Objective:
Our long-term objective is to understand the age effects on craniofacial bone healing and, in doing so, we are able to devise methods to improve fracture repair in the elderly.
Material and Methods:
We first developed a standardized osteotomy model of facial bone in ovariectomized rats. Two unique features to this model were included: first, the rats exhibited an osteopenic phenotype, reminiscent of the bone health that has been reported for the aging population. Second, osteotomies were created in the mandibular bone and therefore represented the fracture healing of craniofacial bone in elderly patients. The same osteotomy procedures were used in a patient cohort and in the rat model.
Results:
Molecular, cellular, and histologic analyses demonstrated a close alignment between the osteotomy site healing of craniofacial bone in human and rats. Osteotomy site produces trauma that creates a radial zone of dead and dying osteocytes, therefore triggers and apoptotic program of craniofacial bone. Then the osteocyte apoptosis and necrotic bone at osteotomy site is remodeled and replaced by new bone formation. Most notably in both human and rats, aging negatively affects bone healing in an osteotomy site.
Conclusions:
Collectively, these analyses support the use of an ovariectomy surgery rat model to gain insights into the response of craniofacial bone to osteotomy site healing in elderly patients. The data also suggest that elderly patients may show a greater degree of bone remodeling compared to the young population with normal bone density. While these inferences for patients remain speculative, it is nonetheless clear that methods to reduce osteocyte apoptosis caused by osteotomy will be of considerable value to any patient, especially those elderly patients with sub-optimal bone health

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