No difference in clinical outcomes between functionally aligned cruciate-retaining and posterior-stabilized robotic-assisted total knee arthroplasty

Purpose: To compare the clinical outcomes of subjects undergoing primary robotic-assisted total knee arthroplasty (RA-TKA), following functional alignment (FA) principles, with cruciate-retaining (CR) or posterior-stabilized (PS) bearing designs, at a minimum of 24 months of follow-up. Methods: This observational, retrospective study included 167 consecutive patients undergoing RA-TKA with cemented PS and cementless CR implants performed with a CT-base robotic-arm assisted system (Mako, Stryker), following FA principles, between 2017 and 2020. Patients were followed up with a clinical and radiographic assessment and were administered the Forgotten Joint Score-12 (FJS-12), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR), and the 5-level Likert scale (5-LLS). Results: Three TKA revisions were performed (2 PS, 1 CR); therefore, a total of 164 knees with a mean age of 71.7 years (SD 8.9) were considered (80 cemented PS; 84 cementless CR). No statistically significant differences were recorded between study groups relative to FJS-12, KOOS-JR, and 5-LLS at a minimum of two year follow-up (FJS-12 89.3 ± 9.2 vs 87.5 ± 12.8, p-value 0.46; KOOS-JR 88.8 ± 10.0 vs 86.7 ± 14.0, p-value 0.31; 5-LLS 4.5 ± 0.7 vs 4.5 ± 0.8, p-value 0.34). Conclusion: No significant outcome differences were reported between patients undergoing PS and CR RA-TKA at a minimum of two year follow-up. RA-TKA achieves excellent clinical results and high satisfaction scores, regardless of the implant design used.