Distal femoral torsion positioning in total knee arthroplasty shows equal reliability using a computer-assisted system or a robotic arm

Introduction: Computer-assisted or robot-assisted surgery in theory enables optimal positioning in total knee arthroplasty (TKA). The aim of the present study was to evaluate the rotational positioning of the femoral TKA implant using the ROSA Knee® robotic system. The hypothesis was that the accuracy of the rotation obtained by the ROSA Knee® robotic arm was comparable to that obtained by navigation.

Material and methods: This was a retrospective comparative consecutive study involving 140 patients receiving first-line TKA, divided into two equal groups: Navigation, and Robot. Distal epiphyseal torsion of the femur (DETF) was analyzed by comparing preoperative (native DETF) and postoperative (prosthetic DETF) CT scans between groups.

Results: The mean prosthetic DETF was 2.3° ± 1.3 for the Navigation group and 2.3° ± 1.4 for the Robot group (p = 0.96), with no significant difference in deviation from DETF target (p=0.07). Assuming ± 2° range of error, the Navigation group showed 88.6% and the Robot group 90% accuracy (p = 0.79).

Conclusion: The Rosa Knee® robotic system provided accuracy equivalent to navigation for rotational positioning of the femoral implant.

Level of evidence: IV; retrospective study.