Abstract: An instrument for cutting elongated pins used in orthopedic surgery includes a housing having a reduced diameter portion in which is disposed a piston reciprocable in a fluid chamber. An enlarged diameter portion of the housing forms a further part of the fluid chamber in which is disposed a second piston connected to a member forming a first cutting edge which is movable toward an anvil having a second cutting edge cooperable with the first cutting edge to shear a pin to a predetermined length. The smaller piston is engaged by a screw actuator disposed on the housing and which may be rotated to provide a substantial force multiplication whereby a sufficient cutting force is exerted on a pin. The instrument is provided with a transverse handle portion to facilitate handling and to hold the instrument against reaction forces of the screw actuator. The cutting edges are formed on cooperable anvil and actuating member portions.