The effect of head injury on systemic physiology, including bone healing is still a topic of vivid discussion. We aimed to investigate whether in patients with long bone fractures the presence of head injury is associated with excessive callus formation. Data on patients with head injury and femoral diaphyseal fracture admitted to our trauma unit between 1997- 2002 were collected and analysed. Patients with factors that could influence bone healing such as smoking, NSAIDs and hormonal disorders were excluded. The severity of head injury was quantified using GCS, AIS and CT scan reports. Patients matched for age, sex and ISS with femoral shaft fractures and no head injury formed the control group of the study. All the fractures were stabilised with reamed femoral nail. The quantification of fracture healing response was estimated by taking the radiological ratio of the largest diameter of callus formed into two planes and the adjacent normal diameter of femoral canal. The minimum follow-up of the patients was 12 months.

In total 42 patients were studied, 17 with head injury and femoral fracture and 25 with an isolated femoral fracture, (control group). Both groups were comparable in terms of age, sex, ISS. The difference between the mean callus to diaphyseal ratio was statistically significant for both the AP and Lateral projections (AP – mean difference 0.462, 95% CI 0.312 to 0.602, p<0.0001, LAT – mean difference 0.289, 95% CI 0.142 to 0.436, p<0.001) with the head injured patients having more florid callus compared to the control group.

This study supports the view that head injury leads to exuberant callus formation in patients with long bone fractures. The mechanisms of this response could be both central and local. Research is ongoing to elucidate the pathways involved in this biological phenomenon.