1.5,2.0,and 2.5 mm/day)was performed on 20 goats and 20 rabbits.It was found that a relatively slow lengthening rate of 1mm/day was better since it induced less tissue reactions and quicker bony regeneration and created more dense and more mature bony trabeculae in the lengthened zone than the other 3 rates.In addition,it was also found the new bone formation in the lengthened zone of the proximal metaphysis of the tibia proceeded quickly and both intramem-branous and endochondral ossifications contributed to the bone healing process with the former in predominance.