Interfascial Hydrodissection Added to Ultrasound-Guided Piriformis Injection for Piriformis Syndrome

NCT07813455 | Recruiting

• 1 other identifier: HNEAH-PIR-HD-2026-01
• Study Type: interventional
• Target: 110
• Locations: 1 country
• Sites: 1

Brief Summary

The gluteus maximus overlies the piriformis muscle and forms a broad fascial interface with it. Restricted movement, increased tension, or adhesions between these tissue layers may contribute to persistent buttock pain in piriformis syndrome. Interfascial hydrodissection is an ultrasound-guided procedure in which fluid is introduced between the gluteus maximus and piriformis muscles to gently separate restricted fascial planes, improve tissue gliding, reduce local mechanical irritation, and potentially modulate nociceptive input from pain-sensitive nerve endings within or adjacent to the fascial interface. The goal of this clinical trial is to learn whether adding ultrasound-guided interfascial hydrodissection to a piriformis injection provides better pain relief and improves function in adults with piriformis syndrome. Piriformis syndrome can cause buttock pain that may spread to the back of the thigh or leg. Interfascial hydrodissection is a procedure in which fluid is injected between the gluteus maximus and piriformis muscles. The fluid gently separates the tissue layers and may help them move more freely. The main questions this trial aims to answer are:

• Does adding interfascial hydrodissection to a piriformis injection lower overall pain more than the piriformis injection alone at 3 months after treatment?
• Does it provide greater improvement in pain at earlier follow-up visits, hip-related function, and overall recovery? All participants will first receive one ultrasound-guided local anesthetic injection into the piriformis muscle. The early pain response will help support the diagnosis, and the same injection will serve as the common treatment received by both groups. Participants whose pain improves by at least 50 percent will be randomly assigned to either continue with the piriformis injection alone or receive additional interfascial hydrodissection. After the 1-week assessment, participants in both groups will begin the same home-based piriformis stretching program. Participants will:
• Receive one ultrasound-guided piriformis injection and, depending on group assignment, may also receive interfascial hydrodissection
• Have follow-up assessments later on the treatment day and at 1 week, 1 month, and 3 months
• Follow the same home-based stretching program after the 1-week assessment
• Report their pain, daily function, overall improvement, pain medicine use, additional treatment needs, and any side effects

Conditions

Piriformis Syndrome

Keywords

Interfascial Hydrodissection; Ultrasound-Guided Piriformis Injection; Piriformis Muscle Injection; Gluteus Maximus-Piriformis Fascial Interface; Deep Gluteal Pain; Buttock Pain; Sciatica-Like Pain

Outcome Measures

Primary Outcomes (1)

• Change From Pre-Injection Baseline in Overall Pain Intensity on the 11-Point Numeric Rating Scale at 3 Months

  Overall pain intensity will be measured using an 11-point Numeric Rating Scale ranging from 0 (no pain) to 10 (worst imaginable pain). The change score will be calculated as the 3-month score minus the pre-injection baseline score. More negative change scores indicate greater improvement in pain.

  Pre-injection baseline and 3 months after randomization

Secondary Outcomes (3)

• Change From Pre-Injection Baseline in Overall Pain Intensity at Earlier Follow-Up Time Points

  Pre-injection baseline and 1 hour, 1 week, and 1 month after randomization

• Change From Pre-Injection Baseline in the Situation-Specific Pain Profile

  Pre-injection baseline and 1 week, 1 month, and 3 months after randomization

• Change From Baseline in Hip-Related Function Measured by the Non-Arthritic Hip Score

  Baseline and 1 week, 1 month, and 3 months after randomization

Study Arms (2)

Ultrasound-Guided Piriformis Injection Alone

ACTIVE COMPARATOR

Before randomization, participants will receive a single ultrasound-guided injection of 5 mL of 2% lidocaine into the piriformis muscle with both diagnostic and therapeutic intent. The early pain response will be used to determine eligibility for randomization. Participants with at least a 50 percent reduction in overall pain who are assigned to this arm will receive no additional invasive procedure. After completion of the 1-week assessment, participants will begin the standardized 6-week home-based piriformis stretching program.

Procedure: Ultrasound-Guided Piriformis Injection; Behavioral: Standardized Home-Based Piriformis Stretching Program

Ultrasound Guided Piriformis Injection Plus Interfascial Hydrodissection

EXPERIMENTAL

Before randomization, participants will receive an ultrasound-guided injection of 5 mL of 2% lidocaine into the piriformis muscle with both diagnostic and therapeutic intent. The early pain response will be used to determine eligibility for randomization. Participants with at least a 50 percent reduction in overall pain who are assigned to this arm will receive a single ultrasound-guided interfascial hydrodissection between the gluteus maximus and piriformis muscles using 18 mL of 0.9% normal saline and 2 mL of 1% lidocaine. Hydrodissection will be performed after the early response assessment during the same study visit. After completion of the 1-week assessment, participants will begin the same standardized 6-week home-based piriformis stretching program.

Procedure: Ultrasound-Guided Piriformis Injection; Procedure: Ultrasound-Guided Interfascial Hydrodissection; Behavioral: Standardized Home-Based Piriformis Stretching Program

Interventions

Ultrasound-Guided Piriformis Injection PROCEDURE

Before randomization, participants who meet the initial clinical eligibility criteria will receive one ultrasound-guided injection of 5 mL of 2% lidocaine into the piriformis muscle. The injection will have both diagnostic and therapeutic intent. The early pain response will be used to support the diagnosis and determine eligibility for randomization. In participants who demonstrate at least a 50 percent reduction in overall pain and proceed to randomization, the same injection will constitute the common active treatment received by both arms.

Ultrasound Guided Piriformis Injection Plus Interfascial Hydrodissection; Ultrasound-Guided Piriformis Injection Alone

Ultrasound-Guided Interfascial Hydrodissection PROCEDURE

After assessment of the early pain response and randomization, participants assigned to the experimental arm will receive one ultrasound-guided interfascial hydrodissection of the tissue plane between the gluteus maximus and piriformis muscles. Hydrodissection will be performed using a total volume of 20 mL consisting of 18 mL of 0.9% sodium chloride and 2 mL of 1% lidocaine.

Also known as: Gluteus Maximus-Piriformis Interfascial Hydrodissection

Ultrasound Guided Piriformis Injection Plus Interfascial Hydrodissection

Standardized Home-Based Piriformis Stretching Program BEHAVIORAL

After completion of the 1-week assessment, participants in both arms will begin the same standardized home-based piriformis stretching program and will continue the program for 6 weeks. The exercise will be demonstrated by a member of the rehabilitation team, written instructions will be provided, and adherence will be recorded during follow-up.

Ultrasound Guided Piriformis Injection Plus Interfascial Hydrodissection; Ultrasound-Guided Piriformis Injection Alone

Eligibility Criteria

• Age: 18 Years - 70 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 18 to 70 years.
• Buttock or gluteal pain that may radiate to the posterior thigh and/or leg.
• Medical history and physical examination findings consistent with piriformis syndrome.
• Tenderness on palpation over the piriformis muscle.
• A positive result on at least one of the following piriformis provocation maneuvers: FAIR, Freiberg, Pace, or Beatty.
• Ability to understand and sign the written informed consent form.
• Ability and willingness to attend the scheduled follow-up visits.
• Additional criterion for randomization:
• \- At least a 50 percent early reduction in overall pain after the single ultrasound-guided local anesthetic piriformis injection.

You may not qualify if:

• Active lumbar radiculopathy, clinically significant lumbar disc herniation, spinal stenosis, or another spinal disorder that could explain the participant's symptoms.
• Clinically significant neurological deficit.
• Marked limitation of lumbar spine and/or hip range of motion.
• Previous surgery involving the lumbar spine or hip region.
• Pregnancy or breastfeeding.
• Known allergy or hypersensitivity to lidocaine or another local anesthetic used in the study.
• Current anticoagulant treatment or a clinically significant coagulation disorder.
• Active infection at the injection site.
• Body mass index greater than 35 kg/m².
• Active inflammatory or infectious disease that may affect participant safety or study assessments.
• Active psychiatric condition that may interfere with informed consent, adherence to study procedures, or outcome assessment.
• Uncontrolled hypertension.
• Uncontrolled diabetes mellitus.
• Decompensated cardiac, hepatic, or renal failure.
• Vascular or neoplastic disease that could explain the symptoms or increase the risk of the study procedures.

Sponsors & Collaborators

• Haydarpasa Numune Training and Research Hospital: lead

Study Sites (1)

University of Health Sciences, Haydarpasa Numune Training and Research Hospital, Department of Physical Medicine and Rehabilitation

Istanbul, Uskudar, 34662, Turkey (Türkiye)

RECRUITING

Related Publications (3)

• Misirlioglu TO, Akgun K, Palamar D, Erden MG, Erbilir T. Piriformis syndrome: comparison of the effectiveness of local anesthetic and corticosteroid injections: a double-blinded, randomized controlled study. Pain Physician. 2015 Mar-Apr;18(2):163-71.

  PMID: 25794202 BACKGROUND

• Tantanatip A, Patisumpitawong W, Lee S. Comparison of the Effects of Physiologic Saline Interfascial and Lidocaine Trigger Point Injections in Treatment of Myofascial Pain Syndrome: A Double-Blind Randomized Controlled Trial. Arch Rehabil Res Clin Transl. 2021 Mar 9;3(2):100119. doi: 10.1016/j.arrct.2021.100119. eCollection 2021 Jun.

  PMID: 34179755 BACKGROUND

• Kaga M, Ueda T. Effectiveness of Hydro-Dissection of the Piriformis Muscle Plus Low-Dose Local Anesthetic Injection for Piriformis Syndrome: A Report of 2 Cases. Am J Case Rep. 2022 Feb 6;23:e935346. doi: 10.12659/AJCR.935346.

  PMID: 35124689 BACKGROUND

MeSH Terms

Conditions

Piriformis Muscle Syndrome

Condition Hierarchy (Ancestors)

Sciatic Neuropathy; Mononeuropathies; Peripheral Nervous System Diseases; Neuromuscular Diseases; Nervous System Diseases; Nerve Compression Syndromes; Neuralgia; Pain; Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Pelvic Pain

Study Officials

• Kubra Neslihan Kurt Oktay, MD

  University of Health Sciences, Haydarpasa Numune Training and Research Hospital, Department of Physical Medicine and Rehabilitation

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Kubra Neslihan Kurt Oktay, MD

CONTACT

+905352916609; drneslihankurt@gmail.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: The common ultrasound-guided piriformis injection and, when assigned, the interfascial hydrodissection procedure will be performed by a physical medicine and rehabilitation physician experienced in ultrasound-guided interventions. Baseline and follow-up outcome assessments will be conducted by a different physical medicine and rehabilitation physician working in the same clinic. The outcome assessor will not participate in the procedures, will not have access to the allocation record, and will remain unaware of treatment assignment throughout follow-up. Participants will be instructed not to disclose their assigned treatment to the outcome assessor.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Physical Medicine and Rehabilitation Specialist, MD

Model Details: All participants will receive an ultrasound-guided local anesthetic piriformis injection with both diagnostic and therapeutic intent. The early pain response will determine eligibility for randomization. Participants with at least a 50 percent early reduction in pain will be randomly assigned in a 1:1 ratio to either no additional invasive procedure or ultrasound-guided interfascial hydrodissection between the gluteus maximus and piriformis muscles. After completion of the 1-week assessment, both groups will begin the same standardized 6-week home-based piriformis stretching program.

Study Record Dates

• First Submitted: September 4, 2026
• First Posted: September 10, 2026
• Study Start: September 24, 2026
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): October 1, 2027
• Last Updated: September 28, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)