Location of Injection of Local Anesthetics in the Adductor Canal Block

Study Overview
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Brief Summary
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The adductor canal block (ACB) is the standard of care for analgesia after Anterior Cruciate Ligament (ACL) repair. ACB is performed by injecting local anesthetic (freezing) in the subsartorial canal in the thigh which is about 7-10cm long. Preliminary evidence suggests that different injection sites within the canal may produce different degrees of analgesia and quadriceps motor block. This trial seeks to determine the effects of various ACB injection sites on postoperative analgesia and motor power following ACL repair.

Detailed Description
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Adductor canal block (ACB) is replacing femoral nerve block (FNB) as the peripheral nerve block of choice for knee surgery. The ACB aims to inject local anesthetics (LA) within the neurovascular sheath in the subsartorial adductor canal around the femoral nerve. The point where the sartorius muscle crosses over the femoral artery is generally the accepted site for performing ACB. Clinically, injecting LA in the adductor canal blocks the sensory innervation of the knee and thus offers pain relief that is similar to FNB while conserving motor power around the knee. While these benefits are desirable, the exact location for performing ACB that ensures these benefits, remains debatable. The subsartorial adductor canal itself is 7-10cm long and the anatomical location of the sensory and motor nerves that innervate the knee and its surrounding muscles in this canal may vary. This randomized controlled trial is designed to identify and refine the ACB technique by clinically determining the effects of various ACB injection locations on postoperative analgesia and quadriceps motor power following ACL repair.

Official Title
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Location of Injection of Local Anesthetics in the Adductor Canal Block: A Randomized Controlled Trial of the Effect on Postoperative Analgesia and Motor Power

Conditions
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Anesthesia, Adductor Canal Block

Intervention / Treatment
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* Drug: lidocaine
* Drug: ropivacaine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients booked for anterior cruciate ligament surgery under general anesthesia English speaking BMI <38 kg/m2 Exclusion Criteria: Refusal or inability to provide informed consent Allergy to local anesthetics Contraindication to regional anesthesia including coagulopathy or bleeding - diathesis Infection Nerve Injury at the site of the nerve block Malignancy at the site of the nerve block History of drug and/or alcohol dependence History of long term opioid intake or chronic pain disorder History of pre-existing neuropathy in the operative leg History of significant psychiatric conditions that may affect patient assessment Inability to understand the informed consent and demands of the study Allergy to any of the components of multi-modal analgesic regimen Revision ACL repair

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Adductor Canal Block- Injection -Site A<br>AC Block-Injection (lidocaine 2% and ropivacaine 1%) Site A - after the sartorius muscle crosses over the femoral artery | Drug: lidocaine<br>* Local anesthetic<br>* Other names: Xylocaine;Drug: ropivacaine<br>* Local anesthetic<br>* Other names: Naropin;|
| Active Comparator: Adductor Canal Block - Injection -Site B<br>AC Block-Injection (lidocaine 2% and ropivacaine 1%) Site B - before the sartorius muscle crosses over the femoral artery | Drug: lidocaine<br>* Local anesthetic<br>* Other names: Xylocaine;Drug: ropivacaine<br>* Local anesthetic<br>* Other names: Naropin;|
| Active Comparator: Adductor Canal Block -Injection -Site C<br>AC Block-Injection (lidocaine 2% and ropivacaine 1%) Site C - as the sartorius muscle crosses over the femoral artery | Drug: lidocaine<br>* Local anesthetic<br>* Other names: Xylocaine;Drug: ropivacaine<br>* Local anesthetic<br>* Other names: Naropin;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cumulative 24 Hour Oral Morphine Equivalent Consumption | Post-Operative Analgesia | 24 hours | 
| Motor Power - Peak Force as measured by a dynamometer | Percentage decrease in quadriceps motor strength at 30 minutes following adductor canal block compare to baseline | 30 Minutes post Block | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Opioid Consumption | Intra-operative opioid consumption | During surgical procedure | 
| Total opioids in Post Anesthetics (PAC) | Cumulative oral morphine equivalent consumption in PACU | Total length of time in PACU (total time in minutes from arrival in PACU to discharge to the Surgical Day Care is between 60-180 minutes | 
| Pain Scores - Questionnaire | Area under the curve for rest pain scores plotted against time during the first 24 hours | 24 hours post block | 
| Quality of Recovery (QoR-15) | Quality of recovery measured using the QoR-15 at 24 hours postoperatively | 24 hours postoperatively | 
| Patient Satisfaction - Questionnaire | Patient satisfaction with analgesia - NRS Pain Scale 0(no pain to 10(worst pain) | 24 hours postoperatively | 
| Hospital Discharge (Time to hospital discharge) | Time to hospital discharge | Same day as surgical procedure | 
| Nerve Block Complications | Presence/absence of nerve block complications during the first 24 hours postoperatively and 2 weeks after surgery | 24 hours postoperatively and 2 weeks postoperatively |