Callus formation in bone fractures combined with brain injury in rat

Objective: The objective of this study was to determine the speed of bony union and the serum levels of biomarkers in the setting of bone fractures combined with brain injury. Materials and Methods: In this study, Sprague-Dawley rats were randomized into four groups: sham, brain injury, bone fracture, and bone fracture plus brain injury groups. The serum levels of biochemical markers, namely, nerve growth factor (NGF), Wnt-3a, Dickkopf-related protein-1, receptor-Activator of NF-|B ligand, and adrenocorticotropic hormone (ACTH), were measured on the days 1, 3, 7, and 14 following injury. Bony union was evaluated using radiographs every week for 6 weeks. Results: Compared with the brain injury group and bone fracture group, the radiographs of the bone fracture plus brain injury group revealed enhanced callus formations in week 2. From week 3, the callus formation did not differ significantly among the groups. The serum levels of the biomarkers varied at different time points. The serum levels of NGF on days 1 and 3, Wnt-3a on days 3 and 14, and ACTH on days 1, 3, and 7 were significantly higher in the bone fracture plus brain injury group than in the bone fracture group. Conclusions: Brain injury increases callus formation in simultaneous bone fracture. Considering the time point, early NGF, Wnt-3a, and ACTH elevation might be associated with early callus formation enhancement. The results indicate that these brain injury-induced biomarkers might play crucial role in accelerating bone healing.