Abstract:[Objective] To investigate the effect of removal of medial tibial osteophytes during unicompartmental knee arthroplasty (UKA) on postoperative lower limb alignment. [Methods] A retrospective study was done on 186 patients who received UKA in our hospital from December 2019 to December 2021. The difference of osteophyte size and hipknee-ankle angle(HKA) before and after surgery was compared, and the correlation between them was analyzed. [Results] Compared with those preoperatively, the HKA [(172.9±3.7)°, (177.2± 3.1)°, P＜0.001] increased significantly, while the osteophyte uplift [(3.6±1.9) mm, (0.3±1.0) mm, P＜0.001] decreased significantly postoperatively. In addition, Kennedy partition [0/1/2/C/3, (30/69/66/21/0), (1/20/89/71/5), P＜0.001] and osteophyte classification [large/medium/ small: (21/86/79), (0/5/181), P＜0.001] were significantly improved. Regarding correlation, the preoperative HKA was negatively correlated with preoperative osteopathic values (r=-0.308, P＜0.001). The preoperative HKA was negatively correlated with preoperative and postoperative osteophyte difference (r=-0.256, P＜0.001). In addition, there was a significant negative correlation between postoperative HKA and preoperative osteophyte value (r=-0.163, P=0.026), whereas a significant positive correlation between preoperative and postoperative HKA difference and preoperative osteophyte value (r=0.227, P=0.002), a significant positive correlation between the differences of HKA and osteophyte before and after surgery (r=0.239, P＜0.001). [Conclusion] The alignment of lower limbs after UKA is mild varus, which is mainly influenced by preoperative HKA, while the difference of medial tibial osteophytes before and after operation has no a significant impact on postoperative alignment of the lower limb.