What Causes Severe Knee Pain On Movement After An ACL Reconstructive Surgery?

Hi there, I had ACL reconstructive surgery 2 years ago on my right knee. I ve been feeling discomfort and pain on the anterior medial aspect of my knee (about 4-6cm below my patella and to the medial aspect). It feels like a bony protrusion but I m unsure. I know that there were 2 staples left post surgery. I feel the pain worsen after activities, but it is tender to touch the bony prominence and it s right underneath where the surgical scar was. I ve noticed it for a week now. Any thoughts?