To study the difference between single and double bundle ACL graft cross-sectional dimensions compared with native ACL using postoperative 3-D MRI.

The investigators divide 100 patients with ACL rupture into 2 groups. Group A undergo single bundle anterior cruciate ligament reconstruction (ACLR). Group B undergo double bundle ACL reconstruction. At 3-6 weeks post operation, all the patients undergo 3-D MRI examination of both knees. The investigators reconstruct 3-D models of reconstructed ACL and native ACL, and compare the difference between single and double bundle graft.

Inclusion Criteria:

• ACL rupture patients aged between 10 to 50 years

Exclusion Criteria:

• combined severe injuries to the operated knee (additional ligament rupture, major meniscus loss, patella instability, cartilage damage >2°, pathologic leg axis deviation)
• any injury or surgery to the contralateral knee
• any inflammatory or systemic disease, neuromuscular disease in the lower limbs,any recent knee infection