Does the ankle affect knee hyperextension during gait in hemiparetic stroke? A pilot study

Background: Knee hyperextension is common following stroke because of changes in joint range of motion (ROM), muscle tone and strength on the hemiparetic side. There is no clear consensus in the literature as to the cause of knee hyperextension during the stance phase of gait. Objectives: Our study aimed to determine the feasibility of methods to investigate the association between ankle joint function and knee hyperextension in patients with hemiparetic stroke during the stance phase of gait. Methods: We used a cross-sectional observational study to assess bilateral ankle muscle strength using a handheld dynamometer, ROM using a digital inclinometer and muscle tone using the Modified Tardieu Scale. The knee angles of the hemiparetic leg during the stance phase of gait were assessed using the Kinovea movement analysis software. Data were analysed using the Statistical Package for the Social Sciences with significance level set at 0.05 and 95% confidence intervals. Results: Twelve participants were included, and no alterations were necessary to the planned methodology. We found positive associations in six participants between the tibialis anterior muscle tone and the hemiparetic knee angles during heel strike, terminal stance and pre-swing phases ( p < 0.05, p < 0.01 and p < 0.01, respectively). Conclusion: The results of the data analysis suggests that there may be a correlation between tibialis anterior muscle tone and knee hyperextension, a larger study will be imperative to confirm this association. Clinical implications: The methods described in our pilot study are feasible for a larger study to be conducted with the recommendations considered.