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Design Concept
Design Concept
During initial brainstorming, the very rough design concept shown on the left was created in Solidworks to illustrate our planned approach to a variety of design features. A number of primary components were involved...
Foot plate
Foot plate
A strong, stable base was needed to be the contact point with the ground, to support the foot, and to hold the above framework in place.
Telescoping poles
Telescoping poles
The poles would provide the supportive framework around the leg, acting to transfer load directly to the pelvis and serving as an adjustable component to accommodate varying patient heights. The adjustable height would also allow control over how much contact the patient's leg can make with the ground, and thus how much weight they can support on their own.
Hinges
Hinges
The hinges would connect the two sets of poles, while allowing the device to bend at the patient's knee to mimic normal gait.
Circular frame
Circular frame
The circular seat mounting frame would serve several purposes. Primarily, it serves as a site for mounting a load transferring "seat" and any harnesses/body attachment straps. At four 'corners' it connects to the poles below, providing stability for the framework and transferring the load from the poles to the seat.
Seat
Seat
Not pictured in the image, but most crucial to the design, is the seat on which the person rests their pelvis while utilizing the device. This transfers the load to the ischial bones, bypassing the injured femur. The connecting bracket to secure the seat to the circular frame can be seen in the design concept images.
Design Requirements
Design Requirements
Near the beginning of the design process, the following requirements were determined:
The device shall be able to support the weight of an individual without loading the fracture point, likely by distributing the force to the pelvic bones.
The device shall feature an adjustable load-bearing capacity which will allow it to adapt to the evolving needs of a patient throughout the rehabilitation process, ideally with a full range of adjustment from minimal support to support of the entire load for direct postoperative use.
The device shall allow for proper directional loading of the limb when necessary to encourage bone regeneration.
The device shall be able to orient the limb such that it does not interfere with the healing process; any brace, harness, or frame structure that supports the limb must keep it in an orientation that is conducive to proper healing.
The device shall be conducive to independent use, including ease of transport, assembly, and utilization.
The device shall be able to be independently donned and doffed in a timely manner.
The device shall be stable and well balanced without the use of a secondary device.
The device shall remain compatible with the use of a cane or a walker to increase accessibility for users who feel more comfortable doing so.
The device shall be lightweight to ensure usability by patients with decreased strength.
The device shall be comparable in cost to similarly intentioned assistive devices such as walkers and basic wheelchairs so to remain accessible to as much of the population as possible.
Design Process
Design Process
After agreeing on design requirements and an overall approach to the solution, the team began an iterative design process. Components were designed in Solidworks, 3D printed and/or machined by team members, and continuously redesigned to improve their performance throughout the project. The evolution of the design and the steps taken to reach the final product can be viewed on the prototypes page.
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