To investigate whether radiologic spine disc degeneration is associated with increased type II collagen (CII) degradation products in the urine of postmenopausal women, independently of radiologic knee osteoarthritis (OA) and clinical hand OA.
The study group comprised 324 postmenopausal women ages 58-94 years who had no treatment or disease that could alter bone metabolism. Lateral radiographs of the thoracic and lumbar spine were obtained in each woman and scored for disc space narrowing (DSN) and osteophytes. Fixed-flexion posteroanterior radiographs of the knee were obtained to assess femorotibial knee OA. In all women, hand OA was assessed by clinical examination, and the level of urinary C-terminal crosslinking telopeptide of CII (CTX-II), a biologic marker of CII degradation, was measured.
The prevalences of radiographic lumbar and thoracic spine disc degeneration, knee OA, and clinical hand OA were 84%, 88%, 35%, and 58%, respectively. After adjustment for age and body mass index (BMI), patients with lumbar spine DSN grade > or = 1 had, on average, 34% higher CTX-II levels compared with the other women (P = 0.0005), whereas no association was observed with lumbar spine osteophytes. No significant association between thoracic spine DSN or osteophytes and urinary CTX-II levels was observed. Multivariate analysis of variance showed that, after adjustment for age and BMI, lumbar spine DSN (P = 0.0049), knee OA (P = 0.0055), and clinical hand OA (P = 0.0060) were, independently of each other, associated with CTX-II levels. Thus, patients with lumbar spine DSN, knee OA, and clinical hand OA had CTX-II levels 80% higher (P < 0.0001 after adjustment for age and BMI) than those of patients with no lumbar spine DSN, no radiologic knee OA, and no clinical hand OA.
Postmenopausal women with lumbar spine disc degeneration are characterized by increased CII degradation. The contribution of lumbar spine DSN to CII degradation was similar to, and independent of, the contribution of radiologic knee OA or clinical hand OA. Lumbar spine disc degeneration in elderly patients should be assessed when analyzing levels of CTX-II in studies of knee, hip, and hand OA.