Knee and Ankle Biomechanics during Level Walking Both Prior to and Following a Stroke

Abstract

One of the side effects to gait following a stroke is foot drop syndrome. This presents movement challenges at the ankle, which necessitate compensations at other lower extremity joints. The knee joint angle patterns during stance and swing are often altered, though at faster walking speeds knee joint angles tend to be more similar to normal able bodied individuals. Comparisons between able bodied individuals, though beneficial, lack the strengths of a longitudinal study. The inability of predicting a stroke make these types of studies nearly impossible, especially on a large scale. PURPOSE: To compare level walking biomechanics of one participant prior to and following a stroke. METHODS: 3D kinematics and kinetics of the ankle and knee were analyzed during the stance phase of level walking for one participant (age: 64) at a self-selected walking speed prior to and 5 months post-stroke. A faster walking condition was added in post-stroke testing. RESULTS: Pre-stroke walking speed (1.37 m/s) was faster than post-stroke preferred walking speed (1.19 m/s) but similar to post-stroke fast walking speed (1.38 m/s). The ankle joint changed from dorsiflexion to plantarflexion post-stroke at heel strike [pre (4.0±1.2 deg), post-slow (-8.34±1.9 deg), post-fast (-5.11±1.4 deg)] and knee flexion at foot strike became more flexed following the stroke [pre (0.22±0.7 deg), post-slow (-13.02±0.06 deg), post-fast (-16.7±1.28 deg)]. In addition, the peak ankle plantarflexion moments were reduced following the stroke [pre (-1.49±0.4 Nm/kg), post-slow (-1.02±0.06 Nm/kg), post-fast (-1.03±0.05 Nm/kg)]. The peak knee extension moment was only greater in the post-fast condition (1.32 Nm/kg) compared with pre-stroke (1.05 Nm/kg). CONCLUSION: During the fast condition, the participant appears to be more similar to the pre-stroke condition at the ankle, but not at the knee. Similar ankle moments between fast and preferred walking post stroke, paired with the large increase in the post-fast knee extension moment show greater reliance on the knee joint while walking fast. This data is consistent in showing that the subject had to compensate at the knee during the post-slow and post-fast testing. The longitudinal nature of this study help confirm findings of deficits in other studies that compare to healthy able bodied individuals.