Addition of gentamicin for antibiotic prophylaxis in hip hemiarthroplasty does not decrease the rate of surgical site infection

BackgroundThe addition of Gram-negative coverage to antibiotic prophylaxis protocols prior to elective total hip arthroplasty (THA) has been reported to reduce periprosthetic joint infection (PJI). However, it is unknown whether adding a Gram-negative-targeted antibiotic agent improves outcomes in the trauma population. This study aimed to investigate whether the addition of a single, pre-operative dose of Gentamicin is associated with lower rates of PJI in patients undergoing hemiarthroplasty (HA) as treatment for a hip fracture.MethodsWe retrospectively reviewed cases of patients who underwent HA as treatment for a hip fracture from January 2011 to January 2022, and had a minimum 1-year of follow-up. Patients were divided into two groups based on the antibiotic prophylaxis they received during surgery: cefazolin (control group) or cefazolin with addition of Gentamicin (case group). The primary outcome was the rate of surgical site infections (SSI), and secondary outcomes included rates of prosthetic joint infection (PJI) and superficial SSIs.ResultsThe final study population consisted of 1521 patients. 336 patients (22.1%) were in the case group and 1185 (77.9%) patients were in the control group. Rates of SSI were comparable between the groups (3.8% for the case group vs. 2.8% in the control group, p = 0.34). This held true for both PJIs (3.5 vs. 2.5%, p = 0.3) and superficial SSIs (0.29 vs. 0.33%, p = 0.91). The distribution of the causing pathogen was similar between the groups (p = 0.84). Gentamicin susceptibility rates of the Gram-negative bacteria associated with PJI were similar between the cohorts (p = 0.51).ConclusionsThe addition of a single, pre-operative dose of Gentamicin to the antibiotic prophylaxis protocol of patients undergoing HA as treatment for a hip fracture was not associated with lower rates of SSI, PJI or superficial SSI. The findings of this study indicate that the prophylactic benefits of Gentamicin may not apply to HA as they do to THA.