Abstract: Objective To study the feasibility and accuracy of the femur internal and external condyle notch line as the femoral intramedullary localization point used in total knee arthroplasty（TKA）.Methods 64 patients with TKA were randomly divided into the observation group and the control group，32 cases（32 knees）in each group.The observation group was positioned according to the interlocking point between the internal and external condyle notch line and the extension line of the medial lateral condyle of femur.The control group was positioned with traditional technique.The distance between the location points and the anatomical axis of the femur，the femoral external rotation angle and the lower limb force line deviation were observed.Results The average distance between the anatomical axis of femur and the highest point of the intercondylar notch ceiling was（14.27±2.48）mm.The average distance in the observation group was（1.1±0.37）mm，and the distance in the control group was（3.22±1.45）mm，and there was significant difference between the two groups（P<0.05）.The deviation of lower extremity force line and femoral prosthesis valgus angle were measured.In the observation group the deviation was（2.49±1.27）°，and the control group was（3.81±1.74）°，and there was significant difference between the two groups（P<0.05）.In the observation group，the femur prosthesis valgus angle was（88.6±2.71）°，and the control group was（86.7±4.17）°.there was significant difference between the two groups（P<0.05）.Conclusion The interlocking point between the internal and external condyle notch line and the extension line of the medial lateral condyle of femur was a more accurate position for the femoral intramedullary localization point used in total knee arthroplasty，it could provide a satisfactory postoperative femoral prosthesis alignment.

Key words: total knee arthroplasty, the femur internal and external condyle notch, localization point, anatomy