Receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG) have been shown to be important regulators of osteoclastogenesis during bone remodeling, and their expressions were examined during fracture healing in a mouse model of tibial fracture. However, studies linking RANKL and OPG in patients with head injury and fracture are lacking. We evaluated the changes in serum levels of RANKL and OPG in patients with head injury and fracture (head injury group) and in patients with fracture (fracture group) and compared these with levels found in healthy control subjects.

18 male patients of head injury and fracture and 20 male patients of fracture alone were enrolled. 20 healthy men were recruited to serve as controls. Within the first few hours of admission to hospital, at 4, 8 and 12 weeks after injury 20 ml of blood were obtained from 18 patients with head injury and fracture and 20 patients with fracture only.

RANKL levels were significantly lower in the head injury group than in the fracture group at 8 and 12 weeks after injury. OPG levels were significantly higher in the head injury group than in the fracture group at 4, 8 and 12 weeks after injury. RANKL/OPG ratios were significantly lower in the head injury group than in the controls immediately after and 4, 8 and 12 weeks after injury, and were significantly lower in the head injury group than in the fracture group at 8 and 12 weeks after injury.

We have shown changes in the profiles of RANKL, OPG and RANKL to OPG ratio. The altered RANKL, OPG and RANKL/OPG ratio in the head injury group lasted longer than in those of the fracture group.