C-Reactive Protein and Erythrocyte Sedimentation Rates after Total and Unicompartmental Knee Arthroplasty-Less Implant Equals Quicker Normalization.

Abstract

Postoperative follow up after total or unicondylar knee arthroplasty (UKA) includes C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) to scan for and possibly diagnose a periprosthetic joint infection (PJI). The aim of this study was to describe the postoperative changes in CRP and ESR values after UKA and compare them with values obtained after TKA. Patients operated on between 2020 and 2022 were eligible for this retrospective study. Inclusion criteria were patients with at least 4 postoperative visits associated with blood test screening for PJI, aged > 45, with uneventful follow-up for the first 90 days. Exclusion criteria were a history of chronic inflammatory disease, revision for any reason, and readmission for any reason. Blood samples were collected on the 3rd, 15th, and 30th postoperative days and once between the 45th and the 90th day. The mean and peak values were compared between the two groups. The study included 277 patients (243 TKAs and 34 UKAs). Mean age was significantly lower in the UKA group (67.2 ± 7.5 vs. 60.0 ± 5.9). On the 3rd and the 15th postoperative day, the UKA patients had significantly lower ESR and CRP levels. The levels normalized after the first month. While the TKA patients showed higher values, the trend normalized after the 30th day. CRP and ESR values rose significantly after TKA and persisted up to the 15th day postoperatively. CRP and ESR values normalized faster in patients undergoing UKA. Patients > 65 had higher CRP and ESR values during their routine follow-ups.