Intra-articular vancomycin for the prophylaxis of periprosthetic joint infection caused by methicillin-resistant S. aureus after total knee arthroplasty in a rat model: the dosage, efficacy, and safety.

Although intra-articular vancomycin powder (VP) is sometimes applied before the closure of the incision to prevent periprosthetic joint infection (PJI) after joint replacement, the dosage, efficacy and safety remain controversial. This study aimed to explore the dosage, efficacy, and safety of intra-articular VP in the prophylaxis of infection after total knee arthroplasty (TKA) in a rat model. Sixty male rats were randomly divided into five groups after receiving TKA surgery: Control (no antibiotics); systemic vancomycin (SV) (intraperitoneal injection, 88 mg/kg, equal to 1g in a patient weighted 70kg); VP0.5, VP1.0 and VP2.0 (44 mg/kg, 88 mg/kg and 176 mg/kg respectively, intra-articular). All animals were inoculated in the knee with methicillin-resistant S. aureus (MRSA). General status, serum biomarkers, radiology, microbiological assay and histopathological tests were assessed within 14 days post-operatively. Compared with the Control and SV groups, bacterial counts, knee-width, tissue inflammation, and osteolysis were reduced in the VP0.5, VP1.0 and VP2.0 groups, without notable bodyweight loss and incision complications. Among all the VP groups, VP1.0 and VP2.0 groups presented superior outcomes in the knee-width and tissue inflammation than the VP0.5 group. Microbial culture indicated that no MRSA survived in the knee of VP1.0 and VP2.0 groups, while bacteria growth was observed in VP0.5 group. No obvious changes in the structure and functional biomarkers of liver and kidney were observed in both SV and VP groups. Therefore, intra-articular vancomycin powder at the dosage from 88 mg/kg to 176 mg/kg may be effective and safe in preventing PJI induced by methicillin-resistant S. aureus in the rat TKA model.