Large experimental segmental bone defects treated by bone transportation with monolateral external distractors.

Monolateral frames were applied to five dogs and ten lambs for treatment of large segmental bone defects (LSBD) surgically induced in one of their femoral diaphyses. Reconstruction was attempted by bone transport, as developed by Ilizarov. Monolateral frames were used to minimize the draw-backs of Ilizarov's circular device. Radiographic, computed tomographic, and histologic studies were performed. The skin and soft tissues were not a major obstacle for the longitudinal migration of the screws during bone transport. Four months after the operations, healing and remodeling of the bone defect was always satisfactory. Histologically, the repair of the lengthened segment followed an intramembranous ossification pattern in its central areas and in the periphery as well. At the end of the experiment, the new induced bone had a virtually normal diaphyseal bone appearance. Bone transport for the treatment of experimental LSBD can be completed in monolateral frames.