Editorial Comment

Abstract

A Tool is but the extension of a man's hand, and a machine is but a complex tool. He that invents a machine augments the power of man and the well being of mankind. Henry Ward Beecher1 A question that frequently is asked by patients and physicians is, "What is computer assisted orthopaedic surgery?" Many of our ideas and perceptions about the use of robotic or image guided technologies in medicine have been shaped by the entertainment world and industry's depiction of robots. Although these technologies have been applied for more than 20 years in industry and more recently in entertainment, the medical applications are just emerging as a new area of research and development. Much of the early work of computer assisted surgery focused on tumor location in neurosurgery, based on principles of stereotaxis. Stereotaxis is defined as the location of bodily structures using a fixed coordinate system and was introduced nearly a century ago. However, the field has expanded beyond these initial neurosurgical applications to include many surgical subspecialties including orthopaedics. Orthopaedic surgery has led the way in this relatively new area of research development and clinical use. In a landmark application of robotics in medicine, the ROBODOC® system was used to assist surgeons in performing part of a total hip replacement in 1992. This robotic assistive device was the very first active robot to be used in medicine. However, these active robots represent only one end of the spectrum of the new technologies now being developed. Computer assisted orthopaedic surgical technologies actually represent a new class of technologically advanced measurement devices and sensors which blend the field of medicine, computer science, robotics, and engineering to solve real clinical problems. Therefore, a broader definition of this area is necessary to describe these new technologies which include not only robotics but also image guided surgical devices, surgical navigation systems, preoperative planners and simulators, and augmented reality or hybrid reality computer interfaces. One working definition for computer assisted surgery is that a machine's capability is coupled with a human's judgment to perform a task better than either machine or human could do alone. Only by this synergistic action between a computer driven device and the physician can the potential promised by these enabling technologies be reached fully. Therefore, the clinical goals of these computer assisted surgical technologies are as follows: (1) to develop interactive, patient specific preoperative planners and simulators to optimize the performance of surgery and the subsequent biologic response; and (2) to develop more precise and ultimately less invasive smart tools to assist in the actual measurement and performance of a surgical task. Orthopaedics, as a surgical subspecialty, is well suited for computer assisted and image guided surgery. The bones and periarticular soft tissues can be evaluated easily and accurately by diagnostic technologies such as radiographs, fluoroscopy, computed tomography, or magnetic resonance imaging. The bony and soft tissue structures can be reconstructed to create three-dimensional images. These images have the potential to permit simulations of surgical procedures, showing the cause and effect of surgical actions before the patient actually enters the operating room. Bone is a rigid structure, and does not deform significantly when a cutting guide is positioned on its surface or when it is drilled or cut. Because of these inherent qualities of bone, it is possible to apply intraoperatively the preoperative imaging and planning information more easily than for soft tissues such as the brain or abdominal organs. What are the clinical needs these computer assisted surgical technologies address? As surgeons, we understand that there are current limitations in surgical practice. Most critically, we lack the ability to accurately relate precis