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Cormet Hip Resurfacing System
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The Cormet System of metal on metal hip
resurfacing was begun by Corin. The Corin system
has been in use since 1991. It claims to be the
older of the current hip resurfacing systems.
The Cormet Design has:
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head sizes from 40 mm to 56 mm
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10 cup sizes from 46mm to 64 mm
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A unique Displasis cup in 5 sizes
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Small Incision instrumentation allowing
it's use in Minimal Incision Surgery
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Equatorial expansion of cup to optimise
the initial press fit
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Plasma sprayed Ti and HAP coating to
ensure long life
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98% survivorship in patients at seven
years and average age of 50
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Modular head allow revision to a large
diameter THR if needed
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Development of the Corin Hip Resurfacing
System
In the late 1980’s Corin collaborated with a group
of UK orthopaedic surgeons to develop a
metal-on-metal resurfacing hip designed to provide a
solution for treatment of this high demand patient
group. This new generation of metal-on-metal hip
resurfacing implants offered a number of key
advantages to these patients compared to
conventional total hip replacement:
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Hip Resurfacing is a conservative operation,
since the femoral head and neck are not removed
- the femoral head is simply reshaped and
resurfaced with a metal cap.
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Elimination of polyethylene in the bearing
removes the possibility of polyethylene-induced
osteolysis and accompanying failure of the
implant.
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The metal-on-metal bearing is expected to last
much longer than a conventional
metal-on-polyethylene bearing, delaying the need
for revision surgery in high demand patients.
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The large diameter bearing is much more stable
than the small diameter bearing of a
conventional total hip replacement, all but
eliminating the risk of dislocation and allowing
patients to return to a more active lifestyle.
In the early 1990s, Corin developed a Hip Resurfacing
device that combines the principles of conservative
arthroplasty with metal-on-metal bearing technology – an
innovation that provides a solution for the treatment of
younger patients with osteoarthritis or rheumatoid arthritis
of the hip. Today, Corin are world leaders in large diameter
metal-on-metal hip replacement and, since its introduction
in 1991, have developed the hip resurfacing range into a
unique system which addresses the needs of the younger,
active patient.
Faithful to the original design, Cormet Hip Resurfacing is a
conservative treatment for the young, active, high demand
patient group which conserves femoral bone, provides
anatomical bone loading, eliminates polyethylene and is
designed to be a high-function device.
Features of the Cormet system include:
- Extensive range of options
Within the range there are cemented and
cementless femoral components and standard
and dysplasia cups.
- Femoral Component
Cormet femoral components are available in
4mm increments from 40mm to 56mm outside
diameter, and are manufactured to exacting
standards, ensuring optimum sphericity and
surface finish.
- Cementless Heads
Introduced in 1998 to give the surgeon more
flexibility, the femoral head can be
prepared and then an intra-operative
decision can be made between the cemented or
cementless head.
- Acetabular Component
Cups are available in 2mm OD increments from
46mm to 64mm, with two cup sizes for each
head size, providing surgical flexibility.
- Bi-coating
All cups and cementless heads are bi-coated™
with a plasma sprayed porous titanium
coating overlaid with hydroxyapatite, which
provides excellent primary and long-term
fixation.
- Dysplasia Cup
An advanced dysplasia cup is available for
use in the deficient acetabulum in both hip
resurfacing and large diameter total hip
replacement. The use of a unique twin thread
diameter screw design allows the screw to be
advanced within the acetabulum prior to
engagement with the cup flange, thereby
minimising the possibility of the cup being
disturbed from its chosen position during
insertion. The tapered section between the
two diameters of the screw allows the thread
form to be constant over the entire length
of the screw. Based on a standard cortical
bone screw, the screw tip is fluted to allow
self-tapping. This unique design has the
benefits of easy introduction, improved cup
positioning and increased pullout
resistance.
Flexibility of Surgical Approach
Cormet has been developed into a comprehensive
system which allows the surgeon to decide which
surgical approach and device options he wishes
to use and are appropriate for a specific
patient. Cormet instrumentation is suitable for
posterior, antero-lateral and other approaches
including the modified Ganz approach.
Clinical History
Excellent medium-term results have been
published for the Corin Resurfacing Hip system.
Multi-centre results show a 96% survivorship at
7 years1 for the Cormet Hip
Resurfacing.
Precision Instruments
The third generation of advanced instrumentation
for Cormet Hip Resurfacing allows small incision
surgical approaches to be used for Cormet Hip
Resurfacing. The Cormet Precision instruments
eliminate the need for a complex, bulky head
centering jig. The vacuum introducer is a
unique, patented technology - standard theatre
suction is used to attach the cup to the
introducer for implantation of the acetabular
component.
The Precision head centring device eliminates
the need for a lateral pin and allows a smaller
incision to be used in both standard and MIS
approaches, reducing tissue damage and
potentially improving post-operative recovery
times. The instruments are simple to use,
reducing operating time and allowing more
accurate, reproducible placement of the femoral
resurfacing component.
Wear Properties
Exacting manufacturing techniques mean that the
high carbon cobalt chrome bearing surfaces are
optimised to minimise wear. Optimal sphericity,
surface roughness and diametrical separation of
the components result in enhanced lubrication of
the bearing, which reduces wear, as well as
providing effective function and longevity.
Studies have shown that optimised sphericity and
diametrical separation are by far the most
important factors influencing the wear of
metal-on-metal bearings.
“Cormet is a comprehensive system which
adapts to the preferences of
the surgeon while meeting the real
needs of the younger active patient” |
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