NAVIGATED REVISION TOTAL KNEE REPLACEMENT. A COMPARISON STUDY WITH CONVENTIONAL REVISION.

Abstract

Introduction: Navigation system might help improving the quality of implantation of a revision total knee replacement (TKR).

Methods: 30 cases of revision TKR were operated on with an image-free system, and matched to 30 cases of conventional revision TKR. Quality of implantation was analyzed in both groups on post-operative long-leg X-rays. Following items were recorded: coronal femoro-tibial angle, coronal and sagittal orientation of femoral and tibial implants. The rate of globally satisfactory implanted prostheses and the rate of prostheses implanted within the desired range for each criterion were recorded in both groups and compared with a Chi² test and an ANOVA test at a 5% level of significance.

Results: We observed a significant improvement of all radiological items by navigated cases. Limb alignment was restored in 88% of the navigated cases and 73% of the conventional cases. Similar differences were observed for the coronal and sagital orientation of the femoral and tibial implants. Overall, 78% of the implants were oriented satisfactorily for the four criteria for navigated cases, and only 58% for conventional cases.

Discussion: The navigation system enables reaching the implantation goals for implant position in the large majority of cases, with a rate similar to that obtained for primary TKA. The rate of optimally implanted prosthesis was significantly higher with navigation than with conventional technique. The navigation system is a useful aid for these often difficult operations, where the visual information is often misleading.