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

Phase 4Not Yet RecruitingNCT07444827

Duke University25 enrolled

Overview

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 Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

TRIPLE

Enrollment

Conditions

Anesthesia, Local

Interventions

Eligibility

Sex: ALLMin age: 18 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

Quadriceps strength as measured by load cell dynamometer

Load cell dynamometers are highly accurate portable electronic devices used to measure isometric muscle strength.

Time frame: Day 1

Secondary Outcomes

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.