The Use of Percutaneous Screw Fixation Without Fracture Site Preparation in the Treatment of Fifth Metatarsal Base Nonunion.

Nonunion after a proximal fifth metatarsal fracture can cause considerable pain, with high morbidity and loss of work. Although many authors advocate early surgical management of zone 3 injuries (Jones fractures), zone 1 and 2 fractures are generally expected to heal with conservative management. Uncommonly, zone 1 and 2 fractures can develop nonunions. The aim of this study was to evaluate the efficacy of closed intramedullary screw fixation for nonunions of the fifth metatarsal base. We performed a prospective study involving all fifth metatarsal base nonunions treated in our department over 2 years. Only minimally displaced adult fractures were considered for this study. The fracture pattern was categorized using the Dameron classification (zone 1, styloid process; zone 2, metadiaphyseal area; zone 3, proximal diaphysis). All nonunions were fixed percutaneously under radiographic guidance, without fracture site preparation. Zone 1 injuries were fixed using a 3-mm headless compression screw, and those of zones 2 and 3, with an intramedullary 4-mm screw. Of 30 patients included in this study, a minimum 6-month clinical follow-up was obtained. The average time from injury to treatment was 5.9 months (range 3 to 36). There were no smokers in this patient cohort. There were 12 zone 1 injuries, 9 zone 2 injuries, and 9 zone 3 injuries. All patients achieved union by 3 months after screw fixation, with 29 of 30 achieving union by 6 weeks. All patients had resolution of symptoms. There were no complications. We conclude that percutaneous fixation of fifth metatarsal base nonunions, without fracture site preparation, achieves excellent results. We believe that the screw alters the strain of the fracture, thus promoting fibrous-to-osseous conversion and therefore union.