Optimizing Intraoperative Tissue Sampling in Hip and Knee Periprosthetic Joint Infection: Deep Bone Provides Higher Culture Yield in One-Stage Exchange.

BACKGROUND: Periprosthetic joint infection (PJI) is a challenging complication after hip and knee arthroplasty. Accurate pathogen identification is essential for successful treatment, yet the optimal anatomical site for intraoperative microbiological sampling remains uncertain. This study evaluated whether microbiological yield differs by sampling location and whether this differs between hip and knee PJI.

METHODS: We retrospectively analyzed 255 patients who underwent one-stage exchange for PJI (142 hips and 113 knees). Intraoperative specimens were categorized as deep bone, superficial bone, or soft tissue, and culture positivity rates were compared across sites. Generalized estimating equations evaluated the association between sampling site and culture positivity, adjusting for age, body mass index (BMI), Charlson Comorbidity Index, and number of samples.

RESULTS: In hip PJI, culture positivity was 80.8 (273 of 338) for deep bone, 79.6 (370 of 465) for soft tissue, and 65.9% (135 of 205) for superficial bone; in knee PJI, positivity was 80.5 (248 of 308), 71.7 (279 of 389), and 65.4% (123 of 188), respectively. After adjustment, deep bone sampling had higher odds of culture positivity than superficial bone and soft tissue sampling (odds ratio [OR], 1.53; 95% confidence interval [CI], 1.05 to 2.25), with similar effects in both joints. Soft tissue sampling was more likely to yield positive cultures in hip than knee PJI (OR, 2.19; 95% CI, 1.27 to 3.78). Higher BMI was independently associated with lower culture positivity.

CONCLUSIONS: Deep bone sampling provided the highest microbiological yield in both hip and knee PJI, while superficial bone sampling consistently showed the lowest positivity. Soft-tissue sampling performed particularly well in hip PJI, supporting its complementary role during intraoperative microbiological sampling.