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design to reduce its overall weight. This replica was
inserted by Walter G. Stuck, MD, of San Antonio, Texas, for a similar case. It survived 20 years of use before the
femur fractured at the lower end of the device. F, G: Well-known instrument makers Jaenichen and Collison
developed these multisegment trunnion designs with side plates. H–O: These stems represent additional design
modifications based on the original concepts. Lippman prosthesis 1952 (H), Jergensen prosthesis 1960 (I),
Michele medial displacement prosthesis 1947 (J), Leinbach prosthesis 1947 (K), Townley prosthesis (L),
McBride screw-in prosthesis 1948 (M), Scuderi trunnion prosthesis (N), Cathcart ellipsoid-head prosthesis (O).
P, Q: Smith–Brown experimental ceramic (P) prosthesis and Aufranc shaft prosthesis for special cases, 1973
(Q).
Exhibit Figure 1.4. Bipolar replacement. Bipolar cups were introduced as early as 1950. Although initially lined
with Teflon, the inferior mechanical characteristics and subsequent biologic reaction caused a search for a better
bearing material. High molecular weight polyethylene was identified by Charnley in the 1960s and was
subsequently used in many articulation designs. A–C: A McKeever–Collison collaboration from about 1950. The
bearing (B) is Teflon. Trease designed this Teflon-lined cup (C) to mate with the Moore stem in 1960. D, E:
Gilbert and Bateman designed polyethylene bipolar cups. These designs are from 1973.
Exhibit Figure 1.5. Resurfacing arthroplasty. Resurfacing arthroplasty, replacement of both the femoral and
acetabular sides of the joint without violating the femoral canal, was investigated in the 1970s. Problems with
maintaining the viability of the bone under the resurfaced femoral head, eventual loosening of the socket with
substantial acetabular bone loss caused by the large size of the component, and femoral neck fracture were all
problematic in most series. Note that methacrylate fixation was popular on both sides of the articulation until
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porous ingrowth became available. A: 1971 Italian design of Paltrinieri–Tretani. B: M. A. R. Freeman design
from 1979. Note the use of flanged polyethylene pegs instead of cement for fixation of the cup. C, D: The Indiana
Conservative Cup designed in Indianapolis by Eicher in the late 1960s and early 1970s, redesigned by William
Capello, his student in the late 1970s. Note metal backing of acetabular liner. E, F: The original Wagner design
with metal head, metal-backed polyethylene socket with low-profile metal backing. G, H: Harlan Amstutz of UCLA
continued to modify his THARIES resurfacing arthroplasty from the cemented all polyethylene cup (G) of the late
1970s through the era of porous ingrowth in the early 1990s, as seen in the fixation surface of the cup on (H).
Exhibit Figure 1.6. Charnley total hip arthroplasty. Myriad aspects of hip replacements were investigated,
popularized, and some would say perfected by Sir John Charnley. He made many original contributions to the
science and art of hip surgery, including the materials used and the methods of the fixation of the implants, as
well as the design of the implants. He worked hard to reduce operative complications and postoperative
morbidity. His development of the low-friction arthroplasty concept led to his being called the father of the total
hip arthroplasty. A–C: Initially incorporating Teflon, this polymer was brittle and unsuitable. It generated wear
debris rapidly, and this debris produced a significant tissue response. A: Represents original Charnley
resurfacing components from 1958, which were press fit. B: Has a large head and press-fit stem, which were
mated with a Teflon cup (1958 to 1960). C: Represents the adoption of a smaller (22-mm) head diameter, which
produced lower frictional torque and was developed in 1960 to 1962, one of many pioneering developments by
Charnley. This retrieval demonstrates extensive wear in the bisected Teflon cup. Polyethylene as a bearing
surface (D) was another significant contribution of Charnley's still utilized in today's total hip replacement. In 1963
a press-fit metal-backed polyethylene shell was utilized. E, F: The original methyl methacrylate powder and
monomer still in use today. G: Cross section of a cemented Charnley stem and polyethylene cup. H: The wire
mesh Mexican hat designed to plug the centering hole created in the medial wall of the acetabulum to center the
acetabular cartilage reamers. This device was utilized to prevent cement from extruding into the pelvis. I–K:
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Modifications of the original Charnley stem. I: Represents the standard round-back stem, (J) a straight stem, and
(K) the Cobra stem with anterior and posterior flanges on the lateral shoulder to aid in cement pressurization
during insertion. L–N: Additional modifications of the original Charnley system. O–R: Modifications of cup design
included addition of a radiographic marking wire in the cup (O), an extended posterior wall to minimize dislocation
(P), an eccentric socket in the smaller sizes to maximize material where wear is expected (Q), and the Ogee cup
designed with peripheral flanges to contain and pressurize cement during implantation (R).
Exhibit Figure 1.7. Muller total hip arthroplasty. Maurice E. Muller made substantial design modifications during
the 1960s. A: In 1961 a thin curved-stem implant with Teflon socket and small head was press fit. B: In 1963
polyethylene was adapted as the bearing surface. The implant was cemented. Note the hole in the inferior
aspect of the head to trap wear debris. C: Metal-on-metal articulation allowed for a polyethylene liner that could
be interposed between the standard head and cup bearings. D: The Charnley–Muller stem with curved banana-
shaped stem and poly cup, a popular implant in the 1970s. E, F: Two modifications of the Muller straight-stem
design introduced in 1977. These stems had longitudinal ridges. G: In 1988 the cementless self-locking system
was produced. This system incorporated the longitudinal ridges seen in the previous design but added a distal
clothes pin for press fitting, modular collar, and modular heads in cobalt-chrome or ceramic, as well as a metal-
backed porous-surfaced cup fixed with titanium screws. H: Developed in 1977, this acetabular roof-reinforcing
ring was developed for screw fixation into iliac and remaining acetabular bone in cases where acetabular bone
stock was thought to be insufficient to hold the cemented socket. The polyethylene cup was cemented into the
ring.
Exhibit Figure 1.8. Metal-on-metal total hip arthroplasty. Metal on metal as an articulation was attempted in the
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1950s and further modified during the 1960s. More recent concerns about polyethylene wear debris have
sparked a renewal of interest in this articulation in the 1990s. A–C: These sockets were mechanically fixed to
the pelvis and were initially designed for acetabular arthroplasty. However, they were also used with the
nonpolar Moore and Thompson prostheses for metal-on-metal total hip replacements: Urist, 1951 (A), Gaenslen,
1953 (B), and McBride, 1961 (C). D: The first popular metal-on-metal total hip was the McKee–Farar. E, F: Ring
designed an acetabular component with a massive threaded stem that obtained purchase in the ilium and
occasionally traversed the sacroiliac joint. G, H: The Stanmore hip designed by Duff, Barclay, and Scales
employed a two-piece acetabular shell, which was assembled at the time of surgery.
Exhibit Figure 1.9. Cemented total hip arthroplasty. Literally hundreds of cemented total hip designs followed
on these pioneering efforts. During the late 1970s it seemed that every engineering finding led to new stem
design modifications. A: Bucholz from Germany designed this 38-mm head, I-beam stem with rather sharp
internal radii. The socket was 1.5 mm in diameter larger than the head, with an elliptic recess in the anterior
aspect of the cup. B: An