THE EFFECT OF CONTROLLED DYNAMIZATION ON REGENERATE BONE HEALING IN CALLOTASIS

We investigated whether controlled dynamization enhanced regenerate bone healing in callotasis of the tibia in 12 adult mongrel dogs. An average of 2 cm (≒ 10%) lengthening was obtained. The left hindlimb was allowed dynamization of 1 mm, 2 mm, and 3 mm in magnitude when 1 cm (≒ 5%) of lengthening was achieved, whereas the right hindlimb was not dynamized and served as a control. Bone mineral density (BMD) of the regenerate bone was measured periodically until nine weeks after the end of distraction. After sacrifice, uniaxial compression testing was performed. Relative BMD ratio and mechanical properties of the regenerate bone were significantly higher in the dynamization group than in the nondynamization group; no significant difference was found among dynamization subgroups, however. We conclude that 1 mm to 3 mm of elastic dynamization accelerates regenerate bone healing in callotasis of the canine tibia.