What happens to the face if the zygomaticus muscle and retaining ligament were injured during a cheekbone reduction?

Providing that you do not have significant deformity of the bone or signs of partial nerve paralysis (facial nerve) I do not see the reason why you could not have a face lift. Addition of fat grafts to zygomatic area, which we do in majority of face lifts to add some volume and contour cheeks and periorbital area, can additionally improve face lift result and possibly camouflage underlying deformity. In-person consultation with an experienced plastic surgeon with good reputation in facial rejuvenation would help. Good luck.

If the injury was not appreciated at the time the soft tissues may have descended and created an asymmetry to the cheeks. The ability to raise this back is limited by scar contracture over time. The the cheek should be resuspended and the earlier the better . However, if this is now stable and a lift cannot be adequately achieved another option is to add in fillers or fat grafts. An improvement would be possible but total correction may not be. Good luck.

An injury to the zygomaticus major and/or zygomaticus muscles leaves the patient looking as though they have had a rather major stroke on the affected side. Those muscles are the ones that move the cheeks when you smile. I would go to a doc that specializes in facial nerve injuries