Introduction to i-Digits

i-Digits is a multi-articulating myoelectric partial hand prosthesis for individuals with absence of 1 to 5 digits.

i-Digits is created from a kit of components, built into a custom socket to fit the individuals residual limb, with a self contained wristband housing batteries and a microprocessor. The digits can be individually positioned for customisation to the individual's presentation.

i-Digits is not intended to be a cosmetic restoration, instead it focuses on functionality for the user.

i-Digits is a functional prosthesis, replicating the features of a natural hand

Conformable grip:
shapes around
objects​

Manual
thumb rotation:
to achieve a range
of grip positions​

Integrated:

works in
conjunction with any
remaining digits​

Automated grips:
such as pinch and
lateral, for increased precision
in completing tasks​

Multiple control
options: for optimal grip access

Personalisation: create a prosthesis specific to each
individuals functional needs

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i-Digits Quantum

The premium i-Digits product, offering Gesture Control for easy access to up to 4 grips with one easy to learn technique.

  • Speed boost by up to 30%
  • 4 control methods for accessing grips: Gesture, App, Muscle and Proximity
  • 20 automated grips to select from, and an additional 12 fully personalisable My Grips
  • Vari-Grip to increase grip force when required

i-Digits Access

  • Access to automated grips through App and Muscle Control
  • 12 automated grips to select from

i-Digits France

  • Available for individuals with 3-5 digit absence
  • 3 methods of accessing automated grips: Grip Chips, App and Muscle Control
  • Grip Chips for positioning around the environment for access to a specific grip for that location
  • Speed boost by up to 30%
  • 20 automated grips to select from, and an additional 12 fully personalisable My Grips
  • Vari-Grip to increase grip force when required

i-Digits Introduction

User Benefits

i-Digits has a wide range of features designed to benefit the user in their day to day activities.

Feature
User Benefit

Works in conjunction with remaining digits
Digits are positioned to function alongside any anatomical digits

The residual function of the hand is utilised with the i-Digits to maximise user functionality

Conformable digits
The digits shape around the object being held

Provides a secure grip on the object and provides a natural grip appearance

Manual thumb rotation
Position thumb manually throughout range from lateral to opposition

Allows a range of grip positions to be achieved for optimum grasp on objects

Automated Grips
A wide selection of grips to choose from where only specific digits are active

The user can select the grips which are most relevant to their lifestyle, allowing increased precision within those tasks

Control Options
Multiple control options available to access automated grips

The user can choose the methods which best suit them, allowing personalisation of the prosthesis to an individual's needs

Gesture Control
A method of accessing automated grips through movement of the i-Digits Quantum

Enables access to 4 grips via one easy to learn control method

Vari-Grip¹
Increased grip force when required

The appropriate amount of force for the current task can be applied

App
Mobile Apps for clinician and user

The user can personalise the i-Digits to their needs and has control of some features. The myo-graph allows ongoing training of muscle signals

Feature
User Benefit

Works in conjunction with remaining digits
Digits are positioned to function alongside any anatomical digits

The residual function of the hand is utilised with the i-Digits to maximise user functionality

Conformable digits
The digits shape around the object being held

Provides a secure grip on the object and provides a natural grip appearance

Manual thumb rotation
Position thumb manually throughout range from lateral to opposition

Allows a range of grip positions to be achieved for optimum grasp on objects

Automated Grips
A wide selection of grips to choose from where only specific digits are active

The user can select the grips which are most relevant to their lifestyle, allowing increased precision within those tasks

Control Options
Multiple control options available to access automated grips

The user can choose the methods which best suit them, allowing personalisation of the prosthesis to an individual's needs

Gesture Control
A method of accessing automated grips through movement of the i-Digits Quantum

Enables access to 4 grips via one easy to learn control method

Vari-Grip¹
Increased grip force when required

The appropriate amount of force for the current task can be applied

App
Mobile Apps for clinician and user

The user can personalise the i-Digits to their needs and has control of some features. The myo-graph allows ongoing training of muscle signals

¹ Not on i-Digits Access

i-Digits Introduction

User Selection

Suitable Candidates

i-Digits is for individuals with 1 to 5 digit partial hand absence which is: Distal to the wrist AND proximal of the metacarpal-phalangeal joint.

It is designed for low to moderate weight bearing everyday activities.

i-Digits will restore a gross grasp to the hand in most cases - restoration of fine grasp will be dependent upon the physical presentation e.g. if the thumb and index finger are intact then restoration of fine pinch is not required.

The users priority must be for functional gain, as i-Digits is not offered as a cosmetic solution.

User Evaluation

A complete evaluation should be carried out of all potential user's, with particular attention to

  • Skin condition: healing, scaring, sensitivity
  • Strength and range of movement in any remaining fingers
  • Strength and range of movement of the wrist
  • Shape of residual limb to facilitate suspension
  • Control site possibilities
  • Condition of contra-lateral hand/arm

The extent of functional impairment within the hand should be identified, alongside evaluation of how the individual currently completes daily activities.

To achieve optimum outcomes with the i-Digits prosthesis, individuals should

  • Be motivated to use a prosthesis
  • Have clear and realistic functional goals
  • Have an understanding of the time, effort and patience involved in learning to use the prosthesis
  • Be aware that i-Digits will not match the appearance of their sound hand
  • Understand that i-Digits is not a replacement for a human hand, but a tool to assist with functional tasks

Occupational Therapy Training

The Occupational Therapist is a key member of the upper limb multi-disciplinary team. They are responsible for maintaining focus on functional goals and supporting the user on the best ways to incorporate their prosthesis into their day to day life.

Therapy training is person centric, focusing on personal goals, lifestyle and interests.

Optimum user outcomes are achieved when the Prosthetist and Therapist work closely together with the user.

Studies support the inclusion of Occupational Therapy in upper limb prosthetic fitting.

  • Early therapy nearly doubles the rate of daily use. Fletchall, S. “Returning upper-extremity amputees to work”. The O&P Edge. 2005; 4:28-33.
  • Research suggests skilled, individualised therapy with the prosthesis takes an average of 20-30 hours. Resnik, L. Meucci, MR, Lieberman-Klinger, S, Fantini, C, Kelty, DL, Disla,R, Sasson, N. “Advanced upper limb prosthetic devices: Implications for upper limb prosthetic rehabilitation.” Arch Phys Med Rehabil. 2012; 93: 710-717.

i-Digits Introduction

i-Digits Design

i-Digits prosthesis is designed specifically to the individual user's presentation and requirements. There are many options available in relation to design including materials, trimlines and suspension.

Materials

The inner socket is manufactured from medical grade silicone:

  • Allows shaping to the contours of the partial hand
  • Accommodates the i-Digits signal inputs

The outer socket is typically laminate resin:

  • Provides secure attachment for the mounting plate
  • Lightweight
  • Shapes well to contours of silicone socket and i-Digits components

Note: Carbon fibre is not recommended due to interference properties with electrodes.

Trim-Lines

The trim-lines of the socket can be located:

  • At the wrist
  • Just proximal to the wrist
  • Mid/proximal forearm

Socket trim-lines are determined based on:

  • Remaining anatomy
  • Suspension requirements
  • Control site location
  • Range of motion available

Suspension

A secure fitting socket is required to give the user security in completing tasks and also to maintain consistent contact with the electrodes / FSRs. The shape of the residual limb determines the suspension possibilities. Options include:

  • Zipper incorporated into the silicone socket
  • Strap (hook & loop, buckle, ratchet) attached to inner or outer socket
  • Push fit / anatomical suspension

i-Digits Introduction

i-Digits Kit

i-Digits is supplied as a kit comprising of a selection of individual components which are assembled to the custom fabricated socket to create a unique i-Digits prosthesis for the individual user.

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Digits: Fingers

4 different sizes of digit are available: 2, 3, 5, 6.

Standard configuration for XS (5532) and M (6653) mounting plates give the optimum alignment. However, any digit sizes can be selected based on the individual user’s dimensions.

The digit connects to the knuckle assembly, which is attached to the mounting plate.

Digits: Thumb

There is one size of thumb.

The thumb attaches to the rotational thumb assembly, to allow rotation.

An alignment plate is provided to assist in the positioning of the thumb in relation to the fingers during the fitting process. The alignment plate is universal; accommodating left and right prostheses.

Knuckle Assembly

The knuckle assembly connects the mounting plate to the digit.

The proximal end of the wire plugs into the wristband. The digit is mounted onto the knuckle assembly and secured with a pre - loctited screw.

Note: thumb knuckle assembly is different from the fingers; it has wiring protection as it is assembled through the rotational thumb assembly.

Mounting Plate

The mounting plate is the platform to which the digits are attached, via the wired knuckle assembly. The mounting plate is laminated into the outer socket of the prosthesis.

Available in left / right and 2 sizes. The size is selected based on dimensions of the sound hand.

XS: narrower (67 mm) and digits are positioned straight.

M: wider (73 mm) and digits are positioned with splay outwards.

The mounting plate allows for 4 digits to be attached, and can be cut for cases when less than 4 digits are required.

Control Inputs

Options for control of i-Digits include:

  • Compact electrodes
  • Remote electrodes
  • Force Sensing Resistors (FSRs)

It can be controlled with 1 or 2 electrodes/FSRs, but it is not possible to combine input options.

Remote Electrode

Contour well to the shape of the partial hand. 2 electrodes can share a ground/earth contact to reduce components required in the prosthesis.

The remote dome is fitted into silicone suspension piece which is incorporated into silicone inner socket (a double silicone suspension piece holds the 2 signal domes, a single suspension piece holds the ground/earth dome).

Co-axial cables connect the electrode dome to the bellows PCB.

Compact Electrode

Similar to compact electrodes used at other levels of upper limb absence.

Most suited for use when using flexor/extensor muscles on the forearm.

Uses the same co-axial cables as the remote electrode.

Note: When connecting to PCB, the centre cable from the electrode is the ground.

Force Sensing Resistor

Thin touch pads. Control of the movement of the prosthesis requires a physical push from a remnant digit or similar against the Force Sensing resistor (FSR).

FSRs are fitted between the silicone socket and an inner lamination and can require a more precise fitting and fabrication.

Bellows Assembly

The bellows assembly attaches the socket to the wristband, and provides a channel for the digit and input wires.

The bellows is available in 3 types based on the control input type used and the country of use:

  • 50Hz Electrodes
  • 60Hz Electrodes
  • FSRs

Once assembled, a flexible rubber cover is fitted over the bellows assembly to protect the wiring within.

i-Digits Wristband

The i-Digits wristband houses the processor and two removable batteries.

It contains a power on/off switch and LED indicator.

Available in one size, and fits both left and right prostheses.

The strap and buckle fastening should be secured loosely around the forearm.

Batteries & Charger

2x 800mAh Powerpack batteries are used to power the i-Digits prosthesis. There are positioned on the wristband. The batteries are removed from the prosthesis and charged on the charger base unit.

A low battery warning LED on the battery indicates when less than 10% power is remaining. A full charge takes approximately 2hours.

Mains charger cable, with country specific plug, connects to the base unit for charging.

Covers

Covers for the digits are required to provide grip. The covers simply slip onto the digit.

Available in black and clear based on user preference.

Different sizes of cover are available based on the digit sizes fitted.

Supporting Tools

Within the i-Digits kit a selection of components are provided to aid fabrication and assembly.

Fabrication aids included are knuckle dummies, alignment posts, lamination fairings, terminal dummy, electrode dummies for silicone and outer lamination and zipper.

Tools included are an electrode extraction tool, 8mm spanner, TX6 and TX8 drivers.