There are two sesamoid bones under the first metatarsal on each foot. These can easily become inflamed and cause pain. Inflammation is often caused by mechanical overload of the area, this can be because of footshape, biomechanics of an individuals gait, footwear, sporting activity, or other pathology like osteoarthritis or functional hallux limitus. Treatment options depend upon assessment of the cause, but include Orthotics, change of footwear and injection therapy. It is important to have treatment as if left untreated, this can lead to stress fracture, and possibly even necrosis, possibly resulting in surgical excision and should be avoided if possible.