Although relief from pain is usually achieved following total knee
arthroplasty, limited postoperative range of motion can compromise the
restoration of function. At least 90° of flexion is necessary to perform
daily activities such as climbing stairs or rising from a
chair1,2.
The goal of manipulation following total knee arthroplasty is to increase knee
flexion in patients who have failed to achieve approximately 90° of
flexion postoperatively.
Two previous studies of manipulation following total knee arthroplasty
showed enduring gains in flexion following
manipulation3,4,
whereas a third study showed that the gain in flexion was lost within one year
after
manipulation5.
The purposes of this study were to determine whether any specific factors
could be identified as predictors of the need for manipulation and to
determine whether manipflexion. ulation resulted in an enduring improvement in
knee
Between 1987 and 2001, 6297 posterior cruciate-retaining knee
replacements with Anatomic Graduated Components (AGC; Biomet, Warsaw, Indiana)
were performed in 4063 patients at our institution. Of those knees, 113 (1.8%)
in ninety patients underwent manipulation because of limited flexion following
total knee arthroplasty.
Fifty-five (61%; sixty-six knees) of the ninety patients who underwent
manipulation were women. The average age of the patients who had manipulation
was sixty-five years (range, thirty-four to eighty-four years). Eighty-eight
patients (111 knees; 98%) had undergone total knee arthroplasty because of a
diagnosis of osteoarthritis.
Our indications for recommending manipulation were a failure to obtain
=90° of flexion by two months postoperatively. Patients who declined
manipulation at the two-month follow-up evaluation and had not been in a
supervised physical therapy program were entered into one. If knee flexion did
not increase after one month on this program, the patients were encouraged to
undergo manipulation.
Our rehabilitation protocol after total knee arthroplasty includes walking
on postoperative day 1, active and passive knee flexion on day 2, and hospital
discharge when active flexion of =80° is obtained. Continuous passive
motion was not used in our patients. The surgical technique was the same
throughout the study except that, after 1997, the epicondylar axis was used to
determine femoral component rotation. While the protocol remained unchanged,
the average inpatient length of stay decreased from five days to three days
over the course of the study.
All range-of-motion measurements were performed with use of a goniometer by
a physical therapist or an independent reviewer. Flexion was measured before
total knee arthroplasty, intraoperatively after skin closure, at two months,
at six months, and at one, three, and five years postoperatively. The average
duration of follow-up was 4.6 years (range, six months to fifteen years). Knee
Society scores and tibiofemoral alignment were calculated for each patient
preoperatively and postoperatively.
Manipulation Protocol
After induction of general anesthesia and with the hip flexed to 90°,
the knee was gently manipulated into flexion until audible and palpable lysis
of adhesions was complete.
Physical therapy was instituted in the recovery room within thirty minutes
after the manipulation procedure. With the hip flexed to 90°, the knee was
flexed maximally and held by the therapist for thirty to sixty seconds and
then the hip and knee were allowed to extend. This maneuver was repeated five
times. Between active-assisted flexion and extension by the therapist, the hip
and knee were positioned at 90° of flexion. The patients were progressed
by a physical therapist to active and active-assisted range-of-motion
exercises as soon as they were awake enough to follow commands. Cryotherapy,
in the form of ice packs placed on the distal part of the thigh and anterior
aspect of the knee, was used for all patients at the discretion of the nursing
staff and the physical therapy staff. Outpatient physical therapy sessions
were continued three times a week and included active and passive-assisted
range-of-motion and muscle-strengthening exercises. At the discretion of the
operating surgeon, twenty-two patients (24%) received, in addition to the
standard anesthetic protocol, an indwelling epidural catheter for twenty-four
hours.
Statistics
Two-sample t tests were utilized for side-by-side comparisons of multiple
variables, including average age, body mass index, and preoperative flexion in
the cohorts managed with and without manipulation; postoperative flexion at
one and five years in the manipulation group; ultimate flexion in patients
with preoperative flexion of >90° or =90°; ultimate flexion when
epidural or general anesthesia was used; and ultimate flexion when
manipulation was performed within twelve weeks or more than twelve weeks after
the primary total knee arthroplasty.
The Wilcoxon test was used to compare preoperative pain scores in the
cohorts managed with and without manipulation. Two pain
categories—severe or moderate continuous pain and moderate occasional
pain—were compared with use of chi-square analysis. The two groups were
also compared with respect to postoperative pain scores and tibiofemoral
alignment with use of analysis of variance. Logistic regression was used to
evaluate the predictive value of gender, age, or preoperative alignment on the
need for manipulation. A p value of 0.05 was considered significant.
The mean rate of patients who had manipulation during the study
period was 1.8% (range, 0.7% to 3.1%) per year. Several preoperative factors
were significantly associated with an increased risk of manipulation
(Table I). The average age in
the manipulation group was significantly younger (sixty-five years compared
with seventy-one years; p < 0.0001). Logistic regression analysis revealed
that younger patients had a higher risk of manipulation, with the odds of
manipulation being 1.47 times less for every ten-year increase in age. The
mean amount of preoperative flexion was less in the group that had
manipulation (102° compared with 110°; p < 0.0001). The risk of
manipulation was 1.31 times less for every 10° increase in preoperative
flexion. The preoperative Knee Society pain scores were lower in the
manipulation group (p = 0.0027). Seventy percent of the patients in the
manipulation group reported severe or moderate continuous pain compared with
only 55% in the group that had not had manipulation (p < 0.0001). Although
body mass index was not significantly different between the two groups, the
risk of manipulation was 1.76 times less for every increase of 10
kg/m2 in body mass index (logistic regression). Gender and
preoperative tibiofemoral alignment did not appear to have an influence on the
need for manipulation.
Eighty-one (90%) of the ninety patients had improvement in ultimate knee
flexion following manipulation. Six months postoperatively, the manipulation
group had, on the average, lower pain scores than the group managed without
manipulation (43 and 47 points, respectively; p < 0.0001)
(Table II). Although the
average score improved at one year, the differences remained significantly
lower even at five years (p < 0.0001). Eighty percent of the knees treated
without manipulation were rated as pain-free, whereas 73% of the knees treated
with manipulation were rated as having no pain at five years postoperatively
(Table II).
Before manipulation, the mean flexion had decreased from 102° (range,
30° to 130°) preoperatively to 70° (range, 30° to 100°) (p
< 0.0001) (Table III). After
intraoperative manipulation, flexion significantly increased to a mean of
111° (p < 0.0001). Six months after manipulation, the average flexion
was 94° (p < 0.0001). This improvement was maintained up to five years,
with an ultimate mean flexion of 105° (p < 0.0001), resulting in an
overall mean increase of 35° of flexion.
In knees treated with manipulation that had flexion of >90° before
total knee arthroplasty, the average flexion intraoperatively and at each
follow-up period was significantly higher than that of the knees with flexion
of =90° before total knee arthroplasty
(Table IV).
No significant difference in the results was detected on the basis of the
postoperative timing of manipulation (less than or greater than twelve weeks;
p < 0.3597), the type of anesthesia (general or epidural), or the type of
postoperative pain management (patient-controlled analgesia or continuous
epidural; p = 0.1023).
Complications
One patient with osteoporosis sustained a supracondylar femoral fracture
either intraoperatively or postoperatively while under epidural anesthesia.
Nine knees in patients with continuous pain did not gain flexion with
manipulation.
Five knees (4%; five patients) in the manipulation group underwent
subsequent revision total knee arthroplasty compared with twenty-four (0.5%)
of 4583 knees that had not had manipulation in a previously reported cohort (p
= 0.02)6. Two of the
five revision arthroplasties in the manipulation group were performed for
hematogenous infection at five and ten years postoperatively. The three other
revision arthroplasties were performed for the treatment of tibial component
loosening, femoral component loosening, and a late supracondylar femoral
fracture in one knee each.
The results of the present study indicate that manipulation can
result in significant and lasting improvement in knee flexion. The average
increase in flexion from the measurement made before manipulation to that at
the most recent follow-up was 35°, which is consistent with two previous
studies of manipulation following total knee
arthroplasty3,4;
however, it does not support the findings of a third study that indicated an
initial gain in flexion following manipulation was lost within one week after
manipulation5. While
the flexion from week to week following manipulation was not considered in the
current study, we did observe a steady increase in the average flexion at each
of the follow-up periods up to five years postoperatively.
Nine patients (10%) with continuous knee pain failed to gain flexion
following manipulation. Interestingly, the revision rate was higher in this
group and involved a variety of failure mechanisms seemingly unrelated to
manipulation.
With the numbers available, we did not find that the use of adjunctive
epidural anesthesia for twenty-four hours significantly improved the gain in
flexion following manipulation. The interval between primary total knee
arthroplasty and manipulation did not affect the amount of improvement in
flexion achieved following manipulation. When comparing patients who had
manipulation within twelve weeks after total knee arthroplasty with those who
underwent manipulation between twelve and forty-four weeks, we did not find
that earlier manipulation was more successful at achieving greater
flexion.
Patients with less preoperative flexion had lower ultimate flexion after
total knee arthroplasty compared with patients with greater preoperative
flexion. While patients with preoperative flexion of =90° had an
average improvement of 26° with manipulation, they had less flexion at all
follow-up periods than patients with preoperative flexion of >90°
(Table IV).
The patients who had manipulation were significantly younger than those who
did not have manipulation. Daluga et al. also reported that the patients in
their study who required manipulation were younger than those who had not
required it7.
Unfortunately, while the differences in age and pain scores were significant,
they may not be clinically important because the absolute differences between
pain scores and age are probably not helpful in identifying patients
preoperatively who might require manipulation.
The knees that had manipulation in the current study represent only 1.8% of
the knees that had primary total knee arthroplasty at our institution during
the same time-period. This is a considerably lower rate of manipulation than
previous studies have
described3,4,8.
In a previous study of total knee replacements done at our institution, the
survival rate of the prosthesis was 98.9% at fifteen
years6. However, the
rate of revision total knee arthroplasty was significantly higher in the
patients who underwent manipulation (4%) than the rate that is normally
observed for total knee arthroplasties done at our institution. These
revisions were done for late infection in two patients, tibial collapse and
loosening in one, femoral loosening in one, and distal femoral fracture in one
patient.
It is interesting that the manipulation rate at our institution has not
varied substantially over the last eighteen years, even with improvements in
femoral alignment and orientation, thus indicating that the need for
manipulation may be related to the pain perception of the patient and the
preoperative flexion rather than to the surgical technique of total knee
arthroplasty.
In this study, the need for manipulation was associated with preoperative
pain perception, younger age, decreasing weight, and decreased preoperative
flexion. Although these data do not provide absolute predictors of the need
for manipulation, they do imply that preoperative factors are quite important
in determining postoperative results.
It also appears that manipulation can be performed more than twelve weeks
postoperatively and still be beneficial in gaining flexion. However, in the
patients who underwent manipulation, the ultimate revision rate was
significantly higher than that in the cohort managed without manipulation for
reasons that we cannot explain.
The present study supports the use of manipulation as an effective
procedure to improve and maintain flexion after total knee replacement in
knees that do achieve 90° of flexion in the period up to and beyond twelve
weeks postoperatively. ?