Comparison of CT with intra-operative navigation reported implant position utilising a robotic assisted technique in total knee arthroplasty.

BACKGROUND

Validation of navigated total knee arthroplasty (TKA) systems assists clinicians in making treatment decisions. The aim of this study was to independently review a navigation assisted robotic system for use in TKA.

METHODS

We evaluated 87 patients (92 knees) undergoing robotic assisted TKA. Position estimated by the navigation software and postoperative CT scan were compared. Post-operative CT scans were interpreted by a senior radiologist blinded to intra-operative component position. Recorded were femoral varus/valgus, tibial varus/valgus and overall limb alignment in the coronal plane. In the sagittal plane tibial slope and femoral flexion/extension. Femoral component rotation was assessed in relation to the transepicondylar axis (TEA).

RESULTS

Mean difference between software estimation and postoperative CT scan of the femoral component position in the coronal plane was 1.02° (0.86-1.18, 95%CI). Tibial coronal position was 1.19° (0.97-1.41). Sagittal plane component position for the femur was 1.64° (1.41-1.87). Tibial slope was 1.44° (1.21-1.68). Mean femoral component rotation was 1.27° (1.01-1.53). Overall 94.57% of intraoperative measures were within 3° of the component position measured on CT.

CONCLUSION

Robotic assisted navigation used in combination with a novel balancing system can result in very accurate component positioning during total knee arthroplasty.