Continuous monitoring of knee joint kinematics for enhanced clinical diagnostics using optical goniometer

Abstract This study demonstrates the performance of an optical goniometer which sensing mechanism is based on the detection of LED light-beam on respective sensitive pixel on a linear array photodiode sensor. The LED is mounted inside a mechanical compartment that allows it to move along the surface of linear array photodiode with respect to the knee movement. Simultaneous measurements of the knee movement are obtained from the optical goniometer and a standard arm goniometer. With the knee assessment data from 17 subjects, divided into groups with healthy and knee injury record, the device's performances in both static and dynamic conditions are analyzed. Inter-rater and intra-rater reliability were also evaluated through Cronbach's Alpha and Interclass Correlation Coefficient (ICC) analyses. The measured data using optical goniometer demonstrated comparable sensor's repeatability and reliability, with a significant correlation of 98.044% against the manual goniometer in static measurements. Intra-rater reliability yielded an ICC of 0.7, while inter-rater reliability achieved a Cronbach's Alpha value of 0.967, indicating that the proposed sensor provides consistent measurements across different operators. This also demonstrates its robustness against operator-dependent variability in knee measurement. The result from the knee assessment using the proposed optical goniometer demonstrates its value as a potential alternative for arm goniometer in knee treatment and rehabilitation processes. The advantages of using the optical goniometer are due to the continuous measurement capability, wide range of motion for knee assessment and suitable for non-critical knee condition during treatment procedure in clinical environment.