Correlation of aspiration results with periprosthetic sepsis in revision total hip arthroplasty.

A retrospective chart review was performed of all patients who had undergone revision total hip arthroplasty with a synovial aspiration with greater than 100 WBC since the institution of our electronic medical record. Infection was defined using a combination of criteria. A diagnosis of periprosthetic sepsis was established in 52 of the 253 included hips. No significant differences existed with respect to gender, age, BMI, Deyo-Charlson Comorbidity Index, or the cause of initial hip degeneration. Using receiver-operating characteristic curves accuracy was maximized for WBC of 745 or segmented cell count of 73.5% with a sensitivity of 98%, specificity of 37%, negative predictive value of 99% and accuracy of 50%. Application of the current American Academy of Orthopaedic Surgery Clinical Practice Guidelines (AAOS CPG) thresholds revealed a similar accuracy of 49%.