Error reduction in the finite helical axis for knee kinematics

Abstract

Traditionally the FHA is calculated stepwise between data points (sFHA), requiring down sampling to achieve a sufficiently large step size to minimize error. This paper proposes an alternate FHA calculation approach (rFHA), using a unique reference position to reduce error associated with small rotation angles. This study demonstrated error reduction using the rFHA approach relative to the sFHA approach. Furthermore, the rFHA in the femur is defined at each time point providing a continuous representation of joint motion. These characteristics enable the rFHA to quantify small differences in knee joint motion, providing an excellent measure to quantify knee joint stability.

Keywords:

• Finite helical axis
• error reduction
• knee kinematics
• joint stability

Acknowledgements

The authors would like to acknowledge funding support from the Natural Sciences and Engineering Research Council of Canada (NSERC), Alberta Innovates Technology Futures (AITF), the Canadian Institutes of Health Research (CIHR), and Alberta Innovates Health Solutions (AIHS). Additionally, the authors would like to acknowledge Dr. Richard Frayne for his assistance with MRI sequence development and image acquisition.