[The cryoeffect on the growing bone (morphological findings on the kneejoints of rabbits as an example) (author's transl)].

The cryoeffect on growing long bones is studied. The kneejoints including the bordering surrounding epiphyseal disks of the femur, tibia and fibula of 35 young (4-6 weeks old) and 6 adult rabbits were frozen by dipping the knee joints totally or partially into liquid nitrogen (-196 degrees C). The freezing time varies 3-5 min. After different times of survival maximally up to 397 days the animals are sacrified. The length of the cryosurgical treated and untreated extremities are measured and the kneejoints, especially the epiphyseal disks, are studied lightmicroscopically. Totally or partially frozen joints show after a complete necrosis in the phase of regeneration and reparation an uncoordinated overgrowth of cartilage-and bone cells and a proliferation of connective tissue with deformation of the epiphysis. The above mentioned facts and the disturbance of growth in length in young animals is mainly caused by the irregular function of the epiphysical disks after being treated cryosurgically. Also the epiphysical disks being only partially treated cryosurgically show growth disturbances and deformities. Deducing from the animal experiments clinical cryosurgery, has to be applied with extreme caution in the surrounding area of growing bone in children so that the centers of growing bone are not be frozen. Treating bones of adult rabbits cryosurgically there are only time limited reversible morphological findings so that clinically cryosurgery can be used in the surroundings areas of adult bones, especially joints, without any remarkable morphological long term findings.