Effects of Tranexamic Acid on Human Osteoblasts as Proxy for Fracture Healing

To investigate the effect of tranexamic acid (TXA) through in vitro culture of primary human osteoblasts (HOB) and in vivo using an operative rat femur fracture model. It was hypothesized that there would not be any effect on fracture healing in both studies.

Primary HOBs were exposed to varying concentrations of TXA over different time periods. Cells were assessed for viability, metabolism, and mineralization. For the in vivo model, fractures were created in the femora of adult rats, exposed to either TXA or saline, and then assessed for healing at different time points. A modified radiographic union score for tibia was used to evaluate radiographs, callus mineralization was assessed with microcomputed tomography, and biomechanical tests were performed.

Overall, HOB viability and metabolism decreased as TXA concentration and exposure time increased. However, at concentrations below 56.44 mg/mL, HOB viability was not affected. Similarly, mineralization also decreased as TXA concentration and exposure time increased. In both groups, in vivo results demonstrated increasing radiographic healing, callus mineralization, and biomechanical strength as a function of time. There was a trend for increased healing in the TXA group at 6 weeks after fracture; however, the difference compared with untreated animals was not statistically significant.

Although a degradation of HOB viability and metabolism occurred with increased TXA concentrations and exposure times, clinically relevant concentrations do not adversely affect HOB viability, metabolism, or mineralization. In addition, there were no noticeable adverse effects of TXA administration in the in vivo model.