Risk factors for reoperation due to periprosthetic joint infection after elective total hip arthroplasty : a study of 35,056 patients using linked data of the Swedish Hip Arthroplasty Registry (SHAR) and Swedish Perioperative Registry (SPOR)

Background In Sweden, the incidence of a prosthetic joint infection (PJI) after a planned Total Hip Arthroplasty (THA) is 1.3%, but the worldwide incidence of PJI after THA is unknown. This study explores associations between reoperation due to PJI and potential risk factors. Methods Primary elective THA surgery registered in both the Swedish Hip Arthroplasty Registry (SHAR) and the Swedish Perioperative Registry (SPOR) between 1 January 2015 and 31 December 2019 were included in this registry study, resulting in a total study population of 35,056 cases. The outcome variable was reoperation as the result of PJI within a year after surgery. Data were analysed using a multivariable Cox regression model. Results Reoperation due to PJI occurred in 460 cases (i.e., 1.3% of the study population). Each year of age increased the risk with 2% (HR 1.02 Cl 1.01, 1.03 P = < 0.001). Compared to men, women had significantly less risk for reoperation (HR 2.17 Cl 1.79, 2.53 P = < 0.001). For patients with obesity (BMI > 30), the risk increased considerably compared to underweight, normal weight, or overweight patients (HR 1.89 Cl 1.43, 2.51 P = < 0.001). The risk also increased by 6% for every 10 min of operative time (HR 1.06 Cl 1.02, 1.09 P = < 0.001). Patients having general anaesthesia had greater risk compared to those with spinal anaesthesia (HR 1.34 Cl 1.04, 1.73 P = 0.024). Finally, a lateral approach showed higher risk of reoperation than a posterior approach (HR 1.43 Cl 1.18, 1.73 P = < 0.001). Conclusion Recognition of the several risk factors identified in this study will be important for the perioperative management of patients undergoing THA