Hemiplegic gait is characterized by slow and poorly coordinated movements of the affected limb resulting from foot drop or equinus deformities. Ankle-foot orthoses(AFO) are frequently prescribed to improve the gait pattern of hemiplegics. Plastic AFO with different trimlines in controlling ankle motion can cause variable biomechanical effects.

In this study, we analysed the biomechanical effect of donning AFO on hemiplegic gait and assessed whether any differences resulted when the AFO was modified. Gait events, plantar pressure, foot contact and centers of pressure(COP) parameters were measured with F-scan pressure sensitive insole system in 21 hemiplegic stroke patients with Brunnstrom's lower extremity stage 3. And those parameters were compaired in each of four different conditions: 1) before donning AFO, 2) donning AFO without any modification, 3) donning AFO with the distal part of metatarsal head trimmed off, 4) donning AFO with third condition and weaning a cushioned heel shoes.

After donning AFO, total contact area and contact width were increased, and initial contact COP and mean COP were displaced medially. But contact length was not changed and initial contact COP and mean COP were not displaced anteroposteriorly. Anteroposterior displacement of COP, slope and velocity of COP were not also changed after donning AFO. Among various AFO adjustments, there were no significant changes of plantar pressure, foot contact and COP parameters.

The results suggest that 1) AFO provides mediolateral stability, but does not provide additional functional rocker actions during stance phase and 2) There were no definite different biomechanical actions among various adjustments of plastic AFO in hemiplegic gait of Brunnstrom's lower extremity stage 3.