Redesigning a Rotationplasty Prosthetic

Abstract

Patients of Van Nes Rotationplasty often experience pain in their residual limb, due to the novel nature of the surgery. Literature review reveals that this pain occurs in a location on the limb that coincides with an abnormal concentration of force with respect to normal loading conditions. This paper discusses the results of a project where common engineering techniques were used to redesign a prosthetic leg and alleviate this pain for a client. The scope, for the purpose of this process, has been limited to the prosthetic “socket” where the residual limb sits. Use of 3D modeling and printing allows for quick, low cost iteration of the socket for testing, and is thus critical to the process. In full, the paper provides a prescriptive method to redesign a rotationplasty prosthesis towards the same result, for any client. The developed methodology for testing the device utilizes force sensors placed inside the socket, comparing the internal forces between a new model and an original, problematic one. In addition to this force measurement method, the process implements a prosthetic comfort evaluation form, allowing a client to qualitatively provide feedback on a prosthetic. Existing literature implied that reduction of force at the location of observed pain will reduce that pain, and client testing confirmed that notion, confirming the viability of the force sensor testing method.