1. Implant-Retained Finger Prosthesis
October 19, 2007
Client: Greg Gion
Advisor: Professor Tompkins
Dustin Gardner Team Leader
Karen Chen Communicator
Allison McArton BWIG
Richard Bamberg BSAC
Alex Kracht Communicator

2. OverView Background Problem Statement Project Design Specification
Design Alternatives
Future Work

3. Problem Statement
Design durable and functional prosthesis substructure
Design removable and force-resistant connecting mechanism
Currently in US only slip-cover used
New international approaches include bone implants
Implants in distal terminal digit bone
Prosthesis aids increased mobility and use

4. Background – Prosthetic finger
Silicone elastomer, polysiloxane, slips over the amputation
Medical adhesion, vacuum
Cosmetics
Less functionality

5. Background – Implant-retained
In Europe, UK, Austrailia, South Africa
Osseointegration abutment
Anchor solid element & polysiloxane to abutment
Functionality, regain confidence

6. Background – Osseointegration
Titanium implant in rabbit bone
Dentistry fixation, maxillofacial reconstruction
Two surgeries
Implant abutment into skeleton, wound healing
Re-expose abutment, attach prosthesis
3~6 month rehabilitation

7. Summary of Project Design Specification (PDS)
Function
Client Requirements
Design Requirements
Physical and Operational Characteristics
Production Characteristics
Miscellaneous

8. Function A substructure and connecting mechanism
Only one method currently in the U.S
Other countries are more advanced
Increase motility and usage

9. Requirements Client Requirements Design Requirements
New or improved attachment or substructure
Final computer simulation
Keep within budget
Design Requirements
Better functionality and durability of prosthesis

10. Physical and Operational Characteristics
Performance Requirements
Safety
Accuracy, reliability, and life in service
Operating environment
Ergonomics, size, and weight
Materials and Aesthetics

11. Production Characteristics and Miscellaneous
Quantity
Target Product Cost
Standards and Specifications
Customer
Patient-related Concerns
Competition

12. Design Alternatives Part I: Terminal Bone Attachment Mechanisms
Finger Prosthesis Substructure Mechanisms
Part II:

13. Connection DSN Alternatives
Screw and Clip (DSN #1)
Magnet and Clip (DSN #2)
Allen Wrench (DSN #3)
Reverse Screw Clip (DSN #4)

14. (DSN#1)- Screw n’ Clip How it works…
Spring loaded shaft in terminal end
Screw prosthesis into threaded well
Align clip segments with clip wells
Push clips inwards and prosthesis downwards
Finger prosthesis locks in position

15. (DSN#1)- Pros & Cons Pros Provides a smooth, tight fit
Structurally sound and stable
Resists external shear and normal forces
Cons
Hard to install shaft
Difficult to remove mechanism
Complicated construction

16. (DSN#2)- Magnet and Clip
How it works…
Align clips, wells and magnetic poles
Push clips inwards, insert into wells
Attach magnets together and release clips
Release clips simultaneously to lock position

17. (DSN#2)- Pros & Cons Pros Easy to install and remove
Simple construction
Provides a smooth fit
Cons
Lower resistance to shear, normal forces
Easy to fall off
Not structurally stable

18. (DSN#3)- Allen Wrench How it works…
Insert terminal shaft in prosthesis shaft
Position shafts such that slots aligned
Fully insert shaft until locked position
Insert Allen wrench screw through slots
Tighten screw until firm fit achieved

19. (DSN#3)- Pros & Cons Pros Provides a solid, tight fit
Relatively easy to remove
Resists external shear and normal forces
Cons
Non-uniform structure, not aesthetically pleasing
Difficult to remove mechanism
Complicated construction

20. (DSN#4)- Reverse Screw n’ Clip
How it works…
Depress buttons on prosthesis
Slide prosthesis structure over terminal end
Align bottom slots with pins
Click pins into place, release buttons

21. (DSN#4)- Pros & Cons Pros Provides a smooth, tight fit
Easy to remove mechanism
Resists external shear and normal forces
Cons
Hard to install terminal end mechanism
Not structurally stable (top heavy)
Very complicated construction

22. Connection DSN Alternatives Matrix
Functionality (30pts)
Durability
(25pts)
Cost Effectiveness
(10pts)
Feasibility
(35pts)
Total
(100pts)
Screw and Clip Mechanism 24
20.5
7.2 28
79.7
Magnet and Clip Mechanism
15.6 13
25.2 61
Allen Wrench Mechanism 22
8.2
30.8 85
Reverse Screw Clip Mechanism
22.8 17 6 21
66.8

23. Substructure DSN Alternatives
Spring-loaded Sac (DSN #5)
Mech. Joint w/ Spring (DSN #6)
Flat Piece (DSN #7)
Articulation Mech. (DSN #8)

24. (DSN#5)- Spring-Loaded Sac
How it works…
Elastic fibers hold joint in place
Each fiber resists one direction of movement
A spring maintains relaxed position

25. (DSN#5)- Pros & Cons Pros Allows prosthetic to move naturally
Finger can bend while keeping some tension
Cons
Less feasible to create
Could tear if enough force applied
Can’t produce much gripping force

26. (DSN#6)- Mech. Joint w/ Spring
How it works…
Round joint keeps structure solid
Bending limits built into joint
Spring-loaded to produce some gripping force
Maintains 1 degree of freedom

27. (DSN#6)- Pros & Cons Pros
Allows natural movement and reaction to force
Solid construction, long-lasting
Less likely to break from external forces.
Cons
Difficult to produce smaller parts
Can’t produce much gripping force

28. (DSN#7)- Flat Piece How it works… Flat piece of metal
Bent at a natural angle
Flatness prevents prosthetic rotation
Fastened to bone implant
Stiff movement
Very similar to recent designs

29. (DSN#7)- Pros & Cons Pros Looks natural when hand is at rest
Sturdy frame allows maximum gripping force
Least likely to allow prosthetic skin to move around
Cons
Does not bend at all
Prosthetic skin sees large amount of wear and tear

30. (DSN#8)- Articulation Mech.
How it works…
Strap connects to wrist
Strap wraps around specific points
Hand flexion will curl finger inwards
No force applied when wrist is straight

31. (DSN#8)- Pros & Cons Pros Facilitates gripping power
More functional than any other design
Allows for natural finger-like movement
Cons
Complex design may be impossible
Easy for things to go wrong
Strap hanging out of finger

32. Substructure DSN Alternatives Matrix
Functionality (30pts)
Durability
(25pts)
Cost Effectiveness
(10pts)
Feasibility
(35pts)
Total
(100pts)
Spring-loaded Sac 24
15.63 6
22.75
68.38
Mech. Joint w/ Spring
26.25
19.75 7
27.13
80.13
Flat Piece
18.75
22.5
8.75
29.75
79.75
Articulation Mech.
23.25
13.75
5.5
18.38
60.88

33. Future Plans Confirm design with client
Create large scale, functional prototypes
Order necessary components
Consult a hand surgeon
Test prototypes
Create computer simulations

34. Questions???
Thank YOU!!!!