert prosthetist. The model was micro-CT scanned according to (i) an unloaded noise study protocol and (ii) a case study comparison between the two socket designs, loaded to represent two-legged stance. The scans were reconstructed to give 108 µm voxels. The DVC noise study indicated a 64 vx subvolume and 50% overlap, giving better than 0.32% strain sensitivity, and ~3.5 mm spatial resolution of strain. Strain fields induced by the loaded sockets indicated tensile, compressive and shear strain magnitudes in the order of 10%, with a high signal:noise ratio enabling distinction between the two socket designs. DVC may not be applicable for socket design in the clinical setting, but does offer critical 3D strain information from which existing in vitro and in silico tools can be compared and validated to support the design and manufacture of prosthetic sockets, and enhance the biomechanical understanding of the load transfer between the limb and the prosthesis.
个性化假肢接受腔由专业临床医生通过基于技能和经验的流程制作，研究为循证实践提供了支持工具。我们认为数字体积相关技术（DVC）可能有助于更深入地了解从假肢接受腔到残肢的负荷传递以及组织损伤风险。本研究的目的是开发一种用于使用DVC进行体积应变估计的经胫截肢肢体模型，评估其区分接受腔设计的能力。开发了一种软组织模拟材料，由硅橡胶弹性体和沙粒作为图像相关的基准标记组成。根据一名经胫截肢者的MRI扫描结果铸造该材料，以形成模拟残肢，由专家假肢师为其制作了两个聚合物检验接受腔。根据（i）无负荷噪声研究方案和（ii）两种接受腔设计之间的案例研究比较，对模型进行微型计算机断层扫描，加载以代表双腿站立。扫描重建后得到108 µm的体素。DVC噪声研究表明，64 vx的子体积和50%的重叠率，应变灵敏度优于0.32%，应变空间分辨率约为3.5 mm由加载的接受腔引起的应变场表明拉伸、压缩和剪切应变大小约为10%，高信噪比能够区分两种接受腔设计。DVC可能不适用于临床环境中的接受腔设计，但确实提供了关键的三维应变信息，通过这些信息可以比较和验证现有的体外和计算机工具，以支持假肢接受腔的设计和制造，并增强对肢体与假肢之间负荷传递的生物力学理解。
