|
The
Problem:
The
outstanding problem is the young active patient with an arthritic
hip.The problem is worse if the patient is male (higher loosening
rates with THR), 12
has an active job and wishes to play sport or engage in physical
activity to keep himself healthy.
The
most extreme and well known example of this is the American
footballer & baseball star Bo Jackson, who had a total hip replacement
and returned to sport only for his hip to fail in under one
year.
|
|
 |
| The
best results of hip replacement in young patients are published
from Wrightington13.(Fig.13)
If we ignore the most crippled patients with rheumatoid arthritis
and other debilitating conditions, and consider only the patients
with osteoarthritis then the results of the Charnley THR at the
premier centre of excellence show a 50% revision rate at 19 years.
Several reports show worse results in young patients, and the
young active patients with an arthritic hip is recognised by surgeons
across the world as the problem. |
|
What
do Surgeons do with the young active patient?
|
|
Following
the lead by Charnley, and recognising the problems of hip replacement
in this group, the first option employed is to delay as long
as possible. Patients are advised to change their employment
to a more sedentary occupation. However this is not always easy,
and it is common experience to see young patients with arthritic
hips who are no longer able to work. The social consequences
to their families are severe with profound economic consequences
for the country.
|
 |
Patients
are advised to take anti-inflammatory medication in an attempt
to dull the pain. These medicines cost money and have an array
of side effects. The common problems are gastro-intestinal complications,
ranging from indigestion to ulcer, bleeding, perforation of
the stomach or duodenum and strictures of the small intestine.
It is common experience to see patients on anti-inflammatory
medication for hip arthritis rushed into hospital with upper
GI bleeding.
|
|
Other
complications seen are hypertension, congestive cardiac failure
and renal damage. The local effect of long term ingestion of
anti-inflammatory medicines on the osteoarthritic hip are profound,
14,15,16,17 with
destructive arthritis presenting as the major problem in these
young patients. (Fig. 12). The consequences
of damage to the peri-articular bone in these patients who require
fixation of a hip arthroplasty are obvious.
As
a final complication, patients who are on anti-inflammatory
medication bleed excessively from their wounds at hip
replacement and excessive bleeding and haematoma formation increase
the risk of deep infection.
Eventually
intolerable pain and disability drive the surgeon to carry out
total hip replacement on the young patient. In order to prolong
the life of the replacement, patients are advised not to engage
in sport or manual work.
Not
unreasonably, surgeons and design engineers have tried to improve
the conventional hip replacement particularly for use in more
active patients. These alterations in design have focussed on
improving fixation of components and improving wear of the articulating
parts.
|
 |
| Discussion
of the multitude of these THR designs is outside the scope of
this document. |
|
Outstanding
problems with total hip replacement designs:
|
|
Excessive
bone removal
|
|
The
one thing that a surgeon can be sure of when performing a total
hip replacement in a young active patient is that sooner or
later revision surgery will be necessary. When that revision
surgery is performed, shortage of bone will be present and allograft
bone grafting will be necessary, typically using 3 – 6 femoral
heads at a cost of £250 per femoral head.
|
|
Revision
components for more elaborate fixation in the presence of severe
bone loss are sometimes necessary at substantial extra cost
compared to primary THR implants.
|
 |
| (Fig.
16)Typical
bone removal at primary THR |
|
It
does seem conceptually unsound, therefore, to excise so much
bone at the primary operation
particularly in the young patient.
|
|
Dislocation
|
|
| Dislocation
rates of 3 – 4% are reported as usual following total hip replacement.
11,12. These dislocations relate to problems of
restoration of patient’s anatomy with a limited range of “off
the shelf” total hip replacement designs. In this regard, it is
particularly difficult to restore offset in large male patients.
Reduced prosthetic head size is considered by the authors to present
an inevitable problem of dislocation in total hip replacement.
This is disputed, 18
and when the range of head size of 22 to 32 mm is considered,
no difference in dislocation rates occur. However when the patient’s
femoral head is replaced by a prosthesis of the same size (38-58mm)
as will be presented later, then the dislocation rate is seen
to be zero. |
 |
| When
dislocation occurs following total hip replacement the patient
requires readmission to hospital (depending on time of dislocation)
a further general anaesthetic, a variable time on traction in
bed (up to three weeks), supply of a hinged orthosis to prevent
redislocation and outpatient physiotherapy to strengthen muscles.
For the minority who go on to recurrent dislocation the readmissions
are repeated and revision surgery is eventually performed with
variable success. All of this comes at a cost to the health service
and an inevitable economic and social cost to the patient. |
 |
| Thrombo-embolic
complications |
|
Total
hip replacement has the highest rate of thrombo- embolic complications
of any surgical procedure.
|
|
In
the most thorough study performed to date, Gardecki performed
fibrinogen uptake tests daily on patients following THR and
then performed a venogram to confirm positive results. 92% of
patients following THR had deep venous thrombosis.
19
Deep vein thrombosis delays discharge from hospital by five
days while pulmonary embolism necessitates an additional seven
days of hospitalisation. 20
Fortunately only a few patients develop a fatal pulmonary embolus
following THR, but readmission of patients to medical wards
with non-fatal pulmonary embolus and swollen legs from DVT is
not uncommon.In an analysis of 7,547 total hip replacements
Seagroatt et al. determined that 208 patients had had emergency
readmission within twenty-eight days after the procedure. Of
these 208 patients, 54 were readmitted for deep vein thrombosis
or pulmonary embolus. 21
Post-phlebitic limbs and leg ulcers are seen as a late complication.
These complications often do not develop until five to ten years
after the acute event but, when present,they tend to persist
indefinitely. 22
These complications have obvious cost implications to the health
service.
|
|
Lengthening
of the leg after total hip replacement
|
|
Lengthening
of the leg at total hip replacement is a consequence of surgeons
trying to achieve a tight reduction in order to prevent post-operative
dislocation. Love & Wright 23
recorded mean lengthening of 15mm in 18% of cases, Williamson
and Reckling 24
16mm and Turula
25 9mm. 27% of cases in
the latter two series required a shoe-raise to be worn on the
opposite leg.
In the past, patients accepted the wearing of a raised shoe
on the opposite leg but in recent years have followed the trend
in the USA and litigation is commonly pursued. An inevitable
cost to the health service results. As will be shown later it
is virtually impossible to lengthen the leg at hip resurfacing.
|
|
Proprioception
and function
|
|
Patients
are grateful for the pain relief afforded by total hip replacement
but are aware that the hip neither feels like a normal hip nor
functions like a normal hip. Comments like “Its not part of
my body” are common. Although these feeling are, of necessity,
subjective, we have been impressed that hip resurfacing patients
have no such feelings and many patients return to recreational
sport, and some to competitive sport.Resurfacing patients have
participated in the 1998 Soccer World Cup, the London Marathon,
the European Masters Judo Championships, the World Masters Badminton
Championships and the World Seniors Squash Championships. The
most interesting group of patients are those with a total hip
replacement on one side and a resurfacing on the other. Almost
invariably they volunteer that the resurfaced side feels more
normal and is stronger that the replaced side.
|
| David
Walker, European Masters Judo Champion with medals won since hip
resurfacing.(Fig.
19) |
 |
|
Loosening
and osteolysis
|
|
| Loosening
of components has both a mechanical and biological basis. With
regard to the femoral component of conventional total hip replacement,
resection of the femoral head and part of the neck has the inevitable
consequence that the point of loading is at a distance from the
point of fixation, thus subjecting the femoral component to high
bending and torque forces. With resurfacing of the hip, on the
femoral side the point of loading is coincident with the point
of fixation. On the acetabular side, it is recognized that the
acetabulum is a mobile structure. With cemented cups it may be
this micromotion that leads to the inevitable appearance of pseudomembrane
at the cement bone interface. |
 |
|
In
an autopsy study of the Charnley THR, Malcolm 26
found that every single acetabular component was histologically
loose with pseudomembrane at the cement bone interface. Uncemented
porous ingrowth acetabular components can certainly address
this issue of cup fixation, and two autopsy studies have shown
bone ingrowth and solidly fixed uncemented sockets 27,
28 However, this uncemented total hip replacement
cup comes with significant problems. It has been shown that
the use of uncemented cups doubles the polyethylene wear of
the liner. 29
Whilst osteolysis in the cemented acetabular component
presents as a linear pattern with component loosening, osteolysis
in the uncemented cup presents late, with severe cavitary retro-acetabular
bone loss.
|
 |
|
This
is widely appreciated in theUSA,
30,31 but this presentation of osteolysis is only
just appearing in the UK and will present formidable revision
problems in the future. We use an uncemented porous ingrowth
socket with the Birmingham Hip Resurfacing, fixation is a non-problem,
and in the future, osteolysis is not expected, as no polyethylene
is present in the system and the metal on metal bearing has
a 39 year benign clinical history.
Osteolysis
on the femur may be linear or focal. With cemented femoral components
the linear pattern predominates and the clinical and radiographic
presentation is of loosening. Loosening of components is the
No 1 failure pattern in the Charnley THR performed in young
patients.12,13
|
Loose
Charnley THR (Fig. 22).
|
|
With
uncemented femoral components, the focal pattern of osteolysis
predominates. 10 year survivorship of 68% for the PCA and 69%
for the Harris/Galante designs have been reported, using clinical
or radiographic failure as the end point.32
Polyethylene particles have been identified as the main cause
of osteolysis, most of these particles are submicron size and
ingested by macrophages, which initiate a complex cellular response,
including release of substances such as cytokines, growth factors
and inflammatory mediators, ultimately resulting in bone resorption,
mainly by osteoclasts..33
|
|
|
Stress
Shielding
|
|
Stress
shielding of the proximal femur occurs when a metallic stem
is inserted as part of conventional total hip replacement. There
are now reports showing between 30% and 45% proximal femoral
bone loss following stemmed total hip replacement. 34,35
It is unknown whether this proximal femoral bone loss contributes
to loosening of the femoral component of a total hip replacement
but when revision surgery is required then the bone loss from
the primary surgery and the bone loss from the osteolysis and
loosening is added to by bone loss due to stress shielding.
With
hip resurfacing loading of the existing femoral head occurs
and stress shielding is not seen in the proximal femur
|
|
Scientific
explanation for stress shielding following THR (from Rik Huiskes)
|
|
Distribution
of elastic energy in intact femur. Load mainly transferred through
cortices.
|
 |
Following
THR the stem takes part of the load away from cortices.
(Mid-frontal section through 3-D F.E.model.)
Stress protection osteopaenia in
proximal femur will follow.
|
|
Difficulty
with Revision
|
|
Revision
of conventional total joint replacement whether cemented or
cementless is an arduous task and is of far greater magnitude
than the initial total joint replacement. Revision of conventional
joint replacement requires specialist techniques and solutions
and this is expensive for the NHS. A multitude of techniques
are utilized to address the problems at revision surgery but
the common factor is high expense and consumption of time.
In the small number of revisions of surface replacement arthroplasties
that have been carried out, the revision procedure is essentially
a primary total hip replacement with similar technology, expense
and post-operative recovery to a conventional primary total
joint replacement.
|
| 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 |
|
