Device 2 : A Spring Knife

The user holds the device by the handle (21) and inserts it inside the trocar (2).  The guides (30) keep the device aligned with respect to the trocar (2) and the stop (31) makes sure that the device is in place.

Once the device is in place, the user closes the handles (21).  When the handles (21) are closed, the end of the links (23), that are connected to the tube (22), move down, thus moving the tube (22) down along with them.  As the tube (22) moves down, the opening mechanism (11) at the distal end of the tube (22) also moves down.  Once the opening mechanism (11) moves down, it comes outside from the covering (12).  The opening mechanism (11) is now free to work.  The user now depresses knobble (25) which moves rod (24) down and triggers the release of coil spring (14) that are inside the mechanism (11).  The coil spring (14) open the blades (10).

Once the blades (10) are opened, the user retrieves the device together with the trocar (2) opening a larger controlled incision.  The size of the incision is determined by the size of the opened blades (10).   The user can now remove the large mass (40) through the new enlarged incision.