LONGITUDINAL OVERGROWTH OF BONE AFTER OSTEOTOMY IN YOUNG-RATS - INFLUENCE OF BONE STABILITY

One hundred and five 5-week-old male rats were used to study the influ ence of the stability of an osteotomy on longitudinal overgrowth of th e bone. In 45 rats (Group 1) a transverse diaphyseal osteotomy of the right tibia Mras made; the left tibia was left untreated. In the secon d 45 rats (Group 2) the right tibia was osteotomized after applying an external fixator; the left tibia underwent a sham operation without o steotomy. Fifteen further rats (Group 3) were used as a nonoperated co ntrol group. After being measured at different periods up to 20 weeks, the osteotomized tibiae of the Group 1 (unstable) were 16-25% longer than those of their nontreated limbs (P < 0.001). The osteotomized tib iae of the Group 2 (stable) were 6-11% longer than those of the sham-o perated opposite limbs (P < 0.001). The osteotomized and unstable tibi ae were 9-17% longer than the osteotomized and stable tibiae (P < 0.00 1) throughout the whole study. Although several factors have been cons idered to be responsible for longitudinal bone overgrowth after fractu re in young animals, this work suggests that bent's stability plays a decisive role in the final outcome.