Inability to straighten the knee after dislocation reset may be caused by joint contracture, muscle injury, joint interlocking and other factors. 1. Joint contracture: if the knee dislocation reset process, improper surgical operation, resulting in the shortening of the soft tissues around the joint, causing joint contracture disease. It can lead to serious limitation of knee joint activities, thus causing the situation that the knee cannot be straightened after dislocation reset. 2. Muscle injury: when the knee dislocation reset, fail to strictly follow the doctor’s instructions for daily care. This leads to local muscle tissue damage, causing secondary trauma to the body, which in turn causes the knee dislocation reset can not be straightened. 3. Joint interlocking: after the dislocation of the knee reset, carry out high-intensity sports, such as playing basketball, playing soccer and so on. This will make the joints interlock, thus affecting the normal activities of the body and inducing the phenomenon of not straightening the knee after dislocation reset. It is recommended to go to the regular hospital for appropriate examination to avoid aggravation of the condition and secondary damage to the body.