Hallux valgus is an acquired deformity of the big toe in which it deviates laterally at the metatarsophalangeal joint I, while the first metatarsal bone drifts medially (metatarsus primus varus).
Clinically, there is an increasing bulge on the medial aspect of the big-toe joint (pseudoexostosis), often with pressure discomfort, callus formation and irritation-related pain. Accompanying findings include splay foot, hammer or claw toes and complaints in the neighbouring metatarsal rays. Diagnosis and severity grading are carried out clinically and radiologically (intermetatarsal and hallux valgus angles).