Essential Training

It is important to support and guide each i-Digits user to enable them to fulfil their potential and optimise their functional outcomes with their prosthesis.

Each user is unique, their physical presentation and their functional requirements will dictate which features and functions available within i-Digits are most applicable to them.

Training is ideally person centric, focusing on personal goals, lifestyle and interests, with an Occupational Therapist and Prosthetist working together alongside the user.

Training on the use of an i-Digits device should follow a staged approach.

The starting point for all users is to understand the Essential Training of i-Digits. This involves developing control of open/closing, correct positioning of objects within the prosthesis and applying the appropriate strength of grip.

In cases where there are intact fingers, learning to co-ordinate the finger motion with the prosthetic digits is also a skill to develop.

Core i-Digits features

Picking Up Objects
Objects are picked up with the i-Digits prosthesis by the user controlling the opening and closing motion of the fingers.
Picking up objects involves good control, and stable positioning.

To securely pick objects up the user should position the i-Digits prosthesis around the object and apply the appropriate grip strength.

Compliant grip is the shaping of the fingers around the object being held. The fingers automatically stop when they meet the resistance of the object, providing a natural shape and secure grip without requiring excessive force.

Guidance on the basic training to pick up objects.

Training of this concept should include:

Practice grasp and release using various size/shaped objects.

Allowing some fingers to wrap under/around objects.

  • Start seated at a table with objects directly in front of the user. Practice simple unilateral grasp and release tasks first, with relatively large objects i.e cones, cups, balls.
  • Focus on bringing the i-Digits towards the objects, avoiding any compensatory movements of the elbow, shoulder, back etc. The user may need to adjust their wrist and the thumb position to grasp certain objects effectively without compensating.
  • Practice approaching the object from different angles i.e. from the side, from above.
  • Practice moving the objects away from the body, to different heights and positions in space, without sending any unexpected signals i.e. reaching to a cabinet or reaching down to the floor.
  • Introduce smaller objects as the users' technique develops.

When practicing activities such as carrying heavier objects, pay attention to where the weight is loaded on the i-Digits prosthesis. The weight should be carried between the base of the fingers and the palm of the hand. When lifting heavier objects remember to relax the muscles.

Auto-grasp feature enables the digits to reclose around an object if a quick / accidental open signal is given when the object is being held. This can be turned on/off within global settings of Biosim App.

It is helpful to be aware of accidental signals during initial training by monitoring the myo-graph signals to see when it occurs and encouraging user to fully relax their muscles while holding objects.

Daily Activities
Practice of this technique across many different scenarios will help to consolidate the user's skills.

The open/closing action occurs in many varying activities of daily life. It is important for the user to have a firm understanding of correct grasp and release, and consistent and predictable control from their muscles.

Positioning The Thumb
Moving the thumb position allows for a wider range of grips to be achieved.
The position of the thumb is critical to achieving optimal grip on an object.

The thumb may be manually rotated from the lateral to the opposition position.

Explore positioning of the thumb with a range of object shapes.

Alternatively, the user may have their own thumb, and they should position it optimally for grip against the i-Digits fingers.

The user should become familiar with manually moving the thumb, understand the amount of pressure required to move the thumb, and where it aligns with the i-Digit fingers.

An appropriate training drill would require the thumb to be repositioned between picking up each object. Examples of objects for varying thumb positions are as follows;

  • Lateral - flat objects such as a playing card or plate.
  • Cylindrical - handled objects such as a toothbrush or broom.
  • Palmar Opposition - larger objects requiring gross grasp such as cup or bottle.
  • Pinch / Tripod - smaller objects requiring precision such as toy building blocks or sweets.

For pinch grip the thumb should be aligned with the index finger.

For tripod grip the thumb should be aligned between the index and middle fingers.

Daily Activities
Examples of positioning the thumb in every day life scenarios.

Achieving the correct position of the thumb for the required task is applicable throughout the majority of day to day activities.

Becoming familiar with moving the thumb in the early training stages establishes a useful skill.

Varying The Grip Force
Developing the skill of achieving the correct grip force on an object will allow for a secure grip.
The speed of motion of the fingers and the strength of the grip force are controllable by the user.

Proportional control is the speed of motion of the fingers. If the user applies a gentle open / close signal the fingers will move slowly, if they apply a strong signal the fingers will move more quickly.

The ability to control the speed of the fingers allows precision to be applied to the task when appropriate.

Additionally, the base speed of the i-Digits can be set using the speed boost setting within the Biosim and My i-Limb App.

When a strong, very secure grip is required the user can continue to hold their signal after the fingers have closed on an object. With the prolonged close signal, Vari-Grip applies an additional grip force to each finger in turn. The user can then relax and the secure grip is maintained, until an open signal is given.

Note: Vari-Grip is only available on i-Digits Quantum and i-Digits France.

App Set Up
Video tutorials showing how to set up Vari-Grip and Speed Boost within the App.

Vari-Grip can be switched off or the delay for it to start can be adjusted in the Biosim App.

Speed boost can be adjusted in Biosim and My i-Limb App.

Guidance on how to train the correct control of speed and force of the i-Digits prosthesis.

Proportional control should be trained at an early stage.

The user can even develop this control during myo-training, before the prosthesis is fitted, by practicing gentle and strong signal strength and receiving visual feedback from the myo-graph or the virtual hand. Refer to myo-testing in resources section for further information on myo-testing and training.

Training Proportional Control

With the prosthesis fitted, training of slow and gentle motion can be conducted using soft objects which can compress. The user should avoid compressing or crushing the object.

Useful objects to practice with are stress balls, plastic/paper cups.

Explore moving the object around in space (up high, down low, stretched forward) avoiding accidental crushing of the object during motion.

Training Vari-Grip

The user can initially feel the additional force of Vari-Grip by holding the i-Digits prosthesis around their opposite forearm. The additional grip can be felt as it increases on each finger in turn, the user may also be able to hear the noise of each finger tightening.

Objects to practice repetitive drills with include; releasing tightly stacked training cones and opening bottles / jars / packets. Ensure sufficient force is applied to the grip to prevent the object slipping or turning.

Daily Activities
Daily life examples showing where gentle and strong grips are required.

The use of slow, gentle motion and strong secure grip during daily activities is extremely useful.

Slow gentle grip is useful to avoid crushing soft objects, such as during food preparation or shaking/holding hands with someone.

Activities which benefit from the additional force of Vari-Grip include;

  • Opening packets / containers
  • Tying shoelaces
  • Dressing
Stalling Fingers
i-Digits allows individual fingers to be stalled in a particular position by manually adding resistance to the finger(s).
Stalling fingers allows individual fingers to be positioned in a quick and simple way.

Individual fingers can be stalled by applying resistance to the finger or multiple fingers while closing (or opening) the remaining fingers.

This can be useful to adopt a certain position of the finger for a particular activity or to pre-position the fingers for holding an object.

Training on how to stall out individual fingers manually to achieve a specific position of the i-Digits prosthesis.
  • Practice applying the right amount of resistance to a finger to stop its motion.
  • Practice initially with stalling the index finger open. This would be a useful position for typing, pressing buttons or pointing.

Other practical use of stalling fingers includes;

  • Stalling the index, middle, ring, and small fingers to achieve the position for donning/doffing a shirt sleeve or jacket.
  • Stall thumb to achieve lateral grip.
Daily Activities
Using stalling fingers in daily life scenarios.

During day to day activities, stalling fingers can be quick and easy way to position the i-Digits prosthesis to complete a task.

Additional ADL examples

Once the basics have been established the user can progress to practical day to day activities, gradually increasing in complexity. For some additional ideas on how to approach specific tasks you can explore Ossur Academy YouTube videos.