Does an Isolated Elevated Erythrocyte Sedimentation Rate Warrant Further Work-Up for Periprosthetic Joint Infection...

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are widely used as screening tools for periprosthetic joint infection (PJI) following total knee and hip arthroplasty (TKA and THA, respectively). However, the significance of an isolated elevated ESR with a normal CRP, especially in cases with low clinical suspicion, remains unclear.

We retrospectively reviewed 19,872 primary TKAs and 12,143 primary THAs performed between March 2012 and March 2023 at a high-volume academic orthopaedic hospital. Of these, 656 TKA and 253 THA patients ≥ 18 years old who underwent elective total joint arthroplasty for osteoarthritis had an elevated ESR (higher than 30 mm/hour) and a normal CRP (less than or equal to 10 mg/L) at least 90 days postoperatively. These cutoffs were chosen in concordance with the International Consensus Meeting 2018 diagnostic criteria for PJI. Patients who were already undergoing PJI treatment were excluded, as it was inferred the serum biomarkers were not drawn for screening purposes. The final cohorts consisted of 641 TKA and 252 THA patients. Data collected through manual chart review of clinical progress notes included presenting symptoms, inflammatory markers, and PJI diagnoses. We calculated the incidence of PJI within the cohort of patients who had an isolated, elevated ESR.

Of the 641 TKA patients who had an isolated, elevated ESR, seven (1.1%) were subsequently diagnosed with PJI. Of the 252 THA patients who had an isolated, elevated ESR, three (1.2%) were subsequently diagnosed with PJI. Of the seven TKA and three THA patients subsequently diagnosed with PJI, three (0.5%) TKA and two (0.8%) THA patients had clinical findings highly suspicious for PJI, such as a large effusion and severe, sudden-onset swelling. These patients did not represent cases where a surgeon would encounter true uncertainty regarding whether to pursue further workup and testing. This left four TKAs (0.5%) and one THA (0.4%) patient who had an isolated, elevated ESR who were eventually diagnosed with PJI despite limited clinical concern beyond nonspecific pain. The positive predictive value of an isolated, elevated ESR for the diagnosis of PJI was 1.1% in the TKA cohort and 1.2% in the THA cohort.

Isolated, elevated ESR with a normal CRP should not automatically trigger a full PJI workup. The risk of PJI is low in this specific patient population, especially when only accompanied by nonspecific symptoms. Most PJI cases in this cohort were found in patients who also had relevant clinical symptoms like sudden-onset swelling or large effusions, suggesting that important weight should be given to the presence or absence of additional PJI symptoms when deciding whether to pursue further testing after an isolated, elevated ESR.