The Role of Perioperative C-Reactive Protein Measurement in Primary Hip and Knee Arthroplasty.

BACKGROUND: C-reactive protein (CRP) is an established component of perioperative diagnostics in primary hip and knee arthroplasty; however, its clinical value and the validity of commonly used thresholds remain controversial. The aim of this study was to assess the pre- and postoperative handling of CRP at certified German arthroplasty centres (EPZ) and to critically appraise its clinical relevance. METHODS: A 12-item internet-based questionnaire on the perioperative use of CRP was mailed to all 659 centres certified in April 2024; 134 centres participated anonymously. In 2023, these centres had performed a total of 91793 primary hip and knee arthroplasties. RESULTS: Preoperatively, 130 of 134 centres (97.0%) determined CRP routinely. The thresholds applied varied considerably (< 5 mg/l: 48 centres; < 10 mg/l: 69; > 10 mg/l: 11). When the threshold was exceeded, 78 centres primarily referred patients for external evaluation, whereas 39 performed the work-up themselves. Most centres considered the probability of identifying a treatable focus to be low; when no focus was found, 67 of 130 centres proceeded with surgery nonetheless. Postoperatively, 126 centres determined CRP, but only 93 considered this necessary. The timing varied markedly, with 40.5% measuring as early as the first postoperative day. Additional inflammatory parameters were rarely obtained. Only seven centres based the indication for revision primarily on the CRP value. CONCLUSION: CRP is used frequently but heterogeneously in perioperative diagnostics. Given its limited specificity, particularly for mildly elevated values, and the well-known physiological postoperative increase, routine postoperative CRP measurement appears dispensable in uncomplicated cases. A standardised checklist and a stronger clinical focus could render diagnostics more efficient.