Comparing hip joint centre location methods in an automotive driving position

Several methods have been developed to predict hip joint centre (HJC) location. They can be classified into two types: the regression equations from anatomical landmarks (ALs), and the functional method from thigh marker trajectories from a hip rotation. However, very few studies have estimated their reliability in case of an automotive driving position. Therefore, this study aimed at comparing these two types of methods for the estimation of HJC location in different postures, and at estimating the uncertainty of HJC location in an automotive driving position. From the analysis of data collected on ten subjects, results showed that HJC estimated from regression equations did not depend on measuring posture, but strongly depended on the observer who palpated ALs. However, HJC was found dependent on measuring posture when using functional method. Both regression and functional methods did not give satisfying results, and other methods should be investigated in the future.