The first patient we meet is 49-year-old flight attendant Ronan, who has two knees on his left leg. Or rather, what looks like a second knee is actually a squishy, grapefruit-sized lump hanging off his lower thigh, directly above his knee. Ronan explains that the bump has been with him for years, starting as a tiny spot and then ballooning into a painful mass. It's so painful that it takes Ronan more than 10 minutes to pull on his pants as he tries to slide his legs through the holes without disrupting the lump. And work is no easy walk down the aisle, either: If you've ever walked down a narrow airplane hall and accidentally banged your knee on an armrest, mumbling a string of four-letter words under your breath, you can only imagine how it must feel for Ronan on the daily.