The value of white blood cell counts before revision total knee arthroplasty.
A white blood cell count (WBC) of >50000 cell/mm(3) from a knee aspirate with >or=80% polymorphonuclear cells (PMNCs) is suggestive of infection. This study sought to determine if these same criteria were applicable when interpreting aspirates from a total knee. Of 440 revision total knee arthroplasties, 86 patients had preoperative aspirations of the knee before revision. Fifty-five aspirates were from aseptic failures; 31 aspirates were from patients determined to have septic failure. The mean white blood cell (WBC) count in aspirates from the aseptic group was 645 cells/mm(3) (SD = 878). The mean WBC count in the septic group was 25951 cells/mm(3) (SD = 34994; P=<.001). The mean percentage of PMNCs was statistically higher in the septic group compared with the aseptic group (72.8% vs 27.3%; P=<.001). The synovial fluid WBC count differential analysis is a statistically relevant indicator of the presence or absence of infection in revision knee arthroplasty. Aspirates with a WBC count of 2500 per milliliter and 60% PMNCs are highly suggestive of infection.
Mason
J Bohannon
JB
Charlotte Orthopedic Specialists, Charlotte Hip and Knee Center, Charlotte, North Carolina, USA.
Fehring
Thomas K
TK
Odum
Susan M
SM
Griffin
William L
WL
Nussman
Donna S
DS
D019645:Arthroplasty, Replacement, Knee; D006801:Humans; D007958:Leukocyte Count; D011300:Preoperative Care; D016459:Prosthesis-Related Infections / Q000175:diagnosis / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000166:cytology*