Created by the company responsible for the market-leading bionic hand, the i-LIMB Hand, the ProDigits solution extends the life-changing technology of the i-LIMB to partial-hand patients, either due to congenital anomalies or amputation from a traumatic incident or medical condition. For the first time, partial-hand patients now have the option of a powered prosthetic solution where previously only aesthetic replacements or self-powered devices have been available.

The amputee population that can benefit from ProDigits is considerable, estimated at around 44,000 patients in the U.S. and 1.2 million worldwide, and until now, these people have had no motor-driven prosthetic solution available to them that offered significant function combined with a favourable aesthetic. With the ability to bend, touch, pick-up and point, ProDigits more closely reflects the function of a natural hand.

The modular nature of the ProDigit finger design and the individually powered motor located within each digit means that a clinician can build replacement fingers to an accurate anatomical length – matching the patient’s opposite hand size if the patient is unilateral. If a user has remaining fingers, the socket solution can be built to accommodate the remaining fingers and thumb. Thumb solutions can be built using either powered or non-powered options.

The nature of each partial-hand patient case is unique, and therefore each prosthetic build is also unique. The concept behind ProDigits is something never before commercially available in the prosthetics industry. Touch Bionics’ development of a powered interface for this patient group is truly revolutionary. Sockets are custom-designed and fabricated by clinicians to suit each individual’s specific needs.

Because of the personalized nature of each ProDigits fitting, Touch Bionics is developing a clinical collaborator program in the U.S. that will see the company partner with practitioners in order to fit patients. Around the world Touch Bionics has established relationships and distribution channels in over 40 countries to support the roll-out of ProDigits – supported from its Centre of Excellence in Livingston, Scotland.

During the development of ProDigits, Touch Bionics applied the knowledge and lessons it learned during the development the i-LIMB Hand, including incorporation of the residual limb, consideration for the application and removal of the device and ease of transition and weight, as well as application of the same technological principles of control strategies for traditional myoelectric devices.

There are two control strategies that can be employed to power ProDigits: either myoelectric sensors that register muscle signals from the residual finger or palm, or a pressure sensitive switch input in the form of a force sensitive resistor (FSR), or touch pad, which relies on the remnant digit or tissue surrounding the metacarpal bone to provide the necessary pressure to activate the finger. Either input, or a combination of the two, is chosen on the basis of the viability of the patient’s signal site, the available space and patient’s preference. The control strategy is based on a traditional myoelectric regime. However, Touch Bionics has developed Bluetooth-enabled controller boards, which are embedded in the prosthesis and allow a clinician to adjust the finer motor functions wirelessly. Dependent upon the presentation of the patient, it is also possible to deliver individual finger control – another industry first.

As with the i-LIMB Hand, a unique stall feature allows the device to detect when it has closed around an object, also allowing users to point single digits and configure the hand in various grip patterns.

Ideal candidates have an amputation at the transmetacarpal level or higher of one or more fingers, although there are exceptions. Each patient needs to consider form versus function and share their preferences with their clinician. The prosthetic solution developed for some limb differences will not be able to approximate that of a natural hand so a balance must be struck between aesthetics and functionality. Most partial hand users prioritize function.

Touch Bionics offers a range of coverings for ProDigits, from a high-definition cosmesis that closely approximates natural skin tone and definition to the high-performance i-LIMB Skin, a robust covering that is computer modelled to the shape of the ProDigit finger which protects the componentry from the elements.

As with any effective prosthesis strategy and patient care plan, a holistic approach is best, one that incorporates not only appropriate prosthetic solutions, but also psychological care, rehabilitation plans, occupational therapy and sound medical advice and treatment. ProDigits is a part of a comprehensive care plan and Touch Bionics is sensitive to supporting patients’ mind-body connection as much as possible and playing an integral role in a patient’s rehabilitation and adoption of a prosthetic solution.