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Historical
Metal/Metal Total Hip Replacements:
Seven
surgeons at Birmingham’s Royal Orthopaedic Hospital carried
out metal on metal total hip replacements of Stanmore, McKee
and Ring types between 1966 and 1987.(Fig. 32)
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Lessons
Learned from Historical Metal/Metal THR’s. (Fig.
35)
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It
could not go unnoticed in our clinical follow up practice that
these patient’s hips were performing exceptionally well and
in particular there was a notable absence of osteolysis associated
with the majority of these implants.
Young
active patients whose implants remained secure had no osteolysis.(Fig.36)
45
yr old Dysplastic OA Stanmore Metal/Metal Excellent Function
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In
patients whose implants loosened, however, cement debris was
generated and in these hips’ cement debris did cause osteolysis
just as badly as polyethylene debris.(Fig.
37 & 38.)
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McKee-Farrar,
loose cup at 20 yrs Severe pelvic osteolysis.
(Fig. 37)
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Same case
at revision surgery.
(Fig. 38)
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Histology
-
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Major
pelvic osteolysis
No Metallosis
Cement Debris |
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The
most interesting patients
were those who had the uncemented metal on metal Ring total
hip replacement. We have never seen a case of osteolysis associated
with this implant. As can be seen, many of these implants were
inserted in positions that would not be accepted today but the
key feature of note is that although these implants have been
in situ for a minimum of twenty years, no patient has osteolysis.(Fig.
39)
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20 yr +
F.U.Ring M/M THR
(Fig. 39)
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This
is all the more remarkable because these smooth chrome cobalt
implants had soft tissue at the bone implant interfaces. (Fig.
37) It is regular experience to see patients with an
open interface develop osteolysis as a result of polyethylene
debris ingress, but despite the open interfaces present on all
of these radiographs not a single patient developed osteolysis.
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| Open interfaces
Ring femoral & acetabular components
(Fig. 40) |
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| This
led us to the conclusion that in the absence of other debris a
metal on metal bearing does not cause osteolysis over a twenty
year period. |
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Hip
Resurfacing can work:
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| It seemed
to us that all the theoretical advantages of the hip resurfacing
concept could be realised when thin metal shells were used as
the articulating parts. However, this would require precision
engineering for manufacture of the metal-on-metal bearing with
expertise virtually lost following the abandonment of metal on
metal total hip replacements in the 1970’s, and a quality fixation
that would be durable in young active patients. |
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Birmingham
Experience of Metal on Metal Hip Resurfacing:
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| Design of
the hip resurfacing started in 1989 and the first implantation
was performed in February of 1991. Over the next three years,
three methods of fixation were employed on both the acetabular
and femoral sides to determine optimum fixation. It was clear
at the end of this pilot study that hydroxyapatite cups were best,
and cemented femoral components were best.42
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| Telephone: |
(0121) 455 0411 |
| Fax:
|
(0121) 455 0259 |
| Address: |
The McMinn Centre,
25 Highfield Road, Edgbaston, Birmingham, B15 3DP, England |
| Email: |
enquiries@mcminncentre.co.uk |
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