The purpose of this study is to determine the efficacy of electrotherapy as a coadjuvant in mobility and exercise treatment in the reduction of pain intensity in subacromial impingement syndrome.

Among the different diagnoses covered by the concept of shoulder pain, the most common is subacromial impingement syndrome, which represents 44%-60% of the total.Specific supervised exercises obtain improvements in the range of movement and muscular function by restoring the shoulder's mobility and stability. Physiotherapeutic options include several electrotherapy techniques.

Ultrasound is no more beneficial than exercise alone. Likewise, the results of some more recent studies evaluating the application of ultrasound alone versus placebo, showed that ultrasound alone in physiotherapy treatment of shoulder pain is only effective in patients with calcific tendonitis of the shoulder. All the authors, however, suggest that effectiveness can vary, depending on application conditions, dosage and timing.

The primary objective of the trial is to analyze the efficacy of electrotherapy treatment (monopolar radiofrequency or ultrasound) coadjuvant to mobility and exercise therapy in the reduction of pain intensity in subacromial impingement syndrome.

The secondary objectives of this study are to determine the differences between three intervention groups: monopolar radiofrequency, ultrasound and inactive radiofrequency, in improvement of performance status, quality of life and global impression of improvement.

Inclusion Criteria:

• Men and women over 18 years of age
• Shoulder pain secondary to subacromial impingement syndrome
• Pain at rest and/or with free movement and/or with movement against resistance with a score on the visual analogue scale of 3 or higher.
• Documented X-ray (XR), ultrasound (US) and/or magnetic resonance imaging (MRI) evidence of cuff injury involving oedema, tendonitis, fibrosis or torn tendon.
• Potentially available for the next six months.

Exclusion Criteria:

• Documented US and/or MRI evidence of complete tearing of the cuff and clinical inability to lift the arm (drop arm sign)
• Radiological findings of tumour lesions, avascular necrosis, glenoid development defects, acromial bone, severe degenerative signs affecting inter-articular space and fractures
• Limited range of passive movement with capsular pattern
• Recent history of trauma (contusion, falls or sudden jarring)
• Ischaemic cardiopathy in subacute phase
• History of more than five infiltrations and/or shoulder surgery
• History of rehabilitation treatment for the same reason in the last 12 months
• Cognitive deficit, psychiatric alterations or behavioural disorders that might compromise the patient's collaboration
• Unsuitable for electrotherapy: pregnancy, epilepsy, pacemaker, osteosynthesis, undergoing treatment with Sintrom
• Patients in litigation or in the process of making work-related claims
• Failure to understand Spanish