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

OverView 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 Design 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 Finger Prosthesis Substructure Mechanisms Part II:

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 (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

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 (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

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!!!!