Rat Mandibular Distraction Osteogenesis: Latency, Rate, and Rhythm Determine the Adaptive Response

Abstract

Distraction osteogenesis is a well-established technique of endogenous tissue engineering. The biomechanical factors thought to affect the quality of the distraction regenerate include the latency, rate, rhythm, and consolidation period. In an effort to understand the impact of these parameters on regenerate bone formation, this study was designed to decipher the most adaptive response in a rat model of mandibular distraction osteogenesis. Ninety-six adult Sprague-Dawley rats were divided into 16 subgroups (n = 6 per subgroup) based on variations in the distraction parameters (i.e., latency, rate, and rhythm). After a 28-day consolidation period, the mandibles were harvested, decalcified, and sectioned. A standardized histologic ranking system was used to evaluate the effect of each protocol on the adaptive response of the regenerate bone. In this study, we have demonstrated that the latency period dramatically affects the success of distraction osteogenesis. Furthermore, distraction rates up to 0.50 mm per day stimulated excellent regenerate bone formation, whereas greater distraction rates produced a fibrous union. Finally, higher frequency distraction (i.e., increased rhythm) appeared to accelerate regenerate bone formation. We believe that defining the critical parameters of this model will improve future analysis of gene expression during rat mandibular distraction osteogenesis and may facilitate the development of biologically based strategies designed to enhance regenerate bone formation.

The Influence of Expansion Rates on Mandibular Distraction Osteogenesis: A Computational Analysis

“…26,32,44,34 Predictive computational models can also be used to attain a better understanding of the factors which may influence the clinical procedure. The computational model presented in this paper offers a framework for studying various aspects of MSDOG, the effect of implant design, the duration of the latency period, the rate of expansion, the duration of the maturation period etc.…”

“…11,14 Various studies have investigated the mechanisms of bone formation during distraction of the mandible, however different treatment protocols etc among various authors have made direct comparison of the effects of the applied biophysical stimuli on distraction osteogenesis almost impossible 32 . Using a rat model, Paccione et al 34 demonstrated that both the rate and the frequency (or rhythm) of distraction influences the adaptive response within the fracture callus. The rate of distraction was observed to have a greater effect than the frequency.…”

Comparison of two protocols of periosteal distraction osteogenesis in a rabbit calvaria model

“…Nevertheless, variations in the protocols of distraction differently influenced the success of mandibular DO depending on the model used. [5][6][7] Subtle differences in bone formation induced by differing distraction rates may be noticed at the molecular level rather than histologically. 8 A decrease in bone formation was associated with a decrease in the synthesis of bone-specific extra-cellular matrix (ECM) proteins induced by hyperphysiological strains of distraction 9 or acute mandibular lengthening.…”

Effect of distraction frequency on bone formation during bone lengtheningA study in chickens

“…In early studies in a canine model, Ilizarov (1989) showed with radiographic and histochemical analyses that an increase in the frequency of distraction induced better osteogenesis. More recently, Paccione et al (2001) have found a similar correlation between the distraction frequencies and the histological ranking scores of regenerate bone formation in a rat model of mandibular distraction osteogenesis. On the other hand, Welch et al (1998) assessed bone formation activity during distraction osteogenesis in a goat model, using histomorphometric analysis, and found that an increase in the rhythm of distraction did not stimulate the formation of bone.…”

“…These findings support the view that a faster frequency of distraction stimulates the formation of more bone. Like Ilizarov (1989) and Paccione et al (2001), we used skeletally mature animals, while Welch et al (1998) chose skeletally immature goats as their animal model. The greater osteogenic potential in skeletally immature animals may surpass the acceleratory effect produced by increasing the rhythm.…”