TWIICE One powered exoskeleton: Effect of design improvements on usability in daily-life as measured by Cybathlon race performance

Background Spinal cord injury leading to paraplegia affects the mobility and physiological well-being of nearly one in a thousand people. Powered exoskeletons can temporarily restore the ability to walk. Their relevance in daily life is still limited because of low performance beyond even ground. Cybathlon is an international competition promoting improvements in assistive technology. In this article we present the latest design and results of testing of TWIICE One 2018, one of the competing devices in the 2020 race. Methods A person with a motor-complete spinal cord injury at thoracic level T10 participated as race pilot. Training ahead of the race took place over one week at a rate of 2-5 hours per week. Time to perform each of the 7 tasks of the competition was recorded together with the number of repetitions. Performance is compared over training time and against 2016 race results. Results Progression was observed in all tasks and accounted for by both user training and technology improvements. Final competition rank was second out of 7 participating teams, with a record time of 4'40" min. This represents an average of 40 % improvement with respect to comparable obstacles of the 2016 race, explaining the two ranks of improvement since then. Conclusion These results help understand which features had a positive impact on real life performance of the device. Understanding how design affects performance is a key information to create devices that really improve the life of people living with paraplegia.

Peak Torque Prediction Using Handgrip and Strength Predictors in Men and Women With Motor Complete Spinal Cord Injury

Objectives: To establish predictive equations for peak torque of muscle groups with totally and partially preserved innervation in individuals with motor complete spinal cord injury (SCI), based on hand dynamometry and strength predictor variables. Methods: The cross-sectional study conducted at a rehabilitation hospital consecutively recruited 108 men and women with SCI. All participants performed maximum peak torque tests for shoulder abduction/adduction (isokinetic), trunk flexion/extension (isometric), and handgrip strength testing (hand dynamometer) to establish predictive peak torque equations. The primary outcomes were peak torque variables. Handgrip strength, age, injury level, time since injury, age at injury, body mass, height, body mass index, and physical activity level were the secondary outcomes used as strength predictor variables. Results: Handgrip strength was a predictor variable for shoulder abduction/adduction peak torque. The best predictive models for shoulder abduction/adduction peak torque exhibited R2 = 0.57 and R2 = 0.60, respectively (p ≤ .05). Injury level showed the highest significant predictive capacity for trunk flexion/extension peak torque models (R2 = 0.38 and R2 = 0.29; p ≤ .05). Conclusion: Shoulder abduction/adduction peak torque predictive equations may be an alternative for use in an accessible strength tool (hand dynamometry) to evaluate training and rehabilitation programs. Trunk flexion/extension peak torque equations exhibited moderate correlations and high standard error of the estimates and should be used with caution.