Effects of intermittent claudication due to arterial disease on pain-free gait.

INTRODUCTION: Studies of intermittent claudication gait report inconsistent outcomes. Changes in gait are often attributed to degradation of calf muscles, but causation has not been proven through real-time electromyographic data. Neither have effects of walking speed been fully considered. This study aimed to investigate the effect of intermittent claudication on kinematics, kinetics and muscle activity during pain-free gait. METHODS: 18 able bodied individuals and 18 with intermittent claudication walked at their preferred speed while lower limb kinematic, kinetic and electromyography data were collected. FINDINGS: People with intermittent claudication walk slower and with reduced step length. Internal ankle plantarflexion moment (P = 0.004, effect size = 0.96) and ankle power generation (P < 0.001, effect size = 1.36) in late stance were significantly reduced for individuals with intermittent claudication. Significant moment and power reductions at the knee and power reduction at hip occurred in early stance, with similar reductions in early and late stance for ground reaction forces. Peak electromyography of soleus activity was significantly reduced in late stance (P = 0.01, effect size = 1.1, n = 13). Effects were independent of walking speed. INTERPRETATION: Reductions in ankle plantarflexion moments and power generation were consistent with reduced soleus electromyography activity and reduced peak vertical ground reaction forces during late stance. These effects are not due to a reduced walking speed. Changes in knee and hip function are also unrelated to walking speed. These outcomes provide a platform for the design and evaluation of interventions that seek to restore normal walking and improve pain-free walking distances for people with intermittent claudication.

Restricting ankle motion via orthotic bracing reduces toe clearance when walking over obstacles.

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. This study determined the contribution of sagittal plane ankle motion in achieving lead-limb clearance during obstacle negotiation. METHODS: Twelve 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 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.