Quadriceps Motor Unit Adaptation to Simulated Knee Injury

University of Central Florida

Status: Not yet enrolling

Conditions: Muscle Inhibition; Knee Injury Simulation

Treatments: Drug: Intra-articular Lidocaine; Device: Joint Effusion via 60 mL Sterile Saline; Other: Sham injection

Study type: Interventional

Funder types: Other

Identifiers

NCT06999057

Knee_Injection_Study:6295

Details and patient eligibility

About

This study investigates how simulated knee injury-via artificial joint effusion or deafferentation-affects quadriceps motor unit behavior in healthy young adults. Participants will complete neuromuscular testing during a single 2-hour lab session. This research seeks to improve understanding of muscle inhibition and inform interventions after real-world knee trauma.

Full description

Using a controlled laboratory model, the investigators will simulate knee injury through two methods: (1) intra-articular saline injection to induce effusion, and (2) intra-articular lidocaine injection to induce sensory deafferentation. Healthy participants aged 18-30 will undergo surface and decomposition EMG, isometric strength testing, and reflex measurements before and after the intervention. The primary outcome is motor unit recruitment characteristics, with secondary outcomes including quadriceps inhibition (Hoffmann reflex) and isometric peak torque. The findings will inform future neuromodulatory approaches in rehabilitation.

Enrollment: 45 estimated patients

Sex: All

Ages: 18 to 30 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

1. Age 18-30 years
2. Physically active (Tegner ≥ 5)
3. No prior lower-limb surgery or major injury

Exclusion criteria

1. Lower limb surgery or significant injury in past 2 years
2. Cardiopulmonary, neurological, or psychiatric disorders
3. Needle/electrical stimulation anxiety
4. Medications affecting neuromuscular or psychological function
5. Pregnancy
6. Allergic to lidocaine
7. Inability to elicit Hoffmann reflex

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

---

45 participants in 3 patient groups

Effusion Group

Experimental group

Description:

60 mL sterile saline injected into knee

Treatment:

Device: Joint Effusion via 60 mL Sterile Saline

Deafferentation Group

Active Comparator group

Description:

Lidocaine (single intra-articular dose)

Treatment:

Drug: Intra-articular Lidocaine

Control Group

Sham Comparator group

Description:

Sham procedure with fake needle

Treatment:

Other: Sham injection