Robotic and computer technologies have been integrated into orthopaedic surgery to assist surgeons with complicated procedures, and the improvements in surgical accuracy have been clinically validated in studies worldwide. However, higher surgical accuracy is achieved at the expense of higher procedural complexity, leading to an unnatural workflow and lower efficiency in the operating room. In this thesis, a surgeon-centred surgical workflow is proposed so that technical assistance can be provided to the surgeon more efficiently. The primary contribution is a novel registration method for orthopaedic surgery based on depth imaging, which utilises the surface geometry of the bone, instantaneously captured by a depth camera, to localise the bone automatically. The fast capture rate of the depth camera enables real-time bone tracking without percutaneous markers. To obtain the bone surface from depth images, free from surrounding tissues, artificial neural networks have been established and trained to identify the surgical site and then segment out the desired part on the depth image of the surgical site. Robotics has also been integrated into the registration process, with the depth camera mounted on its end-effector, to track the registration target in motion. An obstacle avoidance algorithm has been designed for the robot to move the camera away from potential obstacles, which reduces the risk of line-of-sight interruption. Finally, utilising the registration results, an intuitive surgical navigation system has been developed based on augmented reality. Three-dimensional holographic surgical navigation is overlaid on the patient's anatomy directly, which exempts the surgeon from looking away to external monitors, thus improving procedural efficiency. Experimental validation of these contributions shows the potential of integrating these novel technologies naturally into the surgical workflow, demonstrating that the use of robotics and computer navigation could not only provide reliable surgical accuracy, but also improve ergonomics and efficiency in robot/computer assisted orthopaedic procedures.