1. What was the cause of the Injury: Sports or Trauma?
2. Because Sciatic nerve
supplies the muscles of back of the knee, either it can be a referred pain
or else your Orthopedic Doctor is in better position to explain the condition.
3. In Ayurveda we hold Ligaments (Snayu) similar in properties to that of Kapha (Prakriti) i.e. both provide STABILITY to the body, thus whenever there is any derangement in one of them this results in reduced activities .
4. Rheumatic disease is one such Autoimmune disease
which affects the Joints,so ask about it with your Physician.
5. You can Practice Utkatasan (chair pose),Trikonasan (triangle pose), Utthita Parsvakonasan (extended side angle pose) to strengthen your Knees,thighs,hips and ankles