Abstract:[Objective] To compare clinical outcomes of unicompartmental knee arthroplasty (UKA) versus total knee arthroplasty(TKA) for medial compartment knee osteoarthritis (MC-KOA) in the elderly. [Methods] A retrospective analysis was conducted on 109 el-derly patients who received knee arthroplasty for MC-KOA from September 2021 to September 2022. According to the preoperative doctorpatientcommunication, 59 patients underwent UKA, while other 50 patients underwent TKA. The perioperative, follow-up and imaging dataof the two groups were compared. [Results] The UKA group proved significantly superior to the TKA group in terms of operation time [(61.8±4.7) min vs (80.4±6.5) min, P<0.001], length of incision, [(5.7±0.3) cm vs (6.9±0.4) cm, P<0.001], intraoperative blood loss [(94.3±13.1) mlvs (147.5±19.8) ml, P<0.001], postoperative drainage volume [(169.8±10.0) ml vs (366.7±41.1) ml, P<0.001], time to regain active knee flex-ion of 90° [(13.8±2.2) days vs (17.1±2.4) days, P<0.001], and hospital stay [(9.8±1.8) days vs (14.4±2.4) days, P<0.001]. As time went on,the VAS and KSS scores, knee extension-flexion ROM, stride speed, stride frequency and stride length were significantly improved in bothgroups (P<0.05). At the last follow-up, the UKA group was also significantly better than the TKA in terms of KSS score [(88.2±3.6) vs (82.7±3.1), P<0.001], knee extension-flexion ROM [(123.9±5.7)° vs (116.4±5.1)°, P<0.001], stride speed [(98.4±5.3) cm/s vs (85.1±5.9) cm/s, P<0.001], stride length [(89.3±10.1)cm vs (80.1±11.2) cm, P<0.001]. As for imaging, femorotibial angle (FTA), hip-knee-ankle angle (HKA),medial proximal tibial angle (MPTA) and posterior tibial slope (PTS) were significantly improved in both groups at the last follow-up com-pared with those preoperatively (P<0.05). However, there were no significant differences in the above image indexes between the two groupsat any corresponding time points (P>0.05). [Conclusion] Both UKA and TKA do achieve satisfactory clinical consequences for MC-KOA inelderly. In comparison, the UKA has more advantages in reducing surgical trauma, promoting functional recovery of knee joint and improvinggait over the TKA.