CHANGES IN CARTILAGE AND BONE METABOLISM IDENTIFIED BY SERUM MARKERS IN EARLY OSTEOARTHRITIS OF THE KNEE-JOINT

Serum concentrations of two extracellular matrix molecules were determ ined over a 3 yr period in individuals with chronic knee pain to inves tigate whether sequential serum measurements of cartilage-and bone-der ived molecular fragments reflect early stages of osteoarthritis (OA) o f the knee joints. Thirty-eight individuals with chronic knee pain (>3 months at inclusion) with or without radiographic evidence of knee jo int OA at the 3 yr follow-up radiographic examination were studied. Se rum concentrations of cartilage oligomeric matrix protein (COMP) and b one sialoprotein (BSP) increased significantly (P < 0.001) in the 13 i ndividuals with radiographic OA at follow-up, while remaining unchange d in the 15 individuals with normal radiographs at follow-up. The base line concentrations of the two variables did not differ between the gr oups. These findings suggest that pathological processes in cartilage and subchondral bone coincide in OA. and appear to be reflected by cir culating levels of macromolecules released from cartilage and bone. Ch anges in serum levels of COMP and BSP are potential tools in studies o f knee joint OA in subjects with chronic knee pain.