US Patent 10117661 Stone extracting medical device with better stone retention

A medical device comprising a cannula having a stone extracting unit on its distal end and a hand piece on its proximal end for operating the unit through the cannula. The unit includes more than four annularly arranged tubular elements with fixed proximal ends and distal ends movable between opened and closed position by the movement of an equal number of wire elements extending through the tubular elements with their distal free ends fixed to the distal ends of tubular elements so as to define a 5 or 6 pointed star configuration.