Study hypothesis: The impingement syndrome of the rotator cuff is a common cause of shoulder pain for which the most effective treatment is unknown. Steroid injections and anti-inflammatory analgetics are considered as effective methods. Physiotherapy and acromioplasty are commonly used treatments.

Hypothesis: Arthroscopy and acromioplasty in addition to conservative treatment is equally effective as conservative treatment alone for shoulder impingement syndrome.

The aim of this study was to examine the effectiveness of arthroscopic acromioplasty in the treatment of the shoulder impingement syndrome. Nonoperative treatment consisted of information given by a trained physiotherapist. The patients were supervised with a progressive programme to improve the mobility and muscle strength of the shoulder region which was regularly controlled. The exercises aimed at strengthening the stabilising muscles of the glenohumeral joint (m. trapezius, m. deltoides, m. supraspinatus and m. infraspinatus) and activating the decompressive muscles of the the subacromial space (m. teres major and minor, m. subscapularis). The programme lasted for three months. In addition the patients were given advice for daily home exercise.

In the surgical group the patients underwent an arthroscopic examination and acromioplasty done by one experienced orthopaedic specialist. Postoperatively the patients received similar physiotherapeutical information and training programme than in the conservative treatment group.

The follow-up evaluations were performed at 3, 6 and 12 months from the beginning of each treatment in addition at 24 months counted from the randomization. A trained research physiotherapist who was blinded to the treatment group and had not been involved in their treatment performed a standardized assessment of all patients. The range of motion, muscle strengths and Neer´s tests were recorded. At each evaluation the patients completed a structured questionnaire.

Inclusion Criteria:

• a positive clinical Neer's test
• shoulder pain resistant to rest
• shoulder pain resistant to anti-inflammatory drugs
• shoulder pain resistant to subacromial steroid injections
• shoulder pain resistant to ordinary physiotherapy with a minimum history of three months

Exclusion Criteria:

• glenohumeral or acromioclavicular arthritis
• glenohumeral instability
• total rupture of the rotator cuff
• cervical syndrome
• adhesive capsulitis
• neuropathy of the shoulder region