Metatarsus Adductus Association With Fifth Metatarsal Fractures: Radiographic Analysis

Metatarsus adductus is a congenital forefoot deformity associated with pathologies including proximal fifth metatarsal fractures. The aim of this study is to assess the presence of metatarsus adductus and alignment in patients with proximal fifth metatarsal fractures. We hypothesize that there is an increased incidence of metatarsus adductus in patients with proximal fifth metatarsal fractures.

A retrospective analysis was performed of patients who were treated for fifth metatarsal fractures from 2022 to 2024. Radiographic measurements including metatarsus adductus angle (MAA), lateral Meary angle, fracture zone, and foot alignment were recorded for each fracture.

Forty-nine patients were included. Patients with a zone 1 fracture had an average MAA of 14.2°. Of these patients, 10% had a cavus and 18% had a planus midfoot. Patients with a zone 2 fracture had an average MAA of 19.9°. Of these patients, none were cavus and 4% were planus. Patients with a zone 3 fracture had an average MAA of 26.8°. Four percent of patients had a cavus midfoot, whereas 4% had planus. Patients with a dancer's fracture had an average MAA of 15°. Of these patients, 8% were cavus and 4% were planus. A significant difference (P < .001) was detected between the average MAA of zone 1 vs zone 3 fractures and between zone 3 and dancer's fractures, suggesting an association between increasing metatarsus adductus severity and more proximal diaphyseal fracture location.

Cavovarus deformity was infrequent in our cohort, whereas most patients had some degree of metatarsus adductus. Twenty-two percent in zone 1 and 6% in zone 2 were mild metatarsus adductus. Six percent in zone 2 and zone 3 were moderate, whereas 10% in zone 3 were severe. The authors recommend assessing for the presence of metatarsus adductus in patients with fifth metatarsal fractures, particularly zone 2 and 3, although further study in larger cohorts is needed to confirm these findings.

Level IV, retrospective case series.