Upper Limb Prosthetic Adaptation/Redesign

Group 6Cassie Edwards, Meg Stevenson, Amy Thomas, Meagan Williams

Advisor: Dr. Mark Richter Aaron Fitzsimmons

Project Objectives

Design or modify an existing design of an upper limb prosthetic for a boy with upper limb deformities

Create an upper limb prosthesis

Existing Device

Drawbacks: Taking prosthesis on and off takes considerable amount of time and effort

Prosthesis is a very old design that does not work

Need to create a prosthesis that would be more functional for an active 8-year-old boy

Goals for New Device

Short-term Goals Dress independently Go to the bathroom on his own

Long-term Goals Be able to live independently

i.e. – drive a car, cook for himself, use standard household items, etc.

Original Ideas for Device

Humeral cuff with Velcro closure Stump sock interface over humerus External elbow hinges Myobock hand with myoelectric

interface Figure 9 suspension

system

Work Completed Made a cast of

Matthew’s arm, which was used to make a mold of Matthew’s arm in order to test prosthetic designs.

Originally did a cast with flexible fiberglass material

Had to redo the cast with plaster

Work Completed: Measurements

Took measurements to ensure correctly proportioned device

From the AC joint to the lateral epicondyl of the humerus: 21 cm

From the lateral epicondyl to the tip of the thumb: 19.5 cm (on left arm)

From base of metacarpal to the tip of the thumb: 5.5 cm (left hand) & 5 cm (right hand)

Work Completed: Test Sockets

Test socket made from mold Met with Matthew and his mother to fit first test

socket Original plastic is Thermolyn Soft,

manufactured by Otto Bock more flexible and easier to form onto very

small mold shapes Now using 3/16” thickness Vivak plastic, a high

temperature PETG plastic to use a plastic which had zero creep

Work Completed

Met with Aaron, Matthew, and his mother and father to test for myoelectric activity in Matthew’s arm.

Matthew was found to have myoelectric activity and was able to open and close MyoBock hand.  

MyoBoy Software

MyoBoy measures patient muscle potentials with the same electrodes used in the definitive prosthesis

Matthew was found to have independent control of his muscles

MyoBoy Software

MyoBoy's fun "racecar" training module helps to train the patient for their device before they are fitted.

Work Completed

Gave Matthew and his parents software and electrodes to use at home in order to practice contracting muscles to control MyoBock hand.

Current Work

4th socket device with electrodes Sleeve to keep socket in place and

prevent air from escaping socket Vacuum seal

Concerns about socket

Sleeve is tight Pressure from

electrodes hurts Restrict circulation? Vacuum seal

himself? Ability to get on and

off himself

Future Work: Myoelectric Hand

Ottobock Electrohand 2000 4.8 V DMC (Dynamic Mode Control)- speed of

opening, closing and grip force determined by the level of muscle signal

Grip Force=55 N Wt=130 g (4.586 oz) More closely mimics natural hand

Future Work: Elbow Component

Ottobock 12K19 Body Powered Passive Elbow Lock 10 locking positions in 8 degree

increments Can push a button to lock elbow

or can connect button to a figure 9 harness

Future Work: On Our Way to a Finished Device

Assess how the socket is fitting and Matthew’s ability to control the electrodes

Obtain parts to complete device Put device together, let Matthew use

it and test it out for a period of time and then reassess

Future Work: After the Finished Device

May need to adjust gain Myobock ErgoArm Electronic Plus

Future Work: Meeting our goals

Matt must learn how to use the electronic hand well before adding additional components

Accomplishing reaching tasks will be put on hold until hand is mastered, then controlling elbow can be mastered.

Better product in the long run, but it will require work on Matthew and his family’s part