Getting hit after rhinoseptoplasty with grafts?

A functional rhinoplasty will usually result in grafts being placed to help support and strengthen the nose. However, with any trauma there is always a risk of the grafts weakening or fracturing. The grafts are usually secured to surrounding structures with sutures, but any trauma can potentially cause them to migrate. If this does happen, revision surgery can be performed to reposition or replace the grafts if needed. Depending on the how much septal cartilage is available for a revision surgery, cartilage may need to be taken from the ear or rib to create new grafts.
At the very least, I would recommend wearing a protective face mask while playing sports after surgery.