Abstract
Background: The purpose of this study was to evaluate the types and
prevalence of complications associated with bilateral total knee replacement
performed four to seven days apart during a single hospitalization and to
compare them with those associated with bilateral knee replacement performed
sequentially under the same anesthetic session or staged unilateral
replacements performed during separate hospitalizations.
Methods: Using a computerized database and medical records, we
retrospectively evaluated 332 consecutive patients who underwent bilateral
total knee replacement performed by two surgeons. A total of 241 patients
underwent staggered bilateral knee replacement with the procedures performed
four to seven days apart during one hospitalization, twenty-six underwent
sequential bilateral total knee replacement, and sixty-five underwent staged
bilateral knee replacement performed during two separate hospitalizations. The
data on major complications, including death, return to operating room,
myocardial infarction, and pulmonary embolism, and on minor complications,
including atrial fibrillation, deep-vein thrombosis, and urinary tract
infection, were evaluated.
Results: Patients undergoing sequential bilateral total knee
replacement and staged bilateral knee replacement had an overall rate of
complications that was 2.5 times higher than that of the staggered group.
Major complications were rare in all groups, but they occurred most often in
the staged bilateral replacement group. The overall rate of complications for
the patients who had staggered bilateral knee replacement (13%) was
significantly less (p = 0.0009) than that for the patients who had sequential
bilateral knee replacement (35%) or staged bilateral knee replacement (31%).
The length of inpatient stay for those with staggered total knee arthroplasty
was four days longer than that for the sequential arthroplasty group (p =
0.0001).
Conclusions: Staggered bilateral total knee replacement, with the
procedures performed four to seven days apart in a single hospitalization, is
a safe and practical method for performing bilateral total knee
replacement.
Level of Evidence: Therapeutic Level III. See
Instructions to Authors for a complete description of levels of evidence.
Controversy continues about the optimal timing of surgery for patients with
bilateral symptomatic degenerative arthritis of the knee. Bilateral total knee
replacement may be performed with the patient under a single anesthetic
session either simultaneously with two surgical teams or sequentially with one
team; it may be staggered and managed as separate procedures during a single
hospitalization; or it may be staged in two hospitalizations, separated by a
variable period of
time1-7.
For the patient, the physiologic insult from undergoing simultaneous or
sequential procedures is greater than that from separate unilateral
procedures8-10.
The purpose of this study was to compare the early complications associated
with staggered bilateral total knee replacement and those associated with
sequential procedures and staged procedures performed by the same surgeons. We
hypothesized that, in a community setting, fewer complications would occur
following the staggered procedures. We also investigated the differences in
reimbursement to the hospital and surgeon among the three timing
schedules.
Using a computerized patient database and medical records, we
retrospectively identified 332 consecutive patients who underwent primary
bilateral total knee arthroplasty (664 knees) from October 1997 through June
2001. All procedures were performed by one of two surgeons (D.D.G. and
S.G.T.). The data were collected in a prospective fashion; the groups were
assigned retrospectively. There were three groups of patients. The staggered
group underwent bilateral total knee arthroplasty as separate procedures
performed within four to seven days of each other during a single
hospitalization. The sequential group underwent bilateral total knee
arthroplasty performed by a single surgical team during a single anesthetic
session. The staged group underwent two unilateral total knee arthroplasties
performed during separate hospitalizations. Two hundred and forty-one
patients, the majority of patients in this study, underwent staggered
procedures spaced four to seven days apart (average, 4.5 days). Sixty-five
patients underwent staged procedures spaced an average of 70.5 weeks apart
(range, 1.6 to 270.9 weeks). Twenty-six patients underwent sequential
bilateral replacement during a single anesthetic session.
The demographic data for the three groups are shown in
Table I. A total of 319
patients (96%) had a diagnosis of primary osteoarthritis. Preoperative medical
comorbidities were identified in 278 of the 332 patients. Hypertension was the
most common medical comorbidity in all three groups and was present in 50% of
all patients. Other common comorbidities included hypercholesterolemia (20%),
obesity (15%), thyroid disorder (14%), diabetes mellitus (12%), and coronary
artery disease (11%). There were significantly fewer medical comorbidities in
the sequential group than in the staggered and staged groups (p = 0.012) (see
Appendix). In the analysis of specific comorbidities, a significant difference
was found with respect to the distribution of patients with hypertension.
Patients with staged procedures had the highest rate of hypertension (63.1%);
in comparison, the sequential group had a rate of 30.8% (p = 0.014).
During the study period, preoperative autologous blood donation was used by
patients who requested it. Patients with substantial cardiac, pulmonary, or
other serious comorbidities generally underwent staged procedures after
receiving medical clearance from an internist.
Staggered or sequential replacements were generally performed on healthier
patients. If the consulting internist concluded that the patient was not
healthy enough to undergo staggered or sequential procedures, the patient
received a unilateral procedure on the more symptomatic side and then
underwent replacement of the contralateral side at a later date. Patients who
were deemed to be healthy enough to undergo a bilateral procedure were then
evaluated by an anesthesiologist. If the anesthesiologist concurred that the
patient was a candidate for a bilateral procedure, he or she was offered a
staggered procedure. If the patient requested a sequential procedure instead,
the final decision was made in consultation with the surgeon and was based
upon further evaluation of the potential medical risks
(Fig. 1).
If medically stable after the first arthroplasty, patients in the
sequential group then underwent the second arthroplasty. Patients in the
staggered group who had an uncomplicated first knee replacement had the second
knee replacement four to seven days later. If there was any problem
intraoperatively or postoperatively, then the second arthroplasty was
performed electively at a later hospitalization.
All patients underwent arthroplasty in a laminar airflow room and received
perioperative antibiotics beginning thirty minutes prior to incision and
continuing for forty-eight hours. The surgical team wore body-exhaust suits.
All patients were admitted to an inpatient floor postoperatively. All patients
received postoperative anticoagulation treatment with low-dose Coumadin
(warfarin), low-molecular-weight heparin, or aspirin for four weeks. Patients
were examined throughout the hospitalization for clinical evidence of
deep-vein thrombosis, and additional workup was obtained if clinically
indicated. Routine venous Doppler examination at the time of discharge was not
obtained.
We recorded perioperative complications that occurred within the initial
sixty postoperative days, blood transfusion requirements, length of acute
inpatient hospitalization, and the need for placement in a rehabilitation
hospital. A reimbursement analysis that included surgeon, anesthesia, and
hospital charges was performed.
Major complications were defined as death, myocardial infarction, pulmonary
embolism, cerebrovascular accident, deep infection, or a return to the
operating room for any reason. Minor complications included urinary retention,
urinary tract infection, deep-vein thrombosis, pneumonia, superficial
infection, early knee manipulation for poor motion, atrial fibrillation, and
admission to the hospital without monitoring in the intensive care unit.
Statistics
The Fisher exact test was used for comparisons between nominal data, such
as gender, diagnosis, comorbid medical conditions, inpatient rehabilitation
stay requirements, and complications. A Wilcoxon rank-sum test was performed
for comparisons of nonparametric ordinal data. A least squares means test was
used to compare the mean ages among the three groups. The Student t test was
used to compare age at the time of surgery and complications. Odds ratios were
determined to compare minor complications among the groups. The Kruskal-Wallis
test was used to compare reimbursement among the three groups of patients.
When the test for overall group difference was significant, post hoc pairwise
multiple comparisons based on the Kruskal-Wallis rank sums were performed.
Asignificant difference was found in the gender distribution among the
three groups, with the sequential group having more male patients (54%) and
the staged group having more female patients (78%) (p = 0.006). A significant
difference was detected in the mean ages for the staged group (67.2 years) and
the sequential group (59.3 years) (p = 0.0002). Comparisons of age between the
sequential and staggered groups and between the staged and staggered groups
showed no significant difference (p = 0.07 and p = 0.4, respectively). No
significant difference was found among the three groups with respect to the
distribution of the diagnosis (p = 0.16).
The mean length of acute inpatient hospitalization was five days (range,
four to nineteen days) in the sequential group, nine days (range, seven to
twenty days) in the staggered group, and nine days (range, four to twenty-one
days), when both hospitalizations were summed, in the staged group. The
sequential group had a significantly shorter inpatient hospitalization than
the other two groups (p = 0.0001).
An allogenic or autologous blood transfusion was required in 165 patients
(50%). A total of 140 (58%) of the 241 patients in the staggered group and
fourteen (54%) of the twenty-six patients in the sequential group required a
transfusion. In contrast, only eleven (17%) of the sixty-five patients in the
group that had staged procedures required a transfusion at either operation (p
= 0.0001). The median number of units of blood transfused was two (range, one
to six units) in the sequential group, one (range, one to six units) in the
staggered group, and one (range, one to two units) in the staged group.
A greater proportion of patients in the sequential group (31%; eight of
twenty-six) and the staggered group (33.6%; eighty-one of 241) required
skilled rehabilitation services compared with that in the staged group (17%;
eleven of sixty-five) (p = 0.029).
The overall rate of complications was 13% (thirty-two patients) in the
group managed with staggered knee replacements, 35% (nine patients) in the
sequential group, and 31% (twenty patients) in the staged group. The staggered
group had approximately 2.5 times fewer complications than the other groups;
the difference was significant (p = 0.0009). Major complications were rare and
occurred only in the staggered group and the staged group
(Table II). There were no major
complications in the sequential group. The only death was a patient in the
staggered group who had an early postoperative fatal cardiac arrhythmia. With
the numbers available, no significant difference was detected with respect to
major complication rates between the sequential group and the staggered group
(p = 1.0), the sequential group and the staged group (p = 1.0), or the staged
group and the staggered group (p = 0.085).
Minor complications occurred in 12% of the patients in the staggered group,
35% of those in the sequential group, and 25% of those in the staged group
(see Appendix). The odds of a patient undergoing sequential knee replacements
having a minor complication was 3.92 times (95% confidence interval, 1.40,
10.41) greater than the odds of a minor complication occurring in a patient in
the staggered group (p = 0.009). The odds of a patient in the staged group
having a minor complication was 2.64 times (95% confidence interval, 1.23,
5.56) greater than the odds of a minor complication occurring in a patient in
the staggered group (p = 0.012). No significant difference was detected with
respect to the odds of a minor complication occurring in the sequential group
compared with that in the staged group (p = 0.59). The readmission rate for
treatment of a deep-vein thrombosis without pulmonary embolism was 1% for the
staggered group, 3% for the staged group, and 0% for the sequential group.
The age at the time of surgery did not correlate with the prevalence of
major or minor complications. The mean age (and standard deviation) was 66.1
± 9.6 years for the patients with complications and 65.9 ± 9.0
years for those without complications (p = 0.885).
At least one medical comorbidity was identified in fifty-four (89%) of
sixty-one patients with either a major or minor complication and in 224
(82.7%) of 271 patients without a complication (see Appendix). Seven of the
eight patients who had a major complication and 271 (83.6%) of 324 patients
who did not have a major complication were found to have a comorbid condition
(see Appendix).
Complete reimbursement data were available for 253 patients (76%) who had
the surgical procedures performed after December 1997. These included
twenty-one patients (81%) in the sequential arthroplasty group, 186 (77%) in
the staggered arthroplasty group, and forty-six (71%) in the staged
arthroplasty group. All reimbursement data were converted to 2001 dollars with
use of the Consumer Price Index conversion factors made available by the
United States Bureau of Labor Statistics. Hospital reimbursement differed
significantly among the groups. A pairwise comparison of the groups showed a
significantly greater mean hospital reimbursement for the staged group
($18,958.39) compared with the sequential group ($14,291.85) (p < 0.0001)
and the staggered group ($15,506.42) (p = 0.010). No significant difference in
reimbursement was detected between the sequential and staggered groups (p =
1.0) (see Appendix).
Although no significant difference was found with respect to the mean
surgeon reimbursement among the groups, the data demonstrated a trend toward
higher surgeon reimbursement for staged (two-admission) procedures compared
with bilateral procedures in a single hospitalization (p = 0.073) (see
Appendix).
The timing sequences for bilateral total knee replacement have been well
described in the
literature1-5,11-14.
Sequential bilateral knee arthroplasty under a single anesthetic session has
been associated with an increased risk of mortality compared with unilateral
total knee
arthroplasty8. Blood
loss is greater in bilateral
replacement15,16.
Fat and marrow embolism syndrome has also been reported in sequential
bilateral total knee
replacement9,10,17.
Although Ritter et al. reported low complication rates for patients undergoing
sequential total knee
replacement13,
their patients were treated in a highly specialized center for total joint
replacement with resources that may be unavailable to many orthopaedic
surgeons performing knee replacement surgery in a community setting. Our study
examined the three timing sequences of total knee arthroplasty when performed
in a community hospital.
One of the most important concerns regarding the timing of the surgical
procedures is whether the method of replacement increases the mortality rate.
In our study, one death occurred in the staggered group for a prevalence of
0.41%. This mortality rate is comparable with the rate of 0.49% reported by
Parvizi et al.8 in a
study of 2679 patients who had bilateral total knee arthroplasty.
Many authors have shown that blood loss and the transfusion rate are
greater in bilateral knee replacement than in unilateral
replacement1,2,15-17.
In our patients who were managed with bilateral knee replacement during the
same hospitalization, either staggered or sequential, we noted that the
transfusion rate was approximately three times greater than that for the
patients who underwent staged procedures.
Numerous studies have noted that sequential procedures often reduce the
number of inpatient hospital days after the
procedure1,3,4,12,17.
The hospital stay for our patients with sequential arthroplasties was four
days shorter than that for either the staggered group or the staged group.
Some reports have noted that the need for postoperative rehabilitation
increased after bilateral total knee arthroplasty compared with that after
unilateral total knee
replacement2,
whereas other studies have demonstrated that there was less
need1. Our patients
who had bilateral knee replacement during a single hospitalization, either
staggered or sequential, required nearly twice the rate of inpatient
postoperative rehabilitation compared with those undergoing staged
arthroplasty. This increased need for inpatient rehabilitation after a
bilateral replacement during a single hospitalization in some respects
mitigates the reported cost advantages of sequential replacement.
The data for our patients demonstrated a significant difference in hospital
reimbursement for the sequential and staggered groups compared with the staged
group. Greater hospital reimbursement was associated with two hospital
admissions, while the number of inpatient hospital days had a minimal impact
on reimbursement, which was probably related to the diagnosis-related group
reimbursement rates.
A weakness of this study was selection bias in retrospectively constructing
the three groups. The sequential group was healthier, with significantly fewer
medical comorbidities than either the staggered group or the staged group. In
addition, a sequential procedure was performed only at the request of the
patient and was always at the surgeon's discretion; hence, the number of
patients in this group was small. Nevertheless, on the basis of medical
criteria alone, it would have been expected that the sequential group would
have fewer overall complications. However, this group had the highest overall
complication rate of all the groups, confounding the bias introduced into this
study by the patient selection process. Nevertheless, the sequential group did
not have any major complications, and, while no significant difference was
found with respect to the rate of major complications among the groups, our
inability to detect a difference may have been the result of the small number
of patients who received sequential knee replacements.
Minor complications occurred most frequently in the sequential and the
staged groups. This may have been due to the greater surgical insult to the
patients undergoing simultaneous total knee arthroplasty and to the overall
worse general health of the group of patients who had staged procedures.
Other studies have attempted to identify risk factors that preclude or
stratify risk in certain patients who are to undergo sequential bilateral knee
replacement8. In our
study, medical comorbid conditions were present in the vast majority of
patients. However, the presence of a medical comorbidity (or the number of
comorbidities) did not predict whether a particular patient would have a
perioperative complication. Likewise, no particular comorbidity was found to
be associated with a minor or major complication. Increased age was not a
factor in predicting complications despite a large number of patients (132)
who were more than seventy years old. Of these patients, 120 underwent either
staggered or staged procedures, indicating that age was an important
determinant in excluding a patient as a candidate for a bilateral arthroplasty
during a single anesthetic session.
In conclusion, patients who had bilateral knee replacement with the
procedures performed in close succession, either sequentially or staggered,
required more blood transfusions and were more likely to require an additional
inpatient rehabilitation. The sequential group had the shortest mean hospital
stay but the greatest overall rate of complications. Minor complications
occurred less frequently when patients had staggered bilateral knee
replacement, but with the numbers available, no difference was detected among
the groups with regard to major complications. No risk factors that could be
used to predict the occurrence of complications were identified. Bias that was
introduced by the patient selection process reinforces our ultimate conclusion
that staggered bilateral total knee replacement is a safe and effective method
of bilateral knee replacement and is associated with a low overall
complication rate.
Tables presenting medical comorbidities, complications, and reimbursement
comparisons for the three study groups are available with the electronic
versions of this article, on our web site at
(go to
the article citation and click on "Supplementary Material") and on
our quarterly CD-ROM (call our subscription department, at 781-449-9780, to
order the CD-ROM). ?
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