If I got a knee injury how that can affect my PCS orders?

You have orders for an ABN assignment with ABK TDY Enroute. If you don’t attend ABN you will not be qualified for your assignment. If I remember correctly you re-enlisted for Airborne. You need to request a medical deferment until you are healed. If you try to show up at a USASOC assignment skipping ABN, you may lose your chance to ever attend because you were a no show at the course. Plus, the USASOC unit will send you down the road

You are going to need to update your airborne physical post op. You will likely be put on profile resulting in a potential deferment of orders with the worst case a deletion of assignment. You best bet is to speak with your retention NCO or branch manager.