1. The first Generation Cementless Total Hip Replacement
In 1983 and 1984, when the first proximal fixation implants were introduced, the orthopaedic community already was aware that the AML (Anatomic Medullary Locking, DePuy. Warsaw, IN) provided good fixation´"´). The concern, however, of the diaphyseal fixing implant was stress-shielded bone loss occurred proximally. Therefore, the concept of fixing the implant only into the proximal femur was popular because of a desire by orthopaedic surgeons to load the femur in a manner that would be as physiological as possible. This required that the femur be loaded from the top to the bottom of the bone, rather than having fixation primarily concentrated in the diaphysis.
1) Clinical Results
The clinical results of the first generation cementless femoral stem designs incorporating proximal fixation were reported. The first generation of the proximally fixed
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implants had a relatively high incidence of undersized implants, which caused a significant influence of early loosening and failure
of these total hip replacements"- Q.22....1 The
error in surgical technique(and the resultant failures caused by it) was one of the factors that contributing to the relatively high incidence of thigh pain and loosening noted with first generation cementless implant that resulted in discouragement with these implants.
2) Anatomic Versus Tapered-Stem Design
There were two different philosophies about the best design for achievement of proximal fit and fixation. The anatomic design was favored by those who desired to achieve maximum fixation in the metaphysis and to concentrate as much off-loading of the stem as possible in the metaphysis. The tapered design was favored by those who wanted the stability that could be provided by this design as it wedged itself into the
femur1413-1´33´ At the present time, with the
current surface levels of fixation used, there
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