Analysis of synovial fluid in culture-negative samples of suspicious periprosthetic infections.
Synovial fluid analysis can help to rule out a periprosthetic infection. The goal of this study was to evaluate the prognostic significance of synovial fluid suspicious for a periprosthetic infection given the synovial leukocyte count and percent of neutrophils. From August 2006 to November 2008, patients who had synovial fluid aspirated for painful knees and elevated C-reactive protein levels after total knee arthroplasty but revealed no growth of any microorganism were retrospectively evaluated by medical record review. Mean follow-up period was 827.7±250.6 days from the date of joint aspiration results. The optimal cut-off values for synovial leukocyte counts and percent neutrophils were determined using receiver operating characteristic curves. From a total of 56 patients, 14 were classified as having poor results. The remaining 42 patients had an uneventful clinical course with a stable prosthesis on radiographs without specific therapy during the follow-up period. The receiver operating characteristic curve showed that a synovial leukocyte count of 3600/uL had an 86% sensitivity and 79% specificity; with 89% synovial neutrophils, the sensitivity was 72% and specificity 62%. The synovial fluid leukocyte count and percent neutrophils were significant predictors of outcome in patients with cultures that were negative but suspicious for periprosthetic infections.
Department of Orthopedic Surgery, Himchan Hospital, 404-3, Mok-dong, Yangcheon-gu, 158-806, Seoul, Korea.
Su Chan
SC
Lee
Kwang Am
KA
Jung
Ji Yeol
JY
Yoon
Chang Hyun
CH
Nam
Seung Hyun
SH
Hwang
Il Seok
IS
Park
D000368:Aged; D018771:Arthralgia / Q000175:diagnosis / Q000209:etiology / Q000382:microbiology; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D009504:Neutrophils; D011379:Prognosis; D016459:Prosthesis-Related Infections / Q000175:diagnosis* / Q000382:microbiology; D012372:ROC Curve; D013582:Synovial Fluid / Q000166:cytology / Q000382:microbiology*