The Causes and Costs of Surgical Site Infection in Total Hip and Total Knee Arthroplasty: A Retrospective Review of 4,973 Procedures

BACKGROUND: The purpose of this article is to delineate risk factors associated with SSI (surface, deep tissue, and periprosthetic joint infections) in hip and knee total joint replacement (TJR) surgeries for both primary and revision procedures. METHODS: Retrospective case-control study of non-emergent TJR procedures performed at a tertiary level academic medical center between 2014-2018. Multivariable logistic regression was used to determine which factors are associated with an increased risk for SSI in TJR. RESULTS: 4,973 procedures (2,543 knee and 2,430 hip arthroplasties) were performed on 4,014 unique patients. There were 82/4,973 total SSI: 43/2,430 (1.8%) in the THA group and 39/2543 (1.5%) in the TKA group. Risk factors associated with the development of an SSI included a female gender (65% increased odds ratio), BMI (increased odds ratio 3% for every 1-point increase in BMI (10-point BMI increase = 30% increased odds), length of surgery (8% increase for every additional 10 minutes of surgical time). Chronic renal disease and anemia double the odds of an SSI and cardiac arrythmias increased the odds by 88%. A history of skin integrity issues more than doubled the odds and a previous skin ulcer more than tripled the odds of an SSI. Using a multi-layered dressing reduces the odds and not using one more than doubles the odds of suffering an SSI. An SSI increased length of stay by two days and cost of stay by $38,000. CONCLUSION: SSI are problematic and with the changing demographics of TJR patients their incidence will increase. Addressing modifiable risk factors such as early treatment of anemia and postoperative dressing choice may reduce the SSI burden and cost of a TJR. Adapting care routines for non-modifiable risk factors such as chronic diseases and gender may have additional patient benefit. Surgical Site Infection (SSI) is one of the most frequently reported types of hospital acquired infections resulting in increased length of stay, increased healthcare costs and increased morbidity and mortality. This study reviewed 2,543 total knee arthroplasties and 2,430 total hip arthroplasties (4,973 procedures) completed on 4,014 unique patients. Multivariable analysis showed the odds of developing an SSI was increased for patients who were female, younger, had a history of a pressure ulcer or skin integrity issues, anemia, chronic renal disease, a cardiac dysrhythmia, a higher BMI, a longer surgical procedure, and the use of specific types of surgical site dressings. The mean length of stay for a patient who suffered an SSI increased by 1.8 days, the length of time they were on antibiotics doubled to a mean of 16 days, and the mean cost of treatment increased by $38,300. Addressing modifiable causes of SSI such as skin integrity issues and anemia preoperatively, reducing intraoperative time, and changing the type of dressing used postoperatively may improve patient outcomes, improve quality of care, and reduce healthcare costs. Level of Evidence: III