Sagittal ramus osteotomy with tandem screw fixation. Technique and results

Spiessl's traction screw osteosynthesis with compression of the cut surfaces can lead to dislocation of the condyles and crushing of the mandibular nerve in cases of sagittal ramus osteotomy. Such disadvantages can be minimized by joining the bony segments with tandem screws with threads in both parts of the bone. This technique avoids compression at the cut surfaces and permits contact and distance fixing by screws which are adapted to the course of the split. Since 1981, 132 mandibular osteotomies have been performed; they have proved to be adequately stable. The operative technique, the instruments used and the results of the follow-up are described. In order to evaluate the results, an index, namely the joint, relapse and sensation index is proposed for classification. This index can readily be used in practice.