Objective To compare the effect between computer assisted navigation total knee replacement and conventional total knee replacement on rotation alignment,mechanical axes,comPOnent position and clinical outcomes.Methods Eighty-two patients were recruited into this pmspoctive study according to entry criteria and were randomly selected into either control group which treated with standard knee replacements or navigation assisted group which operated with navigation assisted total knee replacements.To analyze the rotation of the femoral component and the tibial component in the transverse plane.the combined rotation of both components and mismatch between two components,the mechanical axes,which were measured from postoperative radiographs and computed tomography images.To compare the functional outcomes at 6 weeks and 6 months.Results There were significant diffefences(P＜0.05)in following parameters between control group and navigation assisted group:average rotation of femoral component were 1.51°±3.55°in control group and-0.63°±3.04°in navigation assisted group,the combined rotation of both components were 2.85°±4.07°in control group and 0.28°±3.43°in navigation assisted group,mismatch between components were 1.44°±4.55°in conlrol group and-0.43°±2.86°in navigation assisted group.There were no significant differences between two groups in rotation of tibial component.In addition,analysis showed that patients in navigation assisted group had significantly better mechanical axes and functional outcomes at 6 weeks.Conclusion The use of navigation can help avoid malrotation and errors in axial rotation,and provides improved alignment accuracy as well as better functional outcomes at 6 weeks.