Myofascial Pain Dysfunction Syndrome, Trigger Points, Myofascial, Trigger Point in Trapezius Muscle
Conditions
Keywords
platelet-rich plasma, PRP, betamethasone, trigger point injection, myofascial pain syndrome, trapezius, randomized controlled trial, pressure pain threshold
Brief summary
Brief Summary Myofascial pain syndrome (MPS) is a common musculoskeletal condition characterized by active trigger points (TrPs), which are hypersensitive, painful nodules within taut bands of skeletal muscle. The upper trapezius muscle is one of the most frequently affected sites. Trigger point injection (TPI) is a widely used minimally invasive treatment for patients who are refractory to conservative management. Corticosteroids provide rapid anti-inflammatory effects, whereas platelet-rich plasma (PRP) has regenerative properties through growth factors that may support tissue healing. Despite their widespread use, the optimal injectate for TPI remains unclear. Additionally, the potential benefit of combining PRP with corticosteroids has not been adequately studied in upper trapezius MPS. This study is a single-center, prospective, randomized, assessor-blinded controlled trial designed to compare the clinical effectiveness of three injection protocols: (1) PRP plus bupivacaine, (2) PRP plus betamethasone plus bupivacaine, and (3) betamethasone plus bupivacaine with saline (volume-matched control). A total of 150 patients with a single active trigger point in the upper trapezius will be included. The primary outcome is pain intensity measured by the visual analog scale (VAS) at 3 months. Secondary outcomes include pressure pain threshold (PPT), cervical range of motion (ROM), rescue analgesic use, recurrence rate, and adverse events at 1 week, 4 weeks, 3 months, and 6 months. All injections are performed by the same investigator using a palpation-guided technique, and outcome assessments are conducted by a blinded evaluator.
Detailed description
Study Design This is a single-center, prospective, three-arm randomized controlled trial. Randomization will be performed using a computer-generated block randomization method (block size: 6, allocation ratio 1:1:1) with sealed opaque envelopes. Patients and outcome assessors will be blinded to group allocation. The injecting physician will not be blinded due to the nature of PRP preparation. Interventions Group A (PRP group): 2 mL autologous leukocyte-poor PRP + 1 mL bupivacaine 0.5% (total 3 mL) Group B (Combination group): 1 mL PRP + 1 mL bupivacaine 0.5% + 1 mL betamethasone (total 3 mL) Group C (Control group): 1 mL betamethasone + 1 mL bupivacaine 0.5% + 1 mL normal saline (total 3 mL) All groups receive equal injection volumes to avoid volume-related bias. PRP Preparation Ten milliliters of peripheral venous blood will be collected into a citrate-containing tube. The first centrifugation will be performed at 1500 rpm for 10 minutes, followed by a second centrifugation at 2500 rpm for 10 minutes. One milliliter of leukocyte-poor PRP will be obtained. No activator will be used. The preparation will be applied within 30 minutes. Platelet concentration and preparation parameters will be recorded. Injection Technique Trigger point injections will be performed using a palpation-guided technique without ultrasound assistance. A 25G needle will be inserted at approximately 30 degrees into the trigger point. Local twitch response will be documented during the procedure. Outcome Assessments Baseline (T0): VAS, PPT (algometer), cervical ROM (digital goniometer) 1 week (T1): VAS, PPT, adverse events 4 weeks (T2): VAS, PPT, ROM, rescue analgesic use 3 months (T3 - Primary endpoint): VAS, PPT, ROM, rescue analgesic use, patient satisfaction 6 months (T4): VAS, PPT, ROM, recurrence evaluation, patient satisfaction Statistical Analysis The primary analysis will be conducted using repeated measures ANOVA with Greenhouse-Geisser correction. Post hoc comparisons will be performed using Tukey HSD with Bonferroni adjustment. Intention-to-treat analysis will be applied. Missing data will be handled using multiple imputation. A per-protocol analysis will be performed as a sensitivity analysis. Recurrence rates will be analyzed using Kaplan-Meier survival analysis and log-rank testing. Statistical analyses will be performed using SPSS version 26.
Interventions
DRUGPRP plus Betamethasone
1 mL autologous LP-PRP + 1 mL Diprospan (betamethasone dipropionate 5 mg + betamethasone sodium phosphate 2 mg) + 1 mL bupivacaine 0.5%. Single palpation-guided trigger point injection. Total volume: 3 mL
DRUGBetamethasone (Diprospan)
1 mL Diprospan (betamethasone dipropionate 5 mg + betamethasone sodium phosphate 2 mg) + 1 mL bupivacaine 0.5% + 1 mL normal saline (0.9% NaCl, volume equalization). Single palpation-guided trigger point injection. Total volume: 3 mL.
2 mL autologous leukocyte-poor PRP prepared by double centrifugation, combined with 1 mL bupivacaine 0.5%. Single palpation-guided trigger point injection into upper trapezius. Total volume: 3 mL
Sponsors
University of Kyrenia
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Masking description
Participants are blinded to treatment allocation; all injections appear identical in volume (3 mL) and technique. The outcomes assessor (who performs VAS, PPT, and ROM measurements) is a separate physician blinded to group assignment and not present during injections. The injecting investigator is unblinded due to the technical requirement of PRP preparation.
Intervention model description
Three parallel arms with 1:1:1 allocation ratio. Block randomization (block size 6) using computer-generated sequence with sealed opaque envelopes. All groups receive equal injection volume (3 mL) to control for volume confounding.
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Age between 18 and 65 years * Presentation to the Orthopedics and Traumatology outpatient clinic with neck and/or shoulder pain * Diagnosis of upper trapezius myofascial pain syndrome based on Simons and Travell criteria, including: * Presence of a taut band * Local tenderness * Referred pain pattern * Local twitch response * Presence of a single active trigger point in the upper trapezius muscle * Symptom duration ≥ 4 weeks * Pain intensity ≥ 4 on the visual analog scale (VAS) * Inadequate response to at least 4 weeks of conservative treatment (physical therapy and/or oral analgesics) * Ability to provide written informed consent
Exclusion criteria
* Presence of multiple active trigger points * Diagnosis of fibromyalgia according to ACR 2010 criteria * Cervical radiculopathy or myelopathy * Trigger point injection in the same region within the past 3 months * Coagulopathy or current anticoagulant or antiplatelet therapy * Known allergy or contraindication to corticosteroids, local anesthetics, or PRP components * Active infection (systemic or local) * Pregnancy or lactation * Thrombocytopenia (platelet count \< 100,000/µL) * Malignancy * Inability to cooperate or provide informed consent
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Visual Analog Scale (VAS) Pain Score | Baseline to 3 months | Pain intensity measured on a 10-cm horizontal Visual Analog Scale (0 = no pain, 10 = worst imaginable pain). Assessed by a blinded evaluator separate from the injecting physician. Minimum clinically important difference (MCID): 1.5 cm. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Visual Analog Scale (VAS) Pain Score at 6 months | Baseline to 6 months | Pain intensity on 10-cm horizontal VAS assessed by blinded evaluator. Long-term durability of effect. |
| Pressure Pain Threshold (PPT) | Baseline, week 1, week 4, month 3, month 6 | Measured by digital algometer (kg/cm²) directly over the active trigger point. Mean of 3 consecutive measurements by blinded evaluator. |
| Cervical Range of Motion (ROM | Baseline, week 4, month 3, month 6 | Flexion, extension, lateral flexion, and rotation measured in degrees using a digital goniometer by blinded evaluator. |
| Rescue Analgesic Consumption | Through 6 months | Number of paracetamol 500 mg tablets consumed per week recorded by patient diary. |
| Recurrence Rate | 6 months | Proportion of patients whose VAS score returns to ≥50% of baseline value within 6-month follow-up. |
| Patient Satisfaction | Month 3, Month 6 | 5-point Likert scale (1=very satisfied, 5=very dissatisfied) assessed by blinded evaluator. |
| Adverse Events | Through 6 months | Incidence of injection site reactions, vasovagal syncope, systemic corticosteroid effects, and infection. |
Countries
Cyprus
Contacts
CONTACTUtku Gurhan, md
Outcome results
None listed