Referred to as knuckling over. Correct advice about most likely overcoming it. If not, we usually catch them and use paint sticks and duct tape to splint it up. You can break the sticks in half and double them up, tape the two pieces together to make them twice as thick, and then put one of the doubled pieces on each side after you straighten out the foot. Be sure you don't get the tape too tight, and don't worry if the calf has a little trouble getting up until he gets used to the splint. In about a week, we try to catch ours and cut the tape in one place alongside one of the sticks. It will then come off by itself in another week or two, after getting wet.
I will try to get this sophisticated technique featured, along with photos, in an upcoming issue of the Journal of the AVMA, unless, of course, the greedy practicioners try to sensor me.
Best of luck, but don't lay awake at night over this one!