An attachment for a surgical instrument including a drive input hub for connection to a power source； a drive output hub for connection to a surgical instrument； and a body connecting the drive input hub to the drive output hub, the body including a mechanism for transferring drive from the input hub to the output hub, and wherein the body, the drive input hub and the drive output hub are at least in part not coaxial. A method for surgically preparing a bone using the attachment is also provided.
