Navigating the Learning Curve

At Marins Med, we understand that choosing and adapting to an upper limb prosthesis is a deeply personal journey. Our commitment is to provide innovative solutions that not only restore functionality but also seamlessly integrate into your daily life. One of the critical aspects influencing prosthetic acceptance is the ease with which users can learn to operate their devices. Today, we delve into the nuances of body-powered prosthetic devices, particularly focusing on Voluntary Opening (VO)systems, and explore how thoughtful design and training can bridge the gap between functionality and user comfort.

Understanding Body-Powered Prostheses

Body-powered prostheses have long been favored for their reliability and direct control mechanisms. These devices operate through a harness and cable system that translates body movements into prosthetic actions. Within this category, there are two primary types of terminal devices:

 

1. Voluntary Closing (VC) Devices: These are more intuitive, mimicking the natural      action of closing the hand to grasp objects. Users pull on the harness to close the prosthesis, similar to how one would naturally clasp an object.
2. Voluntary Opening (VO) Devices: These operate in the opposite manner. The      prosthesis remains closed by default and opens when the user activates it. This inverse action can feel counter-intuitive, requiring users to train their brains to perform what is essentially an unnatural hand movement.

 

The Challenge with Voluntary Opening Devices

VO devices, while offering distinct advantages in certain scenarios, present a unique learning curve. The fundamental issue lies in their operation: opening the prosthesis requires an action that isn’t naturally aligned with how we grasp objects. Instead of the intuitive motion of closing a hand to grip, users must train themselves to perform the opening action first, which can be mentally taxing and physically demanding.

A pivotal study published in the Journal of NeuroEngineering and Rehabilitation by Huinink et al. (2016) titled “Learning to use a body-powered prosthesis: changes in functionality and kinematics”sheds light on this very challenge. The researchers investigated how different training regimens affect the functional performance and movement patterns of novice body-powered prosthesis users.

Insights from the Research

The study involved 30 able-bodied participantstrained over two weeks using a body-powered prosthetic simulator. They were divided into groups focusing on:

 

• Direct Grasping (DG): Mimicking the natural action of closing the hand to grasp.
• Indirect Grasping (IG): Transferring objects from the sound hand to the      prosthetic hook.
• Fixation (FIX): Holding objects stationary while performing tasks with the sound hand.    
• Combination (COM): A mix of DG, IG, and FIX tasks.

 

Key Findings:

 

1. Functional Improvement: All training groups, including the control group, showed      significant improvement in functional tasks post-training. However, the DG group exhibited the largest gains, suggesting that training methods closely aligned with natural grasping can enhance prosthetic functionality more effectively.
2. Kinematic Adaptations: Over the training period, participants developed faster      and more efficient movement patterns. Notably, the IG group demonstrated shorter plateau times and better grip force control, indicating that tasks involving the sound hand can facilitate smoother prosthetic operations.
3. Grip Force Control: Improvements in grip force control were modest, highlighting an area where VO devices, in particular, may require more focused training to achieve optimal functionality.

 

Bridging the Gap with ProHensor

At Marins Med, we take these insights to heart. Our ProHensor device is meticulously designed to address the inherent challenges associated with Voluntary Opening systems while leveraging their unique benefits. Here’s how ProHensor bridges the gap between functionality and user comfort:

Voluntary Closing and Locking Mechanism:

Unlike traditional VO devices, ProHensor employs a Voluntary Closing (VC) method, which aligns more naturally with the way we instinctively grasp objects. This intuitive action reduces the cognitive load on users, making the initial learning phase smoother and more aligned with natural hand movements.

Self-Actuating Locking Mechanism:

One of the standout features of ProHensor is its self-actuating locking mechanism. This innovative design allows the prosthesis to maintain a hold on objects without requiring continuous physical or mental effort from the user. By locking automatically once a grasp is achieved, ProHensor minimizes fatigue, enabling users to perform tasks more efficiently and with greater comfort over extended periods.

Enhanced Proprioceptive Feedback:

Building on the research by Huinink et al., the ProHensor integrates design elements that enhance proprioceptive feedback. This means users receive better sensory information about the prosthesis’s position and the force applied during grasping, facilitating more precise and controlled movements.

User-Centric Design:

ProHensor’s ergonomic design ensures that all movements are swift and predictable, reducing the mental effort required to operate the device. The intuitive action of closing the prosthesis, combined with the locking mechanism, allows users to focus on task execution rather than grappling with device responsiveness.

Promoting Prosthetic Acceptance

The ultimate goal is to promote prosthetic acceptance by ensuring that users feel confident and capable with their devices. ProHensor, backed by rigorous research and user-focused design, stands as a testament to what’s possible when innovation meets empathy. By acknowledging the initial challenges posed by VO devices and addressing them through thoughtful design and comprehensive training, we strive to make the transition to prosthetic use as seamless as possible.

Conclusion

Adapting to a body-powered prosthesis, especially a VO device, is undeniably challenging. At Marins Med, we are dedicated to empowering our users with tools and knowledge that foster independence and enhance quality of life. ProHensor is not just a prosthetic device; it’s a gateway to reclaiming functionality and embracing a future where prosthetic acceptance is not just achievable but a reality.

For more information on ProHensor and our comprehensive training programs, contact us today and take the first step towards a more empowered tomorrow.

 

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References:

Huinink, L. H. B., Bouwsema, H., Plettenburg, D. H., van der Sluis, C. K., & Bongers, R. M. (2016). Learning to use a body-powered prosthesis: changes in functionality and kinematics. Journal of NeuroEngineering and Rehabilitation, 13, 90. DOI: 10.1186/s12984-016-0197-7