It could be argued that we need “controlled subsidence” of the distal half of the stem to enable the cement in the upper end of the femur to maintain load–bearing contact with the cancellous bone. This might break the vicious circle, starting as elastic deformation of the upper end of the prosthesis too effectively supported below, and ending as granulomatous resorption of the medial femoral neck.

In 1968, 6 years after the introduction of the LFA into routine clinical practice, and after some 2500 operations have been carried out, stem fracture presented as a serious complication. The incidence peaked in the 8 year period 1974–1982. The attention focused on the stem design and the materials. The stem was made more bulky, angular corners were given a radius, and vaquasheening was used to work harden the surface and to ablate any irregularities that could act as possible stress risers. Proximal dorsal flange was added to improve cement injection. High nitrogen stainless steel was introduced, and the cold forming process gave a very strong material ORTRON (Chas. F. Thackray 1982) for stem manufacture. These changes, together with the technique of closing off the medullary canal with cancellous bone block [1] (October 1976) eliminated stem fracture. The incidence of aseptic stem loosening was also reduced with 99 % survivorship at 10 years in patients with a mean age of 41 years [2].

Regular reviews of radiographs of these clinically successful cases highlighted changes in the proximal femur indicating strain shielding. The process, no longer interrupted by stem fracture, now continued past the 11-year “at risk” period. It was totally asymptomatic.

It is the observation and interpretation of the radiographic changes of the proximal femur, first with stem fracture, then aseptic stem loosening and finally proximal strain shielding of the femur, were the reasons for the design of the C-Stem and the detailed attention to the cementing technique [3].