upper limb prosthetic adaptation/redesign group 6 cassie edwards, meg stevenson, amy thomas, meagan...
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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
Redesign existing prosthesis to make it 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 Met with Aaron to discuss the next step.
He showed us how to make a cast so we can make one of Matthew’s arm.
Made a cast of Matthew’s arm, which will be used to make a mold of Matthew’s arm in order to test prosthetic designs.
Test socket made Met with Matthew and his mother to fit
test socket and discuss how they felt about it.
Work Completed
Met with Aaron, Matthew, and his mother and father to assess how well the test socket fit and 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.
Work Completed Met with Aaron, Matthew,
and his family to fit second test socket, which was too big, so a third one is being made.
Gave Matthew and his parents software and electrodes to use at home in order to practice contracting muscles to control 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.
Casting
Originally did a cast with flexible fiberglass material
Had to redo the cast with plaster
Matt’s Measurements
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)
Test Sockets
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
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