- Discussion:
- tight distal fit techniques achieve toggle control of stem in medullary canal;
- tight distal fit is correlated w/ lower prevalence of thigh pain;
- torsional stress is transferred thru proximal fixation in specimens w/ both proximal and distal fixation despite the fact that the distal stem was rigidly fixed;
- because cementless implants are substantially stiffer than cemented femoral components, degree of stress shielding is greater;
- such bone atrophy of the proximal femur is substantially greater w/ stiff cementless femoral components than w/ cemented components;
- distal fixation may ensure rigidity of fixation but it will lead to proximal stress shielding and bone loss;
- for most pts increased degree of local disuse osteoporosis has not yet had clinical consequences, but there are examples of severe disuse
osteoporosis in which much or all of the proximal femoral cortex has been completely resorbed;
- when stem is smooth and cylindrical distally, proximal stress relief does not occur, even when the stem is fixed tightly distally
Improved outcome in femoral revision arthroplasty with tapered fluted modular titanium stems.