Introduction: The common belief is that navigation-assisted TKR improves the surgical accuracy and reduces outliers, albeit increasing the operating time. We conducted a detailed study of the published studies with four main criteria:
- Reduction of outliers in the placement of implants.
- Increased operating time.
- Reduction of blood loss.
- Higher post-operative score.
Methods: We performed a computerized search of the PubMed repository and a manual search of the proceedings of the International Society for Computer Assisted Orthopaedic Surgery (CAOS, 2001–05) to include all studies that presented clinical data of the results of this procedure. A total of 139 clinical studies were found, a total of 7,158 patients who underwent navigation-assisted TKR.
Results: Of the 139 studies, 39 studies presented data showing a reduction of outliers of the post-operative mechanical axis in the 180±3° range. 2,130 out of 2,401 (89%) patients operated with navigation were within this range. 27 out of the 39 studies compared the postoperative alignment of the navigated technique to that of the non-navigated technique. In the non-navigated technique, only 1,325 out of 1,880 (71%) patients were in that range, close to the published 74–75% for conventional TKR studies.
Regarding the operating time with navigation, 32 studies report an average increase of 21 min. (range 6– 48 min.), or about 20% than conventional TKR.
One of the perceived benefits of using extramedullary jigs in navigation-assisted TKR is thought to be reduction of blood loss. However, of the 15 studies that address this issue, 10 (67%) found no significant difference compared to the conventional technique. Regarding post-operative functional and/or pain scoring, 12 (80%) out of 15 studies found no statistically significant differences between navigated and non-navigated techniques.
Conclusions: The published clinical data so far shows that navigated-assisted TKR provides good alignment of the implants and a reduction of outliers from one in four to at most one in ten at the expense of 15–20 min. (about 20%) increase in operating time. No significant advantage was found for blood loss or functional/pain scoring. From a public health viewpoint, the increased cost of the navigated procedure may very well be compensated by the reduction of future revisions.
