ImplantRetained Finger Prosthesis October 19 2007 Greg Gion

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

Over. View • Background • Problem Statement • Project Design Specification • Design Alternatives • Future Work

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

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

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

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

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

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

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

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

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

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

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

(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

(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

(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

(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

(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

(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

(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

(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

Connection DSN Alternatives Matrix Functionality (30 pts) Durability (25 pts) Cost Effectiveness (10 pts) Feasibility (35 pts) Total (100 pts) Screw and Clip Mechanism 24 20. 5 7. 2 28 79. 7 Magnet and Clip Mechanism 15. 6 13 7. 2 25. 2 61 Allen Wrench Mechanism 24 22 8. 2 30. 8 85 Reverse Screw Clip Mechanism 22. 8 17 6 21 66. 8

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

(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

(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

(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

(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

(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

(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

(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

(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

Substructure DSN Alternatives Matrix Functionality (30 pts) Durability (25 pts) Cost Effectiveness (10 pts) Feasibility (35 pts) Total (100 pts) 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

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

Questions? ? ? • Thank YOU!!!!