Correlation Between Traumatic Brain Injuries and Callus Formation in Long bone Fractures

Orthopaedic aphorism teaches that fractures of long bones when associated with head injuries frequently heal with excessive callus and at a faster rate than normal. However, the evidence on this subject is flimsy and the aphorism remains unsubstantiated. Numerous studies have been conducted evaluating the possible humoral and other factors involved leading to excess callus formation in patients with a head injury. This study was designed to evaluate the effects of a traumatic head injury on bone healing in adults with a diaphyseal fracture of the lower limb.

Fiveteen patients with a closed fracture of tibia or femur and associated head injury (cases) and 15 patients with a closed fracture of tibia or femur without an associated head injury (controls) were included in the study. All patients were evaluated in terms of various serum parameters, including IL-6, growth hormone, PTH, LDH, prolactin levels, and ALP. Head injuries were graded as mild, moderate, or severe. Ventilatory support if required was noted. Serum prolactin was repeated at 5 weeks. Patients were followed up with serial radiographs, and the volume of callus formed was calculated and compared.

The mean value of growth hormone, interleukin-6 levels, and prolactin levels at 5 weeks were found to be higher in patients with head injuries, and the difference was highly significant (p = 0.001). The severity of head injury also correlated proportionately with the spike in IL-6 levels. There was more pronounced callus formation in patients with head injury group when compared to the controls. This difference was significant at all intervals.

There was higher volume of callus noted at the end of 6 months in patients with severe head injury (GCS < 7) when compared to patients with moderate head injury (GCS > 7). The patients with severe head injury were naturally under ventilator support for a prolonged period compared to those with moderate head injury. It was thus indiscernible if the excess callus observed is due to the humoral cascade or as an effect of prolonged ventilation. Patients with head injuries show elevated parathyroid hormone levels, growth hormone levels at the time of injury, and elevated prolactin levels 5 weeks after the trauma-all of which might contribute to enhanced osteogenesis. Interleukin-6 levels are also elevated and the levels correlate to severity of head injury.

Head injury triggers a humoral cascade invloving interleukin-6, parathyroid hormoe, growth hormone, and prolactin that contributes to enhanced fracture healing.