Upper Limb Prosthetic Adaptation/Redesign

Upper Limb Prosthetic Adaptation/Redesign Group 6 Cassie 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

Upper Limb Prosthetic Adaptation/Redesign