[Testing of cementless stepped-stem prosthetic devices replacing the hip shoulder joint of the XXXX . Comparison of two animal models (author's transl)].

@entity1 @entity174 @entity235 @entity4034 @entity572 @entity1349
In 6 @entity235 the @entity572 was experimentally replaced using a ceramic stepped-stem prosthetic device implanted in the thigh bone. In six other @entity235 V4A steel stepped-stem prosthetic devices inserted in the arm bone was used for replacing shoulder joint. The six devices replacing the shoulder joint healed up without complications and proved to be mechanically stable. From six devices replacing the @entity572 only one was successful; the remaining five implants did not heal up due to @entity174 of the stem, @entity1349 in the thigh bone and @entity4034 . We suggest that these different results are based not on the different material, but on the different conditions characteristic for each implantation sites. The devices implanted in the arm bone of the @entity235 , corresponding to the conditions in @entity1 , were stressed mainly by pressure and pull. In such conditions the newly formed bone tissue anchoring in the steps on the stem stabilized the device. On the other hand, the biomechanical load on the @entity572 replacing device in the @entity235 is represented mainly by rotation at stress, for which the devices are not conceived. The stepped profile of the stem can not work; it twists in the thigh bone and remains unstable causing consequences such as @entity174 , @entity4034 and @entity1349 . For experimental testing of bone and joint replacing prosthetic devices of cementless anchoring systems replacing @entity1 @entity572 and thigh bone we recommend the shoulder joint of the @entity235 instead of @entity572 , because of the comparable biomechanics.
