Background: Degenerative changes due to osteoarthritis (OA) may cause atraumatic knee joint pain (KJP). The concept and clinical diagnosis of early KOA (EKOA) are ambiguous and must be investigated.
Objectives: This study tried to assess the possibility of using the estimated serum biomarkers' levels to discriminate EKOA patients among atraumatic KJP patients.
Patients and methods: Patients complaining of KJP were evaluated clinically for pain scoring and diagnosis of OA and radiologically for grading according to the Kellgren–Lawrence (KL) grading scale. Blood samples were obtained from patients and controls with a KL grade of zero for ELISA estimation of serum matrix metalloproteinase-3 (MMP-3), C-terminal cross-linked telopeptides of type II collagen (CTX-II), tumor necrosis factor-α (TNF-α), and interleukin-6.
Results: The median values of MMP-3, CTX-II, and TNF-α were significantly higher in OA than in control (P < 0.001) and EKOA samples (P < 0.001, 0.0003, and 0.0004, respectively) and in EKOA samples (P = 0.034, 0.011, and 0.0045, respectively) than in control samples. The estimated cytokine levels were positively related to the KL grading of KOA and pain score. Statistical analyses defined high levels of MMP-3 and CTX-II as the highly significant identifiers for the EKOA and high serum TNF-α and MMP-3 levels as the highly significant identifiers for patients with severe pain requiring intervention.
Conclusion: EKOA is a possible cause for atraumatic KJP, especially in older and obese subjects. No single cytokine can be used to discriminate EKOA patients. Estimating serum levels of MMP3, CTX-II, and TNF-α might be used to distinguish EKOA patients.