Adjustable, Low Cost, Trans-Tibial Prosthesis

Paradigm DesignsKyle Harbison, Justin Druba, and Tyler Kreipke

Problem: Children in disadvantaged areas often lose their lower leg due to landmines

Problem Statement: Develop a trans-tibial prosthesis that maintains an adaptable and abiding integrity while being able to be produced and maintained with limited resources.

Background

Support normal forces associated with gait

Adjust to account for user growth

Be low cost

Be maintainable in disadvantaged areas

Feasibility Criteria

Modular approach resulted in designing three alternatives per subsystem

Three Subsystems

◦ Socket – Connection to residual limb

◦ Shaft – Major length adjustability

◦ Foot – Accommodation towards varying terrain

Preliminary Designs

Socket Preliminary IdeasCinch Basket Brace Removable Padding Basket

Shaft Preliminary Ideas

Slide ‘n’ Tight Threaded Leg Crutch Leg

Foot Preliminary IdeasSplit Hoof Spring Foot

Slider

Subsystem Merit Criteria Weighting

Socket Durability 45%

Comfort 35%

Concealable 20%

Shaft Durability 45%

Precision of Adjustability 35%

Concealable 15%

Foot Durability 35%

Adaptability to Terrain 30%

Energy Return 20%

Concealable 15%

Merit Criteria

Adjustability in terms of upper leg accommodation is achieved in this system

User comfort is the key determining design aspect for this subsystem

Neoprene coated nylon basket, steel brace components

Socket Subsystem

Adjustability in terms of prosthetic height is achieved in this subsystem

Achieves a range of 11 through 15.4 inches of adjustability

Aluminum 2024

Shaft Subsystem

Polyoxymethylene – same material used in existing products

Multi-axial stability over varying degrees of terrain

Conservation of energy specifically targeted within heel dimensions

Foot Subsystem

Final Assembly

Loading Calculation

Length Calculation

Engineering Calculations

Shortest Length = 11.0”Longest Length = 15.4”

Stress Calculations

Engineering Calculations

Socket Support Beam Thickness (h)

h>0.34”

Engineering Calculations

B>1.37”

Foot Width (b)

Stress Calculations

Budget

Item Total Price

Knee Brace $73.95

Basket Material $17.00

Straps $8.46

Supports $17.82

Aluminum Tubing $55.19

Delrin (Material for Foot) $269.63

Bolts $29.93

Total $471.98

Socket Subsystem: Create a more adjustable basket

Shaft Subsystem: Use a different material for the inner shaft

Foot Subsystem: Perform material tests on Delrin

Further Considerations/Recommendations

Questions?