A great deal of research has been done on the adaptive strategies of individuals who have been affected by a gait altering ailment, but there is little research on the adaptive strategies to imposed restrictions in the healthy population. The role of the ankle in healthy gait is to generate a “push-off” force to create forward propulsion of the body (Winter, 2004). The purpose of this thesis was to identify adaptation patterns and compensation strategies in individuals while wearing and not wearing a device to reduce ankle motion(Ankle Motion Minimizer – AMM). Motion capture and force plate data were collected to determine the lower body kinematics and joint powers during both level ground walking and obstacle avoidance tasks. Repeated Measure ANOVAs with an alpha level of 0.05 determined that differences in the ankle angles and the ankle, knee, and hip powers existed between the various conditions. Results showed that participants had a decreased range of motion and power production at the ankle joint while wearing the AMM. Meanwhile, an increase in the power bursts from the ipsilateral knee were observed during the AMM conditions as well as small increases at the contralateral ankle and ipsilateral hip during the unilateral AMM condition. EMG analysis showed a distinct muscle activation pattern for each individual muscle during the different conditions. From this investigation, individuals who are unable to produce power through the ankle joint, were able to increase power propulsion predominately at the knee to compensate for the lack of propulsion provided by the ankle, therefore allowing ambulation to continue.

A great deal of research has been done on the adaptive strategies of individuals who have been affected by a gait altering ailment, but there is little research on the adaptive strategies to imposed restrictions in the healthy population. The role of the ankle in healthy gait is to generate a “push-off” force to create forward propulsion of the body (Winter, 2004). The purpose of this thesis was to identify adaptation patterns and compensation strategies in individuals while wearing and not wearing a device to reduce ankle motion(Ankle Motion Minimizer – AMM). Motion capture and force plate data were collected to determine the lower body kinematics and joint powers during both level ground walking and obstacle avoidance tasks. Repeated Measure ANOVAs with an alpha level of 0.05 determined that differences in the ankle angles and the ankle, knee, and hip powers existed between the various conditions. Results showed that participants had a decreased range of motion and power production at the ankle joint while wearing the AMM. Meanwhile, an increase in the power bursts from the ipsilateral knee were observed during the AMM conditions as well as small increases at the contralateral ankle and ipsilateral hip during the unilateral AMM condition. EMG analysis showed a distinct muscle activation pattern for each individual muscle during the different conditions. From this investigation, individuals who are unable to produce power through the ankle joint, were able to increase power propulsion predominately at the knee to compensate for the lack of propulsion provided by the ankle, therefore allowing ambulation to continue.

Yes / Background: When trans-tibial amputees cross obstacles leading with their prosthesis, foot clearance is achieved using compensatory swing-phase kinematics. Such compensation would suggest able-bodied individuals normally use swing-phase ankle dorsiflexion to attain adequate obstacle clearance, however, direct evidence of such contribution is equivocal. The present study determined the contribution of sagittal plane ankle motion in achieving lead-limb clearance during obstacle negotiation. Methods: 12 male able-bodied individuals (ages 18-30) completed obstacle crossing trials while walking on a flat surface. Lead-limb (right) ankle motion was manipulated using a knee-ankle-foot orthosis. Trials were completed with the ankle restricted at a neutral angle or unrestricted (allowing ~ ±15  plantar/dorsiflexion). Findings: Restricted ankle motion caused significant increase in trail-limb foot placement distance before the obstacle (p=0.005); significant decrease in vertical toe clearance (p<0.003), vertical heel clearance (p=0.045) and lead-limb foot placement distance after the obstacle (p=0.045); but no significant changes in knee angle at instant of crossing or in average walking speed. Interpretation: The shifts in foot placements altered the part of swing that the lead-limb was in when the foot crossed the obstacle, which led to a decrease in clearance. These adaptations may have been due to being unable to dorsiflex the ankle to ‘lift’ the toes in mid-swing or to being unable to plantarflex the ankle during initial contact following crossing, which changed how the lead-limb was to be loaded. These findings suggest individuals using ankle bracing or those with ankle arthrodesis, will have reduced gait safety when negotiating obstacles.