Over the last decade, orthopaedics has been one of the most active and diverse areas of development in computer-assisted surgery. Othopaedics has been a specially challenging area of development as many orthopaedic surgeons consider the outcomes of conventional procedures generally successful. There is significant pressure to improve the efficiency and ergonomics, reduce cost and dependence on more expensive medical imaging modalities, and simplify the use and interfaces. Increasing emphasis on less invasive and minimally invasive procedures could give a significant boost to the adoption of computer-assisted surgery. In this paper, we present the overview of different approaches using a classification scheme that relies on two important criteria: 1) the autonomy of clinical action permitted to the system and 2) the imaging requirements.