Knee and hip replacements are an effective intervention for improving patient quality of life. Rates of these surgeries in North America are growing, coinciding with increasing frequency of obesity and an aging population. A small number of these surgeries will develop post-operative surgical site infections (SSI), causing substantial patient morbidity and healthcare costs. We present a population based descriptive analysis of SSI following primary hip and knee replacements.
The Alberta Health Services Infection Prevention and Control program collects data prospectively on all SSI after primary total hip and knee arthroplasty done in Alberta, Canada. The data used here contained all SSI within 180 days of surgical procedures between March 1, 2012 and September 30, 2014.
Primary outcomes were rate of infection and causative pathogens. Secondary outcomes included timing of infection after surgery (i.e. 30 days or less, 31-90 days, and greater than 90 days), and the relationship of methicillin-resistant Staphylococcus aureus (MRSA) colonization to infection.
There were 312 SSI cases for review. Overall rate of SSI (per 100 procedures) were 1.69 and 1.20 for hip and knee replacements, respectively. The majority (79%) of infections occurred within the first 30 days following surgery. When stratified by time to infection, the proportion of knee SSIs increased from 47 to 67 percent after 30 days. Causative pathogens were identified in 122 (80%) hip infections and 116 (72.5%) knee infections. Most commonly identified was Staphylococcus aureus (38%), and the type of organism isolated was not related to the timing of infection. Colonization with MRSA was associated with subsequent infection (OR 40).
From this study, we have identified several important characteristics of these infections that may be helpful for determining optimal prevention strategies. For example, intensive post-operative follow up within 30 days of primary knee arthroplasty may help prevent a subsequent SSI. Additionally, decolonization techniques may decrease consequent MRSA SSI in colonized patients.
D. Vickers, None
S. Smith, None