Assessment of the Chignon dynamic ankle-foot orthosis using instrumented gait analysis in hemiparetic adults.

OBJECTIVE: In the hemiplegic adult, gait is frequently perturbed by lack of ankle dorsiflexion at toe-off and may prompt prescription of an ankle-foot orthosis (AFO). Our objective was to evaluate the effect on gait of a dynamic AFO (the Chignon orthosis) in comparison with a prefabricated AFO (PAFO).
METHOD: Ten chronic hemiplegic patients performed a 10 m gait test and then underwent an instrumented treadmill gait test under three different sets of conditions (without an orthosis, with a PAFO and with a Chignon orthosis). The energy cost was calculated by measuring the oxygen consumption during gait.
RESULTS: The patients' free-walking speed was higher with the Chignon orthosis (0.81+/-0.25 ms(-1)) than without it (0.64+/-0.25 ms(-1); p<0.001). The ankle's segmental kinematics were better with the Chignon orthosis than without an orthosis, notably in terms of ankle position at heel strike (-0.8 degrees +/-4.6 versus -7.9 degrees +/-8.3; p=0.009) and ankle dorsiflexion at toe-off (1.7 degrees +/-4.6 versus -5.5 degrees +/-7.2; p=0.006). External mechanical work was lower with both the PAFO (0.61+/-0.2 J kg(-1)m(-1)) and the Chignon orthosis (0.61+/-0.23 J kg(-1)m(-1)), relative to gait without an orthosis (0.73+/-0.25 J kg(-1)m(-1); p=0.003). Total mechanical work was also lower with the PAFO (0.9+/-0.25 J kg(-1)m(-1)) and the Chignon orthosis (0.87+/-0.25 J kg(-1)m(-1)), relative to gait without an orthosis (1.09+/-0.37 J kg(-1)m(-1); p=0.001), whereas the reduction in energy cost with orthosis use was borderline-significant (p=0.06).
CONCLUSION: Mechanical work was similarly improved by the two orthoses. The Chignon orthosis improved the free-walking speed and the ankle's segmental kinematics.