Targeted Nerve Injection to the Knee (Nerve to Vastus Medialis): Comparing Two Adductor Canal Block Approaches

Study of Targeted Injection of Nerves to the Knee-A Volunteer Trial Evaluating Nerve to Vastus Medialis

This randomized, double-blinded volunteer study compares two ways of performing the adductor canal (AC) nerve block at the mid-thigh to see which approach more reliably numbs the anteromedial knee. One approach is the traditional AC block placed near the saphenous nerve; the other separately targets the nerve to vastus medialis (NVM) in addition to the saphenous nerve. Healthy adult participants receive both blocks in one visit (one on each leg), with the order randomized. The primary outcome is change in quadriceps strength (a proxy for vastus medialis anesthesia) measured by load-cell dynamometry. Secondary outcomes include cutaneous sensory mapping (pinprick and cold) and the percentage of a standardized, marked knee-incision line covered by sensory block. The study uses ultrasound guidance and a standard dose of chloroprocaine, with routine monitoring to minimize risks.

Study Overview

• Status: Not yet recruiting
• Conditions: Anesthesia, Local
• Intervention / Treatment: Procedure: Traditional adductor canal block; Drug: Chloroprocaine Injection; Procedure: NVM (nerve to vastus medialis) targeted adductor canal block

• Study Type: Interventional
• Enrollment (Estimated): 25
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: Ashley Burke; Phone Number: (919) 681-2849; Email: ashley.burke@duke.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age ≥18 years
• Able to provide written informed consent
• Able and willing to comply with study procedures and ~6-hour visit
• American Society of Anesthesiologists (ASA) Physical Status 1 or 2
• Weight >70 kg

Exclusion Criteria:

• BMI >35 kg/m²
• Use of analgesics within 24 hours before the procedure
• History of thigh trauma or surgery
• Pregnant or planning pregnancy
• Lower extremity deformities/tattoos interfering with block performance
• Systemic neuromuscular disease
• Contraindications to regional anesthesia (e.g., infection, allergy, challenging sonoanatomy)
• Other health conditions that would affect safe participation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Traditional adductor canal block; 20 mL of 2% chloroprocaine deposited adjacent to the saphenous nerve under ultrasound guidance.	Procedure: Traditional adductor canal block; Ultrasound-guided injection adjacent to the saphenous nerve; 20 mL of 2% chloroprocaine.; Drug: Chloroprocaine Injection; 2% chloroprocaine
Experimental: NVM (nerve to vastus medialis) targeted adductor canal block; 10 mL of 2% chloroprocaine by the NVM (confirmed with nerve stimulation), plus 10 mL by the saphenous nerve (total 20 mL), under ultrasound guidance.	Drug: Chloroprocaine Injection; 2% chloroprocaine; Procedure: NVM (nerve to vastus medialis) targeted adductor canal block; Ultrasound-guided injection; 10 mL 2% chloroprocaine at the NVM (confirmed by nerve stimulation), plus 10 mL at the saphenous nerve.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Quadriceps strength as measured by load cell dynamometer	Load cell dynamometers are highly accurate portable electronic devices used to measure isometric muscle strength.	Day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of hypothetical incision covered	An unblinded anesthesiologist will mark the mock total knee arthroplasty and the length of the hypothetical incision that has diminished sensation to pinprick will be determined.	Day 1

Collaborators and Investigators

• Sponsor: Duke University
• Investigators: Principal Investigator: Brian Mendelson, Duke University

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): December 1, 2027

Study Registration Dates

• First Submitted: February 25, 2026
• First Submitted That Met QC Criteria: February 25, 2026
• First Posted (Actual): March 3, 2026

Study Record Updates

• Last Update Posted (Actual): March 3, 2026
• Last Update Submitted That Met QC Criteria: February 25, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Adductor canal block; Chloroprocaine; Knee joint; Nerve to vastus medialis
• Additional Relevant MeSH Terms: chloroprocaine
• Other Study ID Numbers: PRO00119256

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No