sesamoiditis

noun

ses·​a·​moid·​itis ˌses-ə-ˌmȯi-ˈdīt-əs 

1

: pain and inflammation of either of the two small sesamoid bones or surrounding tendons of the ball of the foot at the base of the big toe

The pain is increased when the first metatarsophalangeal joint is dorsiflexed to its limit. However, the diagnosis of a sesamoid stress fracture should not be based on the above history and physical findings alone. Athletes with a sesamoiditis or a metatarsalgia can present with a similar symptom complex.

—James S. Keene, The Journal of the American Medical Association

2

: inflammation of the navicular bone and adjacent structures in the horse