Ninety-Day Follow-up Is Inadequate for Diagnosis of Fracture-related Infections in Patients with Open Fractures
Authors: Zalavras Charalampos G. , Aerden Laurens , Declercq Peter , Belmans Ann , Metsemakers Willem-Jan 
Published: August 2021

Abstract

Background
Fracture-related infection (FRI) is a challenging complication in musculoskeletal trauma surgery and often complicates the management of open fractures. The CDC currently advocates a surveillance period of 90 days after fracture fixation, but it is unclear what duration of follow-up constitutes adequate surveillance for FRI. Inadequate follow-up will underestimate infections and, in clinical research, will make any interventions studied appear better than they really are, thereby resulting in misleading conclusions.

Questions/purposes
(1) What is the timing of FRI onset in patients with open fractures? (2) What is the proportion of FRIs captured when follow-up is limited to 90 days postoperatively versus when follow-up is extended to 1 year?

Methods
This is a secondary analysis of patient data from a previous retrospective cohort study that investigated whether the duration of perioperative antibiotic prophylaxis was independently associated with FRI in patients with open fractures. Of the 530 eligible patients in the source study, 3% (14) died. Of the remaining 516 patients, 97% (502) patients with 559 long-bone open fractures had 2 years of follow-up constituted the base cohort. Forty-seven fractures in 46 patients were complicated by FRI and were the focus of this secondary analysis. Medical records were reviewed in detail specifically for the current study. Seventy-eight percent (36 of 46) of patients were male, and the mean ± SD age was 42 ± 16 years. The most common mechanism of injury was a motor vehicle accident (63% [29 of 46] of patients), and the tibia was the most involved site (53% [25 of 47] of fractures). The median (interquartile range) time to debridement was 3.0 hours (IQR 2.0 to 4.0). FRIs developed in 3% (7 of 247) of Type I open fractures, 7% (11 of 164) of Type II, 17% (18 of 107) of Type IIIA, 29% (9 of 31) of Type IIIB, and 20% (2 of 10) of Type IIIC open fractures. Each clinic visit of each patient was reviewed, and data about the time of onset of any symptoms and signs suggesting or confirming an FRI, as reported by patients and/or determined by treating surgeons, were recorded. The proportions of FRIs with onset by specific time periods were determined. A Kaplan-Meier survival analysis was performed, and the FRI event rates with 95% confidence intervals were calculated.

Results
The median (IQR) time to the onset of FRI was 52 days (IQR 15 to 153). Follow-up of 90 days captured only 64% (30 of 47) of FRIs, whereas follow-up of 1 year captured 89% (42 of 47) of FRIs. The proportion of FRIs with onset within 1 year increased to 95% (42 of 44) in the presence of an already healed fracture.

Conclusion
Follow-up of 90 days after the management of an open long-bone fracture is inadequate for postoperative surveillance, especially for research purposes. Clinical research on interventions would report results appearing to be much better than they really are, potentially resulting in misleading conclusions. Follow-up of 1 year is preferable because most FRIs will develop before that time, especially when fracture union has occurred. A small percentage of patients may still develop infections beyond the first year after the management of an open fracture. The risk of missing these infections by not extending follow-up beyond 1 year must be balanced against the additional logistical burden. Future prospective multicenter studies and registries with long-term patient follow-up would help clarify this issue.
Level of Evidence Level III, diagnostic study.