Effect of Ultrasound-guided Piriformis Muscle Corticosteroid Injection Versus Extracorporeal Shock Wave Therapy for Piriformis Syndrome: a Randomized Control Trial
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ClinicalTrials.gov Identifier: NCT04684537 |
Recruitment Status :
Active, not recruiting
First Posted : December 24, 2020
Last Update Posted : January 19, 2023
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Condition or disease | Intervention/treatment | Phase |
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Piriformis Syndrome Corticosteroid Injection Extracorporeal Shockwave Therapy Therapeutic Exercise | Procedure: Extracorporeal shockwave therapy (ESWT) Procedure: Ultrasound-guided piriformis steroid injection | Not Applicable |
Piriformis syndrome (PS) is one of the common etiology of low back pain. The cause of PS is due to myofascial syndrome of piriformis muscle, leading to piriformis muscle spasm, string-like taut band, and trigger point. Consequently, it may compresses the sciatic nerve which arise from sciatic notch and passes under the piriformis muscle. Conservative treatment of PS includes therapeutic exercise, diathermy, and local steroid injection. Among them, as radiology techniques advance, ultrasound-guided piriformis injection becomes popular for diagnosis block and treatment. Nowadays, extracorporeal shockwave therapy has widely applied in musculoskeletal disease such as plantar fasciitis, tennis elbow, and calcific tendinitis of the shoulder. However, to the investigators best knowledge, there is no study comparing the therapeutic effect between local steroid injection and shockwave. In this study, the investigators aim to compare the effect of extracorporeal shockwave therapy with ultrasound-guided piriformis corticosteroid injection.
This is a randomized controlled trial. 70 participants will be randomly divided into shockwave group and injection group. The participant in the shockwave group will receive one time extracorporeal shockwave therapy, and injection group will receive one time ultrasound-guided piriformis muscle corticosteroid injection. After the intervention, participant in both groups will receive home-based stretch exercise. Evaluation will be performed at baseline, 1 week, and 5 weeks after intervention. Outcome measures include the pain visual analog scale (VAS), hip range of motion, change of pressure pain threshold, and Oswestry Disability Index (ODI).
Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 70 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Double (Participant, Outcomes Assessor) |
Primary Purpose: | Treatment |
Official Title: | Effect of Ultrasound-guided Piriformis Muscle Corticosteroid Injection Versus Extracorporeal Shock Wave Therapy for Piriformis Syndrome |
Actual Study Start Date : | January 1, 2021 |
Actual Primary Completion Date : | December 31, 2022 |
Estimated Study Completion Date : | December 31, 2025 |

Arm | Intervention/treatment |
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Active Comparator: Shockwave group
each subject will receive extracorporeal shockwave therapy
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Procedure: Extracorporeal shockwave therapy (ESWT)
The therapy will be performed with the focused piezoelectric shockwave (F10G4 Richard Wolf GmbH, Germany). The patient will be kept in the hip flexion, adduction and internal rotation position. After sonography-guided localization of the affected muscle and identification of the trigger point by the participant, ultrasound gel is applied to the skin and the applicator couple is placed with an impulse energy flux density of 0.456-0.882 mJ/mm2 for 3500 impulses. |
Active Comparator: Injection group
each subject will receive ultrasound-guided piriformis corticosteroid injection
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Procedure: Ultrasound-guided piriformis steroid injection
all the participants will receive ultrasound-guided piriformis injection with 10 mg triamcinolone and 1 c.c. 1% lidocaine for one time. |
- The pain visual analog scale (VAS) [ Time Frame: change between baseline and at 1 week, 5 weeks after the beginning of the treatment. ]It measures severity of pain. It is performed with a 100-mm horizontal line. The end of the left side is defined as no pain, and the end of the right side as the worst pain. Participants are requested to report the severity of buttock pain in recent one week.
- Oswestry Disability Index (ODI) [ Time Frame: change between baseline and at 1 week, 5 weeks after the beginning of the treatment. ]ODI score is used for disability evaluation. It is a self-reported questionnaire with range 0-100. It has 10 questions with an minimal clinical important difference (MCID) of 10 points, with higher scores indicating more disability. The questions include pain intensity, sleep quality, and ability to perform personal care, work, sit, walk, lift, stand, and travel.
- hip range of motion [ Time Frame: change between baseline and at 1 week, 5 weeks after the beginning of the treatment. ]Internal and external rotation of the hip on the affected side will be measured with a goniometer by the study assistant. The measurement will be performed in the supine position according the standard procedure.
- change of pressure pain threshold [ Time Frame: change between baseline and at 1 week, 5 weeks after the beginning of the treatment. ]It is defined as the amount of pressure needed to shift local sensation from pressure to pain. This is measured with a digital algometer and has been shown to have excellent intrarater reliability in the gluteal region (ICC = .90), with a minimal detectable change of 3.1 N/cm2. The digital algometer, made up of a 1-cm-wide disk, will be placed at the tender point between the ischial tuberosity and the greater trochanter while the patient is lying prone. The algometer's pressure will be increased gradually (with a speed approximately 1 N/cm2 per second) until the participant reports pain. The average value of three repeated measurements is recorded.
- Patient's self evaluation [ Time Frame: change between baseline and at 1 week, 5 weeks after the beginning of the treatment. ]At 1-week and 5-week evaluations, patients are asked to report treatment effect by themselves as the following five grades: 5. Complete relief of symptoms; 4. Much improved, no need for further treatment; 3. Mildly improved, need further treatment; 2.No improvement; 1. Worse.

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Ages Eligible for Study: | 20 Years to 80 Years (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
- Age from 20 to 80
- Unilateral buttock involvement without leg pain or paresthesia
- Duration of symptoms ≥1 month
- Positive trigger point or taut band at piriformis muscle, confirmed by palpation and ultrasound examination
- Positive FAIR (flexion, adduction, internal rotation) test
- Positive piriformis resistive test (patient actively abducts and/or externally rotates the hip while the examiner resists these movements
Exclusion Criteria:
- Having received hip, pelvis, or lumbar spine surgery
- Low back pain or buttock pain due to lumbosacral spine, hip or pelvis lesion other than piriformis syndrome
- Having received shock wave therapy or corticosteroid injection for buttock pain within the past one month
- Neurologic deficit in in the lower limbs
- History of drug allergy to local anesthetics or corticosteroids
- Pregnancy

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04684537
Taiwan | |
Shin Kong Wu Ho-Su Memorial Hospital | |
Taipei, Taiwan |
Principal Investigator: | Lin-Fen Hsieh | Shin Kong Wu Ho-Su Memorial Hospital |
Responsible Party: | Lin-Fen Hsieh, Principal Investigator, Shin Kong Wu Ho-Su Memorial Hospital |
ClinicalTrials.gov Identifier: | NCT04684537 |
Other Study ID Numbers: |
20200715R 2021SKHADR033 ( Other Grant/Funding Number: Shin Kong Wu Ho-Su Memorial Hospital ) |
First Posted: | December 24, 2020 Key Record Dates |
Last Update Posted: | January 19, 2023 |
Last Verified: | January 2023 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
Piriformis syndrome ultrasound-guided intervention corticosteroid injection extracorporeal shockwave therapy therapeutic exercise |
Piriformis Muscle Syndrome Syndrome Disease Pathologic Processes Sciatic Neuropathy Mononeuropathies Peripheral Nervous System Diseases |
Neuromuscular Diseases Nervous System Diseases Nerve Compression Syndromes Neuralgia Pain Neurologic Manifestations Pelvic Pain |