Surgical Case Order is an Independent Risk Factor for Postoperative Infection in Primary Total Knee Arthroplasty

Abstract Background: Total knee arthroplasty is regarded as the most effective treatment for severe knee joint problems. Surgery case order influences operative outcomes according to previous studies. This study aims to evaluate the effect of surgical case order on operative outcomes for TKA.Methods: A retrospective study was conducted on 4,267 TKAs performed by three surgeons at our hospital from February 2008 to February 2018. Variables, such as surgical time, loss of blood, and hospitalization stay, were also recorded and analysed. Logistic regression was used to analyse every variable as a potential risk for a surgical site infection.Results: Of the 4267 cases in this cohort, 1531 TKAs were classified as first-round cases, 1194 TKAs were second-round cases, 913 TKAs were third-round cases, 490 TKAs were fourth-round cases, and 139 were fifth-round or later cases. The mean operating time was shorter in intermediate cases (P< 0.01). Perioperative adverse events were increased in later surgical cases (P< 0.01). Later case order (OR= 1.29 [95% CI: 1.17–1.56], P<0.01) was a significant risk factor for severe arthroplasty complications. The operative time and length of stay were increased for cases performed later in the day. However, blood loss is not statistically associated with case order. Conclusions: Surgical case order is an independent risk factor for surgical infection. Significantly increased operative time and longer LOS were noted for third-round or later TKA cases. Our results identify potentially modifiable risk factors contributing to infection rates in TKA, and cases operated on later in the day in the same room were more likely to have a higher infection risk.