Seven weeks after ligament reconstruction meniscus suture surgery, the leg can not be straightened, which may be caused by the free body, the surrounding soft tissue injury, rehabilitation exercise is not timely and other factors. 1. Free body: In addition to ligament injury and meniscus injury, the knee joint may also be accompanied by the possibility of free body formation, which affects the range of motion of the knee joint and hinders the knee joint activities, thus resulting in the phenomenon of straightening the leg. 2. Surrounding soft tissue damage: In the process of meniscus suture surgery, the surrounding muscles, ligaments and other soft tissues may be damaged, so that the function of straightening the leg is affected, and the leg still can not be straightened even after 7 weeks after the surgery. 3. Inadequate rehabilitation: Failure to carry out timely rehabilitation after suture surgery, or not paying attention to the doctor’s exercise instruction, or carrying out inappropriate exercises will lead to stiffness of the knee joint, muscle adhesion, and consequently, the leg can not be straightened. In order to improve the leg extension problem as soon as possible, it is recommended to go to the orthopedic department of the hospital for a clear diagnosis.