Powered Gait Assistance Torque Control for Crouch Gait
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Solution Overview
Problem
Current interventions for crouch gait in cerebral palsy, such as surgery, physical therapy, and orthotic devices, have variable and inconsistent outcomes, and there is a need for more effective methods to preserve and augment strength continuously in individuals with crouch gait.
Innovation Solution
Powered gait assistance systems that include a programmed controller, sensors, and a torque applicator to provide assistive torque to the patient's leg joints during specific stages of the gait cycle, improving muscle activity, joint actuation, and range of motion, and can be integrated with existing orthotics for adjustable and modular use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthotic bracing is used to increase mobility, then knee extension is temporarily improved, but muscle weakness increases over time due to restricted motion
Solution Approach 1:
The powered orthotic system dynamically adjusts knee joint support based on real-time detection of crouch gait patterns through sensors and controllers, providing active correction rather than passive restriction. The system modulates the orthotic response to match the patient's movement phase and intensity, enabling mobility improvement without the detrimental muscle atrophy associated with static bracing.
Solution Approach 2:
The system incorporates sensors that continuously monitor knee joint angle, gait phase, and crouch patterns, feeding this information to a controller that adjusts orthotic support in real-time. This closed-loop feedback mechanism enables the system to provide precise, adaptive assistance that corrects crouch gait while preserving natural muscle activation patterns, thereby improving knee extension without causing muscle weakness.
2Reliability
If surgery is performed to correct crouch gait, then knee extension may be improved, but the solution is invasive with variable outcomes
Solution Approach 1:
The patent replaces invasive surgical mechanical corrections with a powered orthotic system that uses motors, sensors, and controllers to actively correct crouch gait. This external mechanical system substitutes for surgical intervention, providing adjustable, reversible correction without the risks and variability of surgery. The orthotic system can be tuned to each patient's specific needs and modified over time as gait patterns improve.
Solution Approach 2:
The powered orthotic system allows dynamic adjustment of correction parameters such as knee joint torque, support force magnitude, and activation timing. These parameters can be modified based on patient progress, tolerance, and changing gait patterns, providing a flexible alternative to the fixed anatomical changes produced by surgery. The system adapts to individual patient characteristics and can evolve with the patient's development.
3Strength
If muscle strengthening programs are implemented, then walking capability may improve, but outcomes are inconsistent and activity levels must be maintained
Solution Approach 1:
The powered orthotic system enables patients to actively participate in their own rehabilitation by providing real-time assistance during daily activities and gait training. The system detects crouch gait patterns and automatically provides corrective torque, allowing patients to practice and strengthen muscles during natural movement rather than requiring structured exercise programs. This continuous, context-aware intervention ensures consistent muscle activation without requiring high activity levels or specialized therapy sessions.
Solution Approach 2:
The orthotic system provides continuous muscle strengthening through real-time assistance during all phases of gait and daily activities, rather than intermittent therapy sessions. The sensors continuously monitor for crouch patterns, and the powered orthotic delivers corrective torque whenever needed, ensuring consistent muscle engagement. This continuous intervention produces more reliable strength gains compared to periodic strengthening programs that depend on patient compliance and activity level maintenance.
4Force
If functional electrical stimulation is applied to extend the knee, then muscle activation can be achieved, but the stimulation intensity required is difficult to reach
Solution Approach 1:
The powered orthotic system introduces a mechanical intermediary (motor-driven torque applicator) that assists knee extension without requiring direct high-intensity electrical stimulation of the muscles. The orthotic device applies corrective force through the orthotic structure itself, bypassing the need to overcome severe muscle inhibition or spasticity that limits FES effectiveness. This mechanical mediation enables knee extension assistance even when electrical stimulation alone cannot generate sufficient force.
Solution Approach 2:
The orthotic system segments the knee extension task into multiple components: sensory detection of crouch patterns, control signal generation, and mechanical torque application. By dividing the function across sensors, controllers, and powered orthotic elements, the system achieves effective knee extension assistance without relying on a single high-intensity intervention like maximum FES. The segmented approach allows gradual, controlled force application that is easier to deliver and more comfortable for patients.
Data Source
AI summary
Disclosed are powered gait assistance systems that include a controller, sensors, and a torque applicator (motor, spring, etc.) coupled to a patient's hips, thighs, knee, lower leg, ankle, and/or foot and operable to apply assistive torque to the patient's leg joint(s) to assist the patient's volitional joint actuating muscle output during selected stages of the patient's gait cycle, such that the applied torque improves the patient's leg posture, muscle output, range of motion, and/or other parameters over the gait cycle. The sensors can include a torque sensor that measures torque applied, one or more joint angle sensors, a ground contact sensor that measures ground contact of the patient's foot, and/or other sensors. The controller can determine what stage of the patient's gait cycle the patient's leg is in based on sensor signals and cause the torque applicator to apply corresponding torque to the joint(s) based on the gait cycle stage, sensor inputs, and known patient characteristics.