When total hip arthroplasty is performed with cementing of
the femoral component, it is important to obtain adequate circumferential
filling of the femoral canal and adequate interdigitation of the
cement with bone. Although these goals can be achieved with hand-packing
techniques, improved methods for delivery of the cement should enable
most surgeons to provide an adequate mantle of cement more consistently
and reproducibly.
We evaluated the results at a minimum of twenty years after total
hip arthroplasty performed with use of the Charnley prosthesis and
a so-called second-generation cementing technique (use of a distal
cement plug and retrograde filling of the femoral canal with cement). This
series was previously reported on after a minimum duration of follow-up
of fifteen years1. The goal of
the present study was to determine whether the newer technique of
cementing provided better long-term fixation than that achieved
with a hand-packing technique in another series of arthroplasties
performed by the same surgeon.
Between July 1976 and June 1978, the senior one of us (R.C.J.)
performed 357 total hip replacements in 320 patients (135 men [152
hips] and 185 women [205 hips]) with
use of a contemporary cementing technique. The average age of the
patients at the time of the index arthroplasty was sixty-nine years
(range, twenty-four to eighty-eight years). Eighty-two patients
were alive at least twenty years postoperatively, and their average age
at the time of the index arthroplasty was fifty-nine years (range,
twenty-four to eighty-five years). The results in this group were
compared with those after 330 total hip replacements performed in
262 patients with use of a hand-packing technique of cementing.
The surgery in those patients was performed, between July 1970 and
April 1972, by the same surgeon, with use of the same prosthesis,
and the patients had a comparable duration of follow-up2. The average age at the time of the
index arthroplasty in that group was sixty-five years (range, twenty-nine
to eighty-six years). The operative techniques for the two groups
have been previously described1,2.
With the so-called contemporary femoral cementing technique, the
canal was prepared by removal of all loose cancellous bone and by
meticulous drying. A cement plug was placed distally, and a cement
gun was used to introduce cement in a retrograde manner. No seal
was placed over the proximal opening of the femoral canal to better
pressurize the cement. A Charnley hip prosthesis (Zimmer, Warsaw,
Indiana), consisting of a stainless-steel polished flatback femoral
stem with a 22.25-mm-diameter head and an ultra-high molecular weight
polyethylene acetabular component (sterilized by gamma irradiation
in air) with an outer diameter of either 40 or 44 mm, was used in
all patients in both groups. Both components were inserted with
Simplex-P cement (Howmedica, Rutherford, New Jersey).
We attempted to interview all living patients and the families
of the patients who had died. The living patients either returned
for clinical and radiographic follow-up or, if they were unable
to return, were asked to send radiographs (made locally) to us for
evaluation. All living patients were evaluated in person or were
interviewed by telephone with use of a standard system of terminology
for reporting results as described by one of us (R.C.J.) and colleagues3. The evaluators were not blinded
to the outcome results.
At a minimum of twenty years after the operation, eighty-two
patients (ninety-one hips) were still alive, 234 patients (262 hips)
had died, and four patients (four hips) had been lost to follow-up.
Thus, the status of 353 hips (>98% of the original
357 hips) was known. Of the eighty-two patients (ninety-one hips)
who were alive, forty-five (fifty-one hips [56%])
were evaluated both clinically and with an anteroposterior radiograph
of the pelvis that included the tip of the femoral stem. Thirty-three
of the patients (thirty-six hips) returned for an examination, and
twelve (fifteen hips) sent radiographs that had been made elsewhere.
The remaining thirty-seven patients (forty hips) declined to have
a radiograph made and were evaluated on the basis of a telephone interview
only. Of these forty hips, twenty-one had been followed radiographically
for a minimum of fifteen years after the index procedure; five,
for a minimum of ten years; ten, for a minimum of five years; and
four, for less than five years.
The prevalence of revision was calculated on the basis of 353
hips (all except the four that had been lost to follow-up). The
prevalence of radiographic loosening without infection was determined
on the basis of 336 hips (all except those that had been revised
because of infection or dislocation and the four hips that were
lost to follow-up). The prevalence of revision at least twenty years after
the index operation was calculated on the basis of the ninety-one
hips in the eighty-two living patients. The prevalence of radiographic
loosening without infection at least twenty years after the index
operation was calculated on the basis of the fifty-one hips for
which radiographs were made at the latest follow-up visit; those that
had been revised because of dislocation or infection were excluded
from this analysis. The clinical follow-up data at least twenty
years after the index operation were evaluated on the basis of the
ninety-one hips in the eighty-two living patients. Similar calculations
were made for the cohort managed with the hand-packing technique
of cementing. Clinical results in both serieswere
evaluated with use of a standard system of terminology for reporting
results3.
Radiographic Evaluation
Radiographic evaluation of loosening of the acetabular and femoral
components and osteolysis was the same for the patients who were
managed with the contemporary cementing technique and those who
were managed with the hand-packing technique1-16.
One of the two observers (J.J.C.) was the same for both groups.
The wear measurements for both groups were performed by the same
observer (J.P.O.). The methods for all of these observations have
been previously reported1,2. The
technique for the cementing of the femoral component was graded
according to the criteria defined by Schmalzried and Harris16.
Statistical Analysis
The Kaplan-Meier17,18 method
was used to evaluate survival of the implant with regard to revision
or loosening, or both. Survivorship curves with corresponding confidence
intervals were generated, with failure defined according to six end
points: (1) revision for any reason; (2) revision because of aseptic
loosening; (3) revision because of aseptic loosening of the acetabular
component; (4) revision because of aseptic loosening of the femoral
component; (5) loosening of the acetabular component, defined as
definite or probable radiographic loosening or revision because
of aseptic loosening; and (6) loosening of the femoral component,
defined as definite or probable radiographic loosening or revision
because of aseptic loosening19-21.
The clinical and radiographic results were analyzed with use
of the two-tailed Fisher exact test for categorical variables. The
Wilcoxon rank-sum test was used to compare rates of wear according
to categorical variables, as these rates are not normally distributed.
The Spearman correlation coefficient was used to analyze the association
between patient age and component wear as well as that between weight
and wear. The log-rank test was used to compare the survivorship
curves of the group managed with the contemporary cementing technique
with those of the group managed with the hand-packing technique.
In the group managed with the contemporary cementing technique,
the average age of the eighty-two patients who were still alive
at least twenty years postoperatively was eighty-two years (range,
forty-five to 106 years) at the time of follow-up. For the 234 patients
who had died, the average age at the time of death was eighty-two years
(range, fifty-five to 108 years). Forty-nine patients had died in
the first five years after the index arthroplasty; fifty-nine, between
five and ten years after the arthroplasty; eighty-one, between ten
and fifteen years; and forty-five, between fifteen and twenty years.
Revision of the Original Prosthesis
Of the 353 hips that had not been lost to follow-up, thirty-nine
(11.0%) had had a revision and two (<1%) had
had a Girdlestone resection arthroplasty during the follow-up period.
Twenty-two hips (6.2%) had been revised because of aseptic
loosening of the femoral or acetabular component, or both (two hips);
seven (2.0%), because of loosening with infection; and
ten (2.8%), because of dislocation. The two resection arthroplasties were
performed because of loosening with infection; both were done in
patients who died before the time of the latest follow-up evaluation.
Of the ninety-one hips in the eighty-two patients who were alive
at a minimum of twenty years, twenty-one (23%) had been
revised: fifteen (16%), because of aseptic loosening of
the femoral or acetabular component, or both (two hips); one (1%), because
of loosening with infection; and five (5%), because of
dislocation. Only one hip was revised in the interval between the
fifteen and twenty-year follow-up evaluations. That revision was
performed because of a fracture of the femoral component.
Of the nine infections, eight developed early (less than five
years postoperatively) and one developed ten years after the index
procedure. Six of the nine hips were successfully treated with a
revision. One hip needed a second revision but was stable at the
fifteen-year follow-up evaluation and until the death of the patient,
according to a relative. All reimplantations were performed as a one-stage
procedure. The remaining two hips had a Girdlestone resection arthroplasty.
Of the 336 hips for which the outcome was known at the latest
follow-up evaluation and that had not been revised because of dislocation
or infection, sixteen (4.8%) had been revised because of
aseptic loosening of the acetabular component; four (1.2%),
because of aseptic loosening of the femoral component (three had
a fracture of the stem); and two (<1%), because
of loosening of both components. Of the eighty-five hips in the patients
who were still alive at least twenty years after the initial arthroplasty
and had not had a revision because of infection or dislocation,
ten (12%) had been revised because of aseptic loosening
of the acetabular component; three (4%), because of aseptic
loosening of the femoral component; and two (2%), because
of loosening of both components. The outcomes in both the group
managed with the contemporary cementing technique and the group
managed with the hand-packing technique are compared in Tables I and II.
Other Complications
Twenty-five (7.1%) of the entire series of 353 hips
and nine (10%) of the ninety-one hips in the living patients (including
those that had had a revision because of dislocation) had dislocated
at the time of the latest follow-up evaluation. The trochanteric
wires had been removed because of bursitis in twelve (3.4%)
of the 353 hips and in six (7%) of the ninety-one hips.
Satisfaction
Of the ninety-one hips in the patients who survived at least
twenty years after the total hip arthroplasty, eighty-seven (96%)
were considered by the patient to have better function; eighty-five
(93%), to be less painful; and eighty-five (93%),
to have a satisfactory result. Three patients were dissatisfied
because of recurrent dislocation after a revision performed because
of dislocation, and one was dissatisfied because of a 3-cm limb-length
discrepancy after a revision performed because of aseptic loosening.
Additionally, one patient was displeased that a revision had been
needed because of aseptic loosening even though, after the revision,
the patient was doing well. One patient’s family could
not give a reason for the dissatisfaction.
Radiographic Results
Radiographs were made at least twenty years after the index arthroplasty
for fifty-one (56%) of the ninety-one hips in the patients
who were still alive (Fig. 1). Seventy-four (81%) of
the hips in the living patients had a radiograph made at least fifteen
years after the arthroplasty. In the entire series of 353 hips,
fifty-one (14.4%) had a radiograph made at least twenty
years postoperatively and 116 (33%) had a radiograph made at
least fifteen years postoperatively. The average interval between
the index arthroplasty and the most recent radiograph was nine years
in the entire series of 353 hips and 16.8 years for the ninety-one
hips in the living patients. A comparison of the radiographic results
with those in the group managed with the hand-packing technique
is provided in Table I.
Grade of the Cementing Technique
The immediate postoperative radiographs of the hips were used
to grade the cementing technique according to the criteria of Schmalzried
and Harris16. Of the ninety-one
hips in the patients who were alive at least twenty years after
the index arthroplasty, nineteen (21%) had a grade-A cement
mantle; thirty-eight (42%), grade-B; nine (10%),
grade-C1; and twenty-two (24%), grade-C2. Of the 353 hips
in the entire series, fifty-four (15.3%) had a grade-A
cement mantle; 194 (55%), grade-B; twenty-four (6.8%),
grade-C1; and eighty-four (23.8%), grade-C2. Of the sixteen
hips that had aseptic loosening of the femoral component, two had
a grade-A cement mantle; five, grade-B; three, grade-C1; and six, grade-C2.
In the three hips that had loosening of the femoral component as
the result of a fracture of the stem, the cementing technique was
classified as grade A, grade B, and grade C2 (one each).
A significant association was found, with use of the Fisher exact
test, between the grade of the cementing technique and aseptic loosening
of the femoral component (that is, better results were associated
with the better cementing technique) (p = 0.03). With the
numbers available, we could detect no association between the grade
of the cementing technique and revision performed because of aseptic
loosening of the femoral component (p = 0.18).
Wear and Osteolysis
Wear of the acetabular component was measured in the fifty-one
hips that had been followed radiographically for at least twenty
years. The average amount of linear wear was 0.094 mm (range, 0.00
to 0.396 mm) a year. The calculated volumetric wear was 36.5 mm3 (range, 0.00 to 155.5 mm3) a year. Revision because of aseptic
loosening of the acetabular component was associated with linear
wear (p = 0.044), according to the Wilcoxon rank-sum test; the
average rate of wear was 0.155 mm a year for the revised components
compared with 0.078 mm a year for the stable components. With use
of the Spearman coefficient, we could not detect a significant difference between
the rate of wear and the patient’s weight (p = 0.22)
or height (p = 0.46) or the grade of cementing technique
(p = 0.73).
Of the eighty-five hips in the patients who survived at least
twenty years and had not had a revision because of infection or
dislocation, twenty-eight (33%) had osteolysis in femoral
zone VII, six (7%) had osteolysis in one or more of the
other six femoral zones, and five (6%) had osteolysis on
the acetabular side alone. The prevalence of radiolucent lines (of
any thickness) at the prosthesis-cement interface in femoral zone
I (so-called debonding of the femoral component) was 22% (nineteen
of eighty-five hips).
Radiographic Signs of Loosening
Of the ninety-one hips in the patients who survived at least
twenty years, eighty-five were not revised because of deep infection
or dislocation. Fifty-one (56%) of the ninety-one hips
had at least twenty years of radiographic follow-up, and seventy-four
(81%) had a minimum of fifteen years of radiographic follow-up.
Of the eighty-five hips, ten (12%) had loosening of the
acetabular component (definite in six and probable in four) and four
(5%) had definite loosening of the femoral component. Six
hips (7%) had possible loosening of the acetabular component,
and no hip had possible loosening of the femoral component. Of the
original cohort of 336 hips that had not had a revision because
of infection or dislocation, twenty-five (7.4%) had loosening
of the acetabular component (definite in sixteen and probable in nine)
and ten (3.0%) had loosening of the femoral component (definite
in nine and probable in one). Forty-eight acetabular components
(14.3%) and one femoral component (<1%)
were possibly loose.
The combined prevalence of definite or probable radiographic
signs of loosening of the femoral component, according to the modified
criteria of Harris et al.10, and
of actual aseptic loosening of the femoral component necessitating
revision was 4.5% (sixteen of 353 hips) overall, 10% (nine)
of the ninety-one hips in the eighty-two living patients, 16% (eight)
of the fifty-one hips that had at least twenty years of radiographic
follow-up, and 5% (six) of the 116 hips that had at least
fifteen years of radiographic follow-up. Ten femoral components
had radiographic signs of loosening at the time of the fifteen-year
follow-up study1; hence, six additional
femoral components had loosened in the five-year interval after
the previous study. The combined prevalence of definite or probable
radiographic signs of loosening of the acetabular component14 and of aseptic loosening of the
acetabular component necessitating revision was 12.8% (forty-three
of 336 hips) overall, 24% (twenty-two) of the ninety-one
hips in the eighty-two living patients, 29% (fifteen) of
the fifty-one hips that had at least twenty years of radiographic follow-up,
and 22% (twenty-six) of the 116 hips that had at least
fifteen years of radiographic follow-up (Table I).
Loosening of both the acetabular and the femoral component was
not associated with the patient’s age at the time of replacement,
according to the log-rank test (p = 0.81 and 0.28, respectively).
Revision performed because of aseptic loosening of the acetabular
component was strongly associated with patient age (p = 0.0001).
In addition, a significant relationship was found between age and
revision performed because of aseptic loosening of the femoral component
(p = 0.03).
With the numbers available, no association was found between
loosening of the acetabular or the femoral component and gender
(p = 0.11) or diagnosis.
The average weight was 185 lb (84 kg) for the patients who had
aseptic loosening of the femoral component compared with 160 lb
(73 kg) for those who had a stable hip replacement. However, with
the numbers available, the difference was not significant (p = 0.06).
Survivorship Analysis
At the latest follow-up evaluation, 312 (88%) of the
353 original prostheses were functioning or had been in place when
the patient died. Of the ninety-one hips in the eighty-two patients
who were alive at least twenty years after the arthroplasty, seventy
(77%) were still functioning with the index prosthesis
in place (Table II).
Kaplan-Meier17,18 survivorship
analyses (with 95% confidence intervals) were performed
to compare the survival rates of the Charnley total hip replacements
inserted with a contemporary cementing technique and those inserted
with a hand-packing technique of cementing, as reported by two of
us (R.C.J. and J.J.C.) and colleagues2,
after a minimum duration of follow-up of twenty years. With revision
for any reason as the end point, the probability (and 95% confidence
interval) of survival of the prosthesis was 82% ±
4% and 86% ± 8%, respectively
(p = 0.037, log-rank test) (Fig. 2-A). With revision because of aseptic
loosening as the end point, the probability of survival was 88% ±
4% and 88% ± 8%, respectively
(p = 0.339, log-rank test) (Fig. 2-B). With revision because of aseptic
loosening of the femoral component as the end point, the probability
of survival was 98% ± 5% and 96% ±
3%, respectively (p = 0.290, log-rank test) (Fig. 2-C). With revision
because of aseptic loosening of the acetabular component as the
end point, the probability of survival was 90% ±
4% and 92% ± 8%, respectively
(p = 0.127, log-rank test) (Fig. 2-D). With aseptic radiographic loosening
of the femoral component as the end point, the probability of survival was
87% ± 10% and 92% ±
14%, respectively (p = 0.044, log-rank test) (Fig. 2-E). With aseptic
radiographic loosening of the acetabular component as the end point,
the probability of survival was 58% ± 4% and
84% ± 14%, respectively (p < 0.0001,
log-rank test) (Fig. 2-F).