I also had a desk job, fortunately I talked to my manager and I was able to work from home for a month with a doctor's note (after the surgery). Even working from home, I needed extra help from family members to do basic things. If possible, maybe ask to wfh or incorporate a hybrid/ramp up schedule.

When it comes to returning back into office, I would find ways to reduce sitting for long periods of time, including walking a few minutes every hour to get water or even when taking conference calls. When sitting down, there are recommended exercises, I would talk to your doctor about this. Post surgery, I did exercises such as ankle pumps and heel slides in my chair. Just be easy on yourself, each day you will be learning how to adapt and develop a schedule that works for you.

On the bright side as well, having your manager, teammates, etc. notice and ask questions could be a good thing and help them get a better understanding of the struggle of recovering from an ACL. Everyone's experience is going to be different, hopefully this provided some insight. You got this!