A Herbert screw is a special purpose screw used to compress small fractures fragments. One of the unique feature of the screw is that it is threaded on the both sides. It is also called headless screw.
The screw was invented by Timothy Herbert.
- Herbert Screw
One end of the screw has cancellous threads while the other end has larger diameter cortical screw threads. The cancellous screw is inserted first and crosses the proximal fracture, screwing into the bone of the distal fragment. As it is screwed in, the proximal cortical portion engages the proximal bone fragment.
Herbert screws are especially useful in articular fractures and small bones like scaphoid.
Because of difference in the pitch and the size of the threads, Each turn of the screw causes the distal end to travel farther into bone than the proximal end resulting in compression of the fracture.