Abstract
Background: A theoretical advantage of resurfacing arthroplasty of
the hip is that a failed femoral component can be safely and successfully
revised to a total hip arthroplasty. To our knowledge, this advantage has not
been demonstrated to date.
Methods: Twenty-one metal-on-metal resurfacing arthroplasties in
twenty patients with an average age of 50.2 years were converted to a
conventional stemmed total hip arthroplasty because of femoral component
failure. In eighteen hips, the acetabular component was retained, and in three
hips both components were revised. The results in the resurfacing conversion
group were compared with those in a group of fifty-eight patients who had
undergone sixty-four primary total hip arthroplasties that had been performed
during the same time-period by the same surgeon. Clinical evaluations (the
Harris hip score, the University of California at Los Angeles pain, walking,
and activity scores and the Short Form-12 score) and radiographic evaluations
were performed. The average duration of follow-up was forty-six months for the
conversion arthroplasty group and fifty-seven months for the primary
conventional total hip arthroplasty group.
Results: There was no significant difference between the conversion
arthroplasty group and the conventional arthroplasty group with regard to
operative time, blood loss, or complication rates. At the time of the most
recent follow-up, with the numbers studied, there were no significant
differences between the two groups with regard to the mean Harris hip score;
the University of California at Los Angeles pain, walking, and activity score;
or the SF-12 score. As assessed radiographically, the quality of component
fixation and the alignment of the reconstruction were equivalent between the
two groups. There had been no instances of aseptic loosening of the femoral or
the acetabular component in either group, and there had been no dislocations
after conversion of a resurfacing arthroplasty.
Conclusions: Conversion of a hip resurfacing with a femoral-side
failure to a total hip arthroplasty appears to be comparable with primary
total hip arthroplasty in terms of surgical effort, safety, and early clinical
outcomes.
Level of Evidence: Therapeutic Level III. See
Instructions to Authors for a complete description of levels of evidence.
In patients who are managed with resurfacing arthroplasty of the hip, the
femoral head and neck are conserved and continue to be loaded by the
prosthesis, thereby preventing stress-shielding and preserving the quality of
bone in the proximal part of the
femur1. Should
failure of the femoral component occur, conversion to a total hip arthroplasty
should thus be a straightforward procedure.
Since its inception, "revisability" has been claimed as one of
the major advantages of resurfacing arthroplasty of the hip. However, to our
knowledge, this theoretical advantage has never been clearly demonstrated.
Earlier-generation resurfacing devices with a metal-polyethylene bearing
frequently proved to be difficult to revise on the acetabular side, primarily
because of the use of large, cemented acetabular components and osteolysis,
which was frequently extensive secondary to polyethylene wear. To our
knowledge, only three published reports have specifically addressed the
revision of failed hip resurfacing
procedures2-4.
Unfortunately, they were published in the early 1980s and they lacked adequate
operative details, outcomes measures, and comparative groups to permit
meaningful analyses.
The objective of the present study was to test the hypothesis that a failed
femoral component in a hip with a modern-generation metal-on-metal resurfacing
arthroplasty can be easily and successfully converted to total hip
arthroplasty. To date, the vast majority of resurfacing failures have been
caused by either femoral-sided aseptic loosening or femoral neck fracture.
Therefore, the present report addresses conversions performed for femoral-side
failures.
Study Group
Between May 1997 and October 2005, the senior author (H.C.A.) performed 844
primary metal-on-metal hip resurfacing arthroplasties and 157 primary total
hip arthroplasties. All of the resurfacing procedures were performed with
Conserve Plus devices (Wright Medical Technology, Arlington, Tennessee). The
femoral head was cemented in all hips, but the metaphyseal stem was cemented
in only 328 hips (38.9%). The total hip arthroplasty devices included 115
cementless stems (73%) (ATH; Kinamed, Camarillo, California) and forty-two
cemented stems (27%) (CTN; Kinamed, or Perfecta; Wright Medical Technology).
All femoral components articulated with cementless acetabular components.
Twenty-three total hip arthroplasties (15%) (all of which were performed prior
to the availability of cross-linked polyethylene) involved conventional
polyethylene bearings (Interseal; Wright Medical Technology), sixty-four (41%)
involved cross-linked polyethylene bearings (Trilogy/Longevity; Zimmer,
Warsaw, Indiana, or Duraloc/Marathon; DePuy, Warsaw, Indiana), and seventy
(45%) involved metal-on-metal bearings (Transcend or Conserve; Wright Medical
Technology).
Twenty-one hips in twenty patients with an average age of 50.2 years
(range, twenty-three to seventy-two years) underwent conversion from the
metal-on-metal resurfacing device to a total hip arthroplasty. The indication
for conversion surgery was a femoral neck fracture in five hips and femoral
component loosening in sixteen (Figs.
1-A,
1-B, and
1-C). There were no failures of
the acetabular component in these patients. In the group of patients who
required conversion to a total hip arthroplasty, one patient with
developmental dysplasia of the hip had had a periacetabular and proximal
femoral osteotomy prior to the original resurfacing procedure. None of the
other patients in the conversion group had had previous hip surgery. The
average time between resurfacing and conversion surgery was 40.9 months
(range, 1.4 to 99.8 months). In eighteen hips, the acetabular component was
retained and the femoral component was revised to a stemmed femoral component
with a large femoral head that matched the inner diameter of the cup. The
three remaining hips required acetabular revision because a unipolar head (Big
Femoral Head (BFH); Wright Medical Technology) matching the cup size was not
available at the time of surgery.
Control Group
During the same period, sixty-three patients (sixty-nine hips) who were
younger than sixty-five years of age (average age, 50.8 years; range,
twenty-seven to sixty-four years) underwent a primary total hip arthroplasty
that was performed by the same surgeon at the same institution. The
indications for primary total hip arthroplasty were either a denial from the
patient's insurance carrier for resurfacing (because of the investigational
device status of the implant during this period) or because the bone quality
of the femoral head was thought to be compromised by either extensive
osteonecrosis or cystic degeneration. In addition, some patients chose to have
a traditional total hip arthroplasty instead of a resurfacing arthroplasty. To
allow for a fair comparison between the groups with regard to operative time
and blood loss, five patients (five hips) were excluded from the total hip
arthroplasty group because they had either severe
(Crowe5 type-III or
IV) dysplasia or because they required structural bone-grafting or extensive
hardware removal at the time of the primary total hip arthroplasty. This left
sixty-four hips in fifty-eight patients. The comparative demographic data
between the study and control groups are presented in
Table I.
A posterior approach to the hip was used for all patients in the study and
control groups. In the five patients in whom resurfacing arthroplasty failed
because of a femoral neck fracture, the fracture was well proximal to the
lesser trochanter and therefore did not adversely affect the optimal level for
a neck osteotomy at the time of conversion. Stability of the acetabular
component was tested at the time of conversion by applying a number of blows
through a tamp onto the rim of the cup.
Postoperatively, patients in both groups were instructed to follow
posterior hip dislocation precautions, which included no hip flexion past
120° and avoidance of a position of combined hip flexion, adduction, and
internal rotation. Hip abduction pillows were not used routinely in either
group. Patients were restricted to partial (25% to 50%) weight-bearing for one
month and were told to use crutches during this time, but compliance with
these instructions could not be verified.
Dependent Variables
The clinical outcome of the procedures was evaluated with use of the
University of California at Los Angeles (UCLA) hip-scoring
system6, the Harris
hip score7, and the
Short Form-12
(SF-12)8, which were
administered at the time of the last follow-up visit.
The operative time, the estimated blood loss, all perioperative
complications, and the length of the hospital stay were recorded. The reported
operative time in both groups included the time for patient positioning (the
time between the completion of induction of anesthesia and the application of
the surgical dressing) and the time required to make intraoperative
radiographs (to ensure the accuracy of limb-length restoration).
Radiographic Evaluation
Radiographic assessment included low anteroposterior pelvic, modified
table-down lateral, and frog-leg lateral views of the hip, made both
immediately postoperatively and at the time of the final follow-up. We
measured the femoral offset and the horizontal hip center of rotation as
described by Silva et
al.9 and measured
limb length as described by Austin et
al.10. The
positioning of the stem in the frontal plane was recorded and classified into
one of three categories: neutral, valgus, or varus. A stem was considered to
be in neutral orientation whenever its main axis deviated from the femoral
shaft axis by <5°. The fixation of the femoral component was assessed
for each Gruen
zone11 with use of
the fixation score devised by Engh et
al.12 for
cementless stems. A similar evaluation was made for each DeLee and Charnley
zone13 on the
acetabular side. The radiographic data collection was performed by a single
observer (S.T.B.) who was blinded to patient and group identity.
Student t tests were performed to establish the significance of the
differences in average values observed between groups. The level of
significance was set at p < 0.05.
The study was approved by the research committee/institutional review board
of our institution.
The average duration of follow-up was forty-six months (range, twelve to
113 months) for the study group and fifty-seven months (range, twenty-four to
105 months) for the control group.
Outcome Measures
There were no significant differences between the study group and the
control group with regard to the UCLA pain, walking, function, and activity
scores; the SF-12 physical and mental component scores; or the Harris hip
score. The average values of these tests for the overall study group and the
control group are presented in Table
II.
Intraoperative Variables
The average operative time was 178 minutes (range, 140 to 255 minutes) for
the study group and 169 minutes (range, 110 to 265 minutes) for the control
group. This difference was not significant (p = 0.263). The average
intraoperative estimated blood loss was 509 mL (range, 100 to 1200 mL) for the
study group and 578 mL (range, 250 to 1600 mL) for the control group (p =
0.314).
Acetabular revision was performed during only three of the twenty-one
conversion procedures. These three stable cups had to be removed with use of
curved osteotomes because, at the time of conversion surgery, sufficiently
large prosthetic femoral heads were not available. In the remaining eighteen
hips, the cup was well fixed and only the femoral side was revised. The
operative time and blood loss for the three conversion procedures that
involved cup revision were similar to those for the rest of the conversion
procedures. The average acetabular bone loss in these three hips, as measured
by the change in outer diameter from the original cup to the revision cup, was
4 mm (range, 2 to 6 mm). The average duration of hospitalization was 4.0 days
(range, three to six days) for the study group and 4.2 days (range, three to
eight days) for the control group (p = 0.479). A weak negative correlation (r
= —0.223, p < 0.05) was found between the duration of hospitalization
and how recent the surgery was, illustrating a decrease in hospital stay over
time at our institution.
At the time of conversion surgery, visual inspection of the femoral and
acetabular components revealed no appreciable metallic wear in any of the
hips. Furthermore, osteolysis was not observed in any hip. Wear analysis,
performed for fourteen of the twenty-one retrieved femoral components,
demonstrated an average of 7 µm (range, 0 to 45 µm) of wear. Wear
analysis was performed for only one retrieved acetabular component, which
demonstrated 0 µm of wear. However, this component was revised just 2.1
months after implantation.
Radiographic Outcomes
All of the revision cementless stems were integrated into bone, and the
fixation scores showed no difference between the conversion group and the
control group (p = 0.365). No radiolucent lines were recorded for any of the
cemented stems in either of the two groups. There was no difference in
limb-length discrepancy between the two groups (p = 0.705). Femoral offset and
the horizontal position of the center of rotation of the hip were also similar
between the two groups (p = 0.712 and p = 0.224, respectively). Eighty-one
percent of the stems were in neutral position in the conversion group,
compared with 84% in the control group. Two cementless stems in each group
subsided (by 2 and 5 mm in the conversion group and by 2 mm each in the
control group), but all had stabilized and had good fixation scores at the
time of the latest follow-up. The acetabular fixation scores were also
comparable between the conversion group and the control group (p = 0.279). All
eighteen cups that were retained at the time of conversion surgery remained
stable, with no migration and no progressive radiolucent lines, for an average
of eighty-five months (range, twenty to 116 months) from the date of the
primary resurfacing arthroplasty until the time of the latest follow-up. The
three hips that underwent revision of both the acetabular and the femoral
component also had stable implants with no signs of loosening.
Complications
Three patients in the conversion group experienced a complication. One
patient had a femoral nerve palsy that completely resolved. One patient had an
intraoperative, nondisplaced, proximal femoral fracture, which was treated
with cerclage wires. One patient had a perioperative myocardial
infarction.
There were six complications in the control group. There were three femoral
nerve palsies, each of which also completely resolved. There were two
periprosthetic femoral shaft fractures; one occurred intraoperatively and was
treated with cerclage wiring, and one presented one month after surgery and
was treated with open plate fixation and cerclage wiring. Last, there was one
case of deep infection, which required a two-stage revision.
Current-generation metal-on-metal resurfacing arthroplasty of the hip is
most commonly performed for younger, active adults, in whom conventional total
hip arthroplasty has historically been associated with relatively low
prosthetic survival
rates14-18.
In this high-demand patient population, the reported revision rates for
contemporary resurfacing designs have been comparatively low, ranging from
0.02% to 3% at approximately three to five years of
follow-up19-21.
The most common mechanisms of failure have been aseptic loosening of the
femoral component and femoral neck fracture. Acetabular-side failure is
rare.
The theoretical advantage of easy "revisability" of a
resurfacing arthroplasty is supported by our results. With the numbers
studied, the procedure was similar to primary total hip arthroplasty in terms
of operative time and blood loss. The radiographic results after conversion
were also similar to those in the primary total hip arthroplasty group in
terms of osseointegration, the position of the center of rotation, femoral
offset, stem position, and limb-length equality.
The postoperative clinical outcomes also were similar for the conversion
group and the primary total hip arthroplasty group. At an average duration of
follow-up of approximately three and one-half years, all patients in the
conversion group had a good or excellent outcome as measured with the Harris
hip score and SF-12 scores. Furthermore, these patients maintained a high
level of activity, with an average UCLA activity score of 6.8 and with ten of
the twenty patients continuing to participate in sports regularly.
Historically, the most common complication of conversion hip surgery or
revision total hip arthroplasty has been dislocation. The rate of dislocation
has been reported to be approximately 10% among patients who have been managed
with conversion of a hemiarthroplasty to a total hip
arthroplasty22, and
it has been reported to be 2% among those who have been managed with total hip
arthroplasty after a previous periacetabular
osteotomy23. In a
recent large series, the dislocation rate following revision total hip
replacement was 7% to
11%24. In contrast,
in the present series of conversions of failed femoral resurfacing
arthroplasties, there were no dislocations and no infections. In our patients
in the conversion group, the absence of postoperative instability was likely
related to the large femoral head size (average, 43.5 mm), as the increased
stability of large femoral heads in the revision setting has been clearly
established by a number of previous
studies25-28.
The results of the present study were very encouraging; nonetheless, they will
need to be confirmed in a larger series of patients with a longer
follow-up.
All four of the femoral nerve palsies in our series were related to the use
of a lateral hip decubitus positioning system with anterior pads that were
positioned laterally against the anterior superior iliac spine and medially
against the pubis. The lateral pad often slipped during the procedure and
pressed against the femoral triangle. The device was initially attractive
because it was translucent to x-rays, but, because of the neurologic
complications, its use was discontinued. We now stabilize the pelvis with a
padded support on the pubis, the sacrum, and the anterior and posterior
aspects of the thorax.
After resurfacing arthroplasty, normal stresses and bone density are
maintained in the proximal part of the
femur1,29.
For this reason, conversion to a total hip arthroplasty is similar to primary
total hip arthroplasty with regard to achieving osseointegration of a
cementless stemmed prosthesis, and all twenty-one conversion stems in the
present series were integrated into bone. In contrast, femoral-side revision
of failed conventional total hip arthroplasty can be technically demanding and
the results are less predictable, with increased rates of dislocation,
infection, and aseptic
loosening30-33.
With the current generation of resurfacing implants, the metal acetabular
shell is thin, and, therefore, minimal amounts of acetabular bone are removed
at the time of the index procedure, similar to a traditional total hip
arthroplasty. The fixation of this porous-coated acetabular component has
performed as well as similar porous-coated components that have been used for
decades for total hip
arthroplasty34.
Furthermore, osteolysis is rare in association with metal-on-metal bearings
and was not an issue in this short-term series of hip resurfacing. Three
acetabular components required revision not because of loosening, but because
the conversion surgery predated the availability of matching large femoral
heads to mate with the existing shell. It is important to note that in those
hips, an average of 4 mm of bone was lost.
The present study had two primary limitations. First, the duration of
follow-up was relatively short. This was unavoidable because the first
implantation of current-generation resurfacing devices was performed only nine
years ago. A study of the conversion of earlier-generation resurfacing devices
would allow a longer follow-up period but would not be relevant to today's
designs. The second shortcoming was the relatively small number of patients.
Fortunately, this was because the current-generation devices are performing
well, with only a limited number of revisions to date. Despite these
limitations, the current study supports the premise of the easy and safe
revisability of metal-on-metal resurfacing arthroplasties of the hip. At the
time of early follow-up, the clinical outcomes were excellent after
conversion. In order to determine the long-term efficacy, additional follow-up
is still required.
In conclusion, conversion of a femoral-side failure of this
current-generation metal-on-metal resurfacing arthroplasty design to a total
hip replacement can be performed with a technical effort similar to that for a
primary total hip replacement. The short-term clinical outcomes of these
conversions were similar to those of conventional primary total hip
arthroplasty. The resurfacing acetabular component has performed well and is
unlikely to require revision during conversion for a femoral-side failure. Our
early experience supports the concept of "revisability" as an
advantage of the current generation of hip resurfacing. ?
Kishida Y, Sugano N, Nishii T, Miki H,
Yamaguchi K, Yoshikawa H. Preservation of the bone mineral density of the
femur after surface replacement of the hip. J Bone Joint Surg
Br. 2004;86:
185-9.86185
2004
[PubMed][CrossRef]
Thomas BJ, Amstutz HC. Revision surgery
for failed surface arthroplasty of the hip. Clin Orthop Relat
Res. 1982;170:
42-9.17042
1982
Capello WN, Trancik TM, Misamore G,
Eaton R. Analysis of revision surgery of resurfacing hip arthroplasty.
Clin Orthop Relat Res.
1982;170:
50-5.17050
1982
[PubMed]
Bradley GW, Freeman MA. Revision of
failed hip resurfacing. Clin Orthop Relat Res.
1983;178:
236-40.178236
1983
[PubMed]
Crowe JF, Mani VJ, Ranawat CS. Total hip
replacement in congenital dislocation and dysplasia of the hip. J Bone
Joint Surg Am. 1979;61:
15-23.6115
1979
Amstutz HC, Thomas BJ, Jinnah R, Kim W,
Grogan T, Yale C. Treatment of primary osteoarthritis of the hip. A comparison
of total joint and surface replacement arthroplasty. J Bone Joint Surg
Am. 1984;66:
228-41.66228
1984
Harris WH. Traumatic arthritis of the
hip after dislocation and acetabular fractures: treatment by mold
arthroplasty. An end-result study using a new method of result evaluation.
J Bone Joint Surg Am.
1969;51:
737-55.51737
1969
[PubMed]
Ware JE, Kosinski M, Keller SD.
SF-12: how to score the SF-12 Physical and Mental Health Summary
Scales. 3rd ed. Lincoln, RI: Quality Metric Inc.;
1998.
1998
Silva M, Lee KH, Heisel C, Dela Rosa MA,
Schmalzried TP. The biomechanical results of total hip resurfacing
arthroplasty. J Bone Joint Surg Am.
2004;86:
40-6.8640
2004
[PubMed]
Austin MS, Hozack WJ, Sharkey PF,
Rothman RH. Stability and leg length equality in total hip arthroplasty.
J Arthroplasty.
2003;18(3 Suppl 1):
88-90.1888
2003
[PubMed][CrossRef]
Gruen TA, McNeice GM, Amstutz HC.
"Modes of failure" of cemented stem-type femoral components: a
radiographic analysis of loosening. Clin Orthop Relat Res.
1979;141:
17-27.14117
1979
[PubMed]
Engh CA, Massin P, Suthers KE.
Roentgenographic assessment of the biologic fixation of porous-surfaced
femoral components. Clin Orthop Relat Res.
1990;257: 107-28.
Erratum in: Clin Orthop Relat Res. 1992;284: 310-2.257107
1990
[PubMed]
DeLee JG, Charnley J. Radiological
demarcation of cemented sockets in total hip replacement. Clin Orthop
Relat Res. 1976;121:
20-32.12120
1976
Berry DJ, Harmsen WS, Cabanela ME,
Morrey BF. Twenty-five-year survivorship of two thousand consecutive primary
Charnley total hip replacements: factors affecting survivorship of acetabular
and femoral components. J Bone Joint Surg Am.
2002;84:
171-7.84171
2002
[PubMed]
Dorr LD, Kane TJ 3rd, Conaty JP.
Long-term results of cemented total hip arthroplasty in patients 45 years old
or younger. A 16-year follow-up study. J Arthroplasty.
1994;9:
453-6.9453
1994
[PubMed][CrossRef]
Callaghan JJ, Forest EE, Sporer SM,
Goetz DD, Johnston RC. Total hip arthroplasty in the young adult. Clin
Orthop Relat Res. 1997;344:
257-62.344257
1997
Duffy GP, Berry DJ, Rowland C, Cabanela
ME. Primary uncemented total hip arthroplasty in patients <40 years old:
10- to 14-year results using first-generation proximally porous-coated
implants. J Arthroplasty.
2001;16(8 Suppl 1):
140-4.16140
2001
[PubMed][CrossRef]
Sedel L, Nizard RS, Kerboull L, Witvoet
J. Alumina-alumina hip replacement in patients younger than 50 years old.
Clin Orthop Relat Res.
1994;298:
175-83.298175
1994
[PubMed]
Schmalzried TP, Silva M, de la Rosa MA,
Choi ES, Fowble VA. Optimizing patient selection and outcomes with total hip
resurfacing. Clin Orthop Relat Res.
2005;441:
200-4.441200
2005
[PubMed][CrossRef]
Daniel J, Pynsent PB, McMinn DJ.
Metal-on-metal resurfacing of the hip in patients under the age of 55 years
with osteoarthritis. J Bone Joint Surg Br.
2004;86:
177-84.86177
2004
[PubMed][CrossRef]
Amstutz H, Ball S, Le Duff M, Dorey F.
Hip resurfacing for patients under 50 years of age. Results of 350 Conserve
Plus with a 2-9 year follow-up. Clin Orthop Relat Res. In
press.
Sierra RJ, Cabanela ME. Conversion of
failed hip hemiarthroplasties after femoral neck fractures. Clin Orthop
Relat Res. 2002;399:
129-39.399129
2002
[CrossRef]
Parvizi J, Burmeister H, Ganz R.
Previous Bernese periacetabular osteotomy does not compromise the results of
total hip arthroplasty. Clin Orthop Relat Res.
2004;423:
118-22.423118
2004
[PubMed][CrossRef]
Alberton GM, High WA, Morrey BF.
Dislocation after revision total hip arthroplasty: an analysis of risk factors
and treatment options. J Bone Joint Surg Am.
2002;84:
1788-97.841788
2002
[PubMed]
Smith TM, Berend KR, Lombardi AV Jr,
Emerson RH Jr, Mallory TH. Metal-on-metal total hip arthroplasty with large
heads may prevent early dislocation. Clin Orthop Relat Res.
2005;441:
137-42.441137
2005
[PubMed][CrossRef]
Amstutz HC, Le Duff MJ, Beaulé
PE. Prevention and treatment of dislocation after total hip replacement using
large diameter balls. Clin Orthop Relat Res.
2004;429:
108-16.429108
2004
[PubMed][CrossRef]
Berry DJ, von Knoch M, Schleck CD,
Harmsen WS. Effect of femoral head diameter and operative approach on risk of
dislocation after primary total hip arthroplasty. J Bone Joint Surg
Am. 2005;87:
2456-63.872456
2005
[CrossRef]
Cuckler J, Moore K, Lombardi AJ,
McPherson E, Emerson R. Large versus small femoral heads in metal-on-metal
total hip arthroplasty. J Arthroplasty.
2004;19(8 Suppl 3):
41-4.1941
2004
[PubMed][CrossRef]
Harty J, Devitt B, Harty L, Molloy M,
McGuinness A. Dual energy X-ray absorptiometry analysis of peri-prosthetic
stress shielding in the Birmingham resurfacing hip replacement. Arch
Orthop Trauma Surg. 2005;125:
693-5.125693
2005
[CrossRef]
Engh CA Jr, Ellis TJ, Koralewicz LM,
McAuley JP, Engh CA Sr. Extensively porous-coated femoral revision for severe
femoral bone loss: minimum 10-year follow-up. J Arthroplasty.
2002;17:
955-60.17955
2002
[PubMed][CrossRef]
Moreland JR, Moreno MA. Cementless
femoral revision arthroplasty of the hip: minimum 5 years followup.
Clin Orthop Relat Res.
2001;393:
194-201.393194
2001
[PubMed][CrossRef]
Weeden S, Paprosky W. Minimal 11-year
follow-up of extensively porous-coated stems in femoral revision total hip
arthroplasty. J Arthroplasty.
2002;17(4 Suppl 1):
134-7.17134
2002
[PubMed][CrossRef]
Lawrence JM, Engh CA, Macalino GE, Lauro
GR. Outcome of revision hip arthroplasty done without cement. J Bone
Joint Surg Am. 1994;76:
965-73.76965
1994
Engh CA, Griffin WL, Marx CL. Cementless
acetabular components. J Bone Joint Surg Br.
1990;72:
53-9.7253
1990
[PubMed]
Amstutz H, Le Duff M, Campbell P, Dorey
F. The effects of technique changes on aseptic loosening of the femoral
component in hip resurfacing. Results of 600 Conserve Plus with a 3-9 year
follow-up. J Arthroplasty. In press.