RehabWeek/ISPO Canada Best Student Poster: Brandon Nguyen!

Brandon Nguyen standing in front of his poster at RehabWeek wearing a dark blue shirt. His poster features images of the smartphone app and graphs.

Congrats to Brandon Nguyen who was awarded the Best Student Poster award by the International Society of Prosthetics & Orthotics Canada at RehabWeek in Toronto this past week! Brandon presented his work, “Accuracy and repeatability of using smartphone sensors for orthotic tuning.”

Check out his abstract and poster.

You can also download the HuskySTEPS app to try it out yourself.

The ISPO student award winners for 2019 rehab week, including four students with Brandon in the middle, and the two main conference award organizers.

This work, in collaboration with Nick Baicoianu and Darrin Howell, examined the accuracy of measuring shank-to-vertical angle during walking with a smartphone compared to traditional motion capture systems. Shank-to-vertical angle is a measure used by orthotists and therapists for AFO tuning and gait training. The short story – placing the smartphone on the front of the shank can measure shank-vertical-angle with errors less than two degrees compared to traditional motion capture systems, with high intra-rater and inter-rater repeatability across days.

Brandon dressed in his purple graduation regalia in front of the UW fountain

Brandon also recently finished his Doctorate of Physical Therapy (DPT) degree at the University of Washington – making him one of the rare engineer-therapists. In recognition of his efforts to combine academic scholarship with social awareness and concern, he was awarded the 2019 UW Graduate Medal.

Congratulations Brandon! We are so excited to see what you do next.

H Choi, KM Peters, M MacConnell, K Ly, E Eckert, KM Steele (2017) “Impact of ankle foot orthosis stiffness on Achilles tendon and gastrocnemius function during unimpaired gait.” Journal of Biomechanics

Journal article in Journal of Biomechanics:

How does the stiffness of an AFO impact the muscultendon dynamics of the gastrocnemius?


Method combining ultrasound and musculoskeletal modeling to evaluate changes in muscle and tendon length.

Ankle foot orthoses (AFOs) are designed to improve gait for individuals with neuromuscular conditions and have also been used to reduce energy costs of walking for unimpaired individuals. AFOs influence joint motion and metabolic cost, but how they impact muscle function remains unclear. This study investigated the impact of different stiffness ankle foot orthoses (AFOs) on medial gastrocnemius muscle (MG) and Achilles tendon (AT) function during two different walking speeds. We performed gait analyses for eight unimpaired individuals. Each individual walked at slow and very slow speeds with a 3D printed AFO with no resistance (free hinge condition) and four levels of ankle dorsiflexion stiffness: 0.25 Nm / °, 1 Nm / °, 2 Nm / °, and 3.7 Nm / °. Motion capture, ultrasound, and musculoskeletal modeling were used to quantify MG and AT lengths with each AFO condition. Increasing AFO stiffness increased peak AFO dorsiflexion moment with decreased peak knee extension and peak ankle dorsiflexion angles. Overall musculotendon length and peak AT length decreased, while peak MG length increased with increasing AFO stiffness. Peak MG activity, length, and velocity significantly decreased with slower walking speed. This study provides experimental evidence of the impact of AFO stiffness and walking speed on joint kinematics and musculotendon function. These methods can provide insight to improve AFO designs and optimize musculotendon function for rehabilitation, performance, or other goals.



KM Steele, RW Jackson, BR Shuman, SH Collins (2017) “Muscle recruitment and coordination with an ankle exoskeleton.” Journal of Biomechanics

Synergy structure and activations had minimal changes with increasing exoskeleton torque.

Journal article in Journal of Biomechanics:

How do muscle activations and synergies change when an individual wears an ankle exoskeleton during gait?

Abstract: Exoskeletons have the potential to assist and augment human performance. Understanding how users adapt their movement and neuromuscular control in response to external assistance is important to inform the design of these devices. The aim of this research was to evaluate changes in muscle recruitment and coordination for ten unimpaired individuals walking with an ankle exoskeleton. We evaluated changes in the activity of individual muscles, cocontraction levels, and synergistic patterns of muscle coordination with increasing exoskeleton work and torque. Participants were able to selectively reduce activity of the ankle plantarflexors with increasing exoskeleton assistance. Increasing exoskeleton net work resulted in greater reductions in muscle activity than increasing exoskeleton torque. Patterns of muscle coordination were not restricted or constrained to synergistic patterns observed during unassisted walking. While three synergies could describe nearly 95% of the variance in electromyography data during unassisted walking, these same synergies could describe only 85–90% of the variance in muscle activity while walking with the exoskeleton. Synergies calculated with the exoskeleton demonstrated greater changes in synergy weights with increasing exoskeleton work versus greater changes in synergy activations with increasing exoskeleton torque. These results support the theory that unimpaired individuals do not exclusively use central pattern generators or other low-level building blocks to coordinate muscle activity, especially when learning a new task or adapting to external assistance, and demonstrate the potential for using exoskeletons to modulate muscle recruitment and coordination patterns for rehabilitation or performance.Synergy structure and activations had minimal changes with increasing exoskeleton torque.

H Choi, TL Wren, KM Steele (2016) “Gastrocnemius operating length with ankle foot orthoses in cerebral palsy.” Prosthetics & Orthotics International

Example of gastrocnemius operating length from one subject with different AFOs.

Journal article in Prosthetics & Orthotics International:

How does the operating length of the gastrocnemius vary with different common AFOs in children with cerebral palsy?

Clinical relevance: Determining whether ankle foot orthoses stretch tight muscles can inform future orthotic design and potentially provide a platform for integrating therapy into daily life. However, stretching tight muscles must be balanced with other goals of orthoses such as improving gait and preventing bone deformities.

Michael MacConnell, Bradley Wachter, CJ Smith, and Sasha Portnova Present at the Undergraduate Research Symposium

Undergraduate Research Symposium graphic displaying May 20th in Mary Gates Hall.

Our undergraduate researchers presented in Mary Gates Hall today, presenting their research from 11am-1pm. Member of the community, faculty, and staff stopped by to hear about Bradley and CJ’s work developing an open-source proximal control orthosis, Sasha’s wrist-driven, wrist-hand orthosis, and Michael’s work on ankle foot orthoses as a rehabilitation tool. Great job, everyone!



CJ and Bradley, members of our research team, discuss the outcome measures of their proximal control device with interested community members. Michael MacConnell, a member of our research team, shares his research with members of the community. Sasha Portnova, a member of our research team, fields questions from an interested member of the community about her wrist-driven, wrist-hand orthosis.