The Early Years
In
the 1930’s Phillip Wiles from the Middlesex Hospital designed
& inserted the first total hip replacements. (Fig.
1)
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to this date prosthetic replacement surgery was of the hemi-arthroplasty
type with only one arthritic surface being replaced and the results
were unsatisfactory. The record of Wiles’ cases were lost during
the war but one patient is reported to still have their implant
in situ 35 years later.1 |
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GK McKee (Fig.
2) was a trainee with Wiles and following his appointment
as Orthopaedic Surgeon in Norwich, England, began development
of total hip replacement designs.He developed various uncemented
prototype total hip replacements in the 1940’s and 1950’s. McKee
presented his results to the BOA meeting in Cambridge in 1951.
The results in those early days were initial relief of pain
followed by loosening and mechanical failure.
Haboush
2 introduced polymehyl- methacrylate
for fixation of hip endoprostheses in 1953 and Charnley popularised
this use of bone cement.
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McKee’s
cement fixed McKee-Farrar THR from 1960 was the first widely
used and successful THR.
This THR had a Thompson stem, a chrome cobalt metal on metal
articulation and both the acetabular and femoral components
were fixed with cement.(Fig. 3)
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Professor
Sir John Charnley (Fig.4)
was convinced that the metal on metal articulation of the McKee
joint was unsatisfactory. He performed experiments to show that
the McKee joint had a high frictional torque in the laboratory
and he predicted that this frictional torque would eventually
loosen the fixation of the McKee components in their bony bed.
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He was convinced that the natural elastohydrodynamic lubrication
with synovial fluid could not be used to reduce the frictional
torque of the metal on metal articulation and he began his search
for self lubricating bearings.
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This search took him
into the field of polymers and his first attempt at hip arthroplasty
in the early 1950’s was a Teflon on Teflon bearing used as a
resurfacing for the arthritic femoral head and acetabulum. Unfortunately
the Teflon on Teflon bearings wore out within two years.
(Fig. 5)
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Charnley’s
next attempt at hip arthroplasty spanned the years 1958-1962.
This arthroplasty followed the McKee idea of resecting the femoral
head and inserting a stemmed component cemented into the upper
femur.
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The
metal head of this component articulated against a Teflon socket
inserted into the acetabulum.3 Several hundred patients were
treated by this method but unfortunately, high wear of the Teflon
occurred, causing severe osteolysis and loosening in the surrounding
bone and a large number of revision operations had to be performed.
(Fig. 6 & 7).
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In
this series of patients Charnley used four different head sizes
and noted that the larger femoral heads had a higher volumetric
polymer wear. He therefore determined to use a small (22.25mm)head
against polymer in his future designs in order to minimise plastic
wear volume. This had two undesirable side effects. Linear penetration
into the polymer cup was increased with the small head and stability
was compromised.
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Charnley’s
third attempt at hip arthroplasty began in 1962 and involved
a stemmed cemented femoral component, a 22.25 mm femoral head
and a high density polyethylene cup inserted into the acetabulum.
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That
implant was of course successful in the elderly inactive population
of patients treated and is the basis of all hip arthroplasties
developed since. Charnley recognised that the success of this
arthroplasty would largely depend on the rate and effect of
the polyethylene wear.
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He cautioned against the use of his THR in young patients.
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“In
this age group we look for factors which offer a ‘built-in
restraint’ which will continue after the operation, such as
defective knees or ankles, and impose some general physical
limitations on the patient."
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"Built-in
restraint is any factor which will persist after total hip
replacement, to hold back physical activity below that expected
of a normal subject of the same age”.
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“Below
the age of 65”:
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| “Below
the age of 65 the situation is very different. The younger the
patient the more the surgeon must guard against allowing the
patients subjective symptoms to influence his judgement. The
decision to operate should be made almost entirely on the surgeon’s
objective assessment. He must turn deaf ears to exaggerated
adjectives used to describe the intolerable quality of the pain”.
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“Technique
of delaying operation”:
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| “Obviously
not many patients between 35 and 45 years of age will accept
the advice to delay surgery for a more or less indefinite period
of years (say 5 years) unless the method of presenting this
advice is adjusted to their particular psychology. A good way
of doing this is never to accept for operation at the first
consultation very young patients with only moderate physical
signs. It is essential to see the patient several times, at
first perhaps at 6 monthly intervals”. |
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Charnley
understood well that younger patients with a high activity level
were the problem group for this type of replacement, but he
did accept for operation young patients whose crippled general
condition prevented them from resuming a high activity level
and wearing out the joint.
This
restriction of surgery to the elderly population or the young
crippled population was widely practised and taught by Charnley.
This
is reflected in the case selection in results published from
Wrightington and from other centres that adopted the Charnley
method. This aspect of patient selection must be clearly understood
by those who seek evidence of effectiveness in the published
literature relating to the treatment of the young patient with
an arthritic hip. The published results do not relate to young
patients with an arthritic hip, they relate to young patients
who have another built-in restraint giving them the activity
level of an elderly inactive patient.
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Charnley
did use the McKee metal on metal joint in his clinical practice
and he conceded that the McKee worked just as well in patients
as his own commenting “It is nice to
know that both are British”.
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Peter
Ring
from Redhill, Surrey, (Fig.9) provided
the next development in hip arthroplasty. He distrusted bone
cement and developed a self locking total hip replacement for
uncemented fixation.(Fig. 10)
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This
design also had a metal/metal articulation.
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Thus
by the 1970’s three types of total hip replacement were in common
use, the McKee, Charnley and Ring types.
Surgeons
across the world experienced initial success with all varieties
and attention then focussed on which would be more durable.
Charnley’s intervention at this stage proved decisive.
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He
returned to his favourite theme of frictional torque. He built
a pendulum comparator to test the frictional torque of the McKee
metal on metal joint versus the Charnley metal on polyethylene
joint. (Fig.11).
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Under
test the McKee metal on metal came to a juddering halt and the
Charnley joint kept on swinging.(Fig. 12)
Thousands
of visiting surgeons to Wrightington were immediately convinced
of the superiority of the Charnley joint.
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metal on metal joint finally ended in the late 1970’s when McKee
and Ring themselves switched to metal on polyethylene articulations
for their own hip replacement designs. |
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End
of an era:
Charnley
died believing that his metal polyethylene joint had been totally
vindicated. McKee died believing that his metal on metal joint
had been rightly superceded by the metal on polyethylene articulation.
Peter Ring who is still alive was initially optimistic about
his new polyethylene joint but with the passage of time saw
the results ruined by osteolysis from polyethylene debris, a
complication unheard of in his earlier metal on metal joint.
Ring now deeply regrets ever moving away from the metal/metal
articulation. Satisfactory results have been published for the
McKee metal/metal,4,5
the Charnley 6
and the best for the Ring
Metal/Metal with 5% revision at 17 yrs.7
The
Modern Era:
It
is now accepted that a Charnley type total hip replacement can
give perfectly satisfactory results in an elderly inactive population.
The results published are a reflection of the quality of the
surgical procedure with good results (failure of below 1% per
year) reported from specialist centres.6,8,9,10
Less good results are reported
from general hospitals, with 9% revision at 5yrs and 27% of
patients having a poor outcome.11
(Trent Regional Arthroplasty Study)
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| Telephone: |
(0121) 455 0411 |
| Fax:
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(0121) 455 0259 |
| Address: |
The McMinn Centre,
25 Highfield Road, Edgbaston, Birmingham, B15 3DP, England |
| Email: |
enquiries@mcminncentre.co.uk |
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