Table 1 Inclusion and exclusion criteria

Inclusion criteria

1. Adult men or woman ages 35 to 65 years.

2. Subacromial pain for greater than 3 months with no relief from non-operative means (physiotherapy, non-steroidal anti-inflammatory medication, corticosteroid injections, and rest).

3. Pain provoked by abduction and positive painful arc -sign.

4. Positive impingement test (temporary relief of pain by subacromial injection of lidocaine).

5. Pain in at least 2 out of 3 isometric tests (abduction 0° and 30° or external rotation).

6. Provision of informed consent from the patient.

7. Ability to speak, understand and read in the language of the clinical site.

Exclusion criteria

1. Full thickness tear of the rotator cuff tendons diagnosed on clinical examination (marked weakness in any of the examined muscles) or magnetic resonance imaging with intra-articular contrast (MRA).

2. Osteoarthritis of the glenohumeral and/or acromioclavicular joint diagnosed on clinical examination or on x-rays.

3. Substantial calcific deposits in the rotator cuff tendons found in the preoperative imaging.

4. Previous surgical procedure on the affected shoulder.

5. Evidence of the shoulder instability (positive apprehension/positive sulcus sign).

6. Symptomatic cervical spine pathology.

7. History of alcoholism, drug abuse, psychological or psychiatric problems that are likely to invalidate informed consent.

8. Patient declined to participate.