Background: Prosthetic joint infection (PJI) is a grave complication of total knee arthroplasty (TKA). Two-stage exchange is highly successful at curing infection, but remains morbid and costly. Debridement, antibiotics, and implant retention (DAIR) is an appropriate strategy in some patients, but factors effecting success rates remain unclear. We studied a large cohort with infected TKA treated with DAIR at our specialized orthopedic hospital.
Methods: A retrospective cohort of TKA PJI treated with DAIR over 4.3 years was identified by query of hospital coding records. The primary endpoint was defined as 2-year implant failure. Clinical data from multiple databases were collected.
Results: 111 patients with 115 TKR PJI were identified. 61% of TKA were retained at 2 years. Pathogens included methicillin-sensitive and -resistant Staphylococcus aureus (MSSA, 26%; MRSA, 3.5%), coagulase-negative staphylococci (15%), and streptococci (22%). 20% of cases were culture-negative, of which 70% had histopathologic evidence of infection. Comorbidities included obesity (average BMI 30.1), diabetes (23%), and cardiac (17%), kidney (15%), and rheumatologic (8.6%) disease. 31% had a history of tobacco, with a trend towards worse outcomes in this group (RR=1.4, p=0.1).
81% of patients underwent arthrotomy instead of arthroscopy, and 57% underwent polyethylene liner exchange (PLE). Each was strongly associated with retention (RR=0.49, 95% CI: 0.33-0.75 and RR=0.54, 0.34-0.86 respectively).
S. aureus infections fared poorly, compared to non-S. aureus (70% vs. 28% failure rate, RR=2.6, 1.6-4.1). Among all staphylococcal infections, those treated with rifampin had improved outcomes (RR=0.39, 0.19-0.79). Culture-negative cases had a 78% rate of TKA retention. There were no major differences between subgroups undergoing debridement more or less than 1 year after TKA.
Conclusion: We present 2-year outcomes on the largest reported cohort of TKA PJI treated with DAIR. Arthrotomy and PLE improved outcomes. S. aureus infection was associated with poor outcomes. Rifampin improved outcomes in staphylococcal infection. No link was seen between age of TKA at the time of debridement and primary outcome. Our data may help guide evidence-based decision-making in TKR PJI.
A. Reilly, None
E. Finerty, None
B. Brause, None
G. Westrich, Exachtech, DJO Global, and Stryker Orthopedics: Consultant , Grant Investigator and Speaker's Bureau , Consulting fee , Grant recipient , Research support and Speaker honorarium
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