ossicular replacement prostheses are manufactured from a non - biodegradable shape memory polymer . such prostheses can include torps , porps , and incudo - stapedial joints . the prostheses are reshaped upon application of a stimulus to capture a portion of one or more ossicles . the force of capture of a reshaped polymeric prosthesis is less than a comparable reshaped shape memory alloy prosthesis and thereby prevents recipient discomfort and / or pressure induced necrosis of the bone . in addition , biocompatible shape memory polymers can be designed with recoverable strain that is orders of magnitude higher than shape memory alloys . furthermore , prostheses can be manufactured in a single size and easily trimmed or otherwise modified by the surgeon during the implantation procedure to tailor the prosthesis in size and / or shape for the particular anatomy . such modification does not negatively effect the ability of the prostheses to engage the ossicle .