In vivo evaluation of a computer planning system for total knee arthroplasty

In this paper we report the analysis of a preoperative computer planner for total knee arthroplasty (TKA), when applied to a set of patients by different surgeons. The goal of this work was to study the repeatability and reliability of computer planning, the ergonomy of the system, identify the useful features of this technique and the possible drawbacks. The planning system allows the surgeon to interactively stimulate the implant on a 3D model of the patient computed from computerized tomography (CT) images. In this paper, we summarize the main results of a series of evaluation trials carried out by four surgeons on ten patients. We measured the variability of the main application parameters, evaluated the efficacy and usefulness of the automatic prosthesis positioning provided by the system and carefully analyzed the system ergonomy. The system showed satisfactory repeatability in the interactive definition of the essential parameters. Moreover it showed to be easy to use, consistent, focused on the most important parameters and able to improve the surgeon's insight and confidence in the outcome. Further steps include clinical studies and direct comparison with standard technique.