Pain in knee while sitting cross legged.

I hurt my knee 3 months back while playing football. The MRI revealed that there is intracellular fluid collection in the proximal 1/3rd of the Anterior Cruciate ligament suggestive of ganglion. After the initial assessment from my orthopedic doctor, I was referred to a physiotherapist who recommended some strengthening exercises like straight leg raises, heel slides and other hamstring stretched. I have been doing these exercises for the last 2 months and in the last 2 weeks I have started to run and play tennis with no mechanical difficulty. But there is occasional pain if the heel hits the ground too hard or if there is slight twisting movement. Walking is now normal but straightening the knee after a long duration of sitting is painful. While sitting cross legged the hip gets activated and on relaxing the hip, there is tremendous pain in the knee. What should I do? Is surgery necessary to eradicate pain completely restoring complete movement and pre injury leg state?Please guide