Hallux valgus is a deformity of the base joint of the big toe, involving a lateral (outward) deviation of the big toe. Deformity can occur due to a number of reasons, including hereditary factors, prior forefoot deformity, arthritis and poor footwear. The deformity can lead to irritation and increased pressure over the joint, which may result in the development of localised bursitis or a bunion. Generally, once the deformity has taken place the increased load placed on the tendons crossing the joint leads to further deviation. Hallux valgus generally presents as deformity and pain on the medial (inner) side of the base joint of the big toe.