Mildly Elevated Preoperative Inflammatory Markers and Postoperative Complications Following Total Knee Arthroplasty: A Propensity-Matched Cohort Analysis.

BACKGROUND: There is increasing use of preoperative biomarker assessment in patients undergoing total knee arthroplasty. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are the commonly used measures of ongoing inflammation. The impact of discordance between these values on postoperative outcomes remains poorly understood.

METHODS: Three cohorts were identified: one with a mildly elevated ESR and normal CRP, the other with a mildly elevated CRP and normal ESR, and the third with a mildly elevated ESR and CRP, with laboratory values obtained within 1 month of primary total knee arthroplasty. Groups were compared to patients with normal markers.

RESULTS: At 90 days postoperatively, patients with mildly elevated CRP and ESR had a significantly higher odds of periprosthetic joint infection (PJI) compared to patients with normal inflammatory markers (odds ratio [OR]: 3.90; 95% confidence interval [CI]: 2.28-6.68; P < .001). At 3 years postoperatively, patients with mildly elevated inflammatory markers had significantly higher odds of PJI (OR: 3.80; 95% CI: 2.41-6.00; P < .001), complications (OR: 1.34, 95% CI: 1.00-1.79; P = .047), and revision knee arthroplasty (OR: 3.34; 95% CI: 1.68-6.64; P < .001). At 90 days, patients with mildly elevated preoperative CRP (5.1-15 mg/L) and normal ESR demonstrated significantly increased odds of PJI compared to patients with normal markers (OR: 2.00, 95% CI: 1.37-2.87; P < .001).

CONCLUSIONS: Mildly elevated CRP and ESR were significantly associated with an increased risk of PJI, revision arthroplasty, and composite complications. Elevated ESR with normal CRP was associated with a higher risk of composite complications at 3 years postoperatively.