Defining a Category in Body-Powered Terminal Devices

Prosthetic terminal devices have long been classified into two well-established categories: Voluntary Opening (VO) and Voluntary Closing (VC). Each of these categories offers distinct advantages but comes with inherent trade-offs. The ProHensor introduces a novel category to this landscape, combining the key benefits of these existing systems while addressing their limitations through its Voluntary Closing and Locking (VC&L) mechanism.

This new approach warrants a closer look at how body-powered prosthetics have been traditionally categorized and how the ProHensor redefines these classifications.

Understanding Traditional Categories

Voluntary Opening (VO) Terminal Devices

VO systems rely on body power to open the device using a cable and harness system while rubber bands or springs return the terminal device to a closed position. These devices are practical for holding objects, as users do not need to maintain continuous tension to keep the device closed. However, this design inherently limits the force that can be applied, as grip strength depends on the tension provided by the rubber bands or springs.

For users whose daily activities require moderate grip strength and frequent holding tasks, such as stabilizing objects or carrying lightweight items, VO devices can be suitable. However, their inability to provide a strong grip force restricts their utility in tasks requiring significant pressure or sustained control.

Voluntary Closing (VC) Terminal Devices

VC systems operate in the opposite manner: body power is used to close the terminal device, while it passively opens when tension is released. These devices allow for a more precise and forceful grip, as users can control the amount of force exerted by adjusting the cable tension.

The main limitation of VC systems lies in the need to maintain continuous tension to keep the device closed. For tasks that require holding an object for extended periods, this can lead to fatigue and discomfort. Despite their capability for higher grip force, this trade-off often limits their practicality in everyday use.

The ProHensor’s VC&L Mechanism

The ProHensor’s Voluntary Closing and Locking (VC&L) system introduces a distinct approach that sets it apart from existing categories. The self-actuated locking feature addresses a primary limitation of VC devices by eliminating the need for continuous tension to maintain grip.

With the VC&L system, users gain the advantage of precise and forceful control associated with voluntary closing, while the locking mechanism provides the ability to hold objects securely without exerting ongoing effort. This combination enhances usability for a wide range of tasks, from carrying tools to completing fine-motor activities. By integrating a simple and durable locking system, the ProHensor expands the functionality of body-powered devices without increasing their complexity or cost.

Another distinguishing feature of the ProHensor is its serviceability in the field. The replaceable locking cartridge allows for quick and efficient maintenance, reducing downtime and ensuring consistent performance over time. This feature is particularly valuable for users in remote or demanding environments where access to specialized repair services may be limited. The ability to replace components on-site supports the ProHensor’s emphasis on practicality and durability.

Standing Apart: Practical Implications

The introduction of VC&L technology represents a shift in how body-powered prosthetics can serve users. By addressing the key limitations of VO and VC devices, the ProHensor offers a new level of flexibility and efficiency. Users are no longer constrained by the compromises inherent in traditional categories, gaining both control and practicality in a single device.

The ProHensor’s design also fits seamlessly within the existing framework of body-powered systems. It leverages familiar mechanics, ensuring that training and adoption are straightforward for both users and clinicians. This makes the ProHensor a viable option for users seeking enhanced functionality without the need for extensive adjustments to their current routines or equipment.

A New Direction for Body-Powered Prosthetics

The ProHensor’s VC&L mechanism introduces a new category of terminal devices that prioritizes both function and ease of use. While VO and VC systems have served as reliable options for decades, the addition of a locking feature to a voluntary closing device bridges a long-standing gap in prosthetic design. This innovation provides users with a practical solution that aligns with the diverse demands of everyday life, offering a new direction for body-powered prosthetics to evolve.