Abstract
Purpose: To report concomitant dorsal dislocation of first metatarsophalangeal joint and divergent Lisfranc dislocation, a uniquely “floating forefoot” and analyse clinical pathodynamics.
Methods & Results: We treated concomitant dorsal dislocation of first metatarsophalangeal joint and divergent Lisfranc fracture-dislocation in an intoxicated patient as a heavy weight fell on foot. Closed reduction of first metatarsophalangeal joint was unstable until after open reduction and fixation of first tarsometarsophalangeal joint. First to third tarsometatarsal joints were stabilised with cannulated screws and lateral two rays with Kirschner wires. Prophylactic fasciotomies were performed to preempt potentially high risk of failure of recognition of compartment syndrome in intoxicated patient. Clinical pathodynamic analysis suggests that natural tendency to withdraw the foot contributed to primary medial loading with forced hyperextension of hallux metatarsophalangeal joint and enhanced complementary hyperflexion of midfoot. The former resulted in dorsal dislocation of first metatarsophalangeal joint.
Then load shift toward secondary axis of lateral divergent loading became the operative force to produce divergent Lisfranc dislocation, which effectively resulted in a floating forefoot.
Conclusions: Floating forefoot is a unique injury after high-energy trauma, although floating metatarsal and association between Jahss Type I complex dislocation of first metatarsophalangeal joint and Lisfranc injury were described. Floating forefoot also represents Grade V in the modified classification of metarsophalangeal injuries (Kodali Siva R K Prasad et al Modification of Clanton’s classification) as progression of injury pattern transcends the local barrier and raises the spectrum of dynamic cascade of multidirectional transmission of the operative forces with the resultant unique injury.
Correspondence should be addressed to BOSA at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE, England.
