Lengthening of the first metatarsal through an arthrodesis site for treatment of brachymetatarsia: a case report.

Brachymetatarsia of the first metatarsal is an uncommon condition, but one that is amenable to treatment by lengthening via distraction osteogenesis, a process that employs 2 groups of pins of an appropriate external fixator inserted in the metatarsal to apply gradual distraction across an intervening osteotomy. We present the case of a female, aged 13 years, who presented with congenital bilateral first brachymetatarsia and left foot pain due to transfer metatarsalgia. The short and plantarflexed first ray could not accommodate both groups of fixator pins, even with the fixator set at its shortest length. An alternative strategy was devised that reduced the degree of plantarflexion using a tarsometatarsal arthrodesis, which effected subsequent lengthening through the healing fusion site. Lengthening commenced after 10 days and continued over a period of 52 days, at a rate of 0.5 mm to 1.0 mm per day. Consolidation occurred at 20 weeks with a final increase in length of 25 mm. The patient returned to vigorous sporting activity 1 year after removal of the fixator. To our knowledge, this is the first account of a metatarsal-lengthening arthrodesis at the tarsometatarsal level.