Abstract:
This study investigates the mechanobiology of mandibular distraction osteogenesis (DO) using three-dimensional finite element (FE) analyses based on a rat model. The primary objective was to characterize the local mechanical environment, specifically the hydrostatic stresses and maximum principal tensile strains, within the regenerating tissue during the distraction process. FE models were constructed from three-dimensional computed tomography (CT) scans of rat hemi-mandibles at four distinct time points of an optimal DO protocol: end of latency (post-operative day 5), distraction day 2 (day 7), day 5 (day 10), and day 8 (day 13). A 0.25 mm distraction was simulated at each time point, and the resulting stress and strain fields within the tissue regenerate were analyzed. The findings were correlated with previous histological evidence from the same experimental protocol. The analyses revealed that regions experiencing tensile strains up to 13% corresponded to areas of new bone formation. Conversely, areas with periosteal hydrostatic pressures of less than 17 kPa corresponded to locations of cartilage formation. Strains in the center of the distraction gap were significantly higher, suggesting that tissue damage and subsequent new mesenchymal tissue regeneration would occur there, a prediction consistent with histological findings. The study's use of a time-series approach allowed for a detailed understanding of how the mechanical environment changes over time, providing a biomechanical rationale for the varying levels of bone formation observed at different stages of the DO protocol. The authors concluded that this approach, combining CT imaging with FEA, is a powerful tool for noninvasively determining optimal DO procedures.
