Dorsal Dislocation of the First Metatarso-Phalangeal Joint

Abstract

The anatomy of the first metatarso-phalangealjoint and of dorsal dislocation of the phalanx are described. As with similar lesions in the hand, closed reduction is impossible because of interposition of the volar plate. Open reduction is essential and should be performed as soon as possible after the injury.

Dorsal dislocation of the first metatarsophalangeal joint

“…Four cases with associated dorsal dislocation of the sesamoids could not be reduced and have needed open reduction [2,11,12,18]. Two other cases without sesamoid dislocation were also treated by open reduction [7], but in one of our similar cases we were able to carry out closed reduction without anaesthesia. The difference between the two kinds of type I injuries depends on whether there is dorsal dislocation of the sesamoids with detachment of the fibrocartilaginous plate from its weak metatarsal insertion, or whether, as in our case, the sesamoids do not dislocate, but separation occurs from rupture of the sesamophalangeal ligaments so that the phalanx can pass over the metatarsal head.…”

“…In the latter case, widening of the intersesamoid space may be apparent. Dislocation of both sesamoids could be the cause of irreducibility in Giannikas's cases, although they were type IIA [7] and needed open reduction. Type I can be subdivided depending on whether or not the sesamoids are dislocated.…”

“…In type I there is no sesamoid fracture or dislocation; in type IIA the sesamoids are displaced and in type IIB there is a transverse fracture. Closed reduction is usually impossible in type I [2,3,7,11,18], but is possible in type II.…”

The hallux sesamoids revisited

“…Typically, hyperextension injuries of the great toe result in dorsal dislocation of the base of the proximal phalanx over the metatarsal head [10,19]. The adjacent sesamoids may become displaced laterally, or may separate from each other and be dislodged proximally, dorsal to the metatarsal neck.…”

“…The adjacent sesamoids may become displaced laterally, or may separate from each other and be dislodged proximally, dorsal to the metatarsal neck. Avulsion of the plantar capsule is occasionally associated with a hyperextension injury [19].…”