Analysis of risk factors for wound infection after extremity fracture caused by machete cut in a resource-limited setting

Background: Machete cut fracture is a unique subset of open fracture. The sharp force of a wielded machete that cleanly divides soft tissue envelope with minimal or no contusion results in an open fracture wound that is relatively less prone to infection. However, in resource-limited settings, the wound infection rate after machete cut fracture is relatively high. This study aimed to determine the risk factors for wound infection after extremity machete cut fractures in a Nigerian setting. Methods: We undertook a retrospective analysis of the patients who were seen in the Emergency room of two tertiary hospitals in Nigeria with a machete cut extremity fracture from 2009 to 2018. The association of wound infection with population and wound characteristics as well as intervention related factors were evaluated. Statistical significant factors for wound infection in the Univariable analysis were entered into a Multivariable regression analysis to evaluate the risk of each factor when adjusted to other factors. Results: There were 113 machete-cut fractured bones in 67 eligible patients and wound infection was a complication in 45 (39.8%) of the cases (95%CI 30.3 – 49.7%).The factors significantly associated with high wound infection rate were smoking, haematocrit < 30%, fractures sustained outdoors, lower extremity fractures, a wound size of >5cm in length, injury-to-hospital arrival interval > 6hrs. Multivariable regression analysis identified wound size >5 cm (aOR 14.142, 95%CI (2.716 - 73.636); p = 0.002), injury-to- hospital arrival interval later than 6hrs (aOR 4.410, 95% CI (1.003-19.394); p = 0.050) and administration of antibiotics later than 3hrs of injury (aOR 5.736, 95%CI (aOR1.362 - 24.151; p = 0.017) as independent risk factors for wound infection. Conclusion: Wound infection after open fractures caused by machetecut is more likely to occur in patients that present later than six hours after injury, wounds more than 5cm in length and delayed antibiotic administration. Appropriate treatment protocols can be instituted with this knowledge.