Another Classification of First Metatarsophalangeal Joint Dislocation-Type 3: Review and Case Description of the Plantar Dislocation

Abstract

Plantar dislocation of the first metatarsophalangeal joint is a possible, albeit rare, injury to the foot. The mechanism has been attributed to a hyperflexion motion, with the hallux situated plantar to the first metatarsal head. In this article, we provide a case example of an open, plantar dislocation of the first metatarsophalangeal and perform a literature review of this rare injury. Based on x-ray analysis of the published cases, the sesamoids may or may not dislocate with the phalanx based off of the local capsuloligamentous anatomy. As a result, a modified Jahss classification (type 3A and type 3B) has been proposed to amend the existing system, adding plantar dislocations of the first metatarsophalangeal without (type 3A) and with (type 3B) sesamoid dislocation.

Keywords: 4; Jahss classification; dancer's dislocation; open fracture; plantar plate; sand toe; sesamoids.