Abstract:
Metal on
metal hip resurfacing is now often being considered a viable
option for younger patients as opposed to total hip arthoplasty.
However, it is still considered quite controversial because it
is associated with a higher revision rate than the conventional
arthoplasty operation. There are many different issues suggested
as possible causes of failure. These include femoral neck
fracture, loosening of both the femoral or acetabular component
and infection. At Derby we looked at the 9 cases out 167
procedures which required revision, in analysis with current
literature as to why these cases failed in order to further
understand the causes of hip resurfacing failure.
J.Orthopaedics 2008;5(4)e4
Keywords:
Hip
resurfacing arthoplasty, femoral loosening, acetabular loosening
aseptic lymphocytic vasculitis associated lesion, femoral neck
fracture.
Introduction:
In the
last decade the number of people undergoing hip
resurfacings here and across the world has steadily been
increasing, with records from the National Joint Registry of
England and Wales show in 2004 that out of 3471 patients under
the age of 55 years undergoing primary hip replacement in the
United Kingdom, 1585 received a resurfacing procedure, nearly
46% 1.
Between 1998 and 2003 at
the Derbyshire Royal Infirmary, 167 patients underwent metal on
metal hip resurfacing, using either Cormet 2000 or Birmingham
Hip; of these 9 required revision within 10 years. All
operations were performed by the same surgeon using the
recommended extended posterior approach with long term follow up
on every patient. There was a revision rate of around 6%, a
relatively high revision rate compared to total hip arthoplasty
quoted in some papers of 2% based on surgical experience 2.
This paper reviews these individual cases in relation to current
literature to see what patterns emerge and to see what lessons
can be learnt for future practice.
Case Report 1 :
A 47
year old man underwent left hip resurfacing in October 2002,
following several years of increasing left hip pain from
osteoarthritis, secondary to mild slipped upper femoral
epiphysis as a teenager. The findings during the procedure
showed excessive amounts of osteophytes around the femoral head
(XRAY). He was discharged following a routine inpatient stay. He
had an unremarkable follow up but returned to clinic in June
2006 with clicking in his left hip. A radiograph showed
heterotrophic bone around the outer aspect of the hip (XRAY). A
bone scan demonstrated increase activity around this
heterotrophic bone but with no abnormal features around the
prosthesis components. He returned in February 2008 with
increasing stiffness and pain. The prosthesis was revised in
March 2008. During the operation pus was found in the
trochanteric bursa with no obvious sepsis around the prosthesis,
which was exchanged for a hybrid hip. The acetabulum had a
number of subarticular cysts which required a bone graft from
the femoral cut. Post operatively the pus found in the
trochanteric bursa was consistent with aseptic lymphocytic
vasculitis associated lesion (ALVAL). The patient was discharged
after a routine in patient stay.
Case Report 2 :
A 56
year old lady with right sided hip pain secondary to
osteoarthritis underwent right hip resurfacing in January 2002.
Intra-operatively it was noted her bone stock was osteoporotic.
She was discharged following a routine inpatient stay and had
routine post-operative follow up. She represented June 2004 with
painful right hip and feeling generally unwell, inflammatory
markers at the time of admission were moderately
raised (ESR 59 and CRP 33). A right hip aspiration was
attempted, however there was no draw back and an MRI scan was
performed which demonstrated a collection around her hip joint.
She became pyrexial and her CRP went up to 407.As a consequence
of this she was taken to theatre for a right hip washout. During
the procedure it was noted that her wound and superficial fascia
showed no signs of sepsis. On dividing her tensa fascia lata a
collection of approximately 500ml of pus was observed posterior
to the hip joint but the joint was not breached. The abscess was
washout out and remnants of the cavity excised. Post-operatively
she was started on flucoxacillin and gentamcin, and
unfortunately went into renal failure secondary to sepsis. She
was admitted to the intensive care unit for supportive therapy.
Staphylococcus aureus was grown on culture from her collection
which was sensitive to flucoxacillin. A week later she had a
repeat MRI which showed a second collection around the hip and
she went for a second washout which was shown to be a large
haematoma rather than pus. In August 2004 her inflammatory
markers settled down to CRP 45 and ESR 75, antibiotics were
changed to oral flucoxacillin and rifampicin on advise from the
microbiology department and her renal function returned to
normal levels and she was safe for discharge. She was closely
followed up in outpatients and on review in October 2004
started to complain of increased pain in her right hip but due
to inflammatory markers being low (ESR 18 CRP 8). A decision
was taken to stop her antibiotics and bring her back for an
aspiration of her hip. This aspiration was negative on culture
and her pain settled. She returned in July 2005 with more pain
in her hip and an aspiration of her right hip showed a grey
turbid fluid which grew staphylococcus aureus and she
subsequently became pyrexial. During this admission she had 1st
stage revision, during which there was evidence of sepsis around
the metal component which was removed and her femoral neck was
excised. She was started on Flucoxacillin and Benzyl-penicillin
and was listed for second stage. This took place in November
2005, and during this procedure there was no evidence of sepsis.
She had a cemented total hip arthoplasty. Follow-up a year later
showed she was mobilising well and pain free.
Case Report 3:
A 46
year old man with confirmed bilateral osteoarthritis had a
routine right hip resurfacing in March 2000 and this was
followed up with a left hip resurfacing in November 2000. He had
routine follow up but represented to the clinic with right hip
pain and an audible clicking sound. Radiographs at the time of
this episode were satisfactory and the patient was reassured. He
returned in August 2006 with similar problems and a radiograph
demonstrated loosening of the acetabular component. This was
confirmed at revision of the implant in December 2006. There was
no evidence of sepsis and the implants were exchanged for a
hybrid hip arthoplasty. A year later at routine follow up the
patient was comfortable with both hips.
Case Report 4:
In
February 2002 a 46 year old man with left hip due to pain and
osteoarthritis confirmed on radiograph, underwent routine left
hip resurfacing. There were no immediate complications and he
was discharged after a routine inpatient stay. He had normal
follow up but he represented in March 2005 with increased left
hip pain and a painful limp. A radiograph at this presentation
demonstrated possible loosening of the femoral head component.
Inflammatory levels were normal (CRP 2, ESR 5) and a Bone Scan
showed increased uptake around the femoral component consistent
with loosening. He had the implant revised in June 2006. During
the loosening of the femoral component was confirmed. The ace
tabular component was sound and there was no evidence of sepsis.
The decision was taken to exchange the femoral component for an
uncemented stem. At follow up 1 year later the patient was pain
free and walking without a limp.
Case Report 5:
A 60
year old woman with confirmed osteoarthritis on radiograph
underwent left hip resurfacing in August 2001. At surgery a
large split was noted on the posterolateral edge of the
acetabulum, which on testing was non mobile. The acetabular
component on fitting was stable. A large subarticular cyst was
observed on the femoral head which was less than 25% of the
articular surface with hard sclerotic bone lining the cyst. This
was packed with acetabular reamings. There were no immediate
post operative complications and the patient was discharged
after routine inpatient stay.
The
patient was readmitted after eleven months following a GP
referral feeling unwell with pain radiating down the lateral
aspect of the left thigh. Ultra sound demonstrated an ileo-psoas
abscess. This responded to intra-venous antibiotics and
E.Coli was isolated on aspiration and sensitive to
cefuroxime. She was discharged and reviewed in clinic several
months later when her ESR was down to 50 and CRP was 6 and she
had a satisfactory radiograph. In the following months her
inflammatory markers fluctuated but she remained largely
asymptomatic other than noting that her mobility was
deteriorating. She underwent a left hip aspirate with marcain
injection in September 2003. The aspirate was negative on
culture but she started to complain of a persistent low grade
pain and a Bone Scan was requested. Before it could be performed
she was admitted with a suspected septic joint in October 2003.
On admission her CRP was 86 and ESR113 and she was started on
cefuroxime. An inpatient Bone Scan was performed and was
unremarkable. She improved and was discharged and was listed to
return for a 2 stage revision. The first stage was performed in
December 2003. At operation pus was found on opening the
capsule; the acetabulum was loose with global loss of bone. The
femoral component was not loose, but there was evidence of neck
erosion. Again E. coli was isolated on culture and
sensitive to ciprofloxacin. Later it was surmised that a
possible source of this infection was a diverticular abscess. At
the second stage there was no sign of sepsis and a hybrid hip
arthoplasty was used. At follow up 1 year later she was pain
free and mobilising well.
Case Report 6:
65 year
old man with long standing right hip pain with confirmed
osteoarthritis on radiograph underwent a right hip resurfacing
in June 2000. The procedure was unremarkable with no immediate
complications and the patient was discharged following a routine
inpatient stay. He was readmitted 8 months later with a history
of right-sided sciatica, fever and increasing right hip pain.
On ultrasound an abscess was diagnosed around the right hip,
which was washed out in an open procedure. The abscess extended
around psoas and beneath the inguinal ligament. It was felt that
it originated from a retrocaecal abscess secondary to
appendicitis. On culture Staphylococcus aureus was grown
which was sensitive to flucoxacillin and rifampicin. The
infection settled and as the hip joint did not appear to be
involved the patient was treated with expectant management and
follow up in clinic regularly. 3 months later the patient was
complaining of increased pain but inflammatory markers were only
minimally raised. He was listed for a diagnostic aspiration.
This was negative but his CRP was raised and a repeat radiograph
showed that the acetabular component had migrated and he was
listed for a 2 stage revision. This was carried out in June
2002. At surgery it was found that there was a collection of
100ml of pus posterior to the hip joint. No pus was found inside
the hip joint itself. The acetabular component was loose and the
femoral component was sound but a decision was taken to remove
it due to the presence of pus. During his inpatient stay his ESR
and CRP normalised and as a precaution he was put on oral co-amoxiclav.
He had his second stage in August 2002 and had a cemented total
hip arthoplasty. There were no complications and at 1 year
follow-up he was mobilising well and pain free.
Case Report 7:
A 54
year old lady was referred with a 2 year history of right hip
pain due to severe osteoarthritis, limiting her walking distance
to 300 yards. Due to her age she underwent right hip resurfacing
in January 1999 using a Cormet 2000 prosthesis. 2 years post
surgery she represented with increasing right hip pain and
reduced mobility. Inflammatory markers showed a CRP of 2 and ESR
25. A radiograph showed no signs of loosening. A Bone Scan
showed increased activity around the acetabular component. A
hip arthogram showed no abnormal tracking of the contrast.
Relief from the injection was short lived and as pain was not
settling she underwent a single stage revision in September
2001. The findings at surgery were that the acetabular component
was completely loose with some bone loss and the femoral
component sound. These were both exchanged for a cemented total
hip arthoplasty. All microbiology samples were culture negative.
At I year review the patient was mobilising well and pain free.
Case Report 8:
A 57
year old lady with osteoarthritis in her right hip underwent a
right hip resurfacing using Cormet 2000 prosthesis, in March
1999. At the time there were no complications and
intra-operative findings were unexceptional. At her six month
check she complained of pain mainly on her left hand side and
she was referred for some physiotherapy. At 18 months she
represented with impaired weight bearing on her right hip and
pain on flexion of the hip. A radiograph showed the prosthesis
in a satisfactory position with no evidence of loosening but
with some bone resorption around the neck of femur. On review
because the pain was increasing a Bone Scan was organised. The
scan showed increased uptake around the acetabulum relating to a
cystic region seen laterally behind the acetabular cup.
Inflammatory markers taken at the time were normal. A repeat
radiograph on follow-up showed the acetabular component loosened
and rotated and she was listed for revision in December 2001. At
surgery the aspirate from capsule was clear. Thickening of the
capsule and a granulation membrane were noted. Culture however
was negative. The acetabular component was completely loose
whilst the femur was solid but with areas of resorption in the
medial cortex. There were two bony defects anteriorly and
medially in the remnant of the acetabular component which were
grafted with bone from the proximal femur cut. A plasma cup was
used with 2 screws for stability in the acetabulum. The femur
was cemented, with no immediate complications. At follow up 1
year later the patient was well pain free and mobilising
unaided.
Case Report 9:
A 51
year old male underwent left hip resurfacing in January 2002,
after presenting with left hip pain. Previously as a child he
had DDH which was treated with an osteotomy. However this
resulted in a permanent limp. The pain in his left hip developed
in the preceding years prior to his presentation, and in view of
his age resurfacing was preferred. The findings at the original
procedure showed he had a shortened femoral neck and as expected
the acetabulum was deficient elliptically in an anterior
direction and anterolaterally after reaming. A 50mm acetabular
cup was inserted with bone graft for stability. There were no
immediate complications.
He
presented 2 ½ years post operatively with increasing left hip
pain. Radiographs at the time were unremarkable and inflammatory
markers were normal. A Bone Scan demonstrated increased uptake
around the femoral head consistent with loosening of the
component. Revision surgery was performed in October 2004, which
showed the femoral component was completely loose, with the
cement mantle intact with no bone attached. There was excessive
granulation tissue between the cement mantle and a large amount
of bone loss consistent with avascular necrosis of the femoral
head. The acetabular component was intact with no evidence of
loosening, or sign of infection. As a result only the femoral
component was exchanged, with a cemented Corin taper fit stem.
At follow up 1 year later he was pain free and mobilising well.
Results :
Pt No |
Age at Op |
Primary Diagnosis |
Time of revision
(months) |
Reason for Revision |
Revision Op |
1 |
M47 |
OA/SUFE |
65 |
ALVAL |
THA |
2 |
F56/6 |
OA |
29 |
Infection S. Aureus |
2 stage THA |
3 |
M46/6 |
OA |
81 |
AL |
Hybrid Hip |
4 |
M46/7 |
OA |
50 |
FL |
Uncemented Femur
Acetabulum unrevised |
5 |
F60/4 |
OA |
28 |
Infection E.Coli |
2 Stage THA |
6 |
M65/6 |
OA |
24 |
Infection S.aureus |
2 Stage THA |
7 |
F54/2 |
OA |
32 |
AL |
THA |
8 |
F57/2 |
OA |
33 |
AL |
Hybrid Hip |
9 |
M51/11 |
OA/DDH |
33 |
FL |
Uncemented femur
acetabulum unrevised |
OA=
Osteoarthritis, DDH= developmental dysplasia of the hip,
SUFE= Slipped Upper femoral eypiphesis, AL=
Acetabular loosening, FL= Femoral Loosening, ALVAL=
aseptic lymphocytic vasculitis associated lesion, THA=
Total hip arthoplasty.
Discussion :
Femoral Loosening
Femoral
loosening has been shown to be the next most common
complication, in particular with metal on metal bearings.
Amstutz et al7 looked at how differing techniques
could prevent this. They performed a prospective study
comparing different techniques involved in preparing the femoral
head. There study covered 600 consecutive cases. In the first
generation of cases they used no suction, few key holes in the
femoral dome, the stem was not cemented, and they placed the
femoral component in anatomical position. If they found cysts in
the femoral head they only curetted them as per standard
practise. In the second generation of cases dome suction was
used when preparing the femoral component, the number of key
holes was increased and the stem was cemented. The femoral
component was placed at angle of 140 degrees, and a high speed
burr was used to remove all debris in any femoral cysts. Their
results showed that with this difference in surgical technique
there was a reduction in the amount of femoral loosening, this
was with similar demographics in both patient groups. The
limitations of this study were that it was based at one centre
and with only one surgeon. It could be that the reduction in
complications was related to improvement in surgical technique
over time. The differences in preparation of the femoral head
were introduced gradually rather than at one point in time. It
does suggest however that careful preparation of the femoral
head prior to cementation of the femoral component can reduce
the amount of revisions secondary to femoral loosening. This is
significant particularly since Morlock et al8 in
found in 267 retrieved femoral heads only 31% were cemented
according to recommendations.
In our 2
cases where there was femoral loosening there were no
significant defects with the femoral head at the time of
implantation but rather there had been loosening at the cement
mantle leaving the component loose. There are other possible
reasons for this which include osteolysis which is the result of
wear and tear at the articulating surfaces. Ayers, Allen and
Schoonmaker9 noted the effect of tumour necrosis
factor (TNF) on bone resorption around cement in animal models.
TNF lead to a decreased osteoid concentration and promoted bone
resorption which could lead to failure of bone to bind with the
cement mantle. This is very important to note particularly in
hip resurfacing when one considers the large surface area
involved. Some authors suggest that the orientation of the
implants will have an effect on bone remodelling around the
femoral component with Ong et al noting that femoral components
put in valgus can increase the risk of loosening secondary to
the loss of osseous support from stress shielding. However
Beaule et al10 noted that implants in varus have
significantly higher chance of fracture. Other papers also look
at osteonecrosis as a cause mentioned previously in the paper
of C. P. Little et al3. Out of their 13 cases, 3
had femoral loosening. All of these showed evidence of
osteonecrosis on histology. In our 2 cases there was no
macroscopic evidence of osteo necrosis so consequently samples
were not sent for histology. It would be prudent in future
cases to consider histology at the time of revision. Campbell,
Mirra and Amstutz11 hypothesised that the reason for
osteonecrosis was thermal injury. T.P Gross et al12
have looked at this aspect as well with uncemented femoral
components in hip resurfacing with a patient group of 18 (20
hips) with one lost to follow up. 4 required revision due to
reasons other than femoral loosening. With 15 hips surviving up
to 7 years despite a small study it does suggest another option
for hip resurfacing.
Acetabular
Loosening
Acetabular loosening is another reason for both revising hip
resurfacing and hip arthoplasty. The preferred option in
resurfacing is the uncemented cup. Here, as in hybrid hips, one
common cause of loosening is orientation of the acetabular
component. Morlork et al8 when looking at retrieved
specimens in comparison with radiograph’s in situ noted that cup
inclination could have a possible detrimental effect on metal
wear and fatigue in the implant, particularly as resurfacing in
metal on metal. These cups are cementless. There is therefore
a high reliance on biological fixation of the cup. This in turn
relies on initial stability and orientation of the component.
This aspect has been looked at by others in particular they have
studied different coatings on the cup. Manley et al13
looked at 3 such different methods and concluded that
hydroxyapatite coating alone on a smooth cup is not sufficient
for fixation, but rather a porous coating or another adjunct to
fixation is required such as the central peg in Cormet 2000.
This can lead to additional problems at revision such as reduced
bone stock on removal of the component, as was the case with 2
out 3 of our cases with acetabular loosening. This has meant
re-evaluating the cup design in order to preserve acetabular
bone stock. Some thinner designs on the market to also allow
for larger femoral heads, reducing the risk of dislocation as
well. A complication of this noted by Ong et al14 was
increased risk of cup deformation with diametrical pinching.
This lead to an adverse effect on the fluid- film lubrication
of the metal on metal bearing and lead to increased wear. This
has also been observed in hybrid hip arthoplasty.
Infection
Infection remains a highly feared complication following all
forms of arthroplasty. However there are few papers looking at
infection following hip resurfacing particularly considering the
large metal surface area involved. With such a large metal and
bone surface area there is the possibility for increased
haematogenous spread of infection which can become established
in the hip. It is noteworthy that 2 out of the3 infections at
Derby following hip resurfacing appeared to have originated from
abdominal sources. These infections were all late presentations
occurring 2 years after hip resurfacing.
Pseudo-Tumours
Aseptic
lymphocytic vasculitis (ALVAL) associated lesion as a cause for
hip resurfacing failure is becoming more common as it also
affects other metal on metal arthoplasty procedures15.
It can be associated with inflammatory granulomatous masses
termed pseudotumours, first described by Harris et al in the
1970s 16. Pseudotumours appear to follow a
granulomatous reaction with the macrophage response excessive.
Why there is a macrophage over stimulation is unclear. Pundit
et al 17 looked at 20 hips in 17 patients which were
all similarly affected by phenomenon and found that metal wear
present throughout each case. However histologically as
previously thought, no gross metallosis was present clinically
at revision. All 17 patients in this study were female, which
raised the possibility that pre-operative sensitisation to metal
could be a factor. ALVAL may be a normal body response to metal
on metal prostheses with over stimulation of lymphocytes,
leading to a hypersensitivity style response. Both these
complications appear to be very rare with few cases reported
around the world but certainly as the demand for metal on metal
resurfacing increases, we may begin to see more of them. It is
important to note that both appear to be immunologically
mediated, which may require surgeons to be more selective in
their choice of prosthesis particularly in people with known
sensitivity since it is known that up to 15% of women are
allergic to nickel.
Fracture
One
complication which we did not see in our series of cases is
fracture of the neck of femur. Fracture is one of the most
commonly quoted cause of failure in hip resurfacings with some
studies quoting figures of up to 47% of revisions2.
Research into this suggests that there is a link to early
fractures and osteonecrosis. C. P. Little et al3
found that in 12 out of 13 femoral heads retrieved for revision,
8 had a sustained a fracture following resurfacing and there was
evidence of osteonecrosis in 4 cases. They suggested that this
could be linked to the surgical approach which involves an
extended posterior approach leading to the disruption of the
extraosseous blood supply leading to ischaemia in the remaining
bone. They found that this could occur post operatively since
two of their samples came from fractures within a week of the
implant being established.
The
mainly limitations of this study is its small sample size,
Others such as Shimmin and Back4 looked at the
occurrence of neck fractures following resurfacing in Australia
between 1999 and 2003 from around 3500 procedures performed by
89 different surgeons. They obtained results from 45 out of 50
fractures in their study. Their main conclusions were that
notching of the neck, varus positioning of the implant and
intraoperative technical problems lay behind femoral fractures.
They found that there was little correlation between surgical
experience and this complication. Another study by Marker et al5
looked at the incidence of femoral fractures in a number of
procedures performed by the senior author between November 2000
and august 2006; out 550 procedures they had 14 femoral neck
fractures. They queried if the experience of the surgeon was the
reason for this complication. Their findings suggested that
again the risk of fracture was multifactorial associated with
high BMI, female, evidence of femoral head cysts at the original
operation, intraoperative notching of the femoral head and there
was some correlation with surgical experience. Whilst this is
good review it is limited again by small sample size and only
one surgical operator. Others
suggest that femoral neck fracture does not necessarily warrant
a revision procedure. Cossey et al6 looked at 407
patients who had consecutive primary hip resurfacing at 2
centres. 7 had periprosthetic fractures within 4 months
following their operation and were successfully treated
conservatively. They all presented with painful limp and had
radiographs which demonstrated un-displaced fractures which were
treated with non-weight bearing for 4-6 weeks followed by
partial weight bearing for another 2-4 weeks. They only found 1
patient with notching while the others had femoral components in
valgus.
Summary
There
are a number of causes leading to failure of hip resurfacing
procedures which require revision surgery. Many papers
demonstrate that in particular patient group demographics and
the type of original procedure have a significant bearing on
whether or not the prosthesis will survive. As surgeons we need
to be mindful of patient selection when considering hip
resurfacing and be ready to consider other options if patient’s
demographics predispose them to early failure. The importance of
good surgical technique is crucial in determining the survival
of the components. More research still needs to be carried out
in particular focused at the causes of infection in resurfacing
and the mechanisms and possible prevention of the
immunologically mediated causes of failure.
Reference :
-
National Joint Registry. National Joint Registry for England and
Wales 4th annual report 2007.
-
Buergi M & Walter W. Hip Resurfacing Arthoplasty the Australian
Experience. Journal of Arthoplasty (JA) 2007 Vol. 22: No. 7:
Suppl 3: 61-65.
-
Little C, Ruiz A, Harding I, Mclardy-Smith P, Gundle R, Murray
D, Athanasou N. Osteonecrosis In Retrieved Femoral Heads After
Failed Resurfacing Arthoplasty of the Hip. Journal of Bone and
Joint Surgery (JBJS Br) 2005: 87-B: 320-3.
-
Shimmin A, Back D. Femoral Neck Fractures Following Birmingham
Hip Resurfacing- A National Review of 50 Cases JBJS 2005: Vol.
87-B: 463.
-
Marker D, Seyler T, Jinnah R, Delanois R, Ulrich S. Mont M.
Femoral Neck Fractures After Metal-on-Metal Total Hip
Resurfacing. JA 2007: Vol. 22: 66-71
-
Cossey A, Back D, Shimmin A, Et Al. The Non-operative Management
of Periprosthetic Fractures Associated With The Birmingham Hip
Resurfacing Prosthesis. JA 2005: Vol. 20: 358
-
Amstutz H, Le Duff M, Campbell P, Dorey F. The Effects of
Technique Changes On Aspetic Loosening Of Femoral Component In
Hip Resurfacing. The Results of 600 Conserve Plus With 3 To 9
Year Follow Up. JA 2007: Vol. 22: 481-489.
-
Morlock M, Bishop N, Zustin J, Hahn M, Ruther W, Amling M. Modes
Of Failure After Hip Resurfacing: Morphological And Wear
Analysis Of 267 Retrieval Specimens. JBJS 2005: Vol. 90-A:
89-95.
-
Allen M, Schoonmaker J, Ayer D. Tumour Necrosis Factor Alpha
Induced Endosteal Bone Resorption In Rabbits. JBJS 2004: Vol.
86-B: 432.
-
Beaule P, Harvey N, Zaragoza E, Le Duff M, Dorey F. The Femoral
Head/Neck Offset And Resurfacing. JBJS 2007: Vol. 89-B: 9-15.
-
Campbell P, Mira J, Amstutz H. Viability Of Femoral Heads
Treated With Resurfacing Arthoplasty. JA 2000: Vol. 15: 120-122.
-
Gross T, Liv F. Metal-On-Metal Hip Resurfacing With An
Uncemented Femoral Component A Seven Year Follow Up Study. JBJS
2008: Vol. 90-A: 32-37
-
Manley M, Capello W, D’ Antonio J, Eddin A, Geesink R.
Fixation of Acetabular Cups Without Cement Total Hip Arthoplasty.
A Comparison of 3 different Implant Surfaces at a Minimum
Duration of Follow-up of Five Years. JBJS1998: Vol. 80-A:
1175-85.
-
Ong
K, Manley M, Kurtz S. Have Contemporay Hip Resurfacing Designs
Reached Maturity. A Review. JBJS 2008: Vol. 90-A: 81-88.
-
Minutes
of the Committee on the safety of devices expert advisory group
on metal wear and debris from Hip Implants. April 2007
-
Harris, W. H.; Schiller, A. L.; Scholler, J.-M.;
Freiberg, R. A.; and and Scott, R.: Extensive localized bone
resorption in the femur following total
hip
replacement. JBJS 1976: Vol. 58-A: 612-618.
-
Pandit H, Glyn-Jones S, Mclardy-Smith P,
Gundle R, Whitwell D, Gibbons C, Ostlere S.
Pseudotumours associated with metal-on-metal hip resurfacings.
JBJS 2008: Vol.90-B: 847-51.
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