A protruding bone in the big toe may also be a bunion deformity. A bunion deformity is a deviation of the bunion to the lateral side at the first metatarsophalangeal joint. A bunion is a complex anatomical deformity that is more challenging to treat. Bunions can potentially form, making the protrusion of the big toe bone more pronounced. Genetics is an important factor in the formation of bunions in most cases, especially among adolescent patients, where the first metatarsal inversion causes the bones of the big toe to protrude. In addition, bunions are often seen in patients with systemic joint pathologies, such as rheumatoid arthritis in which synovitis causes destruction of the metatarsophalangeal joint capsule, resulting in a bunion deformity. Flat feet and uncoordinated relationships of the first metatarsal phalangeal joint can also cause bunion deformities, resulting in protrusion of the big toe bone. There are also many cases where a protruding big toe bone can be a deformity caused after a traumatic injury, especially after a fracture that has not been treated well.