Effects of Altered Somatosensory Input on Gait Kinetics and Kinematics Via Different Footwear in Individuals with Chronic Post-Stroke Hemiparesis

<em>Purpose/Hypothesis:</em> Individuals with post-stroke hemiparesis walk with significant asymmetries, leading to slow, effortful walking, and a high risk of falls. One contributing factor is altered sensation on the plantar surface. Studies examining altered somatosensory input via insoles, vibration and other tactile stimuli observed improvements in hemiparesis gait. This study investigates whether altering somatosensory input through different footwear can affect kinetics, kinematics and muscle activity during walking post-stroke. We hypothesized the barefoot conditions would have increased dorsiflexion (heel-strike, swing), increased plantarflexion during toe-off, increased muscle activity and kinetics, compared to memory foam conditions. <em>Participants:</em> 13 individuals with chronic post-stroke hemiparesis (4F/9M, age=56.9±14.4yrs) and 11 age-similar non-impaired controls (4F/7M, age=50.3±12.3yrs) <em>Materials and Methods:</em> All participants were tested under 3 footwear conditions: self-selected sneakers (SS), barefoot (BF), memory foam slippers (MF). Trunk and lower extremity kinematics were collected utilizing a 12-camera Vicon motion analysis system. Ground reaction forces were collected utilizing an instrumented treadmill. Medial gastrocnemius (MG) and tibialis anterior (TA) activity was collected using surface EMG. Ankle angle at heel strike (HS), ankle angle at toe-off (TO), peak dorsiflexion (DF) in swing, TA co-contraction index (TA CCI), and peak propulsive impulsive were assessed using a 3 (limb: control, non-paretic (NP), paretic (P)) x 3 (footwear condition: SS, BF, MF) mixed factorial ANOVA. A priori significance was set at p ≤ .05. <em>Results:</em> For ankle angle at HS, there was a statistically significant limb x footwear interaction (p< .01), where in the control limb, we observed greater peak swing ankle dorsiflexion during MF (p< .01) compared to SS (p=.05) and barefoot (p< 0.01) conditions. For ankle angle at TO, there was a statistically significant main effect of Footwear, where regardless of limbs, greater plantarflexion at TO was observed in SS than the other conditions. For ankle angle during swing we observed a statistically significant main effect of Footwear, where regardless of limbs, greater dorsiflexion was observed when wearing MF (p< .05) than other conditions. For TA CCI, there was a significant main effect of Footwear (p < .01), where regardless of limbs, wearing MF promoted greater TA activity at toe off compared to SS (p = .02) and barefoot (p = .04). Statistically significant main effect of Footwear was observed for propulsive impulse, where regardless of limbs, wearing SS generated greater propulsive impulse than barefoot walking. <em>Conclusions</em>: This study noted that altering plantar somatosensation through different shoes had a significant effect on ankle kinematics and muscle activation during gait. Specifically, foam slippers promoted ankle dorsiflexion angle at heel strike, during swing, and increased TA muscle activity at toe off. These findings suggest that memory foam slippers can be incorporated into post-stroke gait training to address commonly-observed reduced ankle dorsiflexion and insufficient TA muscle activity, which contribute to foot-drop during gait. However, if the goal is to increase propulsive impulse, memory slippers may not be an appropriate choice. Hence, this study may provide clinicians with new ideas for facilitating improved gait kinematics in stroke rehabilitation.