Addition of Clonidine to Ropivacaine in Adductor Canal Block

May 2, 2018 updated by: Borzoo Farhang, University of Vermont

Addition of Clonidine to Ropivacaine in Adductor Canal Block for Postoperative Pain Relief in Total Knee Arthroplasty: A Prospective Randomized Double Blind Placebo Controlled Trial

Total knee arthroplasty (knee replacement) is a common orthopedic procedure for osteoarthritis. This procedure is performed either under general anesthesia or spinal anesthesia; after the procedure in the recovery room, these patients undergo adductor canal block, which is a nerve block to provide 8-14 hours of postoperative pain control. For this nerve block, 15-20 ml of local anesthetic is combined with adjuvant medications to improve the quality of pain control as well as the duration of pain relief. The primary local anesthetic used for adductor canal block is ropivacaine, and the commonly used adjuvants are epinephrine and dexamethasone.

There is conflicting data available in the literature regarding efficacy of addition of clonidine to the local anesthetic injection in peripheral nerve blocks, and there is no data assessing the efficacy of this medication in adductor canal blocks.

Once the consent process is completed, patients are enrolled in two arms. Upon conclusion of surgery, a sealed and coded envelope with either clonidine or the placebo syringe will be given to the acute pain service staff performing the nerve block. This will be mixed with local anesthetic solution and injected in the adductor canal under ultrasound guidance.

The primary outcome measure will be the duration of analgesia, which will be assessed as the time interval between placement of adductor canal block to the first request of opioid analgesic by patients (which will be obtained from hospital electronic medical records). Secondary outcomes will include:

Duration of sensory block, which will be assessed as the time interval between injection of local anesthetic and report of postoperative pain of 3 or more on an 11 point scale (0=no pain; 10= worst pain imaginable) by the patient (this will be assessed every 4 hours).
Duration of motor block, which will be assessed as the time interval between the onset of motor block to complete recovery of motor block by assessing straight leg raise strength (this will be assessed every 4 hours).
Cumulative 24 and 48 hour opioid analgesic use.
Post-block pain scores, evaluated by an 11 point pain score (0-10), which will be done every 15 minutes for the first hour after surgery and every 4 hours thereafter for 24 hours.

Study Overview

Status

Unknown

Conditions

Postoperative Pain

Intervention / Treatment

Study Type

Interventional

Enrollment (Anticipated)

Phase

Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

United States
- Vermont
  - Burlington, Vermont, United States, 05401
    - Recruiting
    - University of Vermont Medical Center
    - Contact:
      
      Borzoo Farhang, DO
      
      Phone Number: 802-881-9927
      
      Email: borzoo.farhang@uvmhealth.org
    - Principal Investigator:
      
      Borzoo Farhang, DO

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

Men and women ages 18 and older
ASA physical status classification system I, II and III (healthy patient or patient with mild to moderate systemic disease)
Patient coming in for elective total knee arthroplasty under general or neuraxial anesthesia and postoperative adductor canal block
Patients staying for at least 24 hrs post operatively
Patients who provide informed consent
Patients presenting for surgery >1 hour in length and <6 hours.

Exclusion Criteria:

History of recent common colds, upper respiratory infections or immune deficiencies
Patients allergic to clonidine
Pregnant women (all women of childbearing age undergo pregnancy testing prior to anesthesia as per UVMMC peri-operative protocol)
Patients who are already on chronic clonidine therapy for management of blood pressure
Patients on chronic opioid therapy defined as more than 10 mg of oxycodone per day (or equivalent doses of other opioid analgesics)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Primary Purpose: PREVENTION
Allocation: RANDOMIZED
Interventional Model: PARALLEL
Masking: QUADRUPLE

Number of Arms

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: Clonidine 50 mcg clonidine + 0.5% ropivacaine + 2 mg dexamethasone + 5 mcg/ml epinephrine in 20 ml solution	Drug: Clonidine 50 mcg Clonidine added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in the treatment group. Drug: Ropivacaine Clonidine or Placebo added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in both treatment and placebo groups. Drug: Dexamethasone Clonidine or Placebo added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in both treatment and placebo groups. Drug: Epinephrine Clonidine or Placebo added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in both treatment and placebo groups.
PLACEBO_COMPARATOR: Placebo 0.5 ml normal saline + 0.5% ropivacaine + 2 mg dexamethasone + 5 mcg/ml epinephrine in 20 ml solution	Drug: Ropivacaine Clonidine or Placebo added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in both treatment and placebo groups. Drug: Dexamethasone Clonidine or Placebo added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in both treatment and placebo groups. Drug: Epinephrine Clonidine or Placebo added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in both treatment and placebo groups. Drug: Placebo Normal saline added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in the placebo group.

Participant Group / Arm

Intervention / Treatment

EXPERIMENTAL: Clonidine

50 mcg clonidine + 0.5% ropivacaine + 2 mg dexamethasone + 5 mcg/ml epinephrine in 20 ml solution

Drug: Clonidine

50 mcg Clonidine added to the solution of 0.5% ropivacaine, 2 mg dexamethasone and 5 mcg/ml epinephrine for adductor canal block-present in the treatment group.

Drug: Ropivacaine