Objective To investigate the correlation between knee joint line and anterior knee pain after total knee arthroplasty (TKA).Methods From January 2008 to December 2010,76 patients with osteoarthritis underwent primary TKA in our hospital,including 11 males and 65 females,aged from 47 to 83 years (average,68.88±7.61 years).Fixed-bearing posterior stabilized TKA (PFC) was used in all patients.All patients were followed up every 12 months after TKA.According to the Figgie's method,pre-and post-operative knee joint line was measured,and the changes of pre-and post-operative knee joint line were calculated.If the knee joint line was elevated,it was defined as positive; on the contrary,it was defined as negative.The Feller's patellar score was used to assess pre-and post-operative patellar function.The correlation between joint line level and Feller's patellar score was analyzed 24 months after operation.Results The joint line level ranged from-6.8 to 10.44 mm (average,2.69±3.31 mm).With the rise of the joint line,the patient's patella score decreased.There is a negative correlation between the elevated joint line level and Feller's patellar score (r=-0.763,P=0.000).The Feller's patellar score decreased with the fall of joint line level,and there is a positive correlation between them (r=0.914,P=0.000).The Feller's patellar score was higher in patients whose joint line change was less than 4 mm than that in patients whose joint line change was greater than 4 mm (t=12.648,P=0.000; t=l 1.775,P=0.000).Conclusion The joint line change was correlated to anterior knee pain after TKA with fixedbearing posterior stabilized prosthesis.The joint line change less than 4 mm can result in a better knee joint function.