Noninvasive extendable prosthesis: a new design

Abstract

The treatment of choice for distal femur malignancies in skeletally immature patients remains controversial. As the mainstream treatment, limb-salvage treatment has been recently investigated, but its application in children remains challenging. Specifically, the procedure causes potential limb-length discrepancy from the continued normal growth of the contralateral lower extremity. We designed a new type of noninvasive prosthesis that is extendable within the body. To evaluate our prosthesis’ reliability and extensibility, in vitro and in vivo (animal) experiments were conducted. The in vitro experiment was used to verify the lengthening performance of the prosthesis. In the in vivo experiment, to determine the extension length and internal structure condition, the prosthesis was implanted into the rear femoral limb of a sheep under fluoroscopic guidance. Expansion was achieved with the aid of an external electromagnetic field, and the experiments proved the extensibility and noninvasiveness of our prosthesis. However, many problems need to be resolved.