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additional socket design by Bucholz. C: Bechtol of California produced the first
Charnley-type stem in the United States. Head size was 25 mm. D: Otto Aufranc and Roderick Turner in Boston
developed the Aufranc–Turner stem featuring a 32-mm head, oval neck cross section, and sharp edges at the
corners of the stem. E: A polyethylene cup designed for the stem seen in (D). F: Harlan Amstutz of California
developed the Trapezoidal 28, which featured a trapezoidal cross-section at the head and neck. Later models
adopted a square cross section. G: The CAD hip (computer-assisted design) was cast and featured a 32-mm
head and a broad short stem with more gentle radii at the stem margins. H, I: The HD-2 stem designed and
popularized by William Harris, MD, of Boston. This stem was forged and featured a larger collar and smaller stem
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configuration. The metal shell allowed for polyethylene liner exchange. J, K: Robin Ling of Exeter, United
Kingdom, designed with a collarless stem (J), which featured tapered surfaces in both planes. This was
designed to allow for stem subsidence within the cement mantle. Later design (K) featured polished surfaces. L:
The STH hip designed by Augusto Sarmiento, MD, appeared to mimic the design of Charnley but was produced
in titanium, representing the first use of titanium for a total hip stem in the United States. M: Phillip Wilson, MD,
and Al Burstein, PhD, of New York, designed the DF-80, which was intended to fill 80% of the intramedullary
canal diameter. N: The IOWA Hip, developed in conjunction with University of Iowa engineers, was popularized
by surgeon/implant designer Richard Johnston. It features a cylindrical stem distally and rounded borders to
minimize cement strain concentrations. O: Charles Townley, MD, of Michigan, developed this stem with an
exceptionally broad proximal platform and collar and step-graduated stem taper. P–R: Fatigue failure of stems
led to attempts to strengthen the stem with I-beam construction. Additional modifications to minimize cement
strains were added, as noted in this Mitchetti–Brown (P) stem. Mack Clayton of Denver, Colorado, designed a
stem that featured a distal taper plus I-beam (Q), whereas Rocco Callundrucio, MD, designed the Titan stem,
which featured a compressed oval cross-section. S: Indong Oh designed this stem to provide compressive
stresses on the cement. T: This stem was similar to the Charnley in stem geometry but featured a collar. U–X: In
the 1980s design modifications appeared that textured the stem to improve interlocking OC stem and cement.
Centralization of the stem was accomplished by the addition of distal centralizers to allow for a more uniform
cement mantle. In addition, head and neck modularity was introduced. This modification is seen on most implants
dating from this period forward. Although providing several advantages for the operating surgeon, as in any
design choice, multiple disadvantages were eventually noted as well. These are well described in multiple
sections of the text. The precision hip featured both proximal and distal centralizers as well as proximal stem
macrotexturing (U). V: Shows a stem that was similar to the Charnley in stem geometry but featured a collar. The
cemented medullary locking stem (CML) (W) utilized a preformed polymethyl methacrylate centralizer in addition
to proximal macrotexturing as did the Proforma stem (X). Y: This stem featured a straight bluntly tapered
geometry with longitudinal grooves to resist rotational forces. Note the absence of a collar. Z: Proximal stem grit
blasting to improve cement stem bonding was a feature of this Mallory-Head implant designed by William Head,
MD, and Thomas Mallory, MD. AA: Nas Eftekhar, MD, of New York, modified the neck angle and proximal stem
of the Charnley-type design.
Exhibit Figure 1.10. Metal-coated total hip arthroplasty. Beginning in the 1970s and continuing through the end
of the century, orthopedic surgeons have attempted to eliminate bone cement as a secondary fixation substance
and obtain direct fixation of bone to the implant. Because of the mechanical requirements of stem stability, bone
implant apposition, and the biologic nature of the interface, multiple design modifications at regular intervals have
marked the development of this path toward improving implant longevity. A–C: Gerald Lord of France developed
the Madreporique implant (A), which had a macroscopic beaded surface and was coated throughout its length.
Extraction of a well-ingrown stem was a daunting task. The later version incorporated a roughened surface and
longitudinal flutes to provide for rotational stability (B). A mainstay of European design through the 1970s, 1980s,
and 1990s has been the threaded screw ring cup (C) for acetabular fixation. Results of this cup in the hands of
P.31
P.32
many American surgeons show high migration and loosening rates. D, E: Tronzo of Florida designed this
stainless steel implant in the 1970s. A trunnion on the stem accepted a polyethylene head, and the long-spiked
acetabular component, which had a porous surface, accepted a polyethylene liner. F–S: First-generation modern
cementless stems employed a multitude of different and, in many cases, contrary design features. A pioneer in
the use of porous-surfaced stems was Emmet Lunceford, MD, who along with Pillar and Engh designed the
Anatomic Medullary Locking Stem (F). It featured varying lengths of porous coating (proximal, 5/8th seen here,
and fully coated). It was matched to a porous cup impacted in place, with rotational stability augmented by small
spikes. One of the most commercially successful of the earlier cementless designs, the porous-coated anatomic
(PCA) was designed by David Hungerford and Robert Kenna (G). The implant was anatomic in shape and
employed a circumferentially beaded surface over the proximal third of the implant. The cup had two small
porous pegs at the superolateral surface, which augmented rotational stability. H: Represents an alternate
screw-in threaded socket design available with this component. The straight-stem prosthesis (designed by
William H. Harris, MD, of Boston, and Jorge O. Galante, MD, of Chicago: the H-G hip) utilized fiber metal as the
porous substrate (I). The pad surface was not circumferential. This was seen over time to allow for the
movement of joint wear debris along the intramedullary canal. The socket was also designed with a fiber metal
ingrowth surface. Note the hole anteriorly for placement of a screw. The feature of screw augmentation to
improve cup stability was an innovation that was eventually copied in most cups and proved particularly useful in
acetabular component revision. Ramon Gustillo, MD, and Richard Kyle, MD, of Minneapolis, Minnesota,
designed the Bias stem (J, K), which also employed patch fiber metal ingrowth surface proximally. Stem length
was substantially longer than in most other first-generation cementless implant designs, and the stem was
curved to fit the isthmic region of the canal, based on the concept of intramedullary rod fixation. Smooth pegs
and supplemental screw fixation were a feature of the cup. Roy-Camille of France designed the mini-
Madreporique stem (L) with smaller bead diameter and less extensive coating than the Lord stem seen in Exhibit
Figure 1.10 (A). Charles Townley, MD, of Port Huron, Michigan, added a lateral fin to improve rotational stability
to a proximally beaded implant (M). The stem in (N) is very broad in the medial–lateral direction and is without a
collar, similar to the designs of Muller. Leo Whitesides of St. Louis, Missouri, designed a very proximally coated
stem with a lateral fin (O), as seen in Exhibit Figure 1.10 (M). Additional innovations included a machined methyl
methacrylate sleeve, which could be placed distally on the stem to improve canal fill in patients in whom the
metaphyseal segment of the femur was disproportionately large in comparison