Does computer-assisted total knee arthroplasty improve the overall component position and patient function?

There remains controversy as to whether computer-navigated total knee replacement (TKR) improves the overall prosthesis alignment and patient function. The aim of this study was to determine whether computer-assisted total knee arthroplasty provides superior prosthesis positioning when compared to a conventional jig-assisted total knee replacement and whether this affected the functional outcome.

This prospective, randomised controlled study compared computer navigated and conventional jig-assisted total knee replacement in 37 patients who underwent bilateral TKR. A quantitative assessment of the spatial positioning of the implant in the 74 total knee replacements was determined using a low-dose dual-beam CT scanning technique. This resulted in six parameters of alignment that were compared. Functional outcomes using the high activity arthroplasty score and Knee Society score were assessed pre-operatively, postoperatively, at three years and at five years. Patients also indicated which knee they felt was subjectively the best.

There was no statistically significant difference in the prosthesis alignment between both groups and the number of outliers was not decreased with navigation. All function scores improved from pre-operative to postoperative but there was no statistically significant difference between the groups at five years. At five years, 40.6% of patients thought their jig-assisted knee was the better knee compared with 21.9% their computer assisted knee and 37.5% of patients who felt they were the same.

Computer-assisted implantation of total knee replacements does not offer a significant advantage in prosthesis alignment. There was no difference in functional outcome or subjective "best knee" between the computer-assisted or jig-assisted knee.