High union rates following surgical treatment of proximal fifth metatarsal stress fractures

Proximal Fifth Metatarsal Fractures: A Retrospective Study of 834 Fractures With a Minimum Follow-up of 5 Years

BACKGROUND

Proximal fifth metatarsal fractures are common fractures. Treatment strategies have been debated. We wanted to investigate whether Lawrence and Botte's classification has prognostic value because of time to fracture union, and evaluate if weightbearing as tolerated (WBAT) and nonweightbearing (NWB) treatment strategy had effect on time to fracture union in nonoperatively treated fractures.

METHODS

Computerized database search, patients diagnosed between January 1, 2003, and December 31, 2015.

RESULTS

We identified 834 fractures; 510 (61.2%) zone 1, 157 (18.8%) zone 2, and 167 (20.0%) zone 3. Most (94.4%) were treated nonoperatively; time to fracture union was 7.5 (SD 7.7), 7.7 (5.6), and 9.2 (8.1) weeks for zone 1, 2, and 3, respectively, which gave a significant longer time to union for zone 3 compared to zone 1 fractures (P = .04). There was no difference in time to fracture union when comparing WBAT and NWB for all fracture zones. Failure to union, defined as crossover to surgery and/or delayed union, was found in 13 (2.7%) zone 1, 5 (3.2%) zone 2, and 6 (3.8%) zone 3 fractures. Refracture during follow-up was found in 3 (0.6%) zone 1 and 14 (8.9%) zone 3 fractures.

CONCLUSION

Proximal fifth metatarsal fractures have high union rates with nonoperative treatment. No difference in time to union could be found between WBAT and NWB treatment strategies for all fracture zones. We observed a significantly longer time to fracture union for zone 3 fractures compared to zone 1 fractures. Refracture occurs in a nonnegligible share of nonoperatively treated zone 3 fractures.