Muscle shortening manoeuvre reduces pain and functional impairment in shoulder impingement syndrome: clinical and ultrasonographic evidence.

To evaluate the short-term efficacy of muscle shortening manoeuvre (MSM), by inducing an increase in strength of the shoulder muscles, for the treatment of shoulder impingement syndrome (SIS).Sixty subjects (mean age: 58.6 years) with SIS were assigned to one of 3 different treatment interventions: 1) MSM: a series of fast accelerations in the upward direction was applied to the upper limb that was also submitted to forces acting in the opposite direction (added mass); 2) traditional physiotherapeutic technique: scapulothoracic gliding; 3) simple traction: the added mass was applied to the limb without the series of fast accelerations. Pain intensity, Neer's impingement sign, range of motion and muscle strength were assessed. Ultrasound (US) examination was performed before, immediately after and 30 days after each treatment to study the width of the subacromial-subdeltoid bursa, long biceps tendon sheath and acromioclavicular joint. Impingement was evaluated by dynamic examination.After treatment with MSM, pain was significantly reduced (p<0.001), Neer's impingement sign was negative, range of motion and muscle strength were increased. US examination showed that the widths of the subacromial-subdeltoid bursa (p<0.001), long biceps tendon sheath (p<0.001) and acromioclavicular joint (p<0.001) were significantly reduced; impingement was no more detected. After 30 days, improvement in clinical and US findings was maintained. In the two control groups, no significant changes were observed after treatment.Clinical and US findings demonstrate that MSM, by inducing an increase in muscle strength, is effective in the short-term treatment of SIS.