First option: rest, immobilized for 2-4 weeks.
Rehab to regain range of motion.
However, surgery may be needed if: cartilage
or other tissue ends protrude into the joint space, which could cause further damage and should be surgically removed. If a ligament is too stretched to recover on its own and this causes the patella to dislocate often.
Answer assisted by Jin Packard, Medical Student