PROSPECTIVE DOUBLE-BLINDED RANDOMIZED CONTROLLED TRIAL ON ROBOTIC ARM-ASSISTED VERSUS CONVENTIONAL ONE-STAGE BILATERAL TOTAL KNEE ARTHROPLASTY WITH TWO-YEAR FOLLOW-UP

Introduction Robotic arm assisted total knee arthroplasty(RA-TKA) has gained popularity. Yet for postoperative pain and patient reported outcomes, high quality evidence is lacking. We hypothesize that RA-TKA would provide better postoperative pain control and patient reported outcomes in Chinese patients. Methods This is a double blinded randomized controlled trial(RCT) with 2-year follow-up in patients undergoing one stage bilateral total knee arthroplasty at a tertiary institution. All patients were randomized to receive one conventional TKA(C-TKA) targeting mechanical alignment while the other received RA-TKA targeting restricted kinematic alignment. Triathlon cruciate retaining cementless TKA were used exclusively. Primary outcome measure was numeric pain score(10). Secondary outcome included patient's preferred side, Oxford knee score(OKS), Knee injury and osteoarthritis outcome score(KOOS), mediolateral laxity, range of motion(ROM), alignment and complications. Measurements were recorded preoperatively, daily during inpatient stay, 6 weeks, 3 months, 6 months, 1 year and 2 years. Results 59 patients(118 TKAs) completed the study. RA-TKA group showed statistically significant better pain score than C-TKA on postop Day 3 (RA-TKA: 4.6, C-TKA: 4.2, p =0.014) up to 6 weeks (RA-TKA: 3, C-TKA: 2.6, p =0.04). There was no difference in patient's preferred side at 6 weeks, 1 year and 2 years with 29% favouring conventional side, 36% favouring robotic side and 35% felt no difference between two sides (p=0.36). Oxford knee scores, KOOS scores were comparable. Operating times were longer for RA-TKA(97 min) compared to C-TKA(81min)(p<0.001). Medial-lateral laxity at both 0° and 90° were significantly more in C-TKA(6° and 6°) compared to RA-TKA(4.1° and 3.7°) respectively(both p<0.001). Postoperative alignment showed significantly more alignment outliers(>3°deviation) with C-TKA(16) compared to RA-TKA(10). Discussion and Conclusion This double blinded RCT demonstrated small but significant reduction in pain for RA-TKA compared with C-TKA before 6 weeks but similar patient reported outcomes. There was no clear preference of robotic or conventional side surgery.