The pathomechanical mechanism of ACL injuries is still a controversial issue. patients with ACL injuries may have multiple pathological factors, such as developmental abnormalities, abnormal knee dynamics or biomechanics, and anatomical factors. The geometry of the lateral femoro-tibial joint plays an important role in non-contact anterior cruciate ligament (ACL) injuries. Recently, Christopher J. Wahl, MD, a sports medicine scholar at the University of Washington, et al. studied the measurement of lateral knee geometry by MRI in patients with ACL injuries. In this study the authors proposed the hypothesis that athletes with ACL injuries have a more convex lateral compartment articular surface of the knee compared to athletes without ACL injuries; in addition, the lateral articular surface of the knee is relatively or absolutely more convex in women than in men. The authors noted that all female cases (ACL-injured and non-injured) and male cases with ACL injury shared the same lateral knee geometry, with a smaller tibial plateau length relative to the femur and a more convex proximal tibial and lateral femoral articular surfaces. The short, highly convex articular surfaces result in poorer stability of the knee joint with respect to tibial anterior translation and rotation. The results of this study may explain, to some extent, why women are more likely to have ACL injuries than men and why some studies have shown no gender-neutral differences in patients with re-injury after ACL reconstruction.