Objective To investigate the current status of bone tunnel enlargement after anterior cruciate ligament(ACL) reconstruction, compare the postoperative outcomes between femoral deflection tunnels and conventional tunnels, and analyze the causes.

Methods Forty patients with ACL injuries were selected for ACL reconstruction, 20 patients were drilled into the femoral tunnel using the deflection tunnel(deflection tunnel group), and the remaining 20 patients were drilled into the femoral tunnel using the traditional transanterior medial approach(normal tunnel group), and the routine rehabilitation training after surgery in two groups was implemented. The statistics of bone tunnel deformation and wiper effect under static load were observed to obtain the mechanical basis and pattern of bone tunnel deformation. The IKDC score and Lyshlom scores in two groups were compared to assess the stability of the knee joint.

Results All patients′ incisions healed well, and the joint activities were normalized. Before operation, there was no statistical significance in the IKDC score and Lysholm score between normal tunnel group and deflection tunnel group(P>0.05). After operation, the IKDC score and Lysholm score in two groups were higher than those before operation, and which in the deflection tunnel group was higher than that in normal tunnel group(P < 0.05 to P < 0.01).

Conclusions The deflection tunnel reconstruction of femur can effectively promote the functional recovery of patients with ACL injury after arthroscopic surgery, and the prognosis is good.