According to SukiMMA, Kid Yamamoto’s knee surgery went well though he’s in a lot of pain. Apparently he took care of a nagging wrist injury at the same time, which is a pretty clever move. He also bought a Nintendo DS to help him get through his rehab and speaks very highly of “SimCity”:

I bought NINTENDO DS to kill my time. I play the role of a mayor in a game called “SimCity.”
I didn’t tell this before, but I had my left wrist operated on as well. I was injured my wrist during my training last September, a week before a fight with Bibiano Fernandes. I had kept training for my fight and I even had a fight without taking care of properly. I knew something was wrong. I couldn’t throw powerful punches by my left hand because of the pain. Finally I had an operation to get rid of bones which don’t stick together. I’m glad that I could have both my knee and wrist treated.

SukiMMA is essential reading, providing English translations of interviews and articles from the Japanese fight media