US Patent 7988731 Lightweight implantable prosthetic device

A reduced weight implantable prosthesis, including, an outer surface shell for encapsulating the prosthesis, a gel mixture comprising a mixture of a cohesive gel and micro-spheres for filling the shell, one or more inner volumes internal to the shell which do not contain the gel mixture; and wherein the gel mixture contains less than 60% by volume of micro-spheres mixed into the cohesive gel.