A bunion, also known as hallux valgus, is an abnormal bony bump of the big toe formed due to a malalignment of the bones of the foot. Bunions cause deviation of the big toe towards the other toes. Similar deformities of the little toe and fifth metatarsal are called bunionettes. Excessive pressure on the bunion by footwear can further lead to development of a callus and may cause pain.
Bunion surgery is performed to relieve pain and realign the soft tissues and bone causing the joint deformity.