| CPC A61B 17/7017 (2013.01) [A61B 17/7025 (2013.01); A61B 17/7216 (2013.01); A61B 17/8023 (2013.01); A61B 2017/00539 (2013.01); A61B 2017/681 (2013.01)] | 15 Claims |

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1. An expandable rod system comprising:
a static rod having an internal cavity and a semi-permeable member disposed therein; and
a piston rod having a first end sealingly positioned within the internal cavity of the static rod, and moveable relative to the static rod,
wherein the static rod includes an osmotic chamber defined within the internal cavity, and the osmotic chamber is fluidly connected to the semi-permeable member such that fluid flow from the semi-permeable member to the osmotic chamber in a first direction facilitates movement of the piston rod in the first direction relative to the static rod to expand the rod system,
wherein the static rod further comprises a hydraulic chamber within the internal cavity between the osmotic chamber and the piston rod, and
wherein a piston allows the transfer of pressure from the osmotic chamber to the hydraulic chamber.
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