Comparison of Urinary CTX-II Levels in Postmenopausal Women with Knee Osteoarthritis with or without Osteoporosis

Objective: In this study, we investigated a cartilage degradation marker; cross-linked C-terminal telopeptide of collagen, CTX-I (serum) and CTX-II (urine) along with other laboratory variables in postmenopausal women with osteoarthritis (OA) of the knee with/without associated osteoporosis (OP). In addition, we aimed to investigate whether CTX-II which is released into the synovial fluid and systemic circulation and excreted by urine was an effective marker for the diagnosis of OA. Futhermore, we evaluated a possible relation of CTX-II with radiological grades of OA. Material and Methods: Postmenopausal women without any history of OA or OP costituted the control group (n=21). Study Group I consisted of 30 post-menopausal women with primary OA of the knee, and Group II consisted of 14 postmenopausal women with primary OA of the knee along with OP. Group I and Group II were categorized by radiological stages according to Kellgren-Lawrence system as stage 2, stage 3 and stage 4. Results: The control group was not statistically significantly different from Group I, II, or radiologically 2nd, 3rd, 4th stage of OA groups for age, body mass index, duration of menopause or levels of alkaline phosphatase, erythrocyte sedimentation rate, C- reactive protein, osteocalcin, CTX-I and CTX-II. The results of CTX-II values (ng/mmol) of the control and staged groups were as follows; median (25th-75th) level:341 (216-850); 609.34 (363-1072); 492 (319-927); 928 (400-1245) respectively; (p=0.210). Percentage change of median values between the control group and group I, II and radiologically 2nd, 3th, 4th stage of OA groups were 61%+, 80%+, 78%+, 44%,+ 172%+, respectively. Conclusion: CTX-II levels of the control group were similar to those of the knee osteoarthritis patients with or without osteoporosis as well as radiologically graded subgroups, and statistical analysis did not show statistically significant differences. , However, percentage change of median values between the control group and group I, II, and between the control group and radiologically 2nd, 3th, 4th stage of OA groups were significant.