Longitudinal growth of the rabbit tibia after callotasis

We investigated the effect of bone lengthening by callotasis on longitudinal growth of the tibia in rabbits. Ninety-nine five-week-old immature rabbits were divided into five groups according to the percentage of lengthening: group I, 10%; group II, 20%; group III, 30%; group IV, 40%; and group V, sham operation without lengthening. Corticotomy was performed at the proximal metaphysis of the left tibia and the right tibia was used as a control. The lengthening rate was 0.25 mm twice daily. Radiological, histomorphometric, and immunohistochemical studies were done on animals killed at the time of corticotomy, at the completion of lengthening, and thereafter every two weeks until 12 weeks. Tibial lengthening did not cause retardation of growth when the bone was lengthened by up to 20%. When the bone was lengthened by 30% or more, growth retardation was evident, and persisted until skeletal maturity.