Analyzing the relative accuracy of leg length restoration we found a mean difference of 0.2 mm ( 95 % CI , -1.0 to +1.4 mm ; p = 0.729 ) between fluoroscopy and navigation , 0.2 mm ( 95 % CI , -0.9 to +1.3 mm ; p = 0.740 ) for global offset and 1.7 mm ( 95 % CI , +0.4 to +2.9 mm ; p = 0.008 ) for femoral offset .