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.
Age between 18 and 65 years
Presentation to the Orthopedics and Traumatology outpatient clinic with neck and/or shoulder pain
Presence of a taut band
Local tenderness
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
Parallel
Autologous Platelet-Rich Plasma (PRP)
Other intervention2 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
PRP plus Betamethasone
Drug1 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
Betamethasone (Diprospan)
Drug1 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.
Change in Visual Analog Scale (VAS) Pain Score
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.
Change in Visual Analog Scale (VAS) Pain Score at 6 months
Pain intensity on 10-cm horizontal VAS assessed by blinded evaluator. Long-term durability of effect.
Pressure Pain Threshold (PPT)
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
Flexion, extension, lateral flexion, and rotation measured in degrees using a digital goniometer by blinded evaluator.
Rescue Analgesic Consumption
Number of paracetamol 500 mg tablets consumed per week recorded by patient diary.
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