Study of serum and synovial fluid Dickkopf-1 levels in patients with primary osteoarthritis of the knee joint in correlation with disease activity and severity

Background Osteoarthritis (OA) is a typical complex degenerative articular ailment that shows focal cartilage loss, new bone formation with involvement of entire joint tissues. Dkk-1 assumes a job in controlling the pattern of bone repair and regeneration in both OA and RA. This study aimed to determine serum and synovial fluid levels of Dickkopf-1 (Dkk-1) in patients with primary OA of the knee joint and study their correlations with disease activity and severity. This study included 45 patients, 30 of them were diagnosed as primary knee OA. Fifteen rheumatoid arthritis patients as well as 15 healthy subjects were enrolled in the study as control groups, serum and synovial levels of Dkk-1 were estimated utilizing the ELISA technique. Results Serum levels of Dkk-1 were significantly higher in OA patients than healthy subjects (p < 0.001), although it was even significantly higher in RA patients than OA patients (p < 0.001). There was a highly significant decrease in the median synovial level of Dkk-1 in OA patients compared to the RA control group (p < 0.001). There was a highly statistically significant inverse correlation between circulating as well as synovial fluid Dkk-1 levels and radiological disease grading in knee OA (p < 0.001). There was a statistically significant decrease in serum levels of Dkk-1 in patients with severe OA (grade 3, 4) compared to those with mild OA (Grade 2) (p < 0.001). Conclusion Dkk-1 is an interesting marker that is related to articular disease .It could play an important role in decelerating the degenerative process of OA and can reflects radiographic severity of the disease as well.