Microscopic evaluation of bone regenerate of radius and ulna in dogs submitted to the lengthening using the Ilizarov external ring fixator

Abstract

The aim of this study was to evaluate, by microscopic analysis, the quality, the type and orientation of the tissue developed in bone regeneration area, during simultaneous lengthening of radius and ulna using the Ilizarov external fixator. A subperiosteal osteotomy of the distal diaphysis was performed and the bone distraction was performed at rate of 0.5 mm twice a day. A two-ring and four telescopic rod configuration was used and bone distraction started at day six after surgery. Fifteen adult crossbreed dogs weighing from 17 to 30 kg were used. These dogs were divided in five subgroups (A, B, C, D, E.) each containing three animals, which were submitted to euthanasia after the following procedure: A- eight days of distraction, B- 15 days of distraction, C- 22 days of distraction, D- 28 days of distraction and eight days of neutral fixation, E- 28 days of distraction, 60 days of neutral fixation, and 45 days with the external fixator removed. No interference in bone regeneration seemed to occur because of the type and location of the osteotomy, as well as the rate of distraction. Bone repair was efficient and it was predominantly formed by intramembranous ossification, although the presence of cartilage was observed in subgroups B and C.