Sodium Hyaluronate for Myofascial Thoracic Pain

The myofascial complex is increasingly recognized as a potential source of thoracic back pain. Sodium hyaluronate is a key component of synovial fluid and has more recently been recognized as an important element of interfascial spaces. The hypothesized mechanism of action of sodium hyaluronate differs from that of local anesthetic agents and is expected to influence outcome timing. Sodium hyaluronate is a key determinant of interfascial lubrication and viscoelastic behavior, facilitating low-friction gliding between adjacent fascial layers. Experimental and biomechanical studies suggest that alterations in sodium hyaluronate concentration or molecular organization may increase interfascial shear resistance, potentially contributing to nociceptive input through abnormal tissue strain and impaired movement patterns. Restoration of sodium hyaluronate is therefore postulated to improve fascial sliding and mechanical load distribution rather than producing immediate analgesia. Although corticosteroids are used by some clinicians as part of injection-based management of spinal and myofascial pain, they were intentionally not included in the present study. The primary objective of this trial was to evaluate the incremental effect of interfascial sodium hyaluronate on pain and function while minimizing pharmacological confounding and potential long-term tissue effects. This trial is designed as a superiority study evaluating the incremental benefit of sodium hyaluronate compared to normal saline added to standard lidocaine injection, which reflects current clinical practice. For this purpose, a clear, colorless, viscoelastic 1% sodium hyaluronate saline solution (10 mg/ml) in a sterile package for single use, was used. Participants will be randomized in a 1:1 ratio by computer-generated random sequence into two groups. Group 1. Interventional - (4 mL of 1% lidocaine followed by 12 mL of sodium hyaluronate) or Group 2. - control group receiving standard lidocaine injection with saline (4 mL of 1% lidocaine followed by 12 ml of normal saline). Group 2. is a control group with no sodium hyaluronate administration; however, the administration of lidocaine represents a standard procedure, so patients will not be left without treatment even in this study arm. All procedures will be performed by two experienced physicians using a standardized technique. Patients will be positioned prone in the procedure room. The transverse processes at the level corresponding to maximal tenderness will be identified using ultrasound guidance.

Inclusion criteria

• Thoracic back pain as the primary complaint
• Clinically significant myofascial contribution, defined by at least two of the following:

• Localized tenderness
• Paravertebral muscle spasm
• Trigger points
• Reduced skin or fascial mobility
• Persistent pain despite at least 6 weeks of conservative treatment
• Absence of more specific causes of pain, as determined by clinical examination and additional investigations when indicated
• Age over 18 years

Conditions to be excluded prior to enrollment include:

• Neuropathic pain patterns, including:

• Cervical or thoracic radicular pain
• Intercostal neuralgia
• Dorsal scapular neuralgia
• Other neuralgias of thoracic region
• Pleural pain patterns
• Ischemic pain patterns (e.g., ischemic heart disease)
• Predominantly postural pain associated with female sex and osteopenia suggestive of vertebral compression fractures

Exclusion criteria

• Lack of written informed consent
• Active malignancy
• Recent trauma
• Age > 70 years
• Local or systemic infection
• Presence of another more likely pain etiology
• Severe scoliosis and/or significant chest wall deformity
• History of thoracic or upper abdominal surgery
• History of spinal surgery of any kind