Characterization of Bilateral Ankle Mechanics Post-Stroke and Its Relationship to Impaired Posture and Gait Function

Among the possible sensorimotor consequences of stroke, impaired control of posture and gait is a major cause of chronic disability, significantly impacting the quality of life of 7 million stroke survivors in the US. Mounting evidence supports the critical role of the human ankle joint in posture and gait control, serving as the first line of defense against external disturbances at the interface between the lower body and the physical world—a mechanism known as the ankle strategy. However, little is known about how stroke affects ankle mechanics during upright posture control and gait. Previous studies characterizing ankle mechanics following stroke have been conducted in overly restrictive settings, often involving a seated position, limiting analysis to a single degree-of-freedom of the ankle in the sagittal plane, and primarily focusing on the paretic ankle. Furthermore, it remains unclear which specific alterations in ankle mechanics contribute to impaired posture and gait control. This lack of comprehensive knowledge prevents clinicians from effectively utilizing current findings to develop rehabilitative strategies. This project aims to address these knowledge gaps with two primary objectives. First, we will characterize ankle mechanics during lower-extremity function. The characterization will encompass both paretic and non-paretic ankles across different planes of motion (specifically, sagittal and frontal planes) during upright posture control and walking (Aim 1). Next, we will conduct a pilot study to evaluate the relationships between various aspects of the characterized ankle mechanics and performance metrics associated with posture control and gait functions (Aim 2). Additionally, we will assess the predictive capacity of robotic characterization outcomes for impaired posture and gait functions in stroke survivors, comparing them to conventional, yet subjective, clinical measures of ankle impairments. This research, involving 20 chronic stroke survivors and 20 age-matched unimpaired individuals, will validate the effectiveness of the proposed robotic approach and provide a foundation for future studies exploring the link between altered ankle mechanics and impaired posture and gait functions in stroke survivors. The contribution of this research is clinically significant because the objective and refined characterization of 2D ankle mechanics bilaterally during upright posture control and gait—unachievable with subjective clinical assess- ments or simple robotic evaluations—will provide clinicians with richer insights into a patient’s particular ankle impairments. Furthermore, understanding the relationship between detailed ankle mechanics and functional per- formance of posture and gait will enable clinicians to identify specific and clinically relevant aspects of altered ankle mechanics and prescribe targeted interventions, such as exercise training programs (e.g., side- and direction- specific stretching or strengthening exercises) and pharmacological treatments (e.g., Botulinum toxin injection targeting specific muscles). Successful completion of this research will not only enhance lower-extremity func- tion in stroke survivors but also yield secondary benefits, such as reduced fatigue during motor tasks, increased independence in daily activities, and lower healthcare costs, ultimately improving their quality of life. Project Number: 1R03HD118030-01A1 | Fiscal Year: 2026 | NIH Institute/Center: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | Principal Investigator: Hyunglae Lee | Institution: ARIZONA STATE UNIVERSITY-TEMPE CAMPUS, SCOTTSDALE, AZ | Award Amount: $160,620 | Activity Code: R03 | Study Section: Special Emphasis Panel[ZRG1 MSOS-E (05)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11303780