CT quantification of enlarged inguinal lymph nodes as a diagnostic approach for periprosthetic joint infection after hip arthroplasty

Abstract

Periprosthetic joint infection (PJI) is a major complication following total hip arthroplasty (THA), posing significant diagnostic challenges. This study prospectively evaluated 114 patients from January 2021 to August 2023, including those with PJI and aseptic loosening, using computed tomography (CT) to count enlarged inguinal lymph nodes with a short-axis diameter greater than 5 mm as assessed by two blinded radiologists. Patients with PJI had significantly higher lymph node counts (median 4.5, range 1–13) compared with those with aseptic loosening (median 1, range 0–5). Using a threshold of more than 2.5 enlarged nodes, CT achieved 86.8% sensitivity and 85.5% specificity, with an area under the curve (AUC) of 0.91, which was superior to conventional markers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). These findings suggest that CT-based enlarged inguinal lymph node counting is a simple, non-invasive, and accurate method for diagnosing PJI, and may enhance current diagnostic strategies. Trial registration number : No. ChiCTR2100050785.