Thank you--They don't mention his knees....
I've heard reports that the knee injuries were just surface wounds--no structural damage. But at this point it's hard to say. He was in surgery for an awfully long while and we'll know better after a few days. But on the whole it seems like he'll be okay and that the wounds are not career threatening.
Although now some websites are raising the valid point that if his jaw is wired shut to allow it to mend, he will be placed on a liquid diet, which would case significant weight loss--not a good thing for athletes. Even if Ben's knees are fine, there is the chance that his facial and jaw fractures could sideline him for at least part of the season.