# Serum and Clinical Factors Associated with Total Knee Arthroplasty in Patients with Knee Osteoarthritis

## TL;DR

This study identifies clinical and serum factors that distinguish patients needing knee replacement surgery from those with less severe knee osteoarthritis.

## Contribution

The study provides new thresholds for IL-6 and COMP as potential biomarkers for predicting the need for total knee arthroplasty.

## Key findings

- WOMAC scores perfectly discriminated between TKA and control groups.
- IL-6 and COMP showed strong discriminatory power with specific thresholds for sensitivity and specificity.
- TKA patients had lower vitamin D3 and calcium levels compared to controls.

## Abstract

Knee osteoarthritis (KOA) is one of the most prevalent chronic joint disorders, with its incidence rising over the past decade due to an increase in risk factors, including age, obesity, metabolic conditions, sedentary behavior, and mechanical stress on the knee joints. We conducted a cross-sectional, two-group comparison including 70 knee-pain patients aged ≥ 44 years: 50 patients meeting clinical and radiological criteria for TKA and 20 patients undergoing knee arthroscopy as controls. All patients underwent clinical assessments, WOMAC scoring, radiography, and 3T knee MRI. Serum interleukin-6 (IL-6), cartilage oligomeric matrix protein (COMP), vitamin D3, calcium, and phosphorus were measured at admission. TKA patients were older and had higher WOMAC scores. WOMAC discriminated groups perfectly (AUC = 1.000), but age discriminated well (AUC = 0.911). IL-6 (AUC = 0.819) and COMP (AUC = 0.838) were significant discriminators, with IL-6 threshold ≥ 4.585 pg/mL achieving 66% sensitivity and 85% specificity and COMP cutoff ≥ 11.52 ng/mL achieving 84% sensitivity and 75% specificity. TKA group vitamin D3 levels were considerably lower but had limited discriminatory performance (AUC = 0.683). Although all patients had adequate mineral metabolism, TKA patients had lower serum calcium and higher serum phosphorus levels than controls.