Characteristics and significance of fever during 4 weeks after primary total knee arthroplasty

PURPOSE: Most previous studies on postoperative fever (POF; ≥38 °C) after total knee arthroplasty (TKA) have reported findings from only the immediate postoperative days (PODs). The hypothesis of the current study is that 4 weeks of follow-up may reveal differences in the characteristics of POF and fever-related factors between a normal inflammatory response and an early acute infection-related response. METHODS: A total of 400 consecutive TKAs (314 patients) were retrospectively investigated. Patients were stratified into those who developed an early acute periprosthetic infection that required subsequent surgical treatment (STG; n = 5 TKAs) and those who did not (non-STG; n = 395 TKAs). RESULTS: Among the 400 knees, 149 (37 %) developed POF, with most reaching a maximum temperature (MT) on POD 0. In 13 TKA patients who had POF with a peak daily temperature ≥38 °C during postoperative weeks 2–4, the causes of POF were respiratory and urinary tract infections (n = 5 for each), superficial infection (n = 2), and periprosthetic infection (n = 1). The STG and non-STG differed significantly with regard to the rate of POF (p = 0.0205) and MT (p = 0.0003), including MTs less than 38 °C, during postoperative weeks 2–4. All five STG patients had elevated C-reactive protein levels and local symptomatic findings before the additional surgery. CONCLUSIONS: The occurrence of POF and MT along with elevated C-reactive protein and local symptomatic findings at 2–4 weeks postoperatively may indicate the need for a positive fever workup to recognize early acute periprosthetic infection.