Planta Albert, Surbeck Raphael, Taylor William R, Plüss Stefan, Vogl Florian, Schütz Pascal
Laboratory for Movement Biomechanics, ETH Zurich, Zurich, Switzerland.
PLoS One. 2025 Jul 24;20(7):e0328351. doi: 10.1371/journal.pone.0328351. eCollection 2025.
Accurate measurement of joint kinematics is a key requirement for understanding injury mechanisms, evaluate rehabilitation techniques, and improve the implant designs and techniques used in total knee arthroplasty (TKA). Fluoroscopy is an experimental technique to directly measure joint kinematics without being affected by soft-tissue artefacts. However, because of its limited field-of-view (FOV), stationary fluoroscopy can only measure small parts of more dynamic/progressive movements, such as walking. This manuscript presents a new generation of moving fluoroscope: The tracking dual-plane fluoroscope (tDPF) combines optical tracking with a bi-planar X-ray system on mechanically independent source and intensifier carriages on rails and model-predictive-control to measure the kinematics of the tibio-femoral joint in vivo during dynamic activities, such as level walking and stair ascent/descent, at all gait speeds. In this proof-of-concept study, the tDPF tracked the knees of 16 young and healthy subjects during complete, consecutive gait cycles of level walking, ramp ascent, ramp descent, stair ascent, and stair descent at self-selected gait speeds. For all gait speeds (average and standard deviation: [Formula: see text] during level walking), tracking performance for each activity was excellent and the knee centre stayed within both simulated image intensifiers' FOVs for [Formula: see text] of frames (no X-ray images were captured in this study). The tDPF is the first dual-plane fluoroscope to track the knee joint during entire cycles of stair and ramp ascent at self-selected gait speeds for young and healthy subjects. Notably, our device does not require any pre-recording of movement patterns-by using real-time position estimates of the tracked joint and tracking each trial independently, even the challenging measurements of tasks with high variability between trials become possible.
准确测量关节运动学是理解损伤机制、评估康复技术以及改进全膝关节置换术（TKA）中使用的植入物设计和技术的关键要求。荧光透视法是一种直接测量关节运动学且不受软组织伪影影响的实验技术。然而，由于其视野（FOV）有限，静态荧光透视法只能测量更动态/渐进性运动（如行走）的小部分。本文介绍了新一代移动荧光透视仪：跟踪双平面荧光透视仪（tDPF），它将光学跟踪与双平面X射线系统相结合，该系统安装在机械独立的源和增强器滑架上，位于轨道上，并采用模型预测控制，以在动态活动（如平地行走和上下楼梯）期间，在所有步态速度下测量体内胫股关节的运动学。在这项概念验证研究中，tDPF在16名年轻健康受试者以自选步态速度进行平地行走、斜坡上升、斜坡下降、上楼梯和下楼梯的完整连续步态周期期间跟踪其膝盖。对于所有步态速度（平地行走时的平均值和标准差：[公式：见原文]），每种活动的跟踪性能都非常出色，并且膝关节中心在[公式：见原文]的帧数内保持在两个模拟图像增强器的视野内（本研究未采集X射线图像）。tDPF是第一台能够在年轻健康受试者以自选步态速度进行楼梯和斜坡上升的整个周期内跟踪膝关节的双平面荧光透视仪。值得注意的是，我们的设备不需要对运动模式进行任何预记录——通过使用被跟踪关节的实时位置估计并独立跟踪每个试验，即使是对试验间具有高变异性的任务进行具有挑战性的测量也变得可行。
