Rate of Delayed Union With Early Weightbearing Following Intramedullary Screw Fixation of Jones Fractures

Background: Jones fractures of the proximal fifth metatarsal are predisposed to delayed union and nonunion due to a tenuous blood supply. Solid intramedullary (IM) screw fixation is recommended to improve healing, traditionally followed by delayed weightbearing (DWB). However, early weightbearing (EWB) postoperatively may facilitate functional recovery. The purpose of this study was to compare union rates and time to union after solid IM screw fixation of Jones fractures in patients treated with an EWB protocol to those treated with a DWB protocol, as well as to identify any factors that may be predictive of delayed or nonunion. Methods: True Jones (zone 2 fifth metatarsal base) fractures treated from April 2012 through January 2018 with IM screw fixation and 6 months follow-up were identified (41 fractures in 40 patients; mean ± SD age, 45.3 ± 17.9 years). Patients were divided into EWB and DWB cohorts (within or beyond 2 weeks, respectively). Delayed union (12.5 weeks) was statistically derived from established literature. Union times were compared between cohorts. Regression analyses were conducted to investigate possible confounders contributing to delayed union. There were 20 fractures in the EWB cohort and 21 fractures in the DWB cohort. Results: There was no significant difference in healing times (EWB: 25% by 6th week, 55% by the 12th week, 20% delayed; DWB: 33% by 6th week, 43% by 12th week, 24% delayed; P = .819) or delayed unions (EWB, 20% vs DWB, 24%; P > .999). There were no nonunions. No significant confounding risk factors were identified. Conclusion: Postoperative protocols using early weightbearing following solid IM screw fixation of Jones fractures appear to be safe and do not delay fracture healing or increase the risk of delayed union. Older age may be a risk for delayed union, but larger studies are needed to evaluate this with appropriate power in light of possible confounders. EWB protocols may allow better functional recovery without compromising outcomes by increasing the risk of delayed union. Level of Evidence: Therapeutic level III, retrospective comparative study.