Abstract: BACKGROUND: Total knee arthroplasty is an important treatment for patients with ineffective conservative treatment or terminal knee osteoarthritis, but its surgical effect and patients’ satisfaction still need to be improved. Range of motion is an important parameter to evaluate patients' postoperative function and satisfaction.   
OBJECTIVE: To investigate the influencing factors of knee flexion limitation after total knee arthroplasty with posterior stabilized prostheses. 
METHODS: From January 2010 to December 2018, 117 patients with knee osteoarthritis were treated in the Second Affiliated Hospital of Chengdu Medical College/Nuclear Industry 416 Hospital, including 29 males and 88 females, all of whom received total knee arthroplasty. After a follow-up of more than 6 months, single factor analysis and Logistic regression analysis were performed on the influencing factors (surgical factors: postoperative joint line height change, postoperative tibial plateau retroversion, femoral condyle offset ratio change; non-operative factors: age, body mass index, preoperative HSS score, preoperative joint range of motion, preoperative visual analogue scale score, and postoperative active exercise) of postoperative knee flexion limitation to identify the independent impact factors of flexion limitation after total knee arthroplasty. The reaserch was approved by the Ethics Committee of the Second Affiliated Hospital of Chengdu Medical College/Nuclear Industry 416 Hospital.  
RESULTS AND CONCLUSION: (1) Single factor analysis showed that the patient’s age, body mass index, preoperative HSS score, preoperative range of motion, preoperative visual analogure scale score, postoperative active exercise and postoperative joint line height change had a significant effect on postoperative knee flexion function (all P < 0.05). (2) Logistic regression analysis: body mass index [OR=0.131, 95%CI (0.065,0.261), P < 0.001], preoperative HSS score [OR=4.297, 95%CI (2.139,8.634), P < 0.001], and preoperative range of motion [OR=10.612, 95%CI (6.565,17.153), P < 0.001] were non-operative independent influencing factors for patients with limited knee flexion after total knee arthroplasty. postoperative joint line height change [OR=0.255, 95%CI(0.167,0.387), P < 0.001] was an independent surgical influencing factor for patients with limited knee flexion after total knee arthroplasty. Body mass index and postoperative joint line height change were negatively correlated with postoperative knee flexion function; and preoperative HSS score and preoperative range of motion were positively correlated with postoperative knee flexion function. (3) The results showed that knee flexion function after total knee arthroplasty with posterior stabilized prostheses had correlations with patient's body mass index, preoperative HSS score, preoperative range of motion and postoperative joint line height change. 

Key words: bone, prosthesis, arthritis, knee, arthroplasty, flexion limitation, influencing factor