Urinary CTX-II and glucosyl-galactosyl-pyridinoline are associated with the presence and severity of radiographic knee osteoarthritis in men

Objective: To investigate the association between biochemical markers of bone, cartilage, and synovial turnover with the presence and severity of knee osteoarthritis (OA) in men. Methods: 176 men aged 59 - 70 years from the MRC Hertfordshire Cohort were studied. Weightbearing anteroposterior and lateral semiflexed radiographs were taken of both knees. A lifestyle questionnaire including basic demographic details and a questionnaire detailing knee pain was completed. This random sample was stratified based on the Kellgren and Lawrence (K&L) score, and the following biochemical markers were analysed: serum osteocalcin, serum C-terminal crosslinked telopeptide of type I collagen (CTX-I), urinary C-terminal crosslinked telopeptide of type II collagen (CTX-II), and urinary glucosylgalactosyl-pyridinoline (Glc-Gal-Pyd). Results: Age, body mass index (BMI), social class, smoking, and alcohol consumption were similar across K&L grades. Only one subject had a grade 4 K&L score, and was amalgamated with grade 3 subjects. A strong significant association was found between the presence of knee OA and urinary CTX-II and urinary Glc-Gal-Pyd (p = 0.0001 and p = 0.009), which persisted after adjustment for age and BMI. A significant positive association was also found between urinary CTX-II and urinary Glc-Gal-Pyd and the severity of K&L grade, joint space narrowing, and osteophytes scores, which persisted after adjustment for age and BMI. No associations between the presence and severity of knee OA were found for serum CTX-I or serum osteocalcin. Conclusions: Urinary CTX-II and Glc-Gal-Pyd, but not systemic markers of bone turnover, are strongly associated with disease severity and the presence of OA at the tibiofemoral and patellofemoral joints in men.