Fifth metatarsal base fractures are the most commonly seen fractures of the foot. Ankle sprains occur with inversion and plantarflexion mechanisms, similar to most fifth metatarsal base fractures. We sought to investigate the possible ankle injuries that accompany fifth metatarsal base fractures.
A hospital's digital database was searched for the International Classification of Diseases, Tenth Revision codes for metatarsal bone fractures (codes S92.30 and S92.35) between January 2015 and January 2018. Thirty-nine patients with fifth metatarsal base fracture who underwent ankle magnetic resonance imaging (MRI) within 14 days of injury were included in the study. The MRI findings were evaluated, and comparisons were performed according to fracture zone, sex, and age.
The most common MRI finding was talocrural joint effusion, which was observed in 28 patients (71.8%). Bone marrow edema was observed in 16 patients (41.0%). Chondral injury at the medial dome of talus was observed in three patients (7.7%). Grade 1 ligament sprain was observed in six patients (15.4%): two in the lateral ligament and four in the deltoid ligament.
Although most fifth metatarsal base fractures and ankle sprains occur as a result of a common mechanism, physical examination findings and patients' complaints are very important. Routine MRI should be unnecessary for most patients. If a patient with a fifth metatarsal base fracture has complaints about the ankle joint, one should be aware of bone marrow edema, which was observed in 41.0% of the study population.