What causes pain in the knee after a tibia or fibula fracture?

Hello doctor,

My fiance had surgery on a tibia or fibula fracture one week ago and has had his pain controlled by Norco. His pain at the site of the break has been well controlled, but throughout the week, he has complained more and more of knee pain. His knee is bruised, extremely swollen, and obviously deformed compared to his other leg. The pain has gotten so bad that he can no longer move his leg or even get out of bed. The surgeon said there were no complications in the surgery. They put a rod in his tibia and plated his fibula and when we called the after-hours number they said this was normal. But it is not normal. He says it feels like his kneecap is dislocated. What do we do? Please help.