Abstract
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.
Highlights
It is well accepted that the accurate quantification of in vivo knee joint kinematics and kinetics is essential for a thorough understanding of knee functionality [1], after total knee arthroplasty (TKA)
In the horizontal direction for level and downhill walking, the maximal accelerations that were recorded by the moving fluoroscope were below the maximal knee accelerations, whereas the maximal velocities of the moving fluoroscope were larger than maximal knee velocities (Table 1)
The knee joint center for all ten subjects remained within the field of view of the image intensifier for all walking tasks and all trials, with an average distance between the knee joint centre and the centre of the image intensifier: vertical 1.8 ± 1.4 cm, horizontal 4.0 ± 2.6 cm
Summary
It is well accepted that the accurate quantification of in vivo knee joint kinematics and kinetics is essential for a thorough understanding of knee functionality [1], after total knee arthroplasty (TKA). Such knowledge allows the verification and improvement of new surgical procedures and rehabilitation techniques, the development of new concepts for knee implants and the advancement or validation of numerical models. Skin marker based measurement is currently still the most employed tool. This method is critically affected by soft tissue artefact (STA), which reduces the ability to assess skeletal kinematics [2, 3].
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