Incidence and risk factors for removal of an internal fixation following surgery for ankle fracture: A retrospective cohort study of 997 patients.

Background: Implant removal in ankle fractures treated by open reduction and fixation is often based on diffuse complaints. This study determined the incidence of implant removal and identified risk factors for two principal causes for removal: complaints and surgical site infection (SSI).
Methods: Retrospective cohort study involving 997 patients operated on 2009-2011 with follow-up through to 2013. The incidence of implant removal was analysed using competing risk analysis. Risk factors for implant removal were assessed using cause-specific hazard ratios (HRs) from a Cox regression analysis.
Results: The mean age at surgery was 51.6 years, 550 (55%) of the patients were female, and 170 patients (17%) had implant removal: 144 due to complaints and 26 due to infection. Multivariable HRs for implant removal due to complaints were 0.70 for male sex (p=0.047), 0.79 for each 10-year increase in age (p<0.001), 0.70 for treatment with a syndesmosis screw (p=0.038), and 1.09 for each 15-min increase in operation duration (p=0.007). HRs for hardware removal due to infection were 1.42 for each 10-year increase in age (p=0.006) and 3.15 for current smoking (p=0.005).
Conclusion: In total 17% of patients had implant removal after open reduction and fixation; the majority because of subjective complaints. The risk factors for implant removal were different for removal due to complaints than for those removed due to infection. This information may be used to inform patients about the risk and risk factors for future implant removal.
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