It would be very helpful for researchers and clinicians if a single valid measure is developed to show objective differences or similarities among the gait patterns, not just through the able-bodied walkers population, but for any population with gait impairments in order to provide more objective gait evaluations to develop better rehabilitation protocols for improving pathological gait.

Agrawal et al (2009) introduced the Symmetry in External (mechanical) Work (SEW) score, a measure expressed in percentage that quantifies the difference of work done by each limb during gait. The objective was to quantify kinetic differences in gait as a consequence of using different prosthetic feet in one patient. The limitations of this study were that just one patient was used, and this measure has not yet been validated in a non-amputee population. The first step in deciding whether this measure has value and validity requires that the SEW score be assessed in an able-bodied group. The purpose of this study was to compute the SEW score in a non-amputee population, analyzing a trial and day effect in the variation of this measurement. If validated then it could be introduced as a new tool for objectively measuring gait symmetry in different populations with gait impairments.

Sixteen male participants between 23 and 35 years performed 10 successful walking trials through a measurement area where kinetic and kinematic data were recorded using a VICON 3D Motion Capture System and two force plates (AMTI and Bertec). SEW scores were calculated for each successful walking trial using the method described by Agrawal et al (2009). To assess the day effect participants returned to the laboratory one week later and repeated the same protocol.

There was no significant interaction between the effects of trial and day (session) on SEW scores (F9,300=0.776, p=0.639) and it was concluded that the SEW score was a reliable, valid tool for measuring gait symmetry.

When the SEW score was applied to a unilateral trans-tibial amputee participant, it was able to detect kinetic changes in gait resulting from differences in the designs of prosthetic feet.