Three-dimensional clinical measurement of bilateral hip and knee rotations

This paper reports a technique of using an electromagnetic system to measure three-dimensional bilateral hip and knee joint rotations during walking and of using peak cross-correlation between rotation angles to describe the pattern of rotations. Three-dimensional rotations of thigh and shank during gait were recorded using five receivers of the electromagnetic system synchronised with four foot-switches. Thirteen normal subjects were tested on two separate occasions to examine repeatability of the measurements. The relationship between the rotations was represented as lags at peak cross-correlation. Twelve parameters of the lags at peak cross-correlation were calculated. The analysis showed that the joint rotation could be measured reliably and the cross-correlation analysis provided parameters that were generally suitable for defining characteristics of hip and knee joint rotations during gait.