Early bone matrix formation during distraction: A biochemical study in sheep

Histomorphometry of Distraction Osteogenesis in a Caprine Tibial Lengthening Model

“…Following fracture, new bone formation begins as early as 24 h (39,40) . In the current study, remnants of bone labeled at day 7 were observed along the original cortical surfaces, which is in agreement with previous reports (17,39) . Primary gap healing occurs under rigid fixation in which woven and lamellar bone are formed perpendicular to the bone axis in areas of noncortical contact of 2 mm or less (32,37,41–44) .…”

“…The acceleratory effect was reported to influence the synthetic activity of individual osteoblast based on electron microscopy (EM) morphology and metabolic indices (2,4) . Bone formation activity in DO has been indirectly assessed using static histomorphometry, (11,14,17–19) quantitative technetium 99 scintigraphy, computer tomography and calcium analysis, and densitometry (12) . In these studies, the rate of regenerate bone formation is reported to significantly exceed that of normal fracture healing.…”

Bone lengthening osteogenesis, a combination of intramembranous and endochondral ossification: an experimental study in sheep

“…Previous reports on distraction osteogenesis at low rates of distraction (0.5–1.0 mm/day) in humans, dogs and sheep showed that the regenerate formed by intramembranous ossification [22, 23, 27–29], as also confirmed by biochemical analysis [28, 30]. However, in a rabbit model of leg lengthening, consecutive cartilage formation from the central fibrous tissue of the distraction regenerate was observed [24].…”

“…Endochondral ossification from the central fibrous tissue has been shown in the distraction gap in experimental models of distraction osteogenesis in rabbits [24, 26]. On the other hand, intramembranous ossification has been proposed to result when a low distraction rate under stable external fixation is applied [22, 23, 27–30]. A combination of both intramembranous and endochondral ossification within the same distraction callus has been found in other experimental investigations [31–34].…”

Increased Distraction Rates Influence Precursor Tissue Composition Without Affecting Bone Regeneration

“…Any cartilage within the distraction gap was assumed to result from either poor fixator stability (and excessive micromotion) or failure to preserve the blood supply during surgery (1,4,5,34) . Molecular analyses of distraction gap tissue have supported this viewpoint (35,36) . However, reports of cartilaginous tissue within the distraction gap have become increasingly common in both ring and monolateral fixator systems (18–22,37) .…”