On this play there was nothing Cam could do, Manhertz whiffed. If he had held his block they were also blitzing up the middle and Armand completely whiffed on the linebacker on the delayed blitz when NE sent five and delayed blitzed a 6th. There was actually a 7th linebacker ready to blitz if the rush didn't get there but he backed off when he saw Cam getting swarmed
The thing about sprains is that there are different grades of sprains. Hence the wide window of recovery. Ligaments do not get the same distribution of blood supply as say muscle and bone so they can take longer to heal in some cases.
At this point we should neither be upset or excited that Cam dodged a fracture.