Improvements in total hip prosthesis implantation technique. A cement-proof seal for the lower medullary cavity and a dihedral self-stabilizing trochanteric osteotomy.
The anchorage of the femoral component of a total hip prosthesis can be improved by the following two refinements to the surgical technique: 1. The femoral medullary cavity is plugged with a bone core taken from the excised femoral head or with a polyethylene bung. The plug prevents the bone cement from being displaced distally into the lower part of the medullary cavity. It contains a small hole through which blood can escape, thus preventing the latter from accumulating in the upper part of the medullary cavity and impairing the bond between the cement and the bone wall of the cavity. 2. The greater trochanter is no longer sliced off with a single cut in one plane but is now removed by dihedral osteotomy, i.e., by making cuts in two planes which intersect each other so as to form a ridge. On compressing this osteotomy by tension band fixation all movement between the fragments is eliminated, including that in the parasagittal plane which results from flexion and extension of the hip. In this manner loosening and pseudarthrosis of the osteotomy are prevented.