Prosthetic Liner Donning Device

Snap into motion is a senior capstone design team that is dedicated in designing a system to enable independent liner donning for transtibial amputees. Our project is to design a device to aid lower limb amputees in donning their prosthetic liner. The device will ensure that the liner sits flush against the limb, properly aligns the pin into the prosthetic, and enables those with low hand dexterity, vision, or flexibility to don their liner independently.

Design Task
There are approximately 34,000 transtibial amputations performed each year in the United States. The causes of these amputations range from infection to tumors with the most prevalent causes being diabetes and severe traumatic injury. Patients with transtibial amputations that wish to use a prosthetic leg must wear a prosthetic liner that protects their skin from the rough prosthetic leg materials and helps suspend their leg in the prosthetic. Prosthetic liners can be difficult to don, especially for patients with limitations in flexibility, hand dexterity, or vision. Our goal is to create a donning system that will be:
 * Comfortable
 * Easy to use
 * Work with commercial liners/prosthetic components
 * Accommodate the majority of patients
 * Reduce strain for the patient
 * Require little to no hand strength or dexterity
 * Aid inflexible individuals
 * Properly align the pin
 * Allow independent donning

Dimensional Analysis of Transtibial Roll-On Style Prosthetic Liners

 * Distal diameter ranges from 2.5" to 12.0"
 * Proximal diameter ranges from 3.1" to 12.0"
 * Target lenght of liners ranges from 12.0" to 16.0"
 * Pin lengths have a standard diameter of 10 mm, standard pitch of 1.5 metric, and varying lengths from 1" to 2.25"

Garter Design Alternatives
A garter is what we have named the device that will be mounted on the end of the device's arms and will be the part of the device that comes in direct contact with the patient's liner. It is named a garter because it needs to expand and accommodate different sizes of the leg.

Design Decision Matrix
We compared the drive design concepts in a design matrix that was scaled from 1-5. Based on the matrix, we decided to follow through with the glider track system with the donning hand. Below is the link to the design matrix:
 * Design Matrix

Whole System
After more project learning and design, we arrived at a final design.



The subsystems include:


 * Linear Track & Linear Actuator
 * Linear Applicator
 * Adjustable Stand
 * Liner Loader

A diagram showing how the donning process will work using this design is shown below.



Linear Applicator
The two linear applicators are what will be in contact with the prosthetic liner and move it up the user's residual limb. There will be pressure sensors that will measure the pressure being applied to the liner/residual limb so that no discomfort or pain will come to the user.

Linear Track & Linear Actuator
There will be two linear tracks on either side of the stand. The tracks will move towards the user's hips during the donning system while the linear actuators move towards the user's residual limb simultaneously to move the prosthetic liner up the residual limb. Once the pressure sensors that are on the linear applicators reach a certain pressure, the linear actuators will move off of the limb and the linear track will move away from the user approximately 1 inch. This process will continue until the liner is fully donned.

Linear Track

Linear Actuator

Adjustable Stand
The adjustable stand will allow for people to set the device at a height that is comfortable for them. It has yet to be decided if this will be at an angle,using a scissor stand, or both integrated together.

Liner Loader
The liner loader is where the user will place the prosthetic liner before the donning process begins. The liner's pin will be guided and locked into the liner loader and then inverted over the liner loader. The liner loader will be a detachable stem so that this is can all be done free of the rest of the donning system. The liner loader is then locked into the stand using a locking mechanism at the end of the stand.



Control System
We will be using an arduino uno microprocessor as our control system. The pressure sensors on the linear applicators will be our input and as an output, the microprocessor will control the movements of the linear track and linear actuators.

Document Archive

 * Project Schedule
 * Meeting Minutes
 * Design Review Presentation
 * Design Matrix
 * Liner Donning Force Test Results

References: