5-Year Survivorship and Outcomes of Robotic-Arm-Assisted Medial Unicompartmental Knee Arthroplasty

Abstract

Purpose. While unicompartmental knee arthroplasty (UKA) has demonstrated benefits over total knee arthroplasty (TKA) in selected populations, component placement continues to be challenging with conventional surgical instruments, resulting in higher early failure rates. Robotic-arm-assisted UKA (RA-UKA) has shown to be successful in component positioning through preop planning and intraop adjustability. The purpose of this study is to assess the 5-year clinical outcomes of medial RA-UKA. Methods. This study was a retrospective review of a single-center prospectively maintained cohort of 133 patients (146 knees) indicated for medial UKA from 2009 to 2013. Perioperative data and 2- and 5-year Knee injury Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Score (WOMAC), and Forgotten Joint Score (FJS) outcome measures were collected. Five-year follow-up was recorded in 119 patients (131 knees). Results. Mean follow-up was 5.1 ± 0.2 years. Mean age and BMI were 68.0 ± 8.1 years and 29.3 ± 4.7 kg/m2, respectively. At 2-year follow-up, mean KOOS, WOMAC, and FJS were 71.5 ± 15.3 , 14.3 ± 7.9 , and 79.1 ± 25.8 , respectively. At 5-year follow-up, mean KOOS, WOMAC, and FJS were 71.6 ± 15.2 , 14.2 ± 7.9 , and 80.9 ± 25.1 , respectively. Mean change in KOOS and WOMAC was 34.6 ± 21.4 and 11.0 ± 13.6 , respectively ( p < 0.001 and p < 0.001 ). For patient satisfaction at last follow-up, 89% of patients were very satisfied/satisfied and 5% were dissatisfied. For patient activity expectations at last follow-up, 85% met activity expectations, 52% were more active than before, 25% have the same level of activity, 23% were less active than before, and 89% were walking without support. All patients returned to driving after surgery at a mean 15.2 ± 9.4 days. Survivorship was 95% (95% CI 0.91-0.98) at 5 years. One knee (1%) had a patellofemoral revision, two knees (1.3%) were revised to different partial knee replacements, and five knees (3.4%) were converted to TKA. Conclusion. Overall, medial RA-UKA demonstrated improved patient-recorded outcomes, high patient satisfaction, met expectations, and excellent functional recovery. Midterm survivorship was excellent. Longitudinal follow-up is needed to evaluate long-term outcomes of robotic-arm-assisted UKA procedures.

Malposition is main cause of failure of Oxford mobile-bearing medial unicompartmental knee arthroplasty

“…Matassi et al 16 reported that robotic-assisted UKA can help doctors with low hand counts improve the accuracy of the prosthetic position and reduce deviation rates. 16 Gaudiani et al 15 and Zhang et al 14 also found that robotic-assisted medial UKA helped to improve the accuracy of prosthetic positioning and recovery of joint function. However, these studies did not investigate the degree to which prosthesis position deviation affected the UKA survival rate.…”

“…13 In recent years, some studies have found that robotic-assisted UKA can improve the positioning of the prostheses, thereby improving their clinical efficacy and reducing revision rates. [14][15][16] To the best of our knowledge, there are no current reports on the impact of UKA prosthesis position deviation on the survival rate. Therefore, in this study we sought to retrospectively evaluate the clinical data of 407 patients who underwent UKA in a single joint arthroplasty centre with long-term follow-up (five to 11 years), and to analyze the clinical efficacy of the procedure and the risk factors for UKA failure.…”