New Classification for Brachymetatarsia

For the first time, orthopedic surgeons present a comprehensive classification and surgical guide for treating each type of brachymetatarsia.

Brachymetatarsia is a congenital soft tissue deformity of a ray of the foot which consists of the metatarsal and corresponding phalangeal bones. Until now, there hasn’t been any real consensus on methodology of lengthening for brachymetatarsia.

The study, “Brachymetatarsia: A Classification for Surgical Treatment,” was published online June 11, 2022, in the Journal of Foot & Ankle Surgery.

This classification combines the number of the metatarsals affected and the letters indicating the type of brachymetatarsia deformity. A is for axial deficiency of the metatarsal, B = bowing of the metatarsal, C = congruency of metatarsal phalangeal joint.

The classification and guidelines were based on a review of 300 brachymetatarsals in 166 patients. Fifty of the 166 patients had bilateral brachymetatarsia. Sixty-four of the metatarsals with brachymetatarsia were first metatarsals, 22 were second metatarsals, 28 were third metatarsals, 12 were fifth metatarsals and 174 were fourth metatarsals.

Of the classification types, there were 165 type A, 6 type B, 72 type AB, 39 AC and 18 type ABC. The mean preoperative amount of shortening of the metatarsal was 15 mm (range, 4-20 mm), determined by the preoperative metatarsal parabola deficiency. A majority of the patients were female.

“Clinically the brachymetatarsia ray will have a shorten toe that sits more dorsal on the foot than the adjacent toes and which greater amounts of shortening cause a deeper plantar skin crease,” the study authors wrote.

“The goals of metatarsal lengthening are to improve foot function, restore the metatarsal parabola for weight bearing, allow for a greater selection of shoe gear, and improve pedal cosmesis. Lengthening metatarsals like limb lengthening requires extensive knowledge of congenital deformities, a great understanding of external fixation, and a comprehensive approach.”

The study authors note that for metatarsal lengthening of 10mm or more, acute lengthening with bone grafting and no external fixation is not recommended. Instead for these patients they recommend staged lengthening where bone length is increased in a staged fashion over a year or more. This technique reduces the risk of soft tissue injury.

The study authors included Bradley M. Lamm, chief, Foot and Ankle Surgery at St. Mary’s Medical Center & Palm Beach Children’s Hospital and Tyler B. Lamm, student, Oxbridge Academy, West Palm Beach, Florida.