A TOOL TO ASSESS BIOMECHANICAL GAIT EFFICIENCY - A PRELIMINARY CLINICAL-STUDY

A goal of many physiatric interventions is to improve biomechanical wa lking efficiency. Thus, a tool that helps assess this efficiency, inde pendent of cardiac, pulmonary, psychologic, or other nonbiomechanical factors, would be useful. Currently used methods to measure efficiency , including comfortable walking speed, are not specific to biomechanic al variables. A potential tool, the biomechanical efficiency quotient (BEQ), which uses three variables-average stride length, vertical disp lacement of the trunk during walking, and sacral height during standin g-is proposed and preliminarily tested. This quotient is based on Saun ders, Inman, and Eberhart's theories and on a prior study in able-bodi ed subjects. The BEQ was computed in 20 consecutive patients with neur ologically based gait disability referred for gait laboratory evaluati on who subjectively reported that one or two ankle-foot-orthoses (AFOs ) reduced the effort necessary to walk. The quotient was calculated wi th and without the AFO(s) by dividing the average vertical displacemen t of the sacrum, which was measured with an optoelectronic system, and by a predicted displacement, which was based on the patient's sacral height and average stride length. The mean BEQ with the AFO(s) (6.3 +/ - 4.4) was significantly less than the mean BEQ without the AFO(s) (9. 7 +/- 7.1); P = 0.005. Furthermore, the BEQ was less with the AFO(s) c ompared with trials without the AFO(s) in all subjects. Percent change in BEQ with the AFO(s) (26.8 +/- 19.6) correlated with percent change in comfortable walking velocity (24.8 +/- 31.8), r = 0.73, P < 0.001, across all subjects. The BEQ may be useful in specifically assessing the effect on biomechanical efficiency of physiatric interventions, de spite variable nonbiomechanical factors. An instrument to measure vert ical trunk displacement during walking outside of the gait laboratory would be extremely useful for further necessary longitudinal studies.