Loading tests showed wide stem-thin cement envelope systems in valgus orientation placed with distal plug to be significantly more stable at higher loads. Narrow stem-thick cement envelope systems in varus without plug were unstable within a marginal factor of safety for cyclic loading. Four cement failures occurred within the thin stem-thick cement system on the upper lateral aspect of the prosthesis cement envelope.
View Article and Find Full Text PDFJ Bone Joint Surg Am
September 1976
We analyzed the biomechanics of Milwaukee brace treatment of idiopathic scoliotic patients through simulation in five computer-constructed model spines. The contributions to correction of each component of the brace were examined in these model spines, and some of the mechanical principles that determine the outcome of brace treatment were studied. The validity of the stimulation findings was then tested by a retrospective analysis.
View Article and Find Full Text PDFA two-dimensional stress analysis was used to study the effects of some of the factors leading to early fatigue failure of the femoral stem in total hip prostheses. The results show that loss of proximal stem support at the level of the calcar femorale will result in stem stress levels which can lead to fatigue failure. In addition, the role of body weight and range of cyclic stress fluctuation play an important role in fatigue life under conditions where the stem has lost proximal support.
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