Shoulder pain is a common musculoskeletal condition that can lead to significant functional limitation and reduced quality of life. Conventional treatments often provide limited or temporary relief, highlighting the need for alternative approaches targeting peripheral pain mechanisms.

This study aims to evaluate the effectiveness of Perineural Injection Treatment (PIT) compared to Transcutaneous Electrical Nerve Stimulation (TENS) in reducing pain and improving functional outcomes in patients with subacute or chronic shoulder pain.

In this randomized controlled trial, participants are assigned to receive either PIT or TENS, in addition to a standardized exercise program. The intervention is delivered over two sessions within a two-week period. Pain intensity is assessed using the Numeric Rating Scale (NRS), and functional outcomes are measured using the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire.

The results of this study are expected to provide evidence on the comparative effectiveness of PIT and TENS, and to support clinical decision-making in the management of shoulder pain.

Shoulder pain is one of the most prevalent musculoskeletal disorders and is associated with substantial disability and reduced quality of life. The etiology is multifactorial, involving structures such as the rotator cuff, glenohumeral joint, and surrounding soft tissues. In addition to nociceptive mechanisms, neuropathic and nociplastic components may contribute to persistent pain, making management challenging.

Conventional treatments, including pharmacological therapy, physical therapy, and injection-based interventions, have shown variable effectiveness and may provide only short-term relief. Therefore, there is increasing interest in minimally invasive interventions that target peripheral sensitization.

Perineural Injection Treatment (PIT) is a therapeutic approach involving subcutaneous injection of low-concentration dextrose solution along peripheral nerve pathways. It is proposed to reduce neurogenic inflammation and modulate nociceptor activity, potentially leading to improved pain and function. However, evidence regarding its effectiveness in shoulder pain remains limited.

This study is designed as a single-blind randomized controlled trial comparing PIT with Transcutaneous Electrical Nerve Stimulation (TENS) in patients with subacute or chronic shoulder pain. A total of 32 participants are randomly assigned to either the PIT group or the TENS group. Both groups receive a standardized exercise program, including active range of motion, stretching, and strengthening exercises.

The intervention consists of two treatment sessions administered over a two-week period. PIT is performed using subcutaneous injections of 5% dextrose along painful peripheral nerve areas. TENS is applied using conventional parameters with frequency 75-100 Hz and pulse width less than 200 microseconds.

Outcome measures include pain intensity assessed using the Numeric Rating Scale (NRS) and functional status evaluated using the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. Assessments are conducted at baseline, immediately after intervention, and at the end of the intervention period.

The primary objective of this study is to evaluate the effectiveness of PIT in reducing pain intensity compared to TENS. Secondary objectives include assessing functional improvement and immediate analgesic effects following intervention.

The findings of this study are expected to contribute to evidence-based management of shoulder pain and support the use of mechanism-based interventions targeting peripheral nociceptive pathways.

Inclusion Criteria:

• Adults aged 18-65 years
• Patients with subacute or chronic shoulder pain
• Pain intensity ≥ 3 on the Numeric Rating Scale (NRS)
• Diagnosed with shoulder conditions such as adhesive capsulitis, rotator cuff tendinopathy or tear, glenohumeral osteoarthritis, acromioclavicular joint sprain, or biceps tendinopathy
• Able to provide informed consent

Exclusion Criteria:

• History of injection therapy or use of analgesic medications within one week prior to intervention
• Presence of neurological or systemic diseases affecting upper limb function
• Pregnancy
• Contraindications to injection therapy (e.g., infection at injection site, needle phobia, allergy to dextrose)
• Refusal to participate or inability to complete the study protocol