A moving fluoroscope to capture tibiofemoral kinematics during complete cycles of free level and downhill walking as well as stair descent.

Videofluoroscopy has been shown to provide essential information in the evaluation of the functionality of total knee arthroplasties. However, due to the limitation in the field of view, most systems can only assess knee kinematics during highly restricted movements. To avoid the limitations of a static image intensifier, a moving fluoroscope has been presented as a standalone system that allows tracking of the knee during multiple complete cycles of level- and downhill-walking, as well as stair descent, in combination with the synchronous assessment of ground reaction forces and whole body skin marker measurements. Here, we assess the ability of the system to keep the knee in the field of view of the image intensifier. By measuring ten total knee arthroplasty subjects, we demonstrate that it is possible to maintain the knee to within 1.8 ± 1.4 cm vertically and 4.0 ± 2.6 cm horizontally of the centre of the intensifier throughout full cycles of activities of daily living. Since control of the system is based on real-time feedback of a wire sensor, the system is not dependent on repeatable gait patterns, but is rather able to capture pathological motion patterns with low inter-trial repeatability.

A Fast Testing Method to Objectively Quantify the Stiffness of Stability Boots.

Stability boots can protect the ankle ligaments from overloading after serious injury and facilitate protected movement in order to aid healing of the surrounding soft tissue structures. For comparing different stability shoe designs and prototypes, a reliable and fast testing method (FTM) is required. The aim of this study was to assess the reliability of a novel custom-built device. Six different stability boots were tested in a novel device that allowed body weight to be taken into account using a pneumatic actuator. The fixation of the boots was controlled using two air pad pressure sensors. The range of motion (RoM) was then assessed during 5 trials at physiological ankle joint torques during flexion/extension and inversion/eversion. Furthermore the intraclass correlation coefficient ICC was determined to assess the repetitive reliability of the testing approach. The measured ankle angles ranged from 3.4° to 25° and proved to be highly reliable (ICC = 0.99), with standard deviations <9.8%. Comparing single trials to one another resulted in a change of 0.01° joint angle, with a mean error of 0.02°. The FTM demonstrates that it is possible to reliably measure the ankle joint RoM in both the sagittal and frontal planes at controlled torque levels, together with the application of body weight force.