During their 20 years of activity members of the Associa tion for the Study of Internal Fixation (AO - ASIF) have made authoritative contributions to the development of internal and external fixation. The close collaboration of surgeons, basic researchers, metallurgists, engineers and the establishment of clinical documentation has made it possible to achieve a solid scientific basis for internal fixa tion. Clear definitions for the standardization of different types of osteosynthesis were possible: interfragmentary compression, splintage and buttressing as well as combina tions of these three techniques. At the same time a scienti fic and workmanlike instrumentation was developed. The idea was to keep diversification within limits but, however, to assemble a comprehensive collection of implants and in struments to answer all the problems presented by the com plexity of bone operations. Osteosynthesis is a difficult and demanding operative method. Its. claims on the surgeon and the theatre staff are high. Therefore plans have existed for a long time to supplement the "Manual of Internal Fixation" with a de tailed description of the AO Instrumentation, its use and maintenance. Our collaborator FRIDOLIN SEQUIN, graduate engineer, has accomplished this task with expert knowledge. He has organized over many years courses for theatre nurses and has been able from the resulting experience to provide helpful suggestions. When RIGMOR TEXHAMMAR R. N. joined AO-International four years ago, it was natural to include her as a co-author."

Functionally stable internal fixation is of particular relevance to maxillo facial surgery, because it obviates the discomforts and inconveniences of intermaxillary fixation. Given the biomechanics and biophysics of the skeletal system, the true im mobilization of bone can be achieved only through highly technical means. Willenegger speaks of an "advanced school" of bone surgery which, when fully realized, will enable excellent results to be achieved even in the most difficult fractures. To accomplish this goal, ongoing refinements are needed in surgical methods and technology. Advancing the state of operative tech nique has been a central concern of the Association for the Study of Inter nal Fixation since its establishment 25 years ago. For this reason, a major priority of the AOI ASIF has been to develop its own surgical instrumen tation. With the help of technical commissions comprised of experts from medi cine, research and manufacturing, the AOI ASIF has been able to develop and successfully test a line of surgical instruments whose trademark is known and respected the world over. For every specialty in traumatology and orthopaedics, including maxillofacial surgery, the AOIASIF has devel oped both a basic and a special instrument set designed to meet specific anatomic requirements."