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Abstract:
Introduction: We report the results of a prospective randomised
trial comparing different modalities of post operative analgesia
in unilateral total knee replacement(TKR) patients.
Methods: 90 patients aged between 50 to 80 years undergoing
unilateral TKR were randomised into 3 groups.
Group 1:. Patients only received patient controlled morphine
analgesia (PCA). (control)
Group 2: Patients received PCA and intra-articular marcaine
via continuous infusion pump.
Group 3: Patients received PCA and intra-operative periarticular
injection of steroid and marcaine.
Visual analogue pain scores (VAS) , morphine consumption via PCA,
number of days to ambulation, active range of movement(AROM) of
operated knee, and length of stay(LOS) were the primary outcomes
measured.
Results:Adequate pain control achieved in all 3 arms.
Group 3 demonstrates :
1.
significant reduction in pain scores (p= 0.002) in the
first 6 hours post surgery.
2.
Significant reduction in the total morphine usage (p=0.042).
3.
Decreased LOS compared to Group 1 (p=0.006) and Group 2
(p=0.01)
The number of days to ambulation, and AROM of the operated knee
during the inpatient stay were similar in all 3 groups.The mean
duration of surgery for Group 2 (100min +/- 23) was
significantly longer compared to the other groups (p=0.03).
After 24 months of follow up, no post surgical complications
(eg, infection) were demonstrated in this study.
Conclusion: The periarticular injection of analgesia with
steroid appears to be a safe and effective modality for pain
control post TKR and demonstrates superiority over both control
and infusion arms.
J.Orthopaedics 2010;7(1)e11
Keywords:
knee; arthroplasty; analgesia
Introduction:
Total knee replacement (TKR) is a major surgical procedure, with
patients often requiring large amounts of post-operative
analgesia. It has been reported that more than 50% of patients
receive suboptimal pain control (1) and half of all
patients undergoing total knee replacement will experience
severe pain (2,3) in the early post op period.
Effective pain management is essential for the early recovery
and rehabilitation after total knee replacement. No amount of
patient education and encouragement can motivate patients to
undergo an accelerated rehabilitation program, if pain control
is not achieved. Hence it cannot be overemphasized that the
focus of any total knee post operative rehabilitation program
should be in controlling post operative pain.
Post operative analgesia with intravenous patient controlled
analgesia with a narcotic has been the gold standard. However ,
it is not without its detrimental and unwanted side effects.
Current methods of post operative pain control include a
multimodal regimen of oral analgesia combined with epidural
analgesia or continuous peripheral nerve blockade, both of which
have risk of side effects and demand expertise(4,5,6).The
concept of multimodal pain control including the use of peri
articular injections has received increasing interest in the
recent literature.(7,8,9)
The use of non-opiod analgesia may possibly decrease or
eliminate opiod use. Better pain management would also encourage
early mobilisation of patients, shorten length of stay and
reduce complications associated with prolonged bed rest(10).
We report the results of a prospective randomised trial
comparing intra-articular anaesthetic infusion to
patient-controlled morphine analgesia (PCA) alone or
intraoperative periarticular injection of anaesthetic and
steroids, as a modality for pain management after TKR.
Materials
and Methods:
We obtained approval for our study protocol from our hospital’s
ethics committee (IRB) and obtained written informed consent
from each patient.
Statistical analysis was performed with SPSS statistical
software. A power analysis was performed to determine the number
of subjects required. To demonstrate a P value less than 0.05,
it was determined that 30 patients were needed in each group for
a total number of 90.
A total of 90 patients aged between 50 to 80 years undergoing
unilateral TKR were randomised into 3 groups below using
randomization tables.
Group 1:. Patients only received PCA. (This is the control
group).
Group 2: Patients received PCA and intra-articular marcaine
via continuous infusion pump for 2 days post surgery.
Group 3: Patients received PCA and intra-operative periarticular
injection of steroid and marcaine.
Exclusion criteria included patients undergoing bilateral total
knee arthroplasties, patients with previous surgeries to the
knees, immunodefiency, hypothyroidism, renal failure and
allergies or intolerance to any component of the injection or to
oral non-steriodal anti-inflammatory medication..
Group 1 received PCA which consists of morphine given as a bolus
of 1mg, followed by patient controlled dose of up to 8mg/hour
and a lock out time of 5 minutes.
The same PCA was used in groups 2 and 3, in order to compare the
amount of morphine consumption used across the three groups and
also to provide “rescue” for breakthrough pain if it occurs.
Group 2 received an initial loading dose of 20ml 0.5% marcaine
given intra-articular after wound closure, followed by a
continuous infusion of 0.25% marcaine given at 4ml/hr (
2ml/site using dual cathether). This is achieved by preparation
of the intra articular marcaine perioperatively into a small
infusion container (Figure A). The patient carries the container
until it is completely emptied of its contents after 48 hours.
Figure A: The apparatus used to set up the intra
articular marcaine continuous infusion.
Group 3 received periarticular injection of 20mls 0.5% marcaine
mixed with 50mg of triamcinolone, diluted to a total of 40mls.
The anaesthetic was then injected into the deep tissues of the
knee pre and post liner insertion and reduction. (Figure B)
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Before insertion of liner and reduction
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After liner insertion and reduction
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|
Posterior capsule
Posteromedial and posterolateral structures
|
Extensor mechanism
Synovium
Capsule
Pes anserinus, anteromedial capsule, and periosteum
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Figure B: Table showing the periarticular injection
sites before and after liner insertion.
Meticulous hemostasis was achieved prior to wound closure after
the leg tourniquet was deflated. No drains were used in our
study, ensuring no leakage of the injected components.
All patients in this study received intravenous antibiotics,
cephazolin 1 gram 8 hourly for 24 hours postoperatively.
Standard post operative analgesia given included paracetamol 1
gram every 6 hours and etoricoxib 120mg once daily.
Visual analogue pain scores (VAS) , morphine consumption via PCA,
number of days to ambulation, active range of movement(AROM) of
operated knee, and length of stay(LOS) were the primary outcomes
measured.
Results :
Total visual analogue pain scores were reduced in all 3 arms (p
>0.05) , implying adequate pain control post operatively.
However in the first 6 hours post surgery, Group 3 has
statistically significant reduction in pain scores compared to
Group 1 and 2 respectively (p= 0.002, 0.028).(Figure D)
Figure D: VAS scores significant reduction in group 3 in
the first 6 hours.
The number of days to ambulation, and AROM of the operated knee
during the inpatient stay were similar in all 3 groups.
The age and BMI profiles of the patients were similar across the
3 groups. There were no significant difference in length of stay
, and the number of days taken for the patient to ambulate.
The mean duration of surgery for Group 2 (103.25 min +/- 23) was
significantly longer compared to the other groups (p=0.03) and
is attributed to the additional time taken to prepare and
insert the intra articular infusion pump intraoperatively.
(Figure C).
| |
Group 1 |
Group 2 |
Group 3 |
|
|
Age (years) |
69.3 |
70.4 |
65.8 |
p>0.05 |
|
BMI |
27.4 |
28.03 |
29.1 |
p>0.05
|
|
LOS (days) |
5.2 |
5.5 |
5.4 |
p>0.05 |
|
Ambulation (days) |
2.4 |
2.3 |
2.3 |
p>0.05
|
|
Op duration (minutes) |
84 |
103.25 |
83.1 |
P<0.05 |
Figure C: Significantly longer duration of surgery in
group 2.
Total morphine usage was reduced in both Groups 2 (p=0.51) and
Group 3 with statistically significant reduction demonstrated in
Group 3 (p=0.042). (Figure E)
Figure E: Significant reduction in morphine usage seen in
group 3.
No immediate post surgical complications (eg, infection, wound
breakdown, bleeding, deep vein thrombosis) and complications
associated with the use of continuous intra-articular infusion
pump, and periarticular steroid injection were demonstrated in
this study.
Discussion :
Our knowledge and understanding of the pain-generating process
is improving, and so does our ability to control pain especially
in the postoperative period. However, the concept of pain is
still not fully understood, which is a complex phenomenon
controlled by humeral, neural and cellular mechanisms, with a
strong emotional and psychologic component.
A multimodal protocol is therefore relevant in this context and
this includes preoperative patient education and clarification
of expectations, preemptive analgesia, good anaesthesia
technique, meticulous surgical technique to minimise tissue
trauma, intraoperative agents and postoperative analgesia and
accelerated rehabilitation protocol.
Ranawat et al(11) have demonstrated that the right
cocktail of periarticular injection offers the most effective
pain control with the least amount of side effects. The safety
and efficacy of this injection has been duplicated by other
authors as well.
A local study done in patients undergoing unicondylar knee
arthroplasty(12) also showed the effectiveness of the
local periarticular injections of marcaine and steroids.
The reported complications of intra articular steroids are rare
and this include septic arthritis, tissue atrophy, tendon
ruptures and avascular necrosis(13). By observing
strict asepsis and stringent exclusion criteria, we did not
encounter any of the above complications in our study at 24
months of follow up.
The use of continuous intra-articular infusion of local
anaesthetic post surgery has been an effective modality for post
operative pain control in arthroscopic shoulder and knee
surgeries(14). In open joint surgeries such as TKR,
mixed results were reported by various authors(15,16)
However, we were unable to demonstrate any advantages of the use
of continuous intra articular marcaine infusion over the PCA
morphine.
In this study, we conclude that periarticular injection of
marcaine and steroid is superior and effective because it
decreases pain significantly in the immediate post operative
period, decreases morphine consumption and there is no increased
risk of infection.
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