["Internal lengthening" for the treatment of large segmental bone defects. An experimental study].

Ilizarov's idea of treating large segmental bone defects (LSBD) by transporting bone along the length of the defect is to us extremely interesting. However, the circular external distractor employed, unlike monolateral frames in cumbersome, transfixing and difficult for both placement and postoperative management. A research project has been carried out at our experimental surgery laboratory to assess the reliability of monolateral frames in the treatment of LSBD following Ilizarov' idea. For this experiment we selected five 6 to 12 month-old dogs, five 6 month-old lambs and five 12 month-old lambs, the latter being skeletally mature. All animals were male. The experiment consisted in an attempo of reconstructing a LSBD of 4-5 cm of the animal's femoral diaphysis by means of Ilizarov' method but using monolateral devices. The evaluation of the results was made by X-rays, muscle and bone histology and measurement of the specimens. On the basis of the results obtained it is concluded that treatment of LSBD by the Ilizarov method can be successfully accomplished by using monolateral external fixator-distractors. The advantages of the monolateral frames include a marked minimization of some the most outstanding drawbacks of Ilizarov's circular device, while keeping the advantages of his original concept.