Abstract
Periprosthetic infection involving TKR has been projected to rise as the burden of implanted TKR continues to grow. A study by Kurtz et al. found a significant increase in the annual incidence of TKR infection, 2001 (2.05%) to 2.18% in 2009. Thus, deep prosthetic infection around a TKR remains a significant problem that has not been solved, even as technologies improve and the operation is more commonly performed.
The economic hospital cost of periprosthetic TKR infection is approximately $100,000 US for a two-stage removal and reimplantation; by the year 2020, it is estimated that 48,000 of these operations will be necessary. The total annual hospital cost for PJI treatment is expected to be over $1 billion by 2020, and does not include the doctor, pharmacologic, and physical therapy fees.
Many factors have been found to be associated with an increased risk of PJI. This lecture will focus upon the peri-, intra-, and post-operative factors that have been found historically to carry an increased or decreased risk of infection.
Preoperative factors that have been found to affect the risk of infection include: perioperative administration of intravenous antibiotics, patient nutrition, weight, and hemoglobin A1C in diabetic patients. Intraoperative factors include the duration of surgery, the use of antibiotic impregnated cement, and the use of dilute povidone/iodine solution irrigation. Postoperatively, wound care with antimicrobial agents, and a resistance to transfusing blood seem to lower the risk of infection.
Yang et al. found that diabetes mellitus carried a 1.6x greater risk of TKR infection, in a meta-analysis of 11 cohort studies. In a registry study of over 32,000 TKA, increasing BMI from 25 kg/m2 to 35 kg/m2 was found to be associated with a greater risk of wound infection in TKR patients, increasing from 3 to 4.1%. Preoperative colonization with MRSA has been found by several investigators to be a risk for surgical site infection, despite attempts at eradication.
Operatively, a wash of the surgical site for 3 minutes with a dilute solution of betadine has been found by Brown et al. to have decreased the incidence of periprosthetic joint infection from 0.97% to 0.15%.
Postoperatively, the type of dressing placed over the incision may play a role; Grosso et al. found a significantly reduced rate of PJI (0.33% vs. 1.58%) when a silver impregnated, antimicrobial, dressing was used as compared to standard xeroform gauze. Finally, patients who received an allogeneic blood transfusion were found to have a higher risk of PJI (1.67%) than those who did not (0.72%).
