Research Report

Background Introduction

With an aging population and the increase in neurological and muscular diseases such as stroke, the risk of tripping and falling due to gait disorders has become a serious problem. Research shows that ankle dorsiflexion is crucial for ensuring foot clearance during the swing phase of gait. However, there is limited research on ankle joint dynamics and mechanical energy exchange during the swing phase. Existing studies mainly focus on ankle dorsiflexion during normal walking, but with the development of various devices providing dorsiflexion assistance, it is necessary to understand the minimum energy requirements in these devices.

In recent years, ankle dorsiflexion assistance technology has developed rapidly, especially with the use of advanced actuators and energy recovery devices to improve gait safety and prevent falls. However, these devices need to provide sufficient mechanical power to ensure ankle dorsiflexion assistance during the swing phase. Understanding the dynamic requirements of ankle dorsiflexion is particularly important for designing lightweight, low-power assistive devices.

Paper Source

This article was written by Soheil Bajelan, W. A. (Tony) Sparrow, and Rezaul Begg from Victoria University, published in the Journal of NeuroEngineering and Rehabilitation in 2024. The corresponding author is Soheil Bajelan (soheil.bajelan@vu.edu.au).

Research Work Introduction

Research Process

This study used real-time treadmill gait feedback technology to control ankle dorsiflexion during the swing phase, increasing the foot-ground clearance height by 4 cm. In the experiment, the Anybody modeling system was used to estimate ankle joint torque and dorsiflexor muscle force during the swing phase. The study hypothesized that by increasing the foot-ground clearance height to 4 cm using only the ankle joint, the required dorsiflexor muscle force and torque would be significantly higher than under normal walking conditions.

Experimental Steps:

1. Participant Recruitment: Recruited 8 healthy, physically active male participants (age 35±4 years, height 175±5.6 cm, weight 78±8.9 kg). All participants signed informed consent forms and were screened through health questionnaires to confirm no health issues affecting participation in the experiment.
2. Instrumentation: Used Vicon motion capture system and AMTI dual-plate force-sensing treadmill to record body posture and foot-ground contact forces. Synchronized collection of EMG signals from the Tibialis Anterior (TA) and plantar flexor muscles.
3. Experimental Design: Set baseline gait, requiring participants to walk at a natural speed, determining the Minimum Toe Clearance (MTC). Then increased MTC by 4 cm for each participant, requiring them to achieve the target height using only ankle dorsiflexion during the swing phase.
4. Musculoskeletal Modeling and Simulation: Developed personalized musculoskeletal models using the Anybody modeling system for inverse dynamics analysis, calculating joint angles and dynamic data.

Main Findings

Results showed that increased ankle dorsiflexion did not significantly increase ankle joint torque. However, the force of the Tibialis Anterior muscle did increase significantly, from 2 N/kg to 4 N/kg after toe-off. This is due to the coactivation of the Tibialis Anterior and Gastrocnemius muscles. To ensure an additional 4 cm minimum foot-ground clearance, approximately 0.003 joules/kg of energy needed to be released immediately after toe-off.

Research Conclusions and Significance

This study reveals the interaction between ankle joint torque, muscle force, and energy requirements during the swing phase, indicating that external assistive devices do not need to significantly increase ankle joint torque but need to provide higher mechanical power to achieve rapid dorsiflexion transition before the Minimum Foot Clearance (MFC) event. This is important for designing bio-inspired ankle assistance technologies, such as artificial muscles and humanoid robots. Understanding the dynamic requirements of ankle dorsiflexion helps develop more effective ankle orthoses and exoskeletons.

Research Highlights

• Research Innovation: Real-time gait feedback technology used to control ankle dorsiflexion.
• Systematic Approach: Detailed musculoskeletal modeling and simulation analysis.
• Practical Application: Provided important dynamic requirement data for the design of ankle assistance devices.

Conclusion

This study demonstrates through experimental data that increasing ankle dorsiflexion during the swing phase does not require significantly increased ankle joint torque but does require sufficient mechanical energy. External devices should focus on providing rapid energy bursts before the critical minimum foot clearance event. This has important guiding significance for developing lightweight, low-power ankle assistance technologies. The research results will help improve gait assistance technology, enhancing gait safety and walking ability.

The above analysis and conclusions have strong guiding significance for future research and development, especially in the development and application of personalized and specific gait assistance technologies.