Neutrophil‐to‐lymphocyte ratio (NLR) distribution shows a better kinetic pattern than C‐reactive protein distribution for the follow‐up of early inflammation after total knee arthroplasty

PURPOSE: This study aimed to assess whether the neutrophil-to-lymphocyte ratio (NLR) distribution could have a better kinetic pattern than C-reactive protein (CRP) distribution to evaluate early post-operative inflammation after total knee arthroplasty (TKA). METHODS: A prospective study was performed on 587 patients. CRP and NLR were collected pre-operatively and at post-operative days 2, 4, 21 and 42. Mean peak values and distribution were compared between CRP and NLR. RESULTS: Mean CRP levels were 163, 161, 9 and 7 mg/L, respectively, at days 2, 4, 21 and 42. Mean NLR levels were 5, 3.5, 2.6 and 2.5, respectively, at days 2, 4, 21 and 42. At days 21 and 42, 20 % (102/503) and 21 % (93/433) of patients had not reached normal CRP levels. At day 21, there were 4.5 % (23/503) of patients with a NLR > 5 and 1 % (5/503) with an NLR > 10. At day 42, there were 5.5 % (24/433) of patients with an NLR > 5 and 0.7 % (3/433) with an NLR > 10. CONCLUSION: NLR has a faster normalization than CRP. It is potentially a better biomarker to follow post-operative inflammation or early infection after TKA. LEVEL OF EVIDENCE: II.