Theme of this quarter: Significant material and design innovations.

This article is an in-depth exploration of the groundbreaking advancements driving Limber’s latest prosthetic devices. Recently, we had our semi-annual Product Roadmap call with our clinical partners. In this overview, Josh, our resident scientist, co-founder, and CEO, delves into the core innovations that are redefining the capabilities and user experience of our prosthetics. This session is designed for our valued clinical partners and prosthetics professionals, offering a clear, credible, and accessible look at the science that makes Limber devices feel more natural, responsive, and durable.

Introducing M3 Material: A Step Forward

The latest evolution in our material science is what we call our “M3 material”, which was set for official release on August 5th. M3 will be integrated into our LF1 Limber Foot and the PX1 complete transtibial prosthesis. This advanced material offers a compelling suite of improvements:

  • 15% lower weight compared to previous generations of our already ultra-lightweight materials. 
  • 10x lower water absorption, ensuring consistent performance in varying environmental conditions.
  • Faster delivery times due to improved production stability.
  • Reduced degradation over extended periods of time, enhancing long-term reliability and fit.

These enhancements in material properties translate directly into an improved product experience for Limber users.

Technical Highlights from Our Presentation

Discussion of Hygroscopic Thermoplastics

Hygroscopic materials are materials that have some ability to absorb moisture from their surroundings. In the context of prosthetics, this can alter their mechanical properties, affecting flexibility, stiffness, and energy return. Understanding these changes is crucial for designing devices that perform reliably across different environments.

Humidity and Energy-Return Performance

Previous materials showed an eventual drop in energy return as they absorbed humidity. This didn’t impact wearers on a practical level, but the M3 material, in any case, demonstrates negligible change in energy return across the full humidity range. This means users can expect consistent, predictable performance whether in dry desert air or humid coastal environments, and for years to come.

The MXT Truss: Engineered for Natural Movement

Limber’s MXT truss structure, formerly referred to as simply “the pylon” is engineered for unparalleled multi-axial flexibility. Its innovative design facilitates optimal load transfer between the foot and socket, crucial for a natural gait. The MXT structure is designed to mimic the natural inversion and eversion movements of the ankle. Furthermore, it possesses a unique ability to coil and capture energy during the stance phase, returning it efficiently during push-off.

Rigorous testing against L5986 requirements confirms its capabilities, including achieving:

  • Up to 10 degrees of dorsiflexion
  • Up to 8 degrees of plantar flexion
  • More than 8 degrees of inversion

Weight Optimization and Center of Gravity Control

Weight reduction remains a cornerstone of Limber’s design philosophy. The previous Unileg achieved an average weight reduction of more than 25% as compared to the previous device worn by Clinical Trial participants. With the introduction of M3 material and the refined PX1 prosthesis, we’ve pushed this further, achieving nearly 40% average weight savings. Critically, this weight reduction is still being coupled with a movement of the center of gravity closer to the knee. This optimization results in a significantly smoother and lighter swing phase, reducing user fatigue and enhancing overall mobility.

Innovations in Bumper Design

The new bumper design incorporates a low-friction, high-return material that significantly enhances the user experience. This advanced material facilitates a smoother heel-strike-to-mid-stance transition, reducing impact forces and improving comfort. We’ve also addressed common user complaints by engineering the bumper to deliver at least 10x better durability while also reducing squeaking and rubber noise. Installation is made way more convenient, with the tool-free tail-wrap method, allowing for quick and secure attachment.

Manufacturing and Design Updates

Enhancing Production and Customization

Our manufacturing processes have seen substantial updates to improve efficiency and expand capabilities in recent months. The new gloss-black M3 devices are being developed to potentially avoid coating, saving three or more production days per unit. We are also experimenting with high-viscosity pseudoplastic coatings for enhanced durability and aesthetics.

Conclusion: A Synthesis of Advanced Engineering

The latest generation of Limber prosthetic devices represents a significant leap forward, driven by a holistic approach to innovation. Our advancements in material science, particularly with the M3 material, provide unmatched durability and consistent performance. The sophisticated flexible structures of the MXT truss mimic natural biomechanics, optimizing energy return and load transfer. Improved weight distribution, with a lower center of gravity, ensures a more natural and less fatiguing gait. Finally, these innovations are underpinned by manufacturing improvements, including advanced 3D printing, enabling us to deliver more refined, responsive, and user-centric prosthetic solutions than ever before. 

If you would like to learn more about becoming a partner clinic, please reach out to us at LimberProsthetics.com