Objective: To investigate the effect of removal of medial tibial osteophytes during unicompartmental knee arthroplasty on postoperative lower alignment. Methods: Patients who underwent unicompartmental knee arthroplasty in Guangdong Hospital of Traditional Chinese Medicine from December 2019 to December 2021 were selected. The difference of osteophyte size and HKA before and after surgery was compared, and the correlation between the size of osteophyte and HKA was analyzed. Results: From December 2019 to December 2021, a total of 186 patients, 150 females and 36 males underwent unicompartmental knee arthroplasty in Guangdong Hospital of Traditional Chinese Medicine and met the set inclusion and exclusion criteria. The mean age was 66.8 years old. The average preoperative HKA was 172.9±3.7°, and the average postoperative HKA was 177.2±3.1°. There was statistical significance in preoperative and postoperative HKA (P＜0.001),and the division of lower alignment before and after operation was statistically significant (P＜0.001). The average preoperative osteophyte size was 3.6±1.9mm, and the average postoperative osteophyte size was 0.3±1.0mm, and the comparison of preoperative and postoperative osteophyte size was statistically significant (P＜0.001), and the grading of osteophytes before and after surgery was statistically significant (P＜0.001). Preoperative osteophyte size was positively correlated with osteophyte difference value (r=0.874，P＜0.001). Preoperative HKA was positively correlated with postoperative HKA (r=0.698, P＜0.001). Conclusion: The lower alignment is mild varus after unicompartmental knee arthroplasty, and the angle of varus is the main factor affecting the lower alignment. Intraoperative removal of medial tibial osteophytes did not significantly change the postoperative lower alignment.