Associations of Urinary Collagen II Neoepitope C2C with Total Knee Replacement Outcomes: Is OA a Systemic Disease in Rapidly Progressive Cases?

The objective of this study was to investigate the dynamics of the urinary collagen type II C-terminal cleavage neoepitope (uC2C) before and after total knee replacement (TKR) in rapid knee OA progressors. C2C in the urine was measured by IBEX-uC2C assay in 86 patients (mean age: 59.9 years) with symptomatic knee OA (kOA) undergoing TKR, assessed before surgery and 3 and 12 months after. The patients' condition was determined by self-assessment questionnaires, by lower limb performance tests, and by radiography. In the preoperative period, the uC2C level was significantly higher in females than in males, and was associated with the radiographic severity of kOA. A weak correlation between the C2C and knee pain was observed in the whole group and in males, but not in females. The individual dynamics of uC2C after TKR were heterogenic. In general, uC2C increased three months after TKR, but fell to the preoperative level after 12 months. A higher preoperative uC2C implied the tendency to diminish as a result of TKR, and vice versa. TKR did not stop the degradation of Coll2 in the tissues in the majority of cases. The pre-TKR uC2C predicts the postoperative uC2C level. The uC2C dynamic seems to be sex-specific, so it could be considered a prospective pre- and post-TKR biomarker for progressive kOA.