The design and development of a measurement system for the investigation of dynamic micromotion in total knee joint replacements

This paper describes the design and development of a measurement system for the investigation of dynamic micromotion in modular total knee joint replacements. The system is composed of miniature displacement sensors integrated into a knee simulator, signal conditioning hardware, a data acquisition card, and a compiled software application developed in a graphical programming environment (LabVIEW). A calibration method for the miniature displacement sensors is presented that ensures calibration to a micrometer-level accuracy. The compiled software application provides features enabling sensor calibration and zero adjustment, simultaneous automated data acquisition and counting of the number of simulated gait cycles from the knee simulator, and automated data recording from all signals in files at user-specified numbers of simulated gait cycles. Experimentally measured results from a test configuration using the system are presented in this paper.