Could adding cupping to acupuncture double shoulder pain relief?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Patients between 18 and 70 years old. * Pain intensity score on the Visual Analogue Scale (VAS) between 4 and 7. * Diagnosis of rotator cuff and/or long head of the biceps tendonitis according to the guidelines issued by the Ministry of Health of Vietnam. * Mechanical pain that increases during movements such as abduction or raising the arm. * Presence of tender points at the long head of the biceps tendon or supraspinatus tendon . * Pain that increases during resisted contraction tests, such as the Jobe test or Palm-up test. * Absence of limitation in the passive range of motion of the shoulder. * Ultrasound findings showing a hypoechoic tendon or evidence of calcification. * Absence of motor weakness or paralysis. * Diagnosis of the TCM syndrome "Qi Stagnation and Blood Stasis" Exclusion Criteria: * Patients who do not agree to participate in the study. * Diagnosis of pseudo-paralysis, acute calcific periarthritis, or frozen shoulder. * Shoulder pain caused by cervical nerve root lesions. * Shoulder pain originating from apical lung tumors, coronary artery disease, or myocardial infarction. * Specific joint lesions caused by infection, tuberculosis, or rheumatoid arthritis. * Bone pathologies including fractures, dislocations, or osteonecrosis of the humeral head. * Shoulder dysfunction resulting from stroke or hemiplegia. * Women who are pregnant. * Patients with mental illness. * Contraindications for vacuum cupping, such as acute skin inflammation, open wounds, or alcohol consumption. * Contraindications for electroacupuncture, including cardiac pacemakers, heart failure, or local skin ulcers. * Current participation in another intervention study. * Use of painkillers, muscle relaxants, or within the last week. * Use of anticoagulants or a history of hemophilia.