Patient reported and clinical outcomes of robotic-arm assisted unicondylar knee arthroplasty: Minimum two year follow-up.

backgroundUnicompartmental knee arthroplasty (UKA) originated in the 1950's. There have been many enhancements to the implants and the technique, improving the precision and accuracy of this challenging operation. Specifically for Robotic Arm Interactive Orthopedic System (Rio; Mako Stryker, Fort Lauderdale, FL), there are many studies reporting clinical outcomes, but our search offered nothing regarding patient reported outcomes using validated surveys.

methodsPatients with onlay tibial components presenting for routine follow-up of robotic-arm assisted UKA performed between May 2009 and September 2013 were invited to participate. Four joints had simultaneous patella femoral resurfacing. Knee Injury and Osteoarthritis Outcomes Score (KOOS) and the 2011 Knee Society Scores were collected. Radiographic evidence of osteoarthritis in the non-operative knee compartments was documented.

resultsEighty-one patients presented for follow-up and consented to participate. Mean follow up was 54 months. Mean patient reported KOOS activities of daily living and pain scores were each 90. Knee Society 2011 mean objective score was 96 and mean function score 81. There was one revision to total knee at 40 months post-op for pain after injury. Seventy-seven percent reported their knee always felt "Normal", 20% sometimes, and only 3% reported that it never felt normal.

conclusionLiterature on UKA failure rates suggests that UKA may be a less forgiving procedure than total knee arthroplasty. Robotic-arm assisted surgery is reported to improve the accuracy of implant placement. Based on our prospectively collected positive patient outcomes, the authors have achieved good results from performing robotic-arm assisted UKA on select patients.