Bunions. Coloured X-ray of bunions (hallux vulgas) on the feet of a 69 year old woman. Bunions (shown here as yellow projections) are swellings of the joint between the big toe and the first metatarsal bone. It causes the base of the big toe to project outwards and the tip of it to point inwards. Bunions are caused by the rubbing of ill-fitting shoes. The deformity can be corrected surgically.