The leg can not be fully straightened after ligament surgery is mostly considered as post-surgery joint stiffness, which can be treated with physical therapy, medication and rehabilitation exercises. 1. Physiotherapy: such as wax therapy, ultrasonic physiotherapy, Chinese medicine fumigation, etc. can improve local blood circulation. 2. Medication: Oral medication can be taken to relieve tendons and activate blood circulation, such as Xiejindan capsule or Xiejindan tablets. 3. Rehabilitation exercise: if the ligament has healed, you can perform rehabilitation exercise, passive flexion and extension activities, you can also gradually perform active flexion and extension activities, exercise for a period of time, joint mobility will generally improve significantly. Ligament surgery can not straighten the leg, need to go to the hospital, and under the guidance of the doctor for treatment.