In recent years there has been a growing recognition of the importance of the functional outcome of orthopedic procedures. This is especially true in total joint replacement, where it has been unequivocally demonstrated that surgical technique is one of the primary factors determining joint function and longevity after the operative procedure. For example, in total hip arthroplasty it is universally accepted that placement of the acetabular and femoral components are critical determinants of post-operative success . Research has shown that many of the parameters describing the function and longevity of an artificial joint such as gait, restoration of leg length, stability, loosening, wear, and osteolysis, can all be impacted by the position and orientation of either the femoral stem in the femur or the acetabular cup in the pelvis [2-4]. Likewise, in the knee it has been shown that the dominant failure mechanisms are related to pre-operative technical factors of component alignment, final overall limb alignment, and ligamentous imbalance . This growing recognition of the importance of surgical technique has led to a need for systematic, validated methods for training and assessing surgical skills. It is increasingly recognized, in virtually all fields of surgery, that practice and skills development must be separated to the extent necessary to prevent undue risk to the patient. While this is true in theory, the tools and systems are not yet in place to adequately train future surgeons. In this context, Computer- Assisted Orthopedic Surgery (CAOS) has much to offer. Computer technology, in some form or other, is universally accepted as a source of simulated reality which is all pervasive in television, advertising, and entertainment. This same technology has made some in roads into education, however, in the orthopedic context, our primary exposure to the potential of computers has been in Surgical Navigation, which is based on the fundamental premise that computerbased systems should be indispensable components of the process of performing surgery. An alternative approach is based on the belief that the goal of all efforts in surgeon training should be empowerment of the surgeon through development of surgical skills, without long-term dependence on technology to implement a surgical plan. Rationale for this approach can be found in the classic field of motor learning, where it has been long established that, aside from practice, information about performance, in the form of both intrinsic and extrinsic feedback, is the single most important variable affecting outcome . The precise format of this information, how much of it is fed back to the performer, and the timing of its presentation all affect performance and learning. In learning a motor skill, it has been shown that terminal feedback in the form of knowledge of results (feedback on the movement outcome in terms of the environmental goal) and knowledge of performance (feedback on the movement itself) can be more effective than concurrent feedback, or guidance, presented during the task itself. Guidance feedback has been shown to have the strongest effects on performance during the trials in which it is administered [7-9] as opposed to the more permanent changes attributed to motor learning achieved through post-performance feedback . In fact, it has been suggested that a heavily guiding form of feedback («enabling») is actually detrimental to learning .
ASJC Scopus subject areas