Objectives The aim of this study is to examine the effect of CACB on decreasing opioid
consumption, increasing the Quality of Recovery (measured via QoR-15) total score and
decreasing opioid-related side effects. Investigators will also assess the rate of
readmissions in primary knee arthroplasty patients.
Rationale
Pain management in knee arthroplasty patients poses unique challenges for the
anesthesiologist, especially in the immediate post-operative period. Early postoperative
analgesia is limited to a unimodality of intravenous opioids. Recently, adductor canal blocks
have started to replace femoral blocks, as this technique can provide similar analgesic
results while avoiding the quadriceps muscle weakness associated with femoral nerve blocks.
The use of a continuous adductor canal catheter in the post-discharge phase shows promising
as the next step in knee arthroplasty pain management allowing for shorter lengths of stay or
even same day discharge (3).
Significance and Innovation
Total knee arthroplasty (TKA) is the second most common inpatient surgery in the U.S. and
Canada, and is associated with severe postoperative pain, limiting early ambulation and
optimal functional recovery. Perioperative opioid use has been linked with many adverse
outcomes including opioid dependence. This study aims to demonstrate the utility of CACB as
an adjunct strategy to reduce opioid consumption and improve quality of recovery in primary
knee arthroplasty patients. The innovation in this approach lies not only in less opioid
consumption and opioid induced side effects but also in reducing the burden of postoperative
pain, leading to an enhanced recovery and better quality of life. Establishing the safeness
of this method in an outpatient setting may have the additional impact of decreasing health
care costs and may lead to reduce opioid prescriptions on discharge from the hospital.
This will be the first study assessing patient's reported quality of recovery after receiving
CACB for primary knee arthroplasties. Investigators expect that that the use of CACB will
improve patients' quality of recovery, alleviate pain and also reduce opioid consumption and
side effects.
Methodology
This will be a prospective, randomized double blind placebo controlled clinical trial. There
will be two arms of treatment: intervention and control group. Preoperatively patients will
be allocated at random to receive either Continuous adductor canal block (CACB) (intervention
group) or sham continuous adductor canal block (ShACB) (control group).
Work Plan
This prospective trial would include unilateral primary TKA done under Fastrack protocol. The
subjects will have their surgeries booked in advance and they will be submitted to the pre
anesthesia consult at the Pre-Admission Unit a few days before the surgery. The study
proposal will be explained to the patients at time of preadmission consult. They will receive
a booklet with information about the study and the Consent Form that they will bring home
with them. Patients will be randomized to one of the two groups using a computer-generated
random numbers table. The elastomeric pumps to be used connected to the catheter will be
previously prepared by hospital pharmacy, accordingly to the randomization made and the
subject study number, with no identification of the content (NaCl 0.9% or Ropivacaine 0.2%).
All patients will receive the same perioperative management. The only difference will be the
postoperative continuous perineural infusion: the CACB group will receive an infusion of 0.2%
ropivacaine 5mL/h and ShACB group will receive an infusion of NaCl 0.9% 5mL/h. Patients will
initially be brought to a dedicated block room where a safety checklist will be performed by
the block room team before performing the block. Standard Canadian Anesthesia Society
monitoring will be provided. After surgery, the patient will be taken to the Post Anesthesia
Care Unit. At this moment, an Arrow® (StimuCath® Continuous Peripheral Nerve Block Catheter)
continuous adductor canal block catheter will be inserted using a Sonosite Edge II ultrasound
machine. The patient may be discharged home after achieving the discharge criteria, keeping
the peripheral nerve catheter with the same infusion rate for the planned time. The adductor
canal catheter will infuse for 48 hours. Prior to going home, patients will receive education
and written information (educational pamphlet) regarding monitoring for local anesthetic
systemic toxicity symptoms, possible CABC associated complications including potential
transient muscle weakness, and instructions on patient removal of the catheter after 48
hours. The study coordinator will collect the data once a day at 24, 48, 72 hrs, seven, 30
and 90 days postoperatively. Data collection will require at maximum 15 minutes.
Sample Size Sample size justification was based on the primary outcome, and the primary
objective. The sample size was calculated based on previous study (12) that showed a 48-hour
opioid consumption of 30mg (+/- 15 mg) morphine equivalents in knee replacement surgeries at
our institute. Investigators anticipate a 50% decrease of opioid use in the intervention
group with an alpha of 0.05, power of 80%, and an enrolment ratio of 1:1 (between the 2
groups). This will require 16 subjects in each group for a total of 32 patients. To
compensate for 15 to 20% anticipated dropouts from the study, investigators plan for an
inclusion of 40 patients.