Staph Infection Post Fem Pop Bypass, Treatment With Moving The Quadricep Muscle, Relocating To Graft To Prevent Infection. Explanation?

My father in law had a fem pop bypass three weeks ago and developed a staph infection. He has been hospitalized on IV antibiotics for the past week and today they went in to insert a drain into the infected abcess and came out after flushing it out without the drain. The surgeon then told my mother in law that they needed to go back in and move the quadricep muscle to relocate the graft to prevent the infection from attacking it. Can you just explain what they are doing and why? We don t quite understand.