Pathomechanics of complex dislocations of the first metatarsophalangeal joint.

Because only 10 complex dislocations of the first metatarsophalangeal joint have been reported to date, a retrospective review was initiated to study the pathomechanics of 11 new cases (9 patients) and to report on the clinical and functional outcomes. Concomitant ipsilateral injuries were frequent: 6 tarsometatarsal joint partial disruptions and 8 cases with multiple midfoot or forefoot fractures or dislocations occurred. Clinical and radiographic assessments suggested that forefoot hyperextension combined with axial loading of the foot in a heel to toe or toe to heel direction produced all. Six cases required open reductions (5 were compound), and 5 cases were managed by closed methods. Associated tarsometatarsal joint disruptions facilitated closed management. The most common complaints at followup assessment (average, 7 years) were sensitive plantar wounds, partial joint ankylosis, and sesamoid sensitivity. All but 1 patient resumed the same or modified work. The data in this series suggest that most complex dislocations of the first metatarsophalangeal joint probably occur frequently with a concurrent tarsometatarsal joint sprain or disruption, and that the primary mechanism of injury is that of axial loading of the foot causing midfoot hyperflexion and forefoot hyperextension. Contrary to current opinion, not all complex dislocations of the first metatarsophalangeal joint are resistant to closed management.