My DD had ACL surgery in early May her freshman year and was out for two weeks and then only part time for most of the rest of the semester. We didn't wait until summer so she could be recovered enough to swim and compete in high school by August. She was on pain meds and used an ice machine a full week and her PT didn't even start until she healed for 2 weeks (her surgeon liked to wait while most started PT right away). Most of her teachers worked with her. They sent work home for her and she was able to do make up most of it. We did make one mistake that really bit her in the butt. I *thought* she had a quiz in Geometry and I sent her in to take it and get out of the way while slightly high on pain meds so it was one less thing to do when she came back. I was wrong. It was a
unit test and she got a "D" on it

which brought her whole grade semester down. Three years later and I'm still kicking myself over that one, lol.
Frankly, I don't think this semester counts nearly as much as other semesters do. The kids have been accepted and they have received their scholarships. I think that, for the most part, colleges understand senioritis and as long as kids pass they will be fine. From what I've read only a "D" or an "F" will make a difference. I do know that sometimes offers
are withdrawn ... I know a boy who was accepted to Brown and had his offered rescinded due to poor grades. Here is a thread about when colleges rescind over on CC:
https://talk.collegeconfidential.co...n-do-colleges-rescind-acceptances.html#latest . I guess what I'm trying to say is that he probably doesn't have to bust his hump to get A's and B's while recovering from surgery.
IIRC, your son was accepted to two auto-admit state schools, right? Texas and A&M? You may want to reach out to the admissions department because the auto-admit might work differently.
Good luck to him on his surgery and I hope he has a quick recovery!
ETA: SHOOT! I just realized that we forgot to put her ACL surgery under "special circumstances" to help explain her freshman 2nd semester GPA (her lowest of all). Oh well.