Between July 1979 and December 1987, we performed an average of 220 primary
total hip arthroplasties per year. For all primary arthroplasties in patients
without loss of acetabular bone stock, our practice is to use cemented
components and not to use bone graft. During this time-period, we performed
forty-two consecutive acetabular reconstructions with use of an impaction
bone-grafting technique and a cemented polyethylene cup in thirty-seven
patients with deficient acetabular bone stock who were younger than fifty
years old. This was the only technique used in our department to treat
acetabular bone stock loss. We reviewed all reconstructions (twenty-three of
which had been performed during primary total hip arthroplasty and nineteen of
which had been performed during revision total hip arthroplasty) after a
minimum duration of follow-up of fifteen years after surgery. Six different
surgeons, including two of the authors (T.J.J.H.S. and J.W.M.G.), performed
the reconstructions. The study group included fifteen men and twenty-two women
who had an average age of thirty-seven years and two months (range, twenty to
forty-nine years) at the time of the operation. One patient (one hip) was lost
to follow-up, and four patients (five hips) died before the final review.
Indications
Primary Acetabular Reconstructions
Twenty-three primary acetabular reconstructions were performed in nineteen
patients who had a loss of acetabular bone stock. The diagnosis was primary
osteoarthritis in two hips, rheumatoid arthritis in eleven, and secondary
osteoarthritis in ten. The causes of secondary osteoarthritis included
congenital dislocation (three hips), avascular necrosis of the femoral head
(two), tuberculous arthritis (two), posttraumatic arthritis (two), and
ankylosing spondylitis (one).
Revision Acetabular Reconstructions
The indication for all nineteen acetabular revisions (in eighteen patients)
was aseptic loosening. Thirteen revisions were performed at the site of a
previous total hip arthroplasty, and six were performed at the site of a
previous resurfacing arthroplasty. The diagnosis at the time of the primary
procedure had been osteonecrosis of the femoral head (five hips),
epiphysiolysis (four), congenital dislocation of the hip (two), rheumatoid
arthritis (three), ankylosing spondylitis (two), protrusio acetabuli (one),
tuberculous arthritis (one), and a bleeding disorder due to hemophilia
(one).
Classification of Acetabular Defects
With use of the preoperative and immediate postoperative anteroposterior
pelvic radiographs and the operative reports, the acetabular defects were
classified on a consensus basis by three of the authors (B.W.S., T.J.J.H.S.,
and V.J.J.F.B.) according to the system of the American Academy of Orthopaedic
Surgeons Committee on the
Hip8. A segmental
(type-I) defect was seen in one hip that was undergoing a primary procedure, a
cavitary (type-II) defect was seen in twenty-seven hips (including sixteen
that were undergoing a primary procedure and eleven that were undergoing a
revision), and a combined (type-III) defect was seen in fourteen hips
(including six that were undergoing a primary procedure and eight that were
undergoing a revision).
Surgical Technique
The posterolateral approach without trochanteric osteotomy was used in all
cases. For all reconstructions, the grafts were morselized with a rongeur and
cancellous bone chips with a diameter of 0.7 to 1.0 cm were created. This
technique has been described in
detail7,9.
Primary Acetabular Reconstructions
After resection of the femoral head, the acetabulum was reamed and all
cartilage was removed. Our goal was to create a bleeding trabecular bone bed,
and any segmental wall defects were closed. The femoral head was the source of
the autograft for twenty of the twenty-three primary total hip arthroplasties,
and an autogenous bone from the iliac crest was used for the other three.
Revision Acetabular Reconstructions
After removal of the failed components, interface tissue was sent for
frozen-section analysis to rule out infection. On the basis of these results,
a two-stage revision procedure was performed in two patients (Cases 30 and 35;
see Appendix) for the treatment of suspected septic loosening. The acetabulum
was reamed to create a bleeding trabecular bone bed. Segmental defects in the
medial wall or peripheral defects of the acetabulum were closed with a slice
of corticocancellous bone or with metal mesh. In four hips undergoing revision
at the site of a failed resurfacing arthroplasty, we used the femoral head
(two hips) or bone from the iliac crest (two hips). In two other such hips,
autogeneous bone from the iliac crest was combined with a femoral head
allograft. In the thirteen hips undergoing revision at the site of a failed
total hip arthroplasty, we used fresh-frozen femoral head allograft, which has
been our practice since 1984.
Both Primary and Revision Reconstructions
During both primary and revision arthroplasties, any remaining sclerotic
areas were perforated with multiple 2-mm drill-holes, the bone bed was cleaned
with use of lavage, and impaction bone-grafting was performed. A trial
acetabular prosthesis and a mallet were used to distribute and impact the bone
grafts. A goal of impaction grafting was to restore the original center of
rotation of the hip, with the level of the transverse ligament used as a
reference. The last trial prosthesis that was used for impaction was at least
2 mm larger than the proposed cup in order to allow for a cement mantle of
sufficient thickness. In thirty-two hips, a thin Vitallium wire mesh (Mecron,
Berlin, Germany) was used on top of the graft reconstruction. After
pressurization of the bone cement, a 32-mm all-polyethylene cup was inserted.
A Müller cup was used in twenty-five hips, and an Allopro cup was used in
the remaining seventeen hips (Sulzer, Wintherthür, Switzerland). Regular
bone cement was used for the primary arthroplasties, whereas
gentamicinimpregnated cement (Palacos R or Palacos R with gentamicin; Merck,
Darmstadt, Germany) was used for the revisions.
Postoperative Regimen
Postoperative treatment for all patients included bed rest for six weeks,
systemic administration of antibiotics for five days, administration of
indomethacin as prophylaxis against heterotopic ossification for seven days,
and oral anticoagulation therapy for three months. Passive exercises were
allowed after twenty-four hours, followed by walking with partial
weight-bearing after six weeks and full weight-bearing after three months.
Follow-up
At the time of the final review, one patient (Case 4; see Appendix) had
been lost to follow-up. Two patients who had been lost to follow-up at the
time of the previous
report7 were found
and were included in this study. Four patients (five hips) (Cases 2, 14, 15,
22, and 33; see Appendix) died from causes that were unrelated to the
operation at 4.3, 5.4, 9.0, and 15.4 years postoperatively. All of the
patients who died had been followed on a regular basis until death and were
included in the present study, but a Harris hip score from the time just prior
to death was not available. None of them, however, had had a reoperation or a
revision. All of the living patients with surviving hips returned for a
clinical and radiographic examination, with the exception of two patients
whose radiographs were sent from other clinics and whose hip scores were
obtained by telephone. In the case of one patient, the hip score was
incomplete at the time of the latest visit, so an update was performed by
telephone. Preoperative Harris hip scores were not known.
Radiographic Follow-up
Serial anteroposterior and lateral radiographs were reviewed to determine
the extent of incorporation of the graft, the presence of radiolucent lines,
migration of the cup, and the formation of heterotopic ossification.
Radiographic data were complete for thirty-eight hips, which were used for
further analysis. The radiographic data were incomplete for two patients
(three hips) and missing for one patient (Case 4; see Appendix) who had been
lost to follow-up. The graft was considered to be incorporated when the graft
and the host bone were of equal radiodensity, with a continuous trabecular
pattern
throughout10. Zones
of radiolucency were assessed on the anteroposterior radiographs with the
method of DeLee and
Charnley11, with a
radiolucent line measuring 2 mm in width considered to be a positive finding.
Radiolucent lines were defined as stable or as progressive over time.
Heterotopic ossification was classified according to the system of Brooker et
al.12.
Survivorship Analysis
Kaplan-Meier survivorship analysis was performed for the entire group of
hips treated with acetabular reconstruction as well as for the subgroups of
hips treated with primary and revision acetabular reconstruction. The
survivorship analysis was performed with three different end points: revision
of the acetabular component for any reason, revision of the acetabular
component for aseptic loosening, and radiographic signs of failure (defined as
a radiolucent line in all three zones or migration of the acetabular component
of =5 mm in any direction relative to the interteardrop line as seen on the
anteroposterior pelvic radiograph).
Clinical Results (see Appendix)
Twenty-eight hips (in twenty-five living patients) that had retention of
the index prosthesis were followed for a mean of 17.5 years (range, fifteen to
twenty-three years). The average Harris hip score in this group was 89 points
(range, 60 to 100 points). Twenty-six of these twenty-eight hips had no or
slight pain. Two hips (Cases 17 and 34; see Appendix) with Harris hip scores
of 64 and 60 points had moderate and mild pain, respectively.
Primary Acetabular Reconstructions
Twenty-three primary reconstructions were performed in nineteen patients
for the treatment of a type-1 defect (one hip), a type-2 defect (sixteen
hips), or a type-3 defect (six hips). Four hips required acetabular revision.
One hip with a type-3 defect (Case 19; see Appendix) was revised because of
culture-proven septic loosening 14.5 years after the index operation. Three
hips (Cases 3, 21, and 23; see Appendix), including one with a type-2 defect
and two with a type-3 defect, were revised because of aseptic loosening 6.4,
15.3, and 20.5 years after the index operation.
Revision Acetabular Reconstructions
Nineteen revision reconstructions were performed in eighteen patients for
the treatment of a type-2 defect (eleven hips) or a type-3 defect (eight
hips). Four hips were rerevised. One hip with a type-2 defect (Case 28; see
Appendix) was rerevised three years after the index operation because of
cultureproven septic loosening. One hip with a type-3 defect (Case 41; see
Appendix) was rerevised 11.7 years after the operation because of aseptic
loosening. Another hip with a type-3 defect (Case 37; see Appendix) was
rerevised 12.3 years after surgery. In that case, a femoral revision had been
planned for the treatment of osteolysis and pain. Intraoperatively, however,
the hip was very unstable after isolated revision of the stem and therefore
the original well-fixed cup was exchanged in order to correct the instability.
Another hip with a type-2 defect (Case 30; see Appendix) was rerevised nine
years after the operation because of recurrent dislocation and wear of the
cup.
Cavitary Defects Compared With Combined Defects
Acetabular reconstruction was performed in twenty-seven hips with a
cavitary (type-2) defect and fourteen hips with a combined (type-3) defect. Of
the eight hips in which the reconstruction failed, two (including one with a
type-2 defect and one with a type-3 defect) were revised because of septic
loosening and two (including one with a type-2 defect and one with a type-3
defect) were revised because of instability. Therefore, of the forty-one
reconstructions, only four failed because of aseptic loosening, including one
primary reconstruction in a hip with a cavitary (type-2) defect and one
revision and two primary reconstructions in hips with a combined (type-3)
defect.
Radiographic Results
Overall Results
Of the twenty-eight hips in twenty-five patients with the implant still in
situ that were available for radiographic review at the time of the final
follow-up, sixteen appeared to have a well-fixed implant, with uniform
radiodensity of the graft and the host bone and without progressive
radiolucent lines (Figs. 1-A,
1-B, and
1-C). None of the hips had
pelvic osteolysis. Ten hips had periarticular heterotopic ossification: five
hips had Brooker grade-I ossification, two hips had grade-II ossification, two
hips had grade-III ossification, and one hip (Case 23; see Appendix) had
grade-IV ossification. The hip with grade-IV ossification was
asymptomatic.
Primary Acetabular Reconstructions
Of the fifteen surviving hips that had undergone a primary reconstruction,
three showed progressive radiolucent lines in one zone and two showed stable
lines in one zone at the cement-bone interface. All four hips that were
revised after a primary reconstruction (including one that was revised because
of septic loosening and three that were revised because of aseptic loosening)
showed complete loosening radiographically: three hips (Cases 3, 19, and 23;
see Appendix) had progressive radiolucent lines in three zones, while the
other hip (Case 21; see Appendix) had 6 mm of migration of the cup. In the
three hips with aseptic loosening the radiolucent lines were seen at the
cement-bone interface, whereas in the one hip with septic loosening the
radiolucent lines were seen at the graft-host interface.
Revision Acetabular Reconstructions
Of the thirteen surviving hips that had undergone a revision
reconstruction, one hip (Case 26; see Appendix) showed progressive radiolucent
lines in three zones as well as 10 mm of vertical migration of the cup 17.3
years after surgery. This hip was considered to have failed radiographically,
but it was not revised because the patient had only mild symptoms. Six other
surviving hips showed progressive radiolucent lines in one zone, and two hips
had progressive lines in two zones. Two hips that were rerevised because of
septic and aseptic loosening (Cases 28 and 41; see Appendix) showed
progressive radiolucent lines in three zones and were considered to have
failed radiographically. Of the other two revised hips, the one that was
revised because of wear (Case 30; see Appendix) showed a progressive
radiolucent line in one zone and the one that was revised because of
intraoperative instability after a femoral revision (Case 37; see Appendix)
was not loose at all. In the hips with aseptic loosening, the radiolucent
lines were seen at the bone-cement interface.
Additional Reoperations and Complications
In addition to the two femoral stem revisions already mentioned (Cases 30
and 37; see Appendix), two stems were revised because of aseptic loosening at
six years (Case 26; see Appendix) and at twelve years (Case 27; see Appendix).
During both reoperations, the acetabular cup was well fixed and was left in
situ. In one patient (Case 17; see Appendix), periarticular ossifications were
removed 1.2 years postoperatively. One patient (Case 26; see Appendix) had
development of a neuropraxia of the peroneal nerve, which resolved fully.
Survivorship Analysis
Overall Results
With revision of the cup for any reason as the end point, the survival rate
was 92% (95% confidence interval, 83.5% to 100%) at ten years, 83% (95%
confidence interval, 71.7% to 95.7%) at fifteen years, and 80% (95% confidence
interval, 67.2% to 93.5%) at twenty years. With revision of the cup for
aseptic loosening as the end point, the survival rate was 97% (95% confidence
interval, 92.1% to 100%) at ten years, 94% (95% confidence interval, 86.9% to
100%) at fifteen years, and 91% (95% confidence interval, 80.4% to 100%) at
twenty years. With radiographic signs of loosening as the end point, the
survival rate was 92% (95% confidence interval, 84% to 100%) at ten years and
89% (95% confidence interval, 80% to 99%) at fifteen years.
Primary Acetabular Reconstructions
With revision of the cup for any reason as the end point, the survival rate
after primary acetabular reconstruction was 95% (95% confidence interval, 85%
to 100%) at ten years, 88% (95% confidence interval, 73% to 100%) at fifteen
years, and 82% (95% confidence interval, 63% to 100%) at twenty years
(Fig. 2). With revision of the
cup for aseptic loosening as the end point, the survival rate was 95% (95%
confidence interval, 85% to 100%) at ten years, 95% (95% confidence interval,
85% to 100%) at fifteen years, and 87% (95% confidence interval, 71% to 100%)
at twenty years. With radiographic signs of loosening as the end point, the
survival rate was 89% (95% confidence interval, 75% to 100%) at fifteen
years.
Revision Acetabular Reconstructions
With revision of the cup for any reason as the end point, the survival rate
after revision acetabular reconstruction was 89% (95% confidence interval, 75%
to 100%) at ten years, 78% (95% confidence interval, 59% to 97%) at fifteen
years, and 78% (95% confidence interval, 59% to 97%) at twenty years
(Fig. 3). With revision of the
cup for aseptic loosening as the end point, the rate of survival was 100% at
ten years, 93% (95% confidence interval, 82% to 100%) at fifteen years, and
93% (95% confidence interval, 82% to 100%) at twenty years. With radiographic
signs of loosening as the end point, the rate of survival was 89% (95%
confidence interval, 76% to 100%) at fifteen years.
Soon after the introduction of modern total hip arthroplasty with cement,
it became clear that replacements in young patients were associated with high
rates of failure due to loosening and
wear13-23.
Despite the introduction of second-generation cementing methods, which
improved the rates of survival of the femoral component, the rate of failure
of the acetabular component in young patients remained high. Ballard et
al.1 reported that
the rate of survival of cemented acetabular components in patients less than
fifty years old was 76% at eleven years with revision because of aseptic
loosening as the end point. Smith et
al.2 reported that
the cumulative rate of survival of cemented cups in young patients was 71% at
eighteen years with revision because of aseptic loosening as the end point.
With radiographic signs of loosening as the end point, the rate of survival of
the cup in a mixed group of hips with metal-backed and all-polyethylene cups
was 63% at eighteen years. Callaghan et
al.3 reported that
the rate of survival of cemented acetabular components in patients less than
fifty years old was 76% at twenty-five years with revision because of aseptic
loosening as the end point. However, the probability of survival of the
acetabular component was only 54% (95% confidence interval, 41% to 67%) at
twenty-five years when radiographic evidence of definite or probable loosening
or revision for aseptic loosening was used as the end point. In the current
study, the rate of survival of the cemented cup was 91% (95% confidence
interval, 80.4% to 100%) at twenty years with revision because of aseptic
loosening as the end point. We believe that the long-term results in this
mixed group of primary and revision acetabular reconstructions are very
acceptable and are at least comparable with those of previous series of
primary reconstructions with cement.
Another option for acetabular revision is the use of a cementless
acetabular component. Although such components are frequently used, long-term
reports with a minimum of ten years of follow-up are scarce. Leopold et
al.24 reported the
results of 138 cementless acetabular revisions in 131 patients after an
average duration of follow-up of 11.5 years. The rate of survival of the cup
with re-revision for any reason as the end point was 89%, with fourteen of 130
hips having been rerevised; no cup was re-revised because of aseptic
loosening. When all cups that had been lost to follow-up were considered as
failures, as suggested by Murray et
al.25, the
worst-case-scenario survival rate (including all acetabular re-revisions that
had been performed for any reason and all hips that had been lost to
follow-up) was 84%. These data are comparable with the results for the
revision group in the present study at the same follow-up interval. Templeton
et al.26 reported
on sixty-one consecutive revisions that were performed in fiftyfive patients
by one surgeon; all acetabular revisions were performed with a porous-coated
Harris-Galante component. At the time of the review, none of the acetabular
components had been re-revised because of aseptic loosening after a mean
duration of follow-up of 12.9 years. However, eight (13%) of the sixty-one
hips underwent additional procedures on the acetabulum during a reoperation
and pelvic osteolysis was observed in 13% of the hips. Therefore, despite the
very low rate of rerevision of the cementless metal shell for aseptic
loosening, we believe that pelvic osteolysis will be the major problem as
these uncemented cups are followed for longer periods.
To our knowledge, although the number of patients in the present study is
not large, the long-term results reported here are among the most favorable
that have been published to date in patients younger than fifty years
old2,3.
The impaction bone-grafting technique is especially attractive for use in
young patients with bone-stock deficiencies (in whom future revisions can be
expected) because bone stock is restored and relatively normal hip mechanics
can be achieved.
The strengths of the present study are that (1) we reviewed all consecutive
reconstructions that had been performed before December 1987 with use of the
impaction bone-grafting technique in young patients and (2) this was not a
single-surgeon study. According to the criteria described by Murray et
al.25, the
reliability of our study is high. The loss-to-follow-up quotient was 0.125,
and the worst-case scenario survival rate (which is based on the number of
rerevisions that were performed for any reason, with all hips that had been
lost to follow-up being considered as failures) was 79% at an average of 17.5
years.
A possible limitation of our study is that fourteen of the reconstructions
were performed in patients with rheumatoid arthritis, who theoretically are
more sedentary than patients with osteoarthritis. While good results have been
reported previously in association with the use of impacted morselized bone
grafts in patients with protrusio acetabuli and rheumatoid
arthritis27-29,
the results of total hip arthroplasty in a nationwide study of young patients
with rheumatoid arthritis who were less than fifty-five years old was
disappointing at longer durations of
follow-up30.
Although Conn et
al.10 suggested
radiographic criteria for graft incorporation, it is difficult to determine
whether there is incorporation of morselized bone grafts on radiographs. Only
a biopsy can demonstrate the incorporation. Heekin et
al.31, and recently
van der Donk et
al.6, demonstrated
that impacted morselized bone graft showed overall good incorporation with
cement. In contrast, other investigators have observed that the incorporation
of structural bone grafts is often
incomplete32,33.
In the group of four hips in the present study that failed after a primary
reconstruction, the bone stock at the time of revision was found to be
satisfactory, with only one hip demonstrating worsening of the defect (from a
cavitary defect to a combined defect). In the group of four hips that failed
after a revision, no hip had progressive bone stock deficiency (two hips had a
cavitary defect both at the time of the index procedure and at the time of
revision, and the other two hips had a combined defect at both time-points).
In all cases, acetabular reconstruction with bone graft was possible in
combination with a standard acetabular implant.
The technique of performing acetabular impaction bone-grafting is demanding
and has pitfalls. On the acetabular side, large trabecular bone chips with a
diameter of between 0.7 and 1 cm should be used because smaller chips with a
diameter of 0.2 to 0.5 cm will produce inferior cup
stability34. The
chips that are produced by most commercial bone mills are too small for
application in the acetabulum. Impaction of the bone grafts must be tight
enough to create stability with use of a hammer and acetabular impactors.
Compressing the grafts with an acetabular reamer in reverse also reduces
initial cup
stability34. An
optimal cementation technique is also essential, including pressurization of
the cement with a seal before introduction of the cup.
According to our current postoperative protocol, these patients begin to
walk on two crutches two days after surgery. For the first six weeks they are
allowed toe-touch weight-bearing, and for the next six weeks they are
permitted to place 50% body weight on the affected hip with use of two
crutches. However, the period of immobilization or restricted weight-bearing
should be adjusted in relation to the complexity of the defects and their
reconstruction.