If posttraumatic chronic instability of the AC-joint causes subjective complaints, this is an indication for operative therapy. In our unit 38 patients were treated at all. In most cases previous treatment had been conservative. Syndesmoplasty was done with local tissue. 33 patients were examined radiological and clinical after a minimum time of twelve months after operative treatment. The AC-joints of 25 patients were stable, in five cases there was a slight instability, in three cases there was a severe instability. Only with four patients the diminuation of mobility was of consequence.