[Consequences of progressive lengthenings on rabbits. Experimental study (author's transl)].

The authors performed 12 femur progressive lengthenings on rabbits during growth period. The lengthening was effected with a small distractor after a transversal bone section. The lengthening was 7,5 mm on 4 rabbits in 5 days (group 1) 10,5 mm on 4 rabbits in 7 days (groups 2), 15 mm on 4 rabbits in 10 days (group 3. At the end of the lengthening, the authors compared the non operated limb with arteris, veins, nerves, muscles and growth cartilage of the operated side. They found no modification of the muscular structure in the 3 groups. They substantieted few arterial and veinous modifications in group 1 and 2 the arteriel modifications were minimal but veinous modifications were important in group 3. The nervous anomalies wer evident in the 3 groups; the more important the lengthening, the more severe the anomalies; ranging from nerve ondulations in group 1, to vacuolar degenerscence and fibres ruptur in group 3. The authors studied the growth cartilage modificate at the furthest extremity from the femur by counting the cells in the various layers of the cartilage. They noted a significant descrease of the cell in the proliferative zone. This descrease might be due to a cartilage suffering. The modifications in the hypertrophic zone are less important, inconstant and result in a increase of the number of the cells. The authors think that the consequences of those important modifications on the nerve and on the growth cartilage are constant enough to complete this study by other lengthenings. This study coroborates their theory that all the consequences of a lengthening performed in a child are far from being perfectly known.