Objective
To investigate the changes of gait patterns in subjects who use the ankle foot orthoses (AFOs) with a variable ankle joint stop.

Method
Six young subjects without a known physical disability were involved in this study. Double upright AFOs with three kinds of ankle joint stops (eg. AFOs with 85^o posterior stop, 90^o posterior stop, and 95^o posterior stop) were used for the right foot and a rigid shoe was used for the left foot. Gait patterns of the subjects using the AFOs with a variable ankle joint stop were evaluated with the three dimensional gait analysis system.

Results
The gait patterns of the subjects with a 85^o posterior stop AFO showed a shorter duration of single support phase than the subjects with a 90^o posterior stop or 95^o posterior stop. They showed the increased maximal knee flexion angles, decreased knee extension angles and decreased ankle range of motions by the kinematics. These linear changes in parameters and kinematics were statistically significant. In kinetics, the gait patterns of the subjects using a AFO with 85^o posterior stop had the largest maximal knee flexion moment and the gait patterns of the subjects using a AFO with 95^o posterior stop had the largest maximal knee extension moment. However these results were not statistically significant.

Conclusion
For the patients with uncontrolled ankle motion, the AFOs with 90^o or 95^o posterior stop would be more desirable than the AFOs with 85^o posterior stop, for the clearance of foot and stability of knees but not for the correction of the knee hyperextension.