A prospective follow-up study was performed including 47 patients who underwent monomaxillary or bimaxillary osteotomy. Fixation after sagittal split osteotomy was achieved with a new adjustable bone fixation system. Significant postoperative changes were found in an analysis of axiographic condylar path tracings. A reduction of condylar path length after mandibular advancement was seen after 12 months during mouth opening and protrusion. By contrast, an increase in mobility was noted after mandibular set-back. The analysis of the condylar path angle revealed a significant increase in protrusion after mandibular advancement. A correlation of the postoperative changes with the use of the adjustable bone fixation system was not found. The results support the hypothesis of muscular and condylar derangement after orthognathic surgery which is followed by typical changes in condylar mobility caused by adaptation within the temporomandibular complex. Keywords: adjustable bone fixation system, sagittal split ramus osteotomy