Biomechanical aspects of femoral stem anchoring during total hip replacement

Stem instability is the major cause of complications following total hip replacement. To prevent its onset, the authors based their method on Wolff's law of bone transformation. Of the known prostheses, the straight-stem one fitting best to the shape of medullar cavity was chosen and by its sagittal enlargement in three different sizes a new stem collection was designed. Stems providing the closest fit to the medullar cavity were selected by computer-assisted adjustment to three-directional X-ray pictures. The principle seems to be supported by preliminary results.