After fixing the acromioclavicular joint using the Wolter clavicular plate (W. C. plate), the rotation center of this joint moves posterior to the original location. We hypothesised that this method may produce limited range of motion of the shoulder joint, elevation, internal rotation and external rotation when the arm is at the side, internal rotation and external rotation when the arm is in 90 degrees abducted position.(Patients and Methods)Using the W. C. plate, we operated on four patients having stage III acromioclavicular dislocation. Patients included three men and one woman, with an average age of 37 years old. At three months after surgery the range of motion of the shoulder joint in elevation, external and internal rotation were assessed. The gleno-humeral joint motion in the scapular plane was measured on conventional X-ray films taken at 0, 30, 60, 90, 120 degrees in an elevated position.(Results)The range of motion of the operated side were restricted compared to the unaffected side. Mean elevation angle was 125 degrees on the operated side, but there was no significant difference between the operated side and the unaffected side with respect to the gleno-humeral rhythm from 0 to 120 degrees in the scapular plane during W. C. plate fixation. We concluded that the W. C. plate did not disturb the gleno-humeral rhythm and the range of motion of the shoulder under 120 degrees elevation in the scapular plane.From these results, we concluded that we should never prescribe a rehabilitation program over 120 degrees elevation for patients during W. C. plate fixation.