The knee osteoarthritis is the most common arthritis in elderly and diagnosed clinically and radiologically. New biomarkers are being tried to diagnose knee osteoarthritis. This work aims to explore the relationship between serum Cartilage Oligomeric Matrix Protein (COMP) and knee osteoarthritis in Indian patients. We recruited 72 elderly patients of knee osteoarthritis (diagnosed according to American College of Rheumatology criteria) and 23 asymptomatic healthy elderly controls from geriatric and medicine OPD. Radiographic severity was determined by K/L grade. The serum COMP level was determined by surface plasmon resonance (SPR) analysis using polyclonal rabbit antibody against COMP. Patients had significantly high level of serum COMP as compared to controls (1.75±.37ng/Ml vs. 0.82±.16ng/mL; p<0.0001). The serum COMP significantly decreased as the duration of disease increased (p<0.0001). Its level was appreciably higher in patients with radiographically proven osteoarthritis (p=0.045). There was no significant difference in the level correlated with gender, body mass index, visual analogue scale, age and laterality of knee osteoarthritis. It was demonstrated that the serum COMP can differentiate between knee osteoarthritis elderly patients and the healthy subjects. It characterizes disease severity and early duration of osteoarthritis.

Keywords: Knee Osteoarthritis; Serum; Surface Plasmon Resonance; Cartilage Oligomeric Matrix Protein; Indian Elderly Population.