Elevated Vacuum: Why it’s Beneficial for Lower Limb Amputees
August 3, 2021
Introducing the BioStep™ Evo Gait Analysis
From its vertical floor reaction force to its ankle power dynamics, BioStep® Evo stands out with a gait experience remarkably close to natural.
Measurement System
Professor Yamamoto employed a sophisticated measurement system, featuring 12 infrared cameras, 4 force plates, and a central computer for precise data collection. This carefully controlled setup allowed for a detailed observation and analysis of gait, ensuring a true-tolife walking scenario.
The results, visualized through a state-of-the-art visual 3D program, provide a holistic understanding of BioStep® Evo’s performance. The skeleton on the left side of the screen represents the prosthetic user, the blue lower limb represents the prosthetic leg, and the red lower limb represents the intact leg. Using this system, the study measures various key elements , such as ground reaction force during the different steps of the stance phase, and represents them on the Y axis of the graphs.
Insights from gait analysis
The study measured various aspects, showing how BioStep® Evo’s NRG Technology™ replicates natural movement:
- Vertical Component of Ground Reaction Force
- Anterior-Posterior Direction of Ground Reaction Force
- Ankle Angle
- Ankle Power
- Knee Joint Angle
Vertical Component of Ground Reaction Force
Gait remarkably close to natural
From this graph, it becomes evident how the gait of the BioStep® Evo closely resembles that of the intact limb, confirming that NRG Technology™ of BioStep® has been designed to replicate the natural movement of the calf and shin muscles.
BioStep® Evo exhibited a higher and more prolonged first peak, indicating a smoother response and roll-over, while competitors showed weaker shock absorption capabilities, potentially causing discomfort and walking issues. BioStep® Evo’s line shape closely resembles the intact limb, indicating a more biomimetic design than the other feet and an enhanced dynamic response.
Anterior-posterior direction component of the ground reaction force
Fluid Step with a continuous dynamic response
BioStep® Evo proved to provide consistent and smooth force curve throughout the mid-stance phase, distinguishing it from its competitors. With BioStep® Evo, the transition from braking (negative value on the y-axis) to propulsion (positive value) is smooth, mirroring natural walking patterns. Conversely, in the other two dynamic feet tested, a tendency highlighted by circle 1, referred to as a “dead spot,” lead to recurrent braking. Towards the end of the stance phase, BioStep® Evo demonstrated higher acceleration, closely resembling a intact limb.
Ankle Angle
Remarkable range of motion in both plantar flexion and dorsiflexion
The BioStep® Evo line representing plantar flexion and dorsiflexion shows a trend which more closely resembles that of the intact limb while the other two feet have a smaller plantar flexion angle as you can see by the pattern of the lines highlighted in circle 1. BioStep® Evo displayed a remarkable range of motion in both plantar flexion and dorsiflexion, emphasizing its excellence in ankle joint design.
Ankle Power
Biomimic gait with superior shock absorption
Evo Foot displayed more natural patterns during the load-response phase and smooth transitions into mid-stance and terminal stance. You can see how the line trend of BioStep® Evo shows in detail:
• greater shock-absorption (Circle 1)
• facilitation of forward leaning (Circle 2), similar to the natural stance where the stretched anterior tibialis muscle pulls on the lower leg
• a smooth waveform after the mid- stance, with a pattern almost identical to that of the intact limb (Circle 3)
CONCLUSION
The gait analysis study of BioStep® Evo positions it as a frontrunner in dynamic prosthetic feet, providing evidence of its capabilities in terms of roll-over smoothness, superior shock absorption, and allowing a natural, reactive gait. It affirms its effectiveness in providing a natural and comfortable walking experience.
