Purpose.
To describe OA-Biomarkers behavior according to risk factors for OA progression, in patients with ACL-Reconstruction, at 2 years follow up.

Methods.
Two OA-Biomarkers were evaluated (U-CTx-II / S-MMP-3) in 40 patients with ACL injury (mean age=26 years old). Pre-op and 2-year post-operative determinations were performed by ELISA. Descriptive analysis and non-parametric tests, were carried out to look for changes in these biomarkers and also identify any relation with age, sex, meniscal and chondral injury, and time from injury to reconstruction.

Results.
Significative higher concentrations were found in both OA-Biomarkers at 2 years. Patients above 24 years old, had higher levels in both biomarkers (U-CTx-II: p=0.003; S-MMP-3: p=0.001). Also, males had significant increase at the second measurement (U-CTx-II: p=0.01; S-MMP-3: p=0.008). Regarding time from injury to reconstruction, Spearman correlation test, was significative but negative in females before reconstruction and at 2 years follow up, (r=-0.55, p=0.04; r=-0.73 p=0.01, respectively). Meniscal injury presence, showed an increment in both biomarkers (U-CTx-II: p=0.001; S-MMP-3: p=0.01). Dividing the population by ICRS classification; males with cartilage lesions greater than grade 2 had higher concentrations at two years, despite of being non-statistically significative. Those who did not have an initial cartilage lesion had higher increase in biomarkers at 2 years.

Conclusions.
Despite ACL-R higher levels of OA-Biomarkers will persist at 2 years follow up, which could indicate that the reconstruction may represent a “second hit” to knee joint, especially in those over 24 years old, women treated in the first year from injury, associated meniscal injury and males with chondral injury > grade 2. These subgroups must be treated differently in a near future or look for treatment options to reduce OA-Biomarker concentrations and avoid early OA.