Foot Malalignment and Proximal Fifth Metatarsal Fractures

Proximal fifth metatarsal fractures are common injuries that are classified into 3 zones according to their anatomical localization. While zone 1 and 2 fractures typically are traumatic, zone 3 fractures may be linked to foot alignment abnormalities, such as hindfoot varus and metatarsus adductus. The aim of the study was to explore the association between hindfoot alignment and different fracture zones, as well as the relationship between traumatic and atraumatic fracture origin and foot alignment.

We conducted a retrospective cohort study of patients with proximal fifth metatarsal fractures who had received a weightbearing computed tomography (WBCT) scan. Feet with zone 1 and 2 fractures were compared to zone 3 fractures and a healthy control group. Additionally, we compared feet with a traumatic fracture origin with those without. Foot alignment parameters, including the foot and ankle offset (FAO) and the forefoot arch angle (FAA), were analyzed alongside data from semiautomated segmentation reports. P <.05 was considered significant.

The study included 45 fractures (23 zone 1 and 2, 22 zone 3) and 19 controls. Zone 3 fractures showed a significant association with higher body mass index (P < .01), hindfoot varus (P < .01), and metatarsus adductus (P < .01) compared with zone 1 and 2 fractures, and they more frequently had a nontraumatic origin (P < .01). Zone 3 fractures also showed a significantly higher transverse arch (P < .01). No differences have been observed between zone 1 and 2 fractures and the controls. Fractures with atraumatic origin were significantly associated with hindfoot varus (P < .01), metatarsus adductus (P < .01), hindfoot varus (P < .01), and metatarsus adductus (P < .01).

Hindfoot varus, metatarsus adductus, and a high transverse arch were significantly associated with zone 3 fractures as well as fractures with atraumatic origin.