The original AO/ASIF Instrumentation manual presented a concise and complete description of the AO instruments. Thoughtfully developed by Fridolin Sequin and Rigmor Tex hammar, the manual discussed in a clear fashion the purpose and care of the various AO instruments that are handled by the operating room staff. One important feature of the first edition was a detailed checklist of the instruments required for the more common operative procedures for treating fractures. Fridolin Sequin was well-suited to author the first edition: his 15 years of experience as a technical engineer for the AO gave him in-depth knowledge of AO instruments, and he drew on the clinical knowledge of Rigmor Texhammar, a consultant and di rector of the AO courses for nurses. Its original feature of com bining a column of text with a column of illustrations meant the manual quickly became accepted as a standard. By 1981, trans lations could be found in English, French, Spanish, and Italian. Not surprisingly, the manual was very popular."

J. SCHATZKER Friedrich Pauwels first postulated that excessive osteotomies and in particular on a group ofJ 09 joint pressure could cause the destruction of ar- osteotomies followed up for 13-15 years after ticular cartilage and lead to osteoarthritis, and surgery. that the reduction of this pressure would bring Erwin Morscher supports the long-term re- about regeneration of articular cartilage and re- sults of Bombelli and Schneider in his analysis gression of the disease. The first chapter of this of a study of over 2,000 osteotomies performed book is a synthesis of Pauwels' lifelong devotion in several Swiss centers. to the biomechanics of the hip. It presents the He also presents a careful analysis of his reader with a clear exposition of the intertro- own smaller series. Based on all these data, he chanteric osteotomy as a procedure based on defines for us the ideal parameters which clear biomechanical principles, and illustrates should be present in order to make the patient how biomechanical regeneration of the joint can an ideal candidate for an intertrochanteric os- be influenced by a reversal of the mechanical teotomy.

It is to the great and lasting credit of LORENZ BOHLER and his school that they have in the last decade developed and demonstrated so thoroughly the techniques for the conservative management of fractures. Nevertheless there have always been many, including some from BOHLER'S school, who have found considerable place for surgical management, and with the significant progress in general surgery seen in postwar years, a new stimulus has been given to this part of traumatic surgery, especially since bone injuries have become more complex and frequent. The concept of internal fixation is not new. The serious criticisms that have been levelled at it retain today their basic significance. Progress in the fields of asepsis, corrosion-free metal implants, operative experience and postoperative care has diminished the dangers but has not relieved the surgeon of responsibility. The Association for the Study of the Problems of Internal Fixation (AO) has devoted itself over a number of years to the basic principles and best methods of open treatment of fractures by means of extended clinical and scientific studies in order to determine in each individual case the most promising line of treatment. At the same time a well designed and tested instrument set has been developed with precise instructions for the appropriate techniques. As a result, the new observations about primary bone healing which have emerged from the practice of rigid internal fixation are as interesting as the uses to which they can be put in allowing early mobilization.

The German edition of our book entitled "Operative Frakturen behandlung" by M. E. MUELLER, M. ALLGOEWER and H. WILLENEGGER (Springer, Berlin . Goettingen . Heidelberg, 1963) has been out of print now for more than three years. We are planning a new edition which will deal with the collective experience of 14,000 new cases, all treated by internal fixation, and will include the newest developments in the field of internal fixa tion. However, it will be some time before this new edition can be published. Increasing demands for a description of the AO technique of internal fixation has stimulated us to publish this manual. In it we shall describe in a comprehensive but somewhat apodictic mann er the principles and techniques of the AO methods of fracture treatment and reconstructive surgery, which in our hands, have stood the test of time. The book is written in a somewhat abbreviated style. It cor responds in subject matter to the teaching given at the AO courses in Davos, but deals with each subject more thoroughly. We have dispensed with pictures of the instruments, as these may be found in the Synthes Catalogue *. This manual should be regarded as the product of collective experiencc, containing new thoughts and new discoveries from basic research. In considering the risks of mistakes and dangers, we can only reiterate what we have already stated in "Technique of Internal Fixation of Fractures": "Open treatment of fractures is a valuable but difficult method which involves much responsibility.

It is with pleasure that we offer these introductory remarks for the Manual of Internal Fixation in the Horse, a book describing a further application of AO or ASIF techniques. The letters A-O stand for the Arbeitsgemeinschaft fUr Osteosynthesefragen and have been trans lated into the Association for the Study of Internal Fixation. The organization is truly a "study group," created in Switzerland, that met for the first time in 1958. The major goal was to establish a task of fracture treatment by force committed to the improvement osteosynthesis. The group's motivation arose out of the then prevailing unsound or inconsistently successful attempts at fracture treatment. According to statistics obtained from the Swiss National Health Insurance Program at the time, the so-called conservative treatment of fractures had resulted in a high rate of persistent morbidity. The problems encoun tered included: irreparable damage due to long-term immobilization; delayed union or pseudoarthrosis; malalignment; and, inadequate reduction of intraarticular fractures with resultant osteoarthritis. Accurate, stable osteosynthesis seemed the only practical way to address those various shortcomings. However, many of the osteosyn theses performed at that time had led to new problems, since most were not stable and, in some cases, actually worked to prevent healing."

Since 1958 the Association for the Study of Internal Fixation (ASIF) has worked to establish the experimental and biomechanical prin ciples of the operative treatment of fractures. It has been proven that immediate, pain-free mobilization, made possible by stable internal fixation, is the key to restoring function in a fractured extremity. The same principles were applied in 1972173 by Roland Schmoker, who developed a universal plate and sophisticated instrument set designed initially for the treatment of comminuted fractures of the mandible. To extend the applications of his plate to reconstructions after ex tensive tumor resections, he supplemented the device with tem poromandibular joint prostheses and anchoring elements for the at tachment of dentures. He first tested the functional stability of these implants experimentally in sheep. Later he found that the minipig had a more human-like jaw shape and masticatory action, and so he tested the implants in 37 mini pigs that underwent extensive mandibular re sections without bone grafting, using sequential dye injections and postoperative weight gain to chart the progress of osseous regener ation. Seven other animals were not operated and served as controls."

Modern endoprosthetics requires the examination of basic principles such as metallurgy, tribology, gait analysis, model and system development, methods of implant fixation, design, surface problems, material characteristics, stability behaviour, and operating techniques. With a background of more than 30 years of experience, this work presents a summary of these fields, providing the reader with the current state of knowledge. It is dedicated to Dr. med. h.c. Otto Frey-Zund who, in conjunction with orthopaedic surgeons, scientists and engineers from all over Europe, developed artificial joints for hips, knees, elbows and wrists in over 30 years of pioneering work.

Bis vor zehn Jahren galt die operative Hiiftversteifung bei der Behandlung der schmerzhaften einseitig teilversteiften oder stark inkongruenten Hiifte als Therapie der Wahl. Bei richtiger Indikation und Operationstechnik erzielte man damit ein standfestes, schmerzfreies Hiiftgelenk, mit dem die meisten Patienten sehr zufrieden waren. Heute glaubt nahezu jeder Hiiftpatient und leider auch mancher orthopadi- sche Chirurg, daB Totalprothesen bedenkenlos bei noch verhaltnismaBig jungen Patienten implantiert werden diirfen. Enttauschungen werden aber nicht lange auf sich warten lassen, denn Patienten unter fiinfzig Jahren werden ihre einstweilen schmerzfreien kiinstlichen Hiiftgelenke trotz allen arztlichen Mahnungen so sehr strapazieren, daB sich schon nach wenigen Jahren manche einzementierte Gelenkkorper lockem werden. Wohl kann eine Prothese ein- oder gar zweimal ausgewechselt werden, was aber dann? 1m Jahre 1970 wurden in einer Kollektivarbeit der neun groBten orthopadi- schen Kliniken der Schweiz die Ergebnisse der intertrochanteren Osteotomie in bezug auf Schmerzen, Gehfahigkeit, Beweglichkeit und Arbeitsfahigkeit kritisch analysiert. Es wurden Richtlinien fUr die Indikationsstellung, Wahl des Verfahrens und Operationstechnik ausgearbeitet. Eine Kollektivarbeit der Schweiz. Gesellschaft fUr Orthopadie solI demnachst die Spatergebnisse der Totalprothese fUr das dritte bis zehnte Jahr nach dem Eingriff zusammenstellen und nach ahnlichen Kriterien auswerten. 1m Laufe der letzten fUnfzehn Jahre hat sich die Technik der Arthrodese grundlegend geandert. Wahrend im Jahre 1958 noch niemand geglaubt hatte, daB eine Hiiftarthrodese ohne Gipsverband fest werden konne, wurden an verschiedenen Kliniken schon sechs Jahre spater die meisten Hiiftarthrodesen mit der Doppelplatte oder der Kreuzplatte versorgt und sofort funktionell nachbehandelt.

Die Arbeitsgemeinschaft fUr Osteosynthesefragen (AO) hat seit 1958 die biomechanischen und experimentellen Grundlagen der operativen Frakturbehandlung erarbeitet. Als beste Voraussetzung zur Wiederer- langung der vollen Funktion einer gebrochenen Extremitat erwies sich die sofortige schmerzfreie Bewegungstherapie, die durch eine stabile Osteosynthese ermaglicht wird. Dieselben Grundsatze wendete Ro- land Schmoker 1972/73nach Entwicklung einer dreidimensional ver- biegbaren Platte und eines ausgekliigelten Instrumentariums zunachst bei Triimmerfrakturen des Unterkiefers an. Um seine Platte auch nach ausgedehnten Tumorresektionen einset- zen zu kannen, erganzte er sie mit Kiefergelenkprothesen und Veran- kerungselementen zur Fixation eines Zahnersatzes. Diese neuartigen Implantate unterzog er einer experimentellen Priifung der Funktions- stabilitat vorerst an 6 Schafen und fand dann im Minipig ein Tier mit menschenahnlicher Kieferform und entsprechender Kaufunktion. So untersuchte er in der Folge an 37 Minipigs nach ausgedehnten Kiefer- resektionen ohne zusatzlicher Knochentransplantation die Knochen- neubildung mit polychromen Sequenzmarkierungen und Gewichtzu- nahme. Als vergleichbare Kontrollgruppe dienten ihm 7 nicht operier- te Tiere. Diese tierexperimentellen Untersuchungen ermaglichten ihm, so- wohl Implantate und Instrumentarium fortlaufend zu verbessern, als auch die Indikation der intra-und extraoralen Verfahren zu prazisie- ren. Damit wurden Voraussetzungen geschaffen, um diese Methode nach Tumorresektionen beim Menschen anzuwenden. Die beim Tier gepriiften Verankerungselemente fUr den Zahnersatz sindaber beim Menschen noch nicht eingesetzt worden, so da8 das Buch diesbeziig- lich kein abschlie8endes Urteil abgeben will.

Dies ist die erste Monographie uber die Bruche des distalen Unterschenkelsegmentes - vor allem die intraartikularen sogenannten Pilon-tibial-Frakturen. Diese wurden bisher aufgrund ihrer Seltenheit und Komplexitat noch nie in dieser Weise besprochen. Auch die Klassifikation, operative Therapie und Prognose werden dargestellt. Nach einer praxisorientierten anatomischen Einleitung wird anhand des vielfaltigen Krankengutes der AO-Dokumentationszentrale und gestutzt auf ausgedehnte eigene Erfahrungen zunachst die Klassifikation erarbeitet und erlautert. Diese schliesst sich eng an die von M.E. Muller et al. 1987 publizierte "Classification AO des Fractures" an. Das bei dieser Lokalisation sehr spezielle Problem der artikularen Impression wird eingehend behandelt. Es folgen eine Zusammenfassung der Geschichte dieser Verletzungen und eine Ubersicht der bisherigen Publikationen. Indikation, Technik und Problematik der oft schwierigen operativen Behandlung werden ausfuhrlich wiedergegeben. Spezielle Abschnitte uber neueste Auffassungen und Techniken, sekundare Eingriffe und Arthrodesen wurden von Mitarbeitern des Autors gestaltet. Ein Anhang enthalt die Detailanalyse des verwerteten Krankengutes unter besonderer Berucksichtigung der Prognose. Ziel des Buches ist es, traumatologisch aktive Chirurgen und Orthopaden moglichst umfassend uber eine Verletzung zu informieren, mit welcher sie nur relativ selten konfrontiert sind. Die Einfachheit der Einteilung soll eine korrekte Indikationsstellung und sorgfaltige Therapiewahl fordern unter Berucksichtigung von Komplikationen und Prognose.

Vor dem Hintergrund einer uber 30jahrigen Erfahrung zeigt dieses Werk den aktuellen Wissensstand der Endoprothetik. Es ist Dr.med.h.c. Otto Frey-Zund gewidmet, der in gemeinsamer Pionierarbeit mit orthopadischen Chirurgen, Wissenschaftlern und Ingenieuren aus ganz Europa Kunstgelenke fur Huft-, Knie-, Ellenbogen- und Handgelenke entwickelt hat.
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What is knowledge and how is it represented? This book focuses on the idea of formalising knowledge as relations, interpreting knowledge represented in databases or logic programs as relational data and discovering new knowledge by identifying hidden and defining new relations. After a brief introduction to representational issues, the author develops a relational language for abstract machine learning problems. He then uses this language to discuss traditional methods such as clustering and decision tree induction, before moving onto two previously underestimated topics that are just coming to the fore: rough set data analysis and inductive logic programming. Its clear and precise presentation is ideal for undergraduate computer science students. The book will also interest those who study artificial intelligence or machine learning at the graduate level. Exercises are provided and each concept is introduced using the same example domain, making it easier to compare the individual properties of different approaches.

What is knowledge and how is it represented? This book focuses on the idea of formalising knowledge as relations, interpreting knowledge represented in databases or logic programs as relational data and discovering new knowledge by identifying hidden and defining new relations. After a brief introduction to representational issues, the author develops a relational language for abstract machine learning problems. He then uses this language to discuss traditional methods such as clustering and decision tree induction, before moving onto two previously underestimated topics that are just coming to the fore: rough set data analysis and inductive logic programming. Its clear and precise presentation is ideal for undergraduate computer science students. The book will also interest those who study artificial intelligence or machine learning at the graduate level. Exercises are provided and each concept is introduced using the same example domain, making it easier to compare the individual properties of different approaches.