A marker based kinematic method of identifying initial contact during gait suitable for use in real-time visual feedback applications.

A gait cycle is typically defined as being from heel strike or initial contact (IC) to the next ipsilateral IC using kinetic data. When these data are not available other methods of event definition are required. An algorithm based upon sagittal plane kinematics of the hip, which defines IC at contralateral peak hip extension (PHE) is presented. Kinematic and kinetic data were recorded while 10 unimpaired participants each completed a minimum of 25 overground gait cycles. The accuracy of 551 IC events was evaluated by comparing the agreement of PHE to other kinematic and kinetic algorithms. The mean temporal difference in IC between the PHE algorithm and a kinetic algorithm was +0.0006±0.008 s. The 95% Limits of Agreement was ±0.018 s. This new PHE algorithm provides simple to implement and accurate gait events for use when kinetic data are not available.