Medical Definition of ARTHRODESIS. : the surgical immobilization of a joint so that the bones grow solidly together: artificial ankylosis. the surgical immobilization of a joint so that the bones grow solidly together. ADVERTISEMENT.
Trapdoor spiders are not particularly harmful to man however, like Tarantulas, the tiny hairs on the legs of some species leave tiny red marks where the toothed hairs on the spiders' feet have clung to the skin. Mouse spiders are also a type of Trapdoor spider with huge chelicerae and may measure up to 35mm in body length.
Of those that are considered toxic, only the Brazilian wandering spider, the funnel web spiders, some of the widow spiders, the Chilean Recluse spider and the Chinese bird spider, which is a type of tarantula, have caused fatalities. The bites are much more dangerous to small children and the elderly.