Dry needling (DN) and percutaneous electrolysis (PE) are minimally invasive physiotherapy techniques commonly used for the management of myofascial trigger points. DN consists of inserting a fine filiform needle into a hyperirritable area within a taut band of skeletal muscle, with the aim of eliciting local twitch responses and reducing myofascial pain. PE follows a similar needle-based approach but combines the mechanical stimulus of the needle with the application of a galvanic electrical current, producing an electrochemical reaction in the targeted tissue. Both techniques have been increasingly used in clinical practice for musculoskeletal pain conditions, including shoulder pain, although the evidence comparing their relative effectiveness remains limited.

Shoulder pain is one of the most prevalent musculoskeletal disorders and is frequently associated with the presence of active myofascial trigger points. Among the shoulder muscles, the infraspinatus has been identified as a clinically relevant structure because its trigger points may reproduce referred pain patterns commonly reported by patients with shoulder symptoms and may contribute to pain, reduced strength, altered mobility, and functional disability. Previous studies have suggested that invasive treatment of infraspinatus trigger points may produce short-term improvements in pain sensitivity and shoulder-related symptoms. However, most available research has examined dry needling or percutaneous electrolysis separately, and direct comparisons between both interventions in patients with shoulder pain remain scarce.

The physiological mechanisms underlying these techniques are not yet fully understood. Dry needling is thought to act through mechanical and neurophysiological mechanisms, including disruption of dysfunctional motor endplates, reduction of local nociceptive input, elicitation of local twitch responses, and activation of segmental and descending inhibitory pathways. Percutaneous electrolysis may share some of these needling-related effects, while also adding a galvanic current that may induce local biochemical changes and promote tissue recovery processes. Nevertheless, it remains unclear whether the addition of electrical current provides superior clinical effects compared with dry needling alone.

Since limited research has directly compared dry needling and percutaneous electrolysis applied to active myofascial trigger points of the infraspinatus in patients with shoulder pain, the present study aimed to compare the effectiveness of both techniques as complementary interventions to manual therapy and therapeutic exercise. Specifically, this study sought to determine whether percutaneous electrolysis or dry needling produced greater short-term improvements in pain intensity and shoulder-related disability.

Inclusion Criteria:

• Adults
• Presence of shoulder pain for at least 3 months.
• Shoulder pain intensity greater than 3 points on the visual analogue scale (VAS).
• Shoulder-related disability greater than 20 points on the DASH questionnaire.
• Presence of at least one active myofascial trigger point in the infraspinatus muscle.
• Reproduction of the patient's familiar shoulder pain during palpation of the infraspinatus trigger point.
• Ability to understand the study procedures and provide written informed consent.

Exclusion Criteria:

• Previous shoulder surgery or traumatic shoulder injury in the affected region.
• Presence of severe structural or systemic pathology affecting the shoulder region, such as fracture, tumour, infection, inflammatory disease, or neurological disorder.
• Clinical signs suggestive of cervical radiculopathy or other neurological conditions that could explain the shoulder symptoms.
• Use of physiotherapy treatment, invasive therapy, or analgesic/anti-inflammatory medication during the week before participation.
• Contraindications to dry needling or percutaneous electrolysis, including needle phobia, anticoagulant therapy, bleeding disorders, pregnancy, pacemaker or implanted electrical devices, local skin infection, or altered skin sensitivity in the treatment area.