Risk factors for meniscus injury include age, gender, body mass index, physical activity, knee ligament damage, and work-related repetitive activities. The increased of posterior tibial slope(PTS) has been considered to affect the type and severity of meniscus injury. Increased lateral tibia slope and asymmetrical media tibia slope and lateral tibia slope may be risk factors for posterior lateral meniscus root tear after anterior cruciate ligament (ACL) injury.The size of PTS is also a factor to be considered in determining early ACL reconstruction to prevent secondary meniscus injuries in patients with ACL injuries.