## 2 Materials and Methods  
We included 111 consecutive subjects who were examined in our University affiliated, emergency regional hospital during 2018. Patients with known inflammatory disease, infection, malignancy, acute trauma and incomplete data were not included. We recorded clinical scores and routine hematology panels. Euroqol EQ-5D-5L Index (converted using the UK tariff) and visual analog scale (VAS) were used to determine the general health status [2,3,15]. For the NLR study, the laboratory values were retrieved from the hospital's electronic records. The hematology panel at admittance was performed using Nihon Kohden Celltac 6500, Sysmex XT-4000i or ADVIA 2120 analyzer.NLR measurements were taken from peripheral venous blood from elbow plicate punctures in the morning after fasting. The patients were divided in two groups: With mild OA (66) and advanced OA (45).  
The mild OA subgroup (66 subjects, out of 82 screened), included patients with atraumatic knee pain who underwent arthroscopy according to current clinical practice guidelines [16]. Early OA was defined based on clinical symptoms, MRI and/or arthroscopy operative reports according to criteria recommended by [PERSON] et al. [3]. The subjects completed the international knee documentation committee subjective knee evaluation form (IKDC) and knee disability and osteoarthritis outcome score for joint replacement (KOOSJR). Afterwards the examining physician (surgeon) completed the Tegner-Lysholm knee scoring scale [2,3,15,17].  
The advanced OA subgroup (45 subjects, out of 73 screened), included patients scheduled for total knee replacement. Diagnosis was made using the ACR (American College of Rheumatology) or EULAR (European League Against Rheumatism) criteria for knee osteoarthritis [1]. Indication for arthroplasty was made based on clinical and radiographic criteria. The subjects completed IKDC and KOOSJR. The treating physician (surgeon) completed the two parts of the original (1989) version of the knee society score (KSS1-part1 knee score and KSS2-part 2 function) [2,3,15,17]. Both pre and postoperative NLR valid values were available and included in the analysis.  
A control group of asymptomatic subjects (n = 1260) for NLR was evaluated by retrieving medical records of hospital employees' medical visits over the last couple of years. We used the backward selection procedure to optimize a multiple linear regression model with respond (dependent) variable NLR, for all sets of data using R version 3.5.3 statistical software [18]. Predictor variables were age, gender, Index, VAS, Tegner-Lysholm, IKDC, KOOSJR, KSS1, KSS2, Neutrophil and Lymphocyte values. The statistical decisions were based on \(t\)-test, F-test, (multiple) coefficient of determination (R\({}^{2}\)--Multiple R-squared) and adjusted coefficient of determination (R\({}^{2}\)--Adjusted R-squared). The study was conducted in accordance with the Declaration of Helsinki and the protocol was approved by the Emergency clinical county hospital 'Pius Brinzeu' Timisoara 'Local ethics committee for scientific research', no 176 from 18 October2019. All patients gave their verbal informed consent for inclusion before they participated in the study.