ObjectiveTo investigate the effect of the femoral tunnel angle on the femoral tunnel after anterior cruciate ligament (ACL) reconstruction in rabbits. MethodsFifty-four healthy 4-5 months old rabbits (weighing, 1.8-2.3 kg, male or female) were randomly divided into 3 groups (n=18). The ACL reconstruction models of the right knee were established in 3 experimental groups using its Achilles tendons, and the left knee served as the control group. On the coronal position, the angle between the femoral tunnel and the femoral shaft axis was 30°, 45°, and 60°. The level of tumor necrosis factor α (TNF-α) in the synovial fluid at 1, 2, and 4 weeks, the maximum load of the ligament and the rate of bone tunnel enlargement at 4, 8, and 12 weeks were detected. ResultsThe level of TNF-α significantly increased, and the maximum load of the ligament significantly decreased in the 3 experimental groups when compared with ones in the control group (P<0.05), but no significant difference was found among 3 experimental groups (P>0.05). The bone tunnel enlargement was observed in 3 experimental groups at each time point and reached the peak at 4 weeks, but no significant difference was shown among 3 groups (P>0.05). ConclusionThe 30-60° angle between the femoral tunnel and the femoral shaft axis in the coronal position has no significant effect on the femoral tunnel enlargement after ACL reconstruction in rabbits.