Effect of enoxaparin and rivaroxaban on cell viability of human osteoblast cultures. Human osteoblast cells were cultured in the presence of varying concentrations of (A) enoxaparin and (B) rivaroxaban for 72 hours after which cell viability was assessed using the MTS assay. Percent viable cells (y) are presented as a proportion of the viability of control cultures. Data are presented as the mean ± the standard deviation. *p < 0.05 from Student's t-test relative to the control treatment (n = 3).