The Role of the Shortened Proximal Phalanx in the Setting of Brachymetatarsia

Brachymetatarsia is a condition in which a metatarsal bone does not grow out to full length. This is caused by premature physeal closure. The proximal phalanx associated with the shortened metatarsal helps achieve the natural parabola of the foot. A hypoplastic proximal phalanx is a common finding in patients with brachymetatarsia. The goal of this study was to determine the length of the proximal phalanx in the setting of brachymetatarsia, and how much the shortening is attributed to the clinically smaller toe. We performed a retrospective study to evaluate the length of the proximal phalanx in the shortened ray. After the metatarsal was brought out to the desired length of correction, the proximal phalanx was measured on radiographs. Ninety-seven feet with congenital brachymetatarsia were reviewed in a cohort of 66 patients who underwent surgical correction between January 2005 and February 2020 at a single institution. The group was comprised of 61 females and 5 males, with a mean age of 27.5 years. The average length of the proximal phalanx associated with the affected metatarsal was noted to be 18.9 ± 3.83 mm for males and 15.6 ± 4.02 mm for females. Our results indicate the shortened proximal phalanx is 5 mm shorter when compared to normal population and is a contributing factor to the shortened clinical appearance of the digit in brachymetatarsia. Treating surgeons should be aware of this to better educate patients on the influence of the digit on the overall shortening seen in cases of brachymetatarsia.