Bone scan and serum markers of bone and cartilage in patients with knee pain and osteoarthritis

Objective: To study the relations between knee joint abnormalities, reflected by bone scintigraphy and serum concentrations of cartilage oligomeric matrix protein (COMP) and bone sialoprotein (BSP). Design: In a group of 38 individuals aged 37-54 years with chronic knee pain for more than four years, both knees were investigated with bone scan. The bone scans were graded for the extent of abnormalities. Radiographs of both knees were graded for tibiofemoral and patellofemoral osteoarthritis (OA). Serum levels of COMP and BSP were measured by immunoassays. Results: Bone scan abnormalities were detected in 26/38 individuals and radiographic OA in 23/38 individuals. The serum concentrations of COMP and BSP were significantly higher in the individuals with bone scan abnormalities (P = 0.02 and P = 0.004, respectively). In addition, the serum levels of COMP correlated positively with the extent of bone scan abnormalities (N = 38), r = 0.56, P = 0.002. Serum BSP did not correlate to the extent of scan abnormalities. Conclusions: In individuals with knee pain, serum levels of COMP and BSP differ between those with or without bone scan abnormalities in the knee joints. This suggests that measurements of the serum levels of these markers have potential as means for evaluation of tissue changes in individuals with long standing knee pain in relation to early stages of OA.