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Histomorphometry of Distraction Osteogenesis in a Caprine Tibial Lengthening Model
Author(s) -
Welch Robert D.,
Birch John G.,
Makarov Marina R.,
Samchukov Mikhail L.
Publication year - 1998
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1998.13.1.1
Subject(s) - apposition , osteotomy , intramembranous ossification , bone remodeling , distraction osteogenesis , bone formation , bone healing , tibia , bone histomorphometry , osteoblast , anatomy , callus , medicine , chemistry , distraction , dentistry , trabecular bone , biology , osteoporosis , biochemistry , neuroscience , in vitro , genetics
Standardized histomorphometry of bone formation and remodeling during distraction osteogenesis (DO) has not been well characterized. Increasing the rhythm or number of incremental lengthenings performed per day is reported to enhance bone formation during limb lengthening. In 17 skeletally immature goats, unilateral tibial lengthenings to 20 or 30% of original length were performed at a rate of 0.75 mm/day and rhythms of 1, 4, or 720 times per day using standard Ilizarov external fixation and an autodistractor system. Two additional animals underwent frame application and osteotomy without lengthening and served as osteotomy healing controls. Histomorphometric indices were measured at predetermined regions from undecalcified tibial specimens. Within the distraction region, bone formation and remodeling activity were location dependent. Intramembranous bone formed linearly oriented columns of interconnecting trabecular plates of woven and lamellar type bone. Total new bone volume and bone formation indices were significantly increased within the distraction and osteotomy callus regions (Tb.BV/TV, 226% [ p < 0.05]; BFR/BS, 235–650% [ p < 0.01]) respectively, compared with control metaphyseal bone. Bone formation indices were greatest adjacent to the mineralization zones at the center of the distraction gap; mineral apposition rate 96% ( p < 0.01); mineralized bone surfaces 277% [ p < 0.001]); osteoblast surfaces 359% [ p < 0.001]); and bone formation rate (650% [ p < 0.01]). There was no significant difference ( p < 0.14; R = 0.4) in the bone formation rate of the distracted callus compared with the osteotomy control callus. Within the original cortices of the lengthened tibiae, bone remodeling indices were significantly increased compared with osteotomy controls; activation frequency (200% [ p < 0.05]); osteoclast surfaces (295% [ p < 0.01]); erosion period (75%); porosity (240% [ p < 0.001]). Neither the rhythm of distraction nor the percent lengthening appeared to significantly influence any morphometric parameter evaluated. Distraction osteogenesis shares many features of normal fracture gap healing. The enhanced bone formation and remodeling appeared to result more from increased recruitment and activation of bone forming and resorbing cells rather than from an increased level of individual cellular activity.