Abstract:[Objective] To explore the influence of variation of anterior condyle height (ACH) on knee flexion-extension range of mo- tion (ROM) after total knee replacement. [Methods] A retrospective study was performed on 72 patients who underwent primary unilateral total knee replacement for knee osteoarthritis in our hospital from October 2018 to January 2020, and followed up for more than 12 months. The general information, ROM, KSS clinical and functional scores, as well as radiographically measured ACH were recorded. Univariate Pearson correlation analysis and multiple stepwise regression analysis were used to explore the factors affecting ROM at the last follow-up. [Results] Patients were divided into three groups according to ACH variation (postoperative ACH minus preoperative ACH), the thinning group with ACH variation <-3mm, the unchanged group with -3~3 mm, the thickening group ≥3mm group. Although there was no a signifi- cant difference in the ROM before operation among the three groups (P>0.05) , the ROM at the latest follow-up was ranked in descending order of the thinning group > the unchanged group > the thickening group, with a statistically significant difference among them (P<0.05) . There was no a significant difference in preoperative KSS clinical scores among the three groups (P>0.05) , however, the ROM at the latest follow-up in descending order was of the thinning group >the unchanged group > the thickening group, which was statistically significant (P<0.05). In term of Pearson correlation analysis, the ROM at the latest follow-up was negatively correlated with ACH variation (P<0.05) , whereas the former was significantly positively correlated with KSS clinical score at the last follow-up (P<0.05) . As results of multiple re- gression analysis, the ROM at the last follow-up was positively correlated with the ROM preoperatively (B=0.317, P=0.021) , whereas nega- tively correlated with ACH variation (B=-2.673, P<0.001) . [Conclusion] ACH variation is closely related to ROM after operation.