I just assumed it was two ACL tears. A growth plate injury is pretty scary though.
I asked my knee surgeon friend about this issue; here's our conversation:
Me: what do you think about Nerlens Noel's knee? people are saying he'll be vulnerable to acl tears because he broke his growth plate in high school
Friend: Well that has no bearing once it is fused I'd agree if he were still like 14 or 15
Me: ah, ok
Friend: But that growth plate has to be closed or very close to it by now
Friend: then the tibia just becomes a rock
Friend: his new ACL will literally be screwed into place and 9 mo. from now when those screws become bone tissue, that plate will be fused with almost 100 percent certainty
Me: so, hypothetically, if he were 15 and had a growth plate injury and then tore his acl, it would be tricky to re-attach it?
Friend: It would be tricky, but any orthopedic dude worth his salt could do it with no sacrifice to the growth plate
Me: oh, and it wouldn't be any weaker long-term?
Friend: 6 mo. Out with vigorous physical therapy and this patient compared to one where the plate was fused will be virtually identical in terms of the tension that ACL can withstand
Me: so it doesn't make sense to say "maybe his growth plate healed badly and now he's going to be at risk for knee problems forever"?
Friend: No, i don't think so because 1) if his growth plate healed badly, his growth would have been extremely stunted and he'd be a lot shorter than he is now and 2) if it did heal badly, he would have torn it already or caused knee problems already. with the information given, one just has to trust that his growth plate did in fact heal and that it is almost fused based off of the fact that he would not be able to compete at his high level and have his height if he had been exposed to bad growth plate healing in the first place
Long story short, it seems like growth plate injuries do exactly what you would expect: affect your growth. Once you're done growing and your growth plates disappear, it's literally impossible to have further complications due to a broken growth plate.