US Patent 7547325 Space keeper with adjustable axial length

A space keeper for insertion between two vertebrae which has a variable axial length is provided. The space keeper possesses a sleeve-like first member (2) and a second member (3) guided in the latter and movable relative to the first member in the axial direction for adjusting an overall length. In order that adjustability during operating is facilitated the two members (2, 3) are connected to one another by a lever (7, 8), wherein one centre of motion (16) of the lever is connected to one member (3) and the other centre of motion (18) is connected in terms of action to the other member (2).