A treadmill-based system for measuring symmetry of gait.

It has been recognised for centuries that various conditions will lead to asymmetries in gait and several researchers have analysed symmetry of gait. However, in general such analyses are based on five steps or fewer. A new system has been designed and manufactured that is based on a motorised treadmill with forceplates (errors +3. 2% and -4.3%) that quickly gathers information on larger numbers of steps. It automatically records the data and then performs a semi automatic analysis to calculate various parameters from each of the measured steps, including: heel strike, toe off, stance phase, swing phase, peak forces and loading and unloading rates. Other parameters can also be easily incorporated into the analysis such as double support time. Student's t tests are performed comparing the means of these parameters. The ratios of the parameters, left to right (or uninvolved to involved limbs), are then quoted as Symmetry Indices. It has been found to be quick and easy to use and produces results that are both readily understood and clinically relevant.