- The use of shoulder manipulation in the treatment of frozen shoulder remains controversial. Humeral fractures and neurological damage are the risks associated with the procedure. A concern of causing a rotator cuff tear exists but the incidence of iatrogenic rotator cuff tears is not reported. The purpose of this study was to assess the effect of shoulder manipulation for frozen shoulder on the integrity of the rotator cuff. In a prospective study, 32 consecutive patients (33 shoulders) with the diagnosis of frozen shoulder underwent manipulation of the shoulder under anaesthesia (MUA), 18 female and 15 males with mean age at manipulation of 50.3 years (range : 42-63). The average duration of symptoms before treatment was 6.2 months (range : 2-18 months). The patients were examined prior to the manipulation and at follow-up for combined shoulder range of motion, external and internal rotation and strength. All patients had an ultrasound assessment of the rotator cuff before and at 3 weeks after manipulation of the shoulder. Mean time between manipulation and last follow-up was 13.3 weeks. None of the patients had ultrasound findings of a rotator cuff tear, prior to the manipulation. In all patients the rotator cuff remained undamaged on ultrasound examination at 3 weeks after the procedure. The mean improvement in motion was 81.2° (from 93.3° pre-op to 174.5° at last follow-up) for forward flexion ; 102.6° (from 68.8° pre-op to 171.4° at last follow-up) for abduction, 49.4° (from 8.8° pre-op to 58.2° at last follow-up) for external rotation and 3.5 levels of internal rotation (range : 2 to 5 levels). These gains in motion were all highly significant (p < 0.0001). No fractures, dislocations or nerve palsies were observed. In this study, manipulation of the shoulder has not been associated with rotator cuff tears. If done properly the procedure appeared to be safe and to result in a marked improvement of range of movement and function.