Are early results of robotic assisted medial unicompartmental knee arthroplasty successful?

Abstract

Objectives: Robotic surgery studies have been increasing in literature in the past years due to its operative advantages on reducing error and improving functional success in partial knee arthroplasty. Methods: Data were prospectively collected in 21 patients (31 knees) who underwent MAKOplasty, robotic assisted unicondylar medial knee arthroplasty, between June 2013 - January 2014 in our clinic with an average follow-up time of 5.5 months. Clinical outcomes were evaluated with American Knee Society Scoring System. Additionally, intra-operative digitally planned implant positions on the robot’s software were compared with post-operative radiographic component alignment. In the radiographic evaluation; anatomic axis of the tibia was observed in the coronal plane. Tibial posterior slope and flexion angle of the femoral component were observed in the sagittal plane. Results: Pre-operatively 1 patient was scored fair (60 points) and 20 patients were scored poor (mean, 46.6 points) on American Knee Society Scoring System. Post-operatively all 21 patients had excellent knee scores (mean, 99.67 points). Function-wise 7 patients were scored fair (mean, 60 points) and 14 patients were scored poor (mean, 30.7 points) again on American Knee Society Functional Scoring System. Post-operatively all 21 patients exhibited excellent function scores (mean, 99.04 points). In the radiological evaluation, intra-operative robotic analyses were compared with post-operative radiographic alignment. No significant difference was observed statistically (paired t-test, p < 0.05). This comparison is valuable as Lonner, Hernigou, Collier report that mal-alignment by as little as 2° may predispose to implant failures. Conclusion: Robotic assistance greatly improves clinical and functional outcomes and may help prevent implant failures due to surgical error and mal-alignment in partial knee arthroplasty.