ObjectivesWe investigated the accuracy of reduction of intramedullary nailed femoral shaft fractures in human cadavers, comparing conventional and computer navigation techniques. MethodsTwenty femoral shaft fractures were created in human cadavers, with segmental defects ranging from 9 to 53mm in length (Winquist 3–4, AO 32C2). All fractures were fixed with antegrade 9mm diameter femoral nails on a radiolucent operating table. Five fractures (“Fluoro” group) were fixed with conventional techniques and fifteen fractures (“Nav 1” and “Nav 2” groups) with computer navigation, using fluoroscopic images of the normal femur to correct for length and rotation. Postoperative CT scans compared femoral length and rotation with the normal leg. ResultsMean leg length discrepancy in the computer navigation groups was smaller, namely, 3.6mm for Nav 1 (95% CI: 1.072 to 6.128) and 4.2mm for Nav 2 (95% CI: 0.63 to 7.75) vs. 9.8mm for Fluoro (95% CI: 6.225 to 13.37) (p<0.023). Mean rotational discrepancies were 8.7° for Nav 1 (95% CI: 4.282 to 13.12) and 5.6° for Nav 2 (95% CI: −0.65 to 11.85) vs. 9.0° for Fluoro (95% CI: 2.752 to 15.25) (p=0.650). ConclusionsComputer navigation significantly improves the accuracy of femoral shaft fracture fixation with regard to leg length, but not rotational deformity.