ao dialogue 2|09

The magazine for the AO community 2 | 09

AO Trustees Meeting 2009The next 50 years

The global trauma crisis | Shoulder arthrodesis in a Minishetty stallion

Parallel plate application | Berton Rahn Research Prize

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Contents

Report

9 | Maurice E Müller: a tribute

Inside AO12 | AO Trustees Meeting: Chicago June 200917 | “Beyond our 50th Anniversary”

From the regions20 | The global trauma epidemic

Internet22 | Emerging health systems

Books23 | Osteotomies Around the Knee

Panorama

4 | News & Events8 | People

AO Dialogue 2 | 09

Editor-in-Chief: James F KellamManaging Editor:Olga HarringtonPhoto Editor:Jürgen StaigerEditorial Advisory Board:Jorge E AlonsoJames HunterFrankie LeungRodrigo PesantezPol M RommensPublisher: AO FoundationDesign and typesetting: nougat.chPrinted by: Bruhin Druck AG, Switzerland

Editorial contact address: AO FoundationClavadelerstrasse 8CH-7270 Davos PlatzPhone: +41(0)44 200 24 80 Fax: +41(0)44 200 24 21E-mail: [email protected] © 2009AO Foundation, Switzerland

All rights reserved. Any re production, whole or in part, without the publisher’s written consent is prohibited. Great care has been taken to maintain the accuracy of the information contained in this publication. However, the publisher, and/or the distribu-tor and/or the editors, and/or the authors cannot be held responsible for errors or any consequences arising from the use of the information contained in this publication. Some of the products, names, instruments, treatments, logos, designs, etc. referred to in this publication are also protected by patents and trademarks or by other intel-lectual property protection laws (eg, “AO”, “TRIANGLE/GLOBE Logo” are registered trademarks) even though specific reference to this fact is not always made in the text. Therefore, the appear-ance of a name, instrument, etc. without designation as proprietary is not to be construed as a representation by the publisher that is in the public domain.

Impressum

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Editorial

James F KellamEditor-in-Chief

[email protected]

On May 18, 2009, I was privileged to a ttend the very moving memorial ser-vice for Maurice E Müller. As one would expect, this ceremony was held in the beautifully appointed gothic cathedral of Bern. The congregation consisted of the who’s who in orthopedic surgery and Müller’s high school provided a guard of honor. This acknowledgement was very fitting for a man who had been both an inventor and a leader in the field of or-thopedic surgery. However, the most im-portant aspect of this service was not the pomp and ceremony nor the recognition of what this man had achieved, which was manifold, but rather the focus was on what Maurice Müller had contrib-uted as a person to both his family and his community. This was very much in evidence from the outset as people congregated on the great square outside the cathedral and talked about what a dedicated friend Müller had been and what he meant to the community of Bern. The music supplied by the Cam-ereta Lysy Gstaad, an organization that he and his wife had sponsored, provided an appropriate backdrop for this tribute to Müller’s career, and more important-ly, to Müller the man. As the last of our Founders has passed away, his greatest message lives on, “No matter how one strives to be a leader, to be a success in his profession, it is probably more important to remember to maintain the strength and involvement with your family and with your community.”

Clinical topic24 | Bridge plating

Clinical topic28 | 90-90 versus parallel plating of distal humeral fractures

Research32 | Berton Rahn Research Prize

AO VET34 | Shoulder arthrodesis in a Minishetty stallion

Expert zone

My view

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PanoramaNews, Events, People

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Eric Johnson honored On July 13th, 2009 Eric Johnson, was conferred with the Honorary Fellowship of the Royal College of Surgeons in Ireland (RCSI). This is the College’s highest honor and is usually reserved for those special and remarkable people who have made outstanding contributions to medicine, surgery or humanity. “Though we are quite accustomed to receiving accolades for our AONA faculty, this represents a truly great honor. Eric is uniquely qualified and deserving of this award due to his very significant contributions, his extensive international exposure and his Irish heritage. We are extremely proud of his accomplishments and congratulate Eric on receiving this prestigious award,” said Jack Wilber, President AO North America. For Eric, the fellowship award was one that he looked forward to receiving with great antici-pation; “This was the singular event highlight of my career: I am forever grateful to the College and my Irish friends.”

Marvin Tile honored On Canada day, July 1, 2009, Marvin Tile was appointed “Member of the Order of Canada”, the highest distinction that can be bestowed upon a Canadian citizen, by her Excellency, the Right Honourable Michaëlle Jean, Governor General of Canada, for his contri-butions as a clinical orthopedic surgeon, teacher, and groundbreaking researcher. “I can not think of too many others who deserve such recognition. He has truly affected the lives of many patients through his commitment to education and most important his mentoring and ideals,” says James Kellam, AO Foundation Past-President. “As for the AO Foundation, Marv was one of the AO pioneers in North America and became the first international president of the AO. Under his lead-ership and innovation as president (1992–94), the AO Foundation truly became worldwide and open to all.”

Appointment of AO research and development director After a long and careful search process, the AO Board of Directors (AOVA) appointed Geoff Richards as Director of AO Research and Development (AO Research Institute Davos/ARI) operative from September 1, 2009. Geoff Richards has been with the AO Foundation for over 17 years and was previously Head of Translational Research and ad interim Head of Preclinical Services. Before taking on this demanding position, Geoff Richards followed an intensive management program to ensure a smooth handover during the transition phase in which the ARI’s organizational structure is aligned to the new AO Research and Development strategy.

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AO Education (AOE)

Lead by Urs Rüetschi, AOE has restructured to competently respond to the needs of the Specialties. The role of “Medical Education Program Developer” has been established to create links between Education Commissions and production teams. This function will translate surgeons’ educational needs into educational activities such as standardized course templates, online and print activities, and faculty support media. Doris Straub Piccirillo, Miriam Uhlmann and two, soon-to-be recruited, specialists will assume this function. The units producing media in collaboration with surgical experts have also been restructured: Kathrin Lüssi is responsible for print publications and faculty support material team (formerly AO Publishing), Thomas Lopatka leads the video team and Michael Redies continues to lead eSevices (formerly Knowledge Services). Michael Redies is also responsible for projects dealing with innovations in education and knowledge translation. Pascal Schmidt will oversee assessment and evaluation projects as well as new research projects in education.

AO Clinical Investigation & Documentation (AOCID)

AOCID reevaluated the situation in North America and decided to close its Princeton office in August. Given the close collaboration with so many clinics, along with improved telecommunications, there was no longer a pressing need to maintain a physical presence in the region. All of the North American studies are continuing as planned, and monitoring services are outsourced when neces-sary. Expert support is provided by AOCID staff in Switzerland. The 2009 AOCID Fellow, Jost van Middendorp, from the Netherlands, started his fellowship in August, staying until the end of the year, and focusing on the reporting of methodological issues in spinal trauma intervention studies.The randomized controlled trial comparing the Angular Stable Locking System (ASLS RCT) to con-ventional locking in patients with distal tibial fractures treated with the Expert Tibial Nail has started well. The BG Unfallklinik in Germany, where the Principal Clinical Investigator Dankward Höntzsch is based, enrolled the first five patients in August (total sample size is 140). All seven study sites in Germany and Austria will be ready for patient recruitment in the Fall.

AO Research Institute (ARI)

Musculoskeletal infection is one of the most common complications asso-ciated with surgical fixation of bones fractured during trauma. ARI has a long history investigating the contribution of the basic design of fracture fixation devices to susceptibility to infection, and recent projects have inves-tigated the resistance to infection of Locking Compression Plates (LCPs). LCPs, commonly available in titanium or steel, improve on previous plate designs by protecting the periosteum and minimising tissue necrosis. Studies involving earlier compression plate designs, which had less periosteum protection, have shown that titanium is more resistant to infection than steel under these conditions. However, for

the locked system, LCP, we have found that titanium and steel are equally resistant to infection under the same conditions. Furthermore, polishing the surface of internal fracture fixation implant mate-rials has been shown to ease implant removal and reduce irritation to gliding tissues, with significant potential clinical benefit in certain situations. In an infection model, we have determined that there is no difference in

susceptibility to infection between standard and polished LCPs. Clinical implementation of polished Ti and TAN plates is not expected to result in an increased infection rate.

LCP being fixed to rabbit tibia

The AO at the EFORT congress The European Fed-eration of National Associations of Orthopaedics and Traumatology 10th annual meeting was held in Vienna, Austria in June. There were 6,000 at-tendees—a figure which reflects the importance of this meeting to Europe’s surgeons. AO Clini-cal Investigation & Documentation was proud to showcase for the first time the AO COIAC at the AO Foundation’s booth in the exhibition hall. In addition, an AO Trauma Symposium on peripros-thetic fracture treatment was chaired by Nor-bert Haas and Pierre Hoffmeyer. Hermann Bail from the Charité Hospital in Berlin and Michael Wagner, Chairman of the AOTrauma Transition Board, were among the presenters. All of the speeches on the evidence base, treatment options, new implants as well as salvage procedures of periprosthetic fractures were very well received. The next EFORT Congress will be held in Madrid, Spain, in June 2010.

From the service units

Standard & polished Ti & TAN LCPs & ESS LCPs

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Changing of the guard During the AO Frühjahrstagung 2009, which took place in the Grand-hotel Giessbach at lake Brienz in the Bernese Oberland, the incoming “foreman” of AO Swit-zerland, Christoph Sommer, paid tribute to the departing president, Roli Jakob, who was the initiator of the very popular Swiss resident courses, of which this was a great example. Another passion of Roli Jakob’s is Eritrea where he started—together with coworkers—an AO-sponsored project with the conviction that “the message of medicine is a better way to help people instead of financing big development projects.” AO Switzerland honored this personal, enduring engagement with a check enabling him to continue his work in Eritrea. At the start of his very active presidency, Roli made a promise to attract more participants—young and old—to the AO annual meetings, a commitment which he has delivered on for many years and which was fulfilled yet again by this fitting end to a successful presidency.

Berton Rahn Research Prize This annual award honors the best research fund projects and this year there were two very deserving awardees: Melissa Knothe Tate for the presenta-tion of the scientific work: “Unravelling endogenous mechanisms of bone regeneration through quantification of the interplay between bone cells and their environment” and James Iatridis for the presentation of the scientific work: “Effects of cyclic compression on intervertebral disc cell metabolism.” At the 2009 Trustees Meeting, Joachim Prein, consultant, and Geoff Richards, Director of AO Research and Development, announced that the former AO Research Fund Prize would be renamed as a tribute to the late Berton Rahn, former AO Research Institute Vice Director. The award ceremony also took place during the Trustees meeting, where both winners gave an enlightening presentation of their research and their prizes were awarded by the chairman of the AO Research Fund, Adrian Sugar. To read abstracts from the award winning scientific papers please refer to the Research article on pages 32 and 33 of the expert zone.

Berton Rahn

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Nepal hosts first AO Principles Course for surgeons and ORP With support from the AO Socio Economic Committee (SEC) in Switzerland and the AO’s industrial partner, Synthes, Ram Kewal Shah fulfilled a lifelong dream to host AO courses in Nepal. Nepal Medical College and Teaching Hospital in Kat-mandu was the site of the May course and the event drew 36 doctors and 36 ORP nurses from Nepal, Bangladesh, and Sri Lanka. It provided a unique opportunity for participants to acquire the latest fracture management knowledge and pre-pared them to put their new skills into practice in their own institutions. The three-day event culminated in a banquet at the Annapurna Hotel, where the president of the Nepal Ortho-paedic Association (NOA) bestowed an honorary membership of the NOA upon Thomas P Rüedi. According to Rüedi, “For some, this was their first exposure to AO principles and tech-niques, as well as Synthes equipment, which is unfortunately very costly for patients who must buy the implants themselves. Nonetheless, the feedback from participants was very positive, and the organizers have to be congratulated on an excellent job.” Course chairman Singh said, the event was a milestone in AO educational activities in Asia and that “Feedback from participants and faculty revealed the usefulness of the course in skill transfer; participants are convinced that this will make a positive impact on their practices.”

New Book in 2009: AO Manual of Fracture Management—Elbow and Forearm (Jesse B Jupiter) This new publication by the editor of the AO Manual on hand and wrist fractures provides a comprehensive approach to the indi-cations, fracture patterns, surgical exposures, contemporary implants, and postoperative management of elbow and forearm fractures.The editor and associate editors have selected a large number of cases for this book, provided to them from outstanding trauma surgeons worldwide. The selection represents a wide variety of fracture patterns, both simple and complex. Each clinical case is richly illustrated and described in detail.

New Chairman of the AOSpine International Board Luiz R Vialle, the first Latin American to the Chair, succeeded Michael Janssen, who remains with the board in the official capacity of Past-Chairman. Luiz Vialle, holds a PhD in Clinical Surgery from Brazil Federal University, and is currently Chief of the Spine Unit at the Cajuru University Hospital in Curitiba, Brazil and also Professor and Head of the Orthopedic Depart-ment at Pontifical Catholic University. His ongoing research includes radiological and histological analysis of a model for disc regeneration in animals, stem cell research for animal disc degeneration, and stem cell research for experimental spinal cord injury. Luiz has been involved with the AO for over 20 years, and was involved in AOSpine from its start, where he successfully chaired and pioneered the first AOSpine Latin America Board and the AO expansion in this region.

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Judith MunthaliCompleted a Fellowship at BG Trauma Clinic

in Tübingen, Germany

Judith Munthali

Judith MunthaliOperating Room PersonnelUniversity Teaching HospitalLusaka, Zambia

[email protected]

“Experience of a lifetime” best describes my recent AO Fellowship. The BG Trauma Clinic deals only with traumatology, pros-thetics, spine, maxillofacial, and hand/microsurgery. Each week day I was in the operating room, where I was allowed to actively circulate and scrub, initially as the second scrub nurse, then later as the main scrub nurse for osteosynthesis operations in traumatology and pros-thetic surgery. I also observed cases in the maxillofacial, ambulant and septic theaters, as well as the plastic/hand sur-gery department. I worked closely with Prof Höntzsch in traumatology and Dr Deswart in prosthetic surgery. Among my experiences at the clinic, I was able to see postoperative clients undergoing hydrotherapy and exercise with a physi-cal therapist and attend rounds with professors on one of the major wards to see how postoperative patients are man-aged. I also had an opportunity to work

in the clinic’s sterilizing department, which is so modern that non-theater medical staff member are able to pack instrument sets using computers. The department is headed by an OR nurse, and the computers are fed all of the instrument set details as well as photos showing the final finish of any graphic tray. The sterilizing staff members work throughout the night, to ensure that everything is prepared for the following day’s list. I also visited the intensive care unit to observe critical care nursing, as well as the other hospital departments. Overall, my AO Fellowship offered me a very productive environment for learning about ideal operating room hygiene, a disciplined work attitude, modern equip-ment, how to pack complete graphic sets with required instruments, the required instruments for specific sets, and osteo-synthesis techniques. I am very grateful for all of this.

Fellow’s opinion

Global Spine Congress 2009 Designed to meet the specific needs and inter-ests of spine specialists from around the world, the event took place in June at the Westin St. Francis Hotel, San Francisco. The congress—organized by AOSpine and supported by world renowned international faculty and a range of industry sponsors—was a resounding success, further establishing AOSpine’s reputation for academic excellence. Participants learnt about the latest approaches to spine care, shared insights from thought leaders and experiences with colleagues, made new contacts, strengthened existing relationships, and honed their ideas and knowledge. Chairperson Jeffrey Wang, Educational Director Bartolomé Marré, and more than 40 faculty members from all over the world led participants through lively debates, symposia, courses, and scientific sessions. In addition, over 200 research papers were presented making it a very extensive program. The program agenda was created through a selection process involving both a public call for abstracts and a thorough investigation of the AOSpine community to identify and invite leading experts and representatives.

Judith Munthali sharing a toast with colleagues in Tübingen

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Maurice E Müller:a tribute

Maurice E Müller, AO Founding Father, passed away peacefully in the presence of his family on

May 10, 2009, at the age of 91. “While Maurice may have left us for his eternal reward, his legacy lives on in the millions of patients who have been treated according to the AO Principles he was cen-tral in formulating. What a noble life he lived.”

These were some of the moving words written by Paul Manson, President of the AO Foundation and Markus Rauh, Chairman of the AOVA ac-knowledging the impact Maurice Müller had on

so many lives. Not surprisingly tributes flowed in from around the world and the AO network from people who had been touched by “A remarkable man who was fortunate to lead a remarkable life. He was given great gifts and used them extraordi-narily well,” Dan Beery’s concluding words from his tribute at the Trustees Meeting in Chicago.

We have taken excerpts below from the wonderful eulogy given on behalf of the international com-munity by Joseph Schatzker, Past-President of the AO Foundation at both Maurice Müller’s funeral and the tribute event at the Trustees Meeting in Chicago.

Report

“The sadness many will feel upon his passing is directly linked to

the very many achievements and friends he made during his life.”

Paul Manson and Markus Rauh

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community zone Report

Excerpt from the funeral eulogy for Maurice E Müller by Past-President Joseph Schatzker.

Two great advances revolutionized orthopedic surgery in the twentieth century. Maurice Müller played a piv-

otal role in both. He was an innovator in joint replacement, helping to bring relief and mobility to those, especially the aged, suffering from crip-pling arthritis. He and his friend and colleague, Sir John Charnley, are the fathers of total hip re-placement.

It was Maurice alone who pioneered one of the most significant surgical advances of modern times, ie, the treatment of fractures through stable internal fixation with plates and screws, allowing immediate movement and rehabilitation of the injured extremity…

…Becoming a surgeon in Switzerland in the 1940s was not easy. There were no formal training pro-grams. Young doctors had to go from hospital to hospital, seeking out the experience and teaching needed to enter surgery…

Maurice subsequently (after returning from a year working in Ethiopia) traveled throughout Europe to visit the famous surgeons of the day. One such visit, to Robert Danis in Belgium in 1950, would be the most important experience of his profes-sional life… That visit to Danis laid the foundation for the revolutionary principles of osteosynthesis Maurice would go on to develop…

…While on military service in 1952, Maurice met an old high school buddy, Robert Schneider, who was chief of a small district hospital in the Can-ton Bern.

Schneider was so impressed by the concepts ad-vanced by his young orthopedic colleague that he invited Maurice to join him at the hospital and operate on difficult trauma. With time he intro-duced Maurice to a number of his friends: Bandi, Schaer, Willenegger, and other general surgeons who worked as chiefs in the district hospitals in Canton Bern…Willenegger introduced Martin All-göwer to Müller. Martin was so impressed with what Maurice was able to achieve with complex injuries that he soon joined the group, and in the spring of 1958 he and Maurice organized a prac-tical workshop in Chur where Martin was chief of surgery. This meeting, which consisted of talks

“

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given by members of the group and then followed by practical exercises on bone, generated such enthusiasm and resolve that on November 6 1958, the group met in Biel and formally founded the Swiss AO.

With the help of Robert Mathys, an instrument maker from Bettlach, Maurice had within just two years designed, built and tested an entirely new armamentarium of screws, plates, nails and power tools. By late 1960, Mathys produced twenty full sets of the now-famous standard four boxes, which contained all that was needed for the in-ternal fixation of any fracture. These were used by the participants of the first AO course held in Davos on December 10 1960…

…The fledgling Swiss AO realized that courses and publications were also necessary. Concepts had to be taught so that the new implants wouldn’t be misused. When Maurice began organizing the now-famous AO courses full of hands-on training on fracture models, postgraduate surgical educa-tion entered a new era.

Maurice also understood what is perhaps the most fundamental problem of all in science, funding. Maurice solved this problem by creating the first ever, joint enterprise between medicine and com-merce, one that was a model of how industry and science could work together to advance medicine.

Maurice himself was a visionary donor of remark-able generosity. He gave to Synthes AG Chur, the financial arm of AO he had created with the help of von Rechenberg, all the intellectual property, patents, instruments and implants that he had de-veloped over the years. This personal sacrifice— for he could have sought commercial gain—became the enduring model for members of the AO…

…Switzerland could not contain Maurice. He brought his formidable talents to the world stage, becoming a founding member of the International Hip Society and, later, its president. In 1984, he became president of SICOT. His legendary generos-ity, flowed to foundations he established in Spain and North America, and he endowed chairs of orthopedic surgery in several countries.

Maurice “retired”—if that’s the right word—in 1981 at the age of 63. This was merely a release from his administrative burdens, and Maurice now threw himself into his passion: Classifica-tion, documentation and evaluation, the pillars of evidence-based medicine. His efforts resulted in the Comprehensive Classification of Fractures of Long Bones, also known as the Müller/AO classifi-cation of fractures which has become the universal standard and will remain his enduring legacy…

…Maurice’s final big project in life was to return to his dream of early years, a dream of creating the perfect community. “Das Letzte…das Höchster-rungene” was the Paul Klee Zentrum that became a reality through the magnanimity of Maurice and Marti Müller…

…The contributions of Maurice Müller have not gone unrecognized: Switzerland gave him the Benoit prize; Bern proclaimed him as an Honou-rary Citizen and SICOT declared him “the ortho-pedic surgeon of the century whose achievements and success have exceeded all others”.

…But from his colleagues, Maurice deserves the noblest titles that we surgeons can confer on members of our profession: Maurice Müller, healer and teacher. ”

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community zone Inside AO

AO Trustees Meeting: Chicago June 2009

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Setting directionsAt his first Trustees Meeting as President of the AO Foundation, Paul Manson on Thursday, June 18, welcomed the participants and guests to Chi-cago, his home town. A welcome cocktail hour and dinner the previous night at the renowned the Drake Hotel’s Gold Coast Room provided par-ticipants with a tasty introduction to Chicago’s various ethnic cuisines.

Joachim Prein, consultant, and Geoff Richards, Director of Research and Development, presented a very personal tribute to the late Berton Rahn, former AO Research Institute Vice Director, who had dedicated himself to AO research in Davos. The speakers announced that, in memory of this mod-est and quiet man and his many scientific contribu-tions, the former AO Research Fund Prize would be renamed the “Berton Rahn Research Prize”.

In his keynote speech, Paul Manson looked beyond the 50th anniversary of the organization. By con-trasting the many facets of the AO’s history with current and upcoming challenges for the founda-tion, he made it very clear that there is a need for a common will and that only reflection on the original values of the AO, like mutual trust and comradeship, will guarantee the AO Foundation’s continued success in the next 50 years.

Tim Pohlemann, Chairman of the Technical Com-mission Executive Board (TKEB), and Michael Wagner, Chairman of the AOTrauma Interna-tional Transition Board, gave insights into new developments and processes as well as, in the case of AOTrauma, the setup of structures for this new flagship specialty plus upcoming activities. In addi-tion to the presentation, during breakout sessions on Friday and Saturday, AOTrauma also offered

”

“ For me this meeting was devoted to bridg-ing the gaps between the generations. Thanks to AO’s solid structure, the positive attitude of the different generations and hard work, we managed to overcome the gaps and build a sound base for the upcoming changes. Rami Mosheiff

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participants various behavior patterns to help overcome old routines and manage change. The sessions’ title “Who moved my cheese?” was based on the best selling book by Spencer Johnson.

Fascinating clinical presentations included the lat-est findings and outcomes in face transplantations, clearly directed at the future of surgery, while the lecture by James W May from the Massachusetts General Hospital with the title “Gain without pain” looked back at the beginnings of anesthesia, a thrill-ing chapter of medicine history.

Following the overarching theme of looking beyond the first 50 years, leading speakers discussed future possibilities in outcome research, technology, edu-cation, and setting up specialty organizations.

At the end of this first day full of groundbreak-ing speeches, participants and guests enjoyed the stunning views of the city of Chicago from the John Hancock Observatory—94 stories above the city’s Magnificent Mile—and a dinner at Fulton’s restaurant, a famous steak house along the Chi-cago River.

From the scientific point of view, this meeting was the most interesting I have had the opportunity to attend. I congrat-ulate myself for having the opportunity to be part of this organization.Sergio Fernandez ”“

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Fostering the networkDuring the AO General Assembly on Friday morn-ing, Trustees made important decisions about the future of the AO Foundation with the aim of mak-ing the organization fit for the next 50 years. Paul Manson had already given a sneak-preview of the program for the 2010 Trustees Meeting planned for Lisbon and presented AO Foundation Past-President, Chris van der Werken, with a photo book as a token of appreciation from colleagues on AO’s Board of Directors for his excellent work during the Foundation’s Anniversary Year.

In addition, Marilyn Moats Kennedy, founder and managing partner of a management con-sulting firm, spoke about managing change and understanding the demographics of the evolv-ing workplace. The presentation, as well as the lively discussions of Trustees afterwards, focused on workplace values and lifestyles of the groups that will dominate the workplace in the next century.

Parallel sessions on mostly clinical topics, as well as reports on the Clinical Priority Program (CPP)

Fracture Fixation in Osteoporotic Bone and on the benefits and risks of a Membership Program, filled the remainder of another exciting meet-ing day.

Due to high water, the planned architectural river boat cruise in the evening was relocated from the Chicago River to Lake Michigan, affording par-ticipants spectacular views of the Chicago sky-line against the backdrop of approaching stormy weather. All boats returned safely for dinner at the River East Art Center, where participants enjoyed a mixture of food, music and art.

Looking into the futureThe last day of the 2009 AO Foundation Board of Trustees Meeting pointed to the foundation’s future while underscoring its strong bonds to the values and people that have made the organization one of the world’s leading medical networks.

In the morning session, speakers focused on sci-entific topics and cutting-edge research—from discussions on bone defects, the Global Spine Con-gress to the Berton Rahn Research Prize Awards—

”

The discussion about the bylaws during the general assembly was intense. However, it was even more impressive to see several people prac-ticing democracy even though they are not living in democratic countries. Once in a while the AO teaches more than just surgery. Frank Kandziora

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and emphasized the role of science and research as a cornerstone of the organization. Both award winners delivered short summaries of their re-search topics: Melissa Knothe Tate reported on endogenous mechanisms of bone regeneration and James Iatridis gave a brief lecture on the mechani-cal effects on intervertebral disc metabolism.

A touching report by Jim Harrison focusing on AO activities under tough conditions in the Beit Cure Hospital in Blantyre, Malawi, led back to the underlying mission of the AO Foundation: To achieve more effective patient care worldwide.

The President officially concluded a successful meet-ing with the final summation and recognition of outgoing and honorary Trustees. Later in the after-noon, the Trustees attended a moving tribute, led by Daniel Berry and Joseph Schatzker, to Founding Father Maurice E Müller, who died in May.

AO Foundation Honorary Trustee Pietro Regazzoni closed the loop between the past and the future with an after-dinner speech at the banquet at Café Brauer in Lincoln Park. In his unique and enter-taining way he described what he had thought he could learn as a result of his work for, and within the AO. To the accompaniment of a blues band, the 2009 AO Foundation Board of Trustees Meeting came to an end.

AOVET was voted to be “Equal” (during the amend-ments to the bylaws discus-sions). The three musketeers AOTRAUMA, AOSPINE, and AOCMF came to the rescue of AOVET, who greatly appreciates this selfless gesture and is proud to be the fourth musketeer. Jean Pierre Cabassu ”

“

Trustees and honorary trustees all took part in the discussion [on the amendments of bylaws] and I felt the different opinions expressed merely represented our passion and sense of ownership of the organization. Frankie Leung ”“

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“Hello Trustees,

…Last June, we spent an entire Trustees Meeting paying homage and tribute to those individuals who founded the AO Foundation, defended it and provided its initial governance…

…But now it is different. We are in the second 50 years! The challenges we face are very different now, from those our founders faced …

… Diverse international communities in the AO demand individual responsibility for their own futures. Our specialty groups feel our organization should not be divided regionally but by specialty, and they seek independence and control over their own resources. They demand responsibility for their own budgets, and for spending the money where they get the most value, irrespective of our central services. They prefer to organize their own research projects with external universities, have course sponsorship provided by other CME provid-ers, and plan and organize their own educational programs in locations which do not respect our traditional ones. Economically underprivileged

“Beyond our 50th anniversary”

Excerpts from AO President Paul Manson’s Keynote speech at the Chicago Trustees Meeting, focusing on the challenges ahead in the

next 50 years.

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Inside AO

areas request our support and indulgence. And threats come to us even from our own constitu-encies. Faced with increasing requests from the specialties, we seek to again devise new methods of organization, this time one that implies some regional responsibility but is really under single specialties governance. Is it possible to have spe-cialties, regional governance and a strong central Foundation which brings us together with the same spirit of cooperation and cohesiveness which char-acterized the AO Foundation in the past? And more importantly, can we afford these changes which consume volumes of additional resources?

We have developed new contracts with our pro-ducer partners, which potentially change the way we work together and profit from each others suc-cess. For now, although the producers continue to grow and develop strongly, our new contract does not allow for AO Foundation growth paral-lel to their success. In less privileged geographic areas we seek to make affordable the advantage of our technology, but the influx of new equipment and devices strains the ability of even the wealthy nations to afford it. We have needs and develop decisions, solutions and programs for our issues, but for the first time in our short history, our goals and plans far exceed our foreseeable resources…

… So let’s discuss what your leadership has done, and what we plan to continue to do in the fu-ture. We have just reorganized the importance

and place of research within the Foundation, and have created the opportunity for specialty driven, practitioner and specialty sensitive and peer re-viewed projects which are meaningful, practical and scientifically sound. We have a new director, who is committed to take us in this direction. But we can’t continue to do everything we want to do in research, because we cannot—and in fact no one can—afford it. We can do good, worthwhile projects if we are committed to drive the bus, and if we are committed to appropriate studies, and if we demand accountability and spend the effort to supervise the spending of our money and not allow ourselves to be driven by “money for friends”. We are committed to make a difference with the money we spend on research, and we are commit-ted to be fiscally sound and accountable, and we can’t and won’t spend a majority of our budget on research. So that’s the “research pillar.”

We have changed the “documentation pillar” to an “outcomes pillar,” because the worth of your care and your treatment in the future, when we will have limited amounts to spend, will be driven by value. We can’t just collect cases, we must use them to determine the worth to our patients of our procedures. We are preparing the AO Founda-tion to be the center for trauma treatment analysis and prediction which is based on the worldwide data which you, our clinicians, generate, so it can consistently look for the best solutions. May I say again that these need to be cost sensitive, which with your volume, you will be able to determine. You could easily derive the data which will gener-ate the decisions to be made by the world’s health care companies. And we would especially need the help of Synthes here, because health care systems cannot absorb continuous unlimited escalation of costs out of proportion to value—or our new competitors will take our intellectual product and make the changes government’s, who are demand-ing cost sensitive solutions, need. Either we do this, or others will do it, and we will be left stand-ing wondering what happened to us and what we should have done…

…The sad truth is that no one cares about the sur-vival of the AO Foundation except for us, you and I, and if you and I and Hansjorg Wyss and Markus Rauh don’t come up with solutions to these needs and issues, the world will leave us behind as it has done for so many corporations in the past who have failed to adapt…

Paul Manson acknowledges both Chicago‘s Blues Brothers roots and the torrential summer downpour, as he gives his keynote address wearing rain gear and sunglasses

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During the Trustees meeting in Chicago AOTrau-ma presented an adaptation of the book “Who moved my cheese?” within their World Café con-cept. Michael Wagner, Chairman of the AOTrau-ma International Transition Board, invited all AO Trustees to attend the AOTrauma World Café and to take the opportunity to voice their concerns and their hopes for the development of AOTrau-ma. Waiting the tables in the World Café were the AOTTB members themselves, happy to serve their customers.

Who moved my cheese?

Who Moved My Cheese?—A best selling book by Spencer Johnson, this is the story of four characters living in a

“Maze” who face unexpected change when they discover their “Cheese” has disappeared. Sniff and Scurry, who

are mice, and Hem and Haw, little people the size of mice, each adapt to change in their “Maze” differently.

…Our educational system is good, but is it still relevant? In the face of high airline fares and hotel costs isn’t it time to offer our courses over the In-ternet? For a small expense, in addition to what we spend now, we could offer these unparalleled educational experiences, on a worldwide basis, in local offices and clinics. We have made much progress with our educational portal, in fact it has received many prestigious awards, but isn’t there really a lot more progress we could make?...

…The AO Revolution did not end last year with our 50th Anniversary. It is not something to be won or achieved and then forgotten, or simply

listed in our founding documents. It is a desire to allow our very best groups to achieve a degree of independence and to function in their country and region as required, to provide comprehensive and cost sensitive solutions to the ongoing struggles of our patients to restore or preserve their health and to, in the minds and hearts of our Trustees generate the courage and determination to live up to our Founders challenges…

…Thank you dear Trustees, for the opportunity to lead you in

this challenging time as your president.”

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The global trauma epidemic

From the Regions

Largely unnoticed in Europe and North America, trauma has become a rapidly expanding epidemic in the world’s low and middle-income countries (LMICs). Currently, trauma from road-traffic ac-cidents alone is the 6th most common cause of death in middle-income countries, and 9th in the world1. Many of these countries are experienc-ing a rapid fiscal growth and with it expansion of their infrastructures. The accompanying increase in personal wealth means, for many, a graduation from foot or bicycle transport to motorcycles and automobiles. Sadly, this is also reflected in a com-mensurate, rapid increase in road-traffic injury rates. The WHO estimates that by 2030 trauma from road-traffic accidents alone will be the 3rd most common cause worldwide of both mortality and disability (as measured in disability-adjusted life years, or DALYs).

Why is this relevant to AO?AO’s mission has always been to “improve patient care”. In this, we have been very successful. The world over, if trauma patients are treated opera-tively today, they are mostly treated according to

AO principles. At the same time, a majority of patients in rich countries (and relatively wealthy patients anywhere in the world) enjoy the privilege of implants and fixation techniques developed by AO, or according to AO principles. While there are fracture types that remain difficult to treat and medical indications exist that prevent a satisfactory outcome even in optimal circumstances, patients in the rich world generally have access to state-of-the art treatment that promises vastly improved outcomes compared to 50 years ago.

This is mostly not the case for patients in LMICs. While state-of-the-art medical facilities exist in virtually all countries of the world, these are avail-able only to a small fraction of the population in most LMICs. Most patients—and their surgeons and other medical caregivers—face challenges in several parts of the system, starting with the state of emergency treatment: Often, lack of trauma protocols and infrastructural deficiencies (such as the absence of ambulance services) lead to higher mortality and disability rates than in HICs. Sec-ondly, LMICs face a number of technological chal-

Michael RediesHead of Knowledge Translation & Innovation AO Education, Davos, Switzerland

[email protected]

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1. The Global Burden of Disease: 2004 Update (2008) World Health Organization, p 51.

2. The Global Burden of Disease, pp 64–83.

3. Arreola-Risa et al (2000) Low-cost improvements in prehospital trauma care in a Latin American city, J Trauma; 48(1):119–124; Mock CN, Jurkovich GJ, et al (1998) Trauma mortality patterns in three nations at different economic levels: implications for global trauma system development, J Trauma; 44(5):804–812.

4. Mock CN, Jurkovich GJ, et al (1998) Trauma Mortality Patterns in Three Nations at Different Economic Levels: Implications for Global Trauma System Development, J Trauma; 44(5): 804–814; Mock CN, Ellis Adzotor K, et al (1993) Trauma Outcomes in the Rural Developing World: Comparison with an Urban Level 1 Trauma Center, J Trauma; 35(4): 518–523.

Population DALYs (total)

DALYs (per 1000

population)

African LMICs 738 million 29’658’000 40.2

SE Asian LMICs 1’672 million 62’818’000 37.9

Americas LMICs 545 million 15’311’000 28.1

European HICs 407 million 3’550’000 8.7

Disability-adjusted life years (DALYs) resulting from injury

How can the trauma epidemic be tackled?A number of studies has compared treatment of pa-tients in different economic settings. These showed that mortality and disability can be reduced sig-nificantly by improvements in pre-hospital care, emergency room care and in the OR4. There seem to be three main steps in dealing with the global trauma epidemic:

lenges, eg, a relative scarcity of tools and imaging equipment. Finally, surgeon education is often a problem, with economics severely restricting ac-cess to medical literature and other authorities, and with principles of fracture management often not being sufficiently taught.

The difference in patient care between HICs and LMICs is strikingly documented in statistics com-paring disability and mortality. Disability result-ing from injuries is almost 5 times higher in Africa than in Western Europe, and mortality from the same cause is almost double in middle-income countries compared to high-income countries2.

As studies have shown, even slight improvements to pre-hospital trauma care, predominantly the intro-duction of emergency trauma protocols and better surgeon education, can dramatically reduce mortal-ity and disability3. This constitutes fertile ground for AO’s mission: fracture treatment and patient care in LMICs is a global challenge of great humanitarian and economic proportions. If we take seriously the improvement of patient care, our engagement in LMICs is bound to have a great effect.

321Prevention

Evidence has shown that national road safety pro-grams, legislation, use of helmets, seat belts and child restraints, enforcing sobriety in traffic, road safety audits and other measures can signi-ficantly lower the rate of traffic accidents.

Emergency treatment Operating room

Mortality and disabi-lity can be reduced significantly by improving pre-hospi-tal care, emergency response and emer-gency room care. The two main factores are infrastructure and education.

The greatest propor-tion of disability results from muscu-loskeletal injuries. This can be significantly reduced in the opera-ting room. Again, the main factors are education and infrastructure.

What can AO do?The essence of AO has always been its network of surgeons, sharing a main mission of improv-ing operative fracture care. AO can take up the challenge of fighting the burden of disease in the operating room by education. There is much that we can do: Adapted principles courses, continuing education courses, fellowships and reverse fellow-ships, Internet reference and distance learning are all means that can contribute significantly. These will have to be discussed by the appropriate boards and units.

Road-traffic accidents

HIV/AIDS

Unipolar depressive disorders

Respiratory infection

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AO Surgery Reference in emerging health systems

Internet

Surgeons in low and middle-income countries (LMICs) around the world today face a trauma pandemic that will almost double the number of deaths from injury over the next two decades. Road-traffic accidents alone will become the third most important cause of burden of disease in the world by 2030, up from rank 9 today, and will surpass such diseases as HIV/AIDS, lower respira-tory infections and diarrhoeal diseases in their disastrous effects on human lives and health.

There are several ways in which AO can help to al-leviate this burden of disease and some have been outlined briefly in the preceding article. We hope that in some ways a new project associated with the AO Surgery Reference will also contribute to helping LMIC surgeons in their fight against the trauma pandemic.

AO Surgery Reference (AOSR) has for some time now been the world’s premier trauma reference service on the Internet, with currently more than 30,000 visits monthly and more than 350,000

page views monthly. Happily, it isn’t only surgeons from the most developed countries—in which AO is traditionally strongest—who use this unique Internet service, but increasingly physicians from LMICs. In fact, in July 2009, India ranked 4th in our statistics, surpassing even Germany in usage; Brazil ranked 6th, Argentina 8th and Mexico 10th (with the US unsurprisingly leading the statisti-cal ranking).

BarriersThis is especially encouraging when one considers that in its current form, AOSR presents a number of unintentional barriers to many surgeons from LMICs. Some of these are technical: The language used is English of which many surgeons in LMIC settings have only a rudimentary grasp. The me-dium is the Internet, which on the one hand en-sures cheap and ubiquitous distribution, but which on the other hand can be riddled with a host of technical limitations. The most widely experienced limitation is slow access speed, which can be a powerful deterrent to users who have to wait a

long time to load each page. Yet another bar-rier is the content which focuses on fixation tech-niques often using top-of-the-range implants and does not include typical LMIC challenges such as delayed treatment of frac-tures, etc.

Michael RediesHead of Knowledge Translation & Innovation AO Education Davos, Switzerland

[email protected]

Improve accessibility of surgical knowledge

Adapt surgical procedu-res to available implants and tools

Focus on common injuries and problems

Teach principles of fracture management

• Offer Spanish and Chinese translations

• Adapt serving technology to lowspeed connections

• Focus on open reduction internal fixation

• Describe fracture treatment with basic range of implants and tool

• Consider alternative limited invasive techniques

• Severe soft-tissue injuries and open fractures

• Delayed treatment

• Complications, as eg, infec-tion, compartment syndrome

• Introduce hitherto unexposed audience to AO principles

• Teach preoperative planning

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Books

AO Book Review

The Emerging Health Systems (EHS) projectA group of surgeons from among the AOSR edi-tors and authors has come together and created a concept to remove these barriers and to expand AOSR so that its value to LMIC surgeons is greatly increased. As described in the chart above, four thrusts are intended to achieve this. In 2008 the malleolar module was translated into Chinese and Spanish as a test; so far with encouraging results.

Currently much of AOSR’s underlying technology is being revised with the goal of making pages load faster and removing other technological ob-stacles.

We are now preparing a revised version of the tibial shaft module which will incorporate—next to the existing content—additional descriptions of surgical procedures aimed at surgeons practicing in typical LMIC “second medical world” environ-ments: rich enough to provide operative fracture care, but with limitations in available equipment

Osteotomies Around the KneeIndications—Planning—Surgical Techniques Using Plate Fixators

Editors: Phillip Lobenhoffer, Ronald J van Heerwaarden, Alex E Staubli, Roland P. JakobCo-editors: Mellany Galla, Jens Ag-neskirchner

This book is a welcome addition to knee surgery literature, providing an extensive overview of the use of os-

teotomy to treat osteoarthritis and knee deformity. Total knee arthroplasty is, nowadays, the surgeon’s first treatment choice so it is good to highlight an-other biological option. The authors are skilled orthopedic surgeons with extensive experience using osteotomies and, particularly, internal fixa-tion techniques which have made this technique more applicable and guaranteed better results.

James F KellamEditor-in-Chief

[email protected]

and complications that hitherto have not been con-sidered in AOSR. Included will also be discussions of how to treat infection, the management of com-plications such as compartment syndrome, and the challenges of severe soft-tissue compromise. This pilot module is scheduled to be launched in December 2009 and will be expanded throughout 2010 until the requirements from all four thrusts have been fulfilled.

Should this pilot prove a success, the long-term plan will be to enhance all of AOSR with contents relevant to LMICs. In summary, the following are the strategical goals of the EHS project:

Strategic goals• To introduce AO principles into previously un-

reached circles.• To improve surgeon education and thereby

patient care.• To enlarge the AO community by adding the

LMIC demography.

The book covers all aspects of osteotomy, from a historical review of the osteotomies about the knee to a discussion of the physiological axes of the limb outlining normal, abnormal and measurement techniques. A chapter on clinical and radiological evaluations is followed by an overview on indications for osteotomy, while basic principles and planning algorithms for os-teotomies, in particularly that of the high tibial osteotomy both closing and opening wedge types and the use of locking and conventional plate fixation, are also covered. There are sections on the mechanics and basic science of osteotomy and how one assesses bone healing. The role of supracondylar osteotomies of the femur and the use of double osteotomies and rotational os-teotomies with various deformities are also pre-sented. Acknowledging that the osteotomy may need revision the authors have included a helpful chapter on the role of total knee arthroplasty after osteotomy.

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Bridge plating

Refections useful for the adapted use of plates and screws in internal fixation More or less all implant systems used in internal fixation con-sist of two main elements—a longitudinal element for the load transfer from one main fragment to the other and a transverse element to assure the coupling of the implant system to bone (Table 1). When comparing internal fixation with intramedul-lary nails or internal fixation with plates some major differences appear. Using an intramedullary nail for a diaphyseal fracture the mechanical concept is more or less independent from the fracture pattern—simple fracture, wedge fracture, comminuted fracture. In addition, the position of the nail, the length and diameter of the nail as well as the position of the locking bolts are more or less given and standardised by the local anatomy of the broken bone segment as well as the implant design.

In contrast to nailing, plating offers two different fixation con-cepts—splinting and interfragmentary compression. Comminut-ed fractures are best treated using a splinting technique, because local bone and soft tissue devascularization can be minimized; while in simple fractures the application of interfragmentary compression can be considered as a stabilization tool.

Plate position is chosen mainly according to the local anatomy and the surgical approach chosen. But, depending on mechani-cal demands, the plate position can be altered (tension side, compression side). In addition, the length of the plate itself, the number and the relative position of screws which need

to be inserted, as well as the type of screws (standard cortical screws or locking head screws, mono- or bicortical screws, self drilling or self tapping screws) remain under debate. Thus, a lot of additional decisions have to be taken by the surgeon when planning and performing plate osteosynthesis. It is also evident that plating is intellectually and technically much more demanding than nailing (Table 2).

The three following main factors influence the stability of the fixation and the loading conditions of the plate bone construct: The overall length of the plate, the overspan length of the plate, and the number, position and design of the screws.

Length of the plateUtilizing the newer minimally invasive techniques of indirect reduction, subcutaneous or submuscular plate insertion and splinting as a stabilization concept, the plate length can be chosen to be very long without the need of additional soft tissue section and devascularization.

Theoretically the plate can equal the whole length of the broken bone. But, at least the minimal length of the internal plate can be determined by means of the two factors: The plate span width and the plate screw density. Plate span width is defined as the quotient of the plate length and overall fracture length. Empirically we find that the plate length should be two to three times higher than the overall fracture length in comminuted fractures and eight to ten times higher in simple fractures. The second factor is the

The use of plates for internal fixation gains more and more importance and acceptance due to the introduction of new implants offering the possibility to lock the screw head with the plate. With this new plate generation, different fixation concepts can be considered and in addition the indication for plating is spread out to the diaphyseal segment of bone. For proper application of the implants—and to avoid technical or mechanical complications—a thorough understanding of the basic concepts of fixation, the bone biology and biomechanics, remains of outstanding importance.

Emanuel Gautier

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plate screw density which is the quotient formed by the number of screws inserted and the total number of plate holes. Empiric ally we recommend values below 0.5, indicating that less than half of the plate holes are occupied by screws (Fig 1a–c).

Number of screwsFrom the mechanical point of view, two screws (monocortical or bicortical) on each main fragment, is the minimum number of screws needed to keep the plate bone construction stable (Fig 2a–c). Unfortunately, such a construction will fail if one screw breaks to due overload or when the interface between bone cortex and screw is threatened due to bone resorption with subsequent screw loosening. Thus, for safety reasons we recommend a minimum of three screws in each the proximal and the distal main fragment.

Adjusting the plate screw density to a maximum value of 0.5 the plate length should not be chosen below a 12-hole plate for treat-ment of a diaphyseal fracture. But, to increase the leverage of the screws the use of a 14- to 22-hole plate would even be better.

Effect of plate length on screw loadingThe length of the plate and the position of the screws modify the loading conditions of the screws. Increasing the length of the plate decreases the pullout force acting on the screw due to an improvement of the active lever arm of each screw (Fig 3a–b). This argument points to the use of long plates (nearly as long as the bone itself).

Characteristics of fixation and implants Nailing Plating

Concept of fixation Mainly splinting Splinting Compression

Load transfer Locking Locking Friction

Position Intramedullary Tension sideCompression side

Insertion Intramedullary Open MIPO

Length Whole length of bone To decide

Dimension Inner diameter of bone In relation with bone and bone segment

Number of screws Minimum 0Maximum 6

Minimum 4Maximum ?

Position of screws Given by nail design To decide

Design of screws BicorticalASLS

MonocorticalBicorticalSelf tappingSelf drillingStandard corticalLocking head

TechniqueOrientation of elements and mechanical function

Longitudinal load transfer Transverse coupling

external fixation Bar Schanz screw

Nailing Nail Locking bolt

Plating Plate Screw

Table 1

Table 2

Fig 1a–c Plate span ratio and plate screw density

In comminuted fracture the plate length should be 2 to 3 times higher than the overall fracture length (a). In simple fractures this ratio should be raised to a value of 8 to 10 (b). In addition the plate screw density should be kept below a value of 0.5, indicating that less than half of the plate holes are occupied by screws (c).

1a 1b 1c

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Fig 2a–c Minimal requirements for internal fixation using plates.

Two screws to couple each main fragment to the plate is sufficient from the mechanical point of view. But, the construct becomes to be unstable if one screw fails due to fatigue failure or due to resorption at the bone-screw interface with subsequent screw loosening. Thus, for safety reasons 3 screws for each main fragment can be recommended.

Example of plate fixation of a humeral shaft fracture using a minimal number of screws showing the undisturbed course of bone healing—postoperative radiograph (a), situation at 3 months (b), and 6 months (c).

Fig 3a–b Influence of lever arm on pull out of screws.

Using a long plate improves the lever arm of the screws. This leads to a low pull out force acting on each screw. A short plate creates higher pull out of the screw (a) compared with a long plate creating lower pull out of the screws (b).

Fig 4a–b Decreasing the implant deformation and strain with adaptation of screw positioning.Bending the plate over a short segment increases the strain within the plate (a). To decrease the relative plate deformation the distance between the innermost screws should be increased (b). This distributes the implant deformation over a longer distance and reduces the strain within the implant —as long as the overall plate angulation remains unchanged due to a distance limitation of the opposite bone cortex.

Fig 5a-c Submuscular splinting of a simple femoral shaft fracture.

Spreading out the two innermost screws leads to a sound strain dis tribution within the implant and a sound bone healing documented by radiographs taken postoperatively (a) at 4 months and 3 years (b and c).

Fig 6a–c In the case of a comminuted diaphyseal fracture spreading out the innermost screws is dictated by the fracture pattern leading to low implant strain under the prerequisite that the overall deformation and angulation is limited by partial contact of intercalated fragments at the opposite cortex (a). In case of no distance limitation plate angulation is not hindered (b) and can equal the critical strain values seen in the schematic drawing with splinting a simple fracture by means of a plate leaving a small gap between the main fragments and positioning the screw as close as possible to the fracture (c).

Fig 7a–d Working length of the screws.

The screw threads need to be engaged in the bone cortex over a certain distance to assure sound anchorage of the plate. A normal cortex is sufficiently thick to allow good anchorage. Even a monocortical screw can withstand the torque potentially acting between two fragments and thus loading the screw thread bone interface (a, b). In case of osteoporosis the cortex is thin reducing the working length of the screw (c). In this situation even low interfragmental torque can damage the screw bone interface with subsequent loosening and instability (d). Thus in osteoporosis it is mandatory to use bicortical screws with improvement of the working langth of he screws (e).

2a

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Effect of plate length and screw position on plate loadingWhen using the concept of interfragmentary compression in a simple fracture pattern, load sharing conditions between plate and bone are present and in this way the screws in the middle of the plate can be inserted as close as possible to the fracture. When using the concept of splinting in a simple fracture pat-tern, the middle plate segment is bent over a short distance enhancing the local strain within the implant. To avoid high implant strain, the innermost screws should be spread apart, which increases the length of the plate segment bending, thus decreasing the implant strain. This protects the plate against fatigue failure (Fig 4a–b). Figures 5a–c show a clinical case of a femoral shaft fracture stabilized according to the previously described principles.

In the case of comminuted diaphyseal fractures, the plate spans over the fracture like a non gliding splint. A longer distance between the two screws adjacent to the fracture is dictated on the one hand, by the fracture pattern itself and on the other hand, for mechanical reasons, by the spreading out of the in-nermost screws thus decreasing the implant loading—but only when there is a distance limitation on the opposite cortex. With-out distance limitation the deformation of each plate segment in the middle depends on the acting bending moment. Each plate segment is deformed according to the external loading condition—thus, the overall deformation is much higher and the implant strain can become high and critical, as in the situ-ation where it is bridging a small gap with a short plate segment between the two innermost screws (Fig 6a–c).

Appropriate screw selectionThe selection of the screws is dependent on the bone qual-ity, cortical thickness, and external loading conditions of the bone segment. We have the choice between monocortical and bicortical screws, self tapping and self drilling screws, as well as standard and locking head screws. The use of locking head screws has advantages where bad bone quality is found as screw loading is no longer only pure pullout but also bending, altering the loading condition at the interface bone-screw thread. The choice between self tapping and self drilling screws should be made according to the anatomy of the segment. Self tapping screws can be used as bicortical screws, whereas self drilling screws should exclusively be used as monocortical screws be-cause the stick out length for anchoring in the opposite cortex is too long which increases possible harm to the soft tissues on the opposite cortex. In very osteoporotic bones, which typically present a thin cortex or a bone segment under high torsional loading, the use of bicortical screws is mandatory to enhance the working length of the screws and to avoid torsional displace-ment of the fractured fragments (Fig 7a–e).

Effects of the internal fixator concept on bone healing Using plates as internal fixators with locking head screws has the advantage that a certain distance is present under the implant. This enables the cortex underneath the plate to form bone callus allowing faster and stronger bone healing.

Take home messages for plating:• Splinting is a sound stabilization principle for fixation of

comminuted fractures.• Splinting can be used for stabilization of simple fractures—

when, on the one hand, a long plate is used to improve the lever arm of each screw, decreasing the screw pullout and, on the other hand, the two innermost screws are spread apart leaving at least two to three plate holes unoccupied at the fracture site to decrease plate loading.

• Interfragmentary compression remains a sound stabilization tool for fixation of simple fractures under the prerequisite of careful soft tissue section and handling.

• The use of locking head screws is advantageous from the biological point of view. Such an internal fixator does not compress the periosteum and thus reduces the amount of avascularity of the bone cortex adjacent to the plate. In ad-dition callus formation is possible in the gap between plate and bone cortex.

• Monocortical screws should only be used in case of good bone quality and sufficient cortical thickness, as well as in bone segment not loaded with high torque.

• Self drilling screws are exclusively used as monocortical screws in the diaphyseal bone segment to avoid harm to the soft tissue due to the long sticking out length of a bicortical self drilling screw.

Emanuel GautierOrthopedic Clinic(Orthopädische Klinik)Freiburg, [email protected]

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While relatively uncommon injuries, intraarticular fractures of the distal humerus continue to provide operative challenges to the surgeon in order that such complications as nonunion, malunion, decreased motion, and instability, are minimized.

One way to accomplish this is to enhance the stability of the plate and screw fixation construct. The long established tech-nique of orientation of two plates relatively perpendicular to each other (90–90) has recently been challenged on both bio-mechanical and clinical perspectives by the concept of parallel plate application.

This fixation strategy focuses on maximizing stability between the distal fragments and the shaft of the humerus at the meta-physeal level. According to O’Driscoll this can be achieved by following a set of eight technical objectives:

1. Every screw should pass through a plate. 2. Each screw should engage a fragment on the opposite side

that is also fixed to a plate. 3. As many screws as possible should be placed in the distal

fragments. 4. Each screw should be as long as possible. 5. Each screw should engage as many articular fragments as

possible. 6. The screws should lock together by interdigitation within the

distal fragment, thereby creating a fixed-angle architecture that provides stability to the entire distal humerus.

What is the evidence?

Thierry G Guitton, Jesse B Jupiter

90–90 versus parallel plating of distal humeral fractures

7. Plates should be applied such that compression is achieved at the supracondylar level for both columns.

8. Plates used must be strong enough and stiff enough to resist breaking or bending before union occurs at the supracon-dylar level (Fig 1a–h).

This review will investigate the evidence for both plating tech-niques for the treatment for complex distal articular humeral fractures.

Materials and methodsThe studies considered for possible inclusion in the current re-view were identified in a search (MeSH), in MEDLINE (National Library of Medicine, Bethesda, MD), EMBASE (Elsevier, Amster-dam, the Netherlands) and the Cochrane review for randomized controlled trials (Wiley InterScience, Hoboken, NJ) for the word distal humerus fractures and the key words plating, perpen-dicular or parallel. The bibliographic citations for each of the articles ultimately selected were also examined to identify any other acceptable studies that were not captured by the database searches. Furthermore, a grey literature search was conducted in an effort to identify all available literature that may not have been identified by the database searches. Selection of core articles was restricted to original research in the English language with human subject that examined the different plating orientations of distal humeral fractures. Randomized controlled and retrospec-tive studies were included while animal studies, review articles, commentary, editorial, or letters were excluded.

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ResultsClinical evidence: While there are numerous reports on internal fixation of distal humeral fractures, they are for the most part retrospective studies using a single plating technique. Unfor-tunately no prospective studies specifically comparing both methods, exist up to the present time.While the placement of plates nearly perpendicular to each other was promoted early on by the AO group the biomechanical study of Helfet and Hotchkiss added credibility to this technique (Fig 2a–e and 3). A number of subsequent clinical studies revealed nearly 75–85% good to excellent results with 90–90 plating. A long term follow-up study at a mean of 19 years after injury by Doornberg concluded that the long term results of open reduc-tion and internal fixation of 19 Type C fractures of the distal part of the humerus treated with perpendicular orientation are similar to those reported in the short term. They suggested that the results are durable over time. The clinical experience with parallel plating has not been as extensive or with longer follow up, however current reports reveal no evidence of failure of the fixation and comparable clinical results as with 90-90 plating.

Biomechanical evidence: Which technique is more stable? Several biomechanical studies compared parallel plating with perpendicular 90–90 orientation, concluding that parallel plat-ing with additional use of bolts was favorable to perpendicular plating. Their observations were supported by Arnander who concluded that, parallel plating was superior to the perpendicu-

Fig 1a–h The technique an important facts developed by the Mayo Clicinc “school” (O’Ddriscoll). (a) Every screw in the distal fragment should pass through a plate. (b) Every screw in the distal fragment should be anchored in a fragment on the opposite side that is fixed by a plate. (c) As many screws as possible should be placed in the distal fragment. (d) Every screw in the distal fragment should be as long as possible. (e) Every screw in the distal fragment should engage as many articular fragment as possible. (f) The screws in the distal fragments should lock together by interdigitation, creating a fixed angle structure, thereby completing the arch or closing the loop. (g) The plate should be applied with compression at the supracondylar level. (h) The plate should be strong and stiff enough to resist bending or breakage.

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1c

1e

1g

1b

1d

1f

1h

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lar orientation although they expressed concern that placing a plate lateral can be technically difficult.Jacobson concluded that perpendicular plate orientation was strongest in the sagittal plane while Korner stated that perpen-dicular plating had increased stiffness to torsional and antero-posterior bending forces. Schwartz found similar stabilization among both plate orientations. How do the results of stability testing relate to physiologic load-ing? Wong tested both fixation methods and concluded that both methods may be above the threshold necessary for early motion and predictable fracture healing, rendering the marginal strength of parallel plating clinically unimportant. Kimball found that the risk of delayed union or nonunion increased by the extensive subperiosteal elevation with parallel plating orientation. Schutzer tested the perpendicular plate orientation with different plate types and concluded that implant choice was not critical in good bone quality. Korner showed that locking plates have a substantial advantage in poor bone quality or if significant metaphysical comminution is present. Otherwise they concluded that there was no difference in plate type and that plate position is critical.

DiscussionAlthough some biomechanical evidence may favor parallel orientation, the real take home message may be that both ori-entations are strong enough to be able to mobilize the elbow after fracture fixation. Additionally it should be noted that biomechanical evidence raises as many questions as solutions. Some biomechanical studies fail to actually resemble the true clinical setting, and often have low samples sizes and a lack of statistical power.

From a clinical perspective, there are not sufficient data to make valid comparisons. Several different outcome measures are used; fractures types vary and non-homogenous patient selections have been reported.

Long term follow-up for parallel plating and clinical trials are needed to compare different plate orientation. Until then both fractures orientations seem adequate enough to treat complex distal articular humeral fractures and the choice should be made by fracture specifications and surgeon’s preference.

Figure 2a–e The AO technique: Reconstructing a multifragmentary distal humeral fracture.

Figure 3 Fixation with two anatomically precontoured perpendicular plates.

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2e

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Suggested reading

Ackerman G, Jupiter JB (1988) Non-union of fractures of the distal end of the humerus. J Bone Joint Surg Am; 70(1):75–83.

Caja VL, Moroni A, Vendemia V, et al (1994) Surgical treatment of bicondylar fractures of the distal humerus. Injury; 25(7):433–438.

Henley MB, Bone LB, Parker B (1987) Operative management of intra-articular fractures of the distal humerus. J Orthop Trauma; (1):24–35.

Jupiter JB, Neff U, Holzach P, et al (1985) Intercondylar fractures of the humerus. An operative approach. J Bone Joint Surg Am; 67(2):226–239.

Ring D, Jupiter JB (2000) Fractures of the distal humerus. Orthop Clin North Am; 31(1):103–113.

Helfet DL, Hotchkiss RN (1990) Internal fixation of the distal humerus: a biomechanical comparison of methods. J Orthop Trauma; 4(3):260–264.

Self J, Viegas SF, Buford WL Jr, et al (1995) A comparison of double-plate fixation methods for complex distal humerus fractures. J Shoulder Elbow Surg; 4(1 Pt 1):10–16.

O’Driscoll SW (2005) Optimizing stability in distal humeral fracture fixation. J Shoulder Elbow Surg; 4(1 Suppl S):186S–194S.

Sanchez-Sotelo J, Torchia ME, O’Driscoll SW (2007) Complex distal humeral fractures: internal fixation with a principle-based parallel-plate technique. J Bone Joint Surg Am; 89(5):961–969.

Sanchez-Sotelo J, Torchia ME, O’Driscoll SW (2008) Complex distal humeral fractures: internal fixation with a principle-based parallel-plate technique. Surgical technique. J Bone Joint Surg Am; 90 Suppl 2 Pt 1:31–46.

Doornberg JN, van Duijn PJ, Linzel D, et al (2007) Surgical treatment of intra-articular fractures of the distal part of the humerus. Functional outcome after twelve to thirty years. (2007) J Bone Joint Surg Am; 89(7):1524–1532.

McKee MD, Wilson TL, Winston L, et al (2000) Functional outcome following surgical treatment of intra-articular distal humeral fractures through a posterior approach. J Bone Joint Surg Am; 82-A(12):1701–1707.

Wong AS, Baratz ME (2009) Elbow fractures: distal humerus. J Hand Surg [Am]; 34(1):176–190.

Arnander MW, Reeves A, MacLeod IA, et al (2008) A biomechanical comparison of plate configuration in distal humerus fractures. J Orthop Trauma; 22(5):332–336.

Jacobson SR, Glisson RR, Urbaniak JR (1997) Comparison of distal humerus fracture fixation: a biomechanical study. J South Orthop Assoc; 6(4):241–249.

Korner J, Diederichs G, Arzdorf M, et al (2004) A biomechanical evaluation of methods of distal humerus fracture fixation using locking compression plates versus conventional reconstruction plates. J Orthop Trauma; 18(5):286–293.

Schwartz A, Oka R, Odell T, et al (2006) Biomechanical comparison of two different periarticular plating systems for stabilization of complex distal humerus fractures. Clin Biomech (Bristol, Avon); 21(9):950–955.

Kimball JP, Glowczewskie F, Wright TW (2007) Intraosseous blood supply to the distal humerus. J Hand Surg [Am]; 32(5):642–646.

Schuster I, Korner J, Arzdorf M, et al (2008) Mechanical comparison in cadaver specimens of three different 90-degree double-plate osteosyntheses for simulated C2-type distal humerus fractures with varying bone densities. J Orthop Trauma; 22(2):113–120.

Korner J, Lill H, Muller LP, et al (2003) The LCP-concept in the operative treatment of distal humerus fractures—biological, biomechanical and surgical aspects. Injury; 34 Suppl 2:B20–30.

Thierry G GuittonHarvard Medical School, Orthopedic Hand and Upper Extremity ServiceBoston, United [email protected]

Jesse B JupiterHarvard Medical School, Orthopedic Hand and Upper Extremity ServiceBoston, United [email protected]

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Research

This project addresses intervertebral disc (IVD) degeneration, a major cause of low back pain, which is a problem afflicting 70–85% of all people at some time in life with annual preva-lence ranging from 15–45% (www.nih.gov). This summary addresses the accomplishments of three 1-year AO Research Foundation grants and a no-cost extension of the applications entitled “Effects of cyclic compression on intervertebral disc cell metabolism”. These studies were aimed at understanding the pathways leading to mechanically induced remodeling of the IVD, matrix breakdown and degenerative disc disease using an in vivo model. An external fixator was surgically installed into the vertebrae of rat tails to allow precise mechanical con-trol over the intervertebral joint loading conditions. The first two grants were focused on short term studies to investigate how cyclic compression affects the kinetics of mRNA expres-sion and to discern healthy from damaging loading conditions. The third grant involved the development of a new device for chronic cyclic compression loading of rat tail IVDs in order to perform chronic studies to investigate the longer-term effects of mechanical loading on IVD remodeling.

The funding involved international collaborations that led to 8 journal papers, training of 4 graduate students (2 PhD, 2 MS) and 3 postdoctoral fellows. This work seeded an NIH R01 grant in 2004 that led to a Presidential Early Career Award for Scientists and Engineers (PECASE) received from the US Government for Dr Iatridis. The most important scientific findings were that:

• This research has shown decisively that dynamic loading of the IVD can manipulate the metabolic activity of the cells, that this response is dependent on the magnitude, frequency, and duration of the applied load, and that chronic application of these loading conditions can lead to matrix and structural remodeling.

Berton Rahn Research Prize: award winners’ summaries

James Iatridis, Melissa Knothe Tate

Effects of cyclic compression on intervertebral disc cell metabolism

• A single mechanical loading event on IVDs stimulates a coordinated and time-varying mRNA expression response that begins with inhibition of tissue breakdown, followed by synthesis of aggrecan and matrix degrading enzymes, and eventually collagen metabolism days later.

• Short-term studies also determined that: – Immobilization and high magnitudes of cyclic compres-

sion had distinct effects on mRNA expression, with im-mobilization causing a more general downregulation in mRNA levels. Furthermore, the mRNA response to cyclic compression is distinctly different depending on whether loading follows immobilization or is initiated on IVDs that have been freely mobile.

– Thresholds of mechanical loading magnitude and frequen-cy were determined where too little stimulus and too much stimulus both resulted in altered disc metabolism.

– Best and worst-case loading conditions were defined in which best combination loads referred to a predominantly anabolic response (upregulation of proteins and downreg-ulation of enzymes) and worst combination loads referred to a predominantly catabolic response (downregulation of proteins and upregulation of enzymes).

• Chronic studies determined that dynamic compression loading on IVDs is a generally healthy loading mode that stimulates biosynthesis with biological remodeling preceding damage to the IVD structure.

Results provide an important mechanobiology understanding of the IVDs which can help determine healthy and damag-ing loading conditions as well as to provide baseline animal model information useful for future studies on degeneration and repair of IVDs.

James Iatridis

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Treatment of diaphyseal long-bone defects arising from trauma or resection of bone following infection, tumor, or avascular necrosis represent a current challenge in orthopaedic surgery. Our recently developed one stage bone transport procedure exploits the regenerative power of the periosteum to fill in critical sized defects without the need for adjuvant bone graft. The periosteum is a niche for mesenchymal stem cells and the bone’s blood supply. Efficacy of the procedure was shown, in an ovine critical sized defect model, based on radiographic and high-resolution micro-computed tomography (µCT) measures of regenerate bone and callus volume as well as density. Com-paring between all experimental groups, superior bone density was shown in groups where the defect was surrounded by pe-riosteum with vascularized bone chips adherent to the inner surface. Bone generated within the defect, without addition of cancellous bone graft, showed significantly higher callus den-sity than regenerate bone in groups where the defect was filled with graft. Furthermore, without the addition of morcellized cancellous bone graft, proliferative woven bone filled the bone defect within two weeks. In contrast, filling of the defect with graft appeared to retard the course of bone remodeling within the defect zone. Thus, the periosteum exhibits a remarkable capacity to generate bone de novo within critical sized defects, even in the absence of the medullary cavity (filled by nail). Clinical reports and recent experiments indicate that the regen-erative capacity of the periosteum is enhanced by mechanical loading. Hence, in a follow on study, we developed a method to elucidate the role of mechanical loading in tissue generation/healing in our critical sized long bone defect model. We cal-culated and measured bone apposition and cell viability along the major and minor centroidal axes (CA) of defect zone cross sections at sixteen weeks after surgery. The centroidal axes serve as specimen specific reference points for major (most able to resist bending) and minor (least able to resist bending)

axes of bending in the defect zone. In bone generated de novo within the long bone defect as well as in bone healing within the graft filled defect zone, significant differences in tissue vi-ability, bone apposition and bone resorption were observed between the minor and major CA’s in both groups. Thus, the viability and bone remodeling of tissue within the defect is mechanically modulated. In sum, cell scale histomorphometric measures can be correlated to tissue scale mechanical loading patterns through comparison of histomorphometric measures taken along the minor and major CA. Based on these experi-mental and several clinical cases, implementation of the one stage bone transport procedure appears to be limited only by the amount of healthy periosteum available. We are currently developing clinical and physical therapy guidelines as well as novel implants to unleash the power of the periosteum for trauma and reconstruction surgery.

Unleashing the power of the periosteum

Melissa Knothe Tate

James IatridisDepartment of Orthopaedics & Rehabilitation, School of Engineering, University of VermontBurlington, Vermont, [email protected]

Melissa Louise Knothe TateProfessor of Biomedical and Mechanical & Aerospace EngineeringCase Western Reserve UniversityCleveland, Ohio, [email protected]

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AO Vet

A chronic shoulder luxation acquired by a Minishetty stallion on pasture was repaired with an arthrodesis using a broad veterinary LCP 3.5. Six weeks after the surgery, the patient is able to trot and canter with minimal lameness. This type of arthrodesis is only possible in very small horses.

Shoulder arthrodesis in a Minishetty stallion

A 7-year-old Minishetty stallion presented with three weeks of severe lameness in the left fore limb. A preliminary diagnosis of a radial nerve paralysis was made and as no improvement occurred, radiographs were taken and a tentative diagnosis of “subluxation of the scapulohumeral joint was made. The sub-luxation could not be manually reduced and the patient was referred to the equine clinic in Zurich. The stallion was in good physical condition with grade IV to V/V lameness and favored the limb constantly (Fig 1). The radiographic evaluation confirmed the tentative diagnosis of subluxation of the left humeral head (Fig 2). As a result of the three week delay, the medial rim of the glenoid edged a linear indentation into the humeral head (Fig 2). Due to the delay in diagnosis and the articular damage on the humeral head, shoulder arthrodesis was recommended.

Joerg A Auer, Annina Widmer

Fig 1 “Sky” at the time of admission, favoring the injured limb constantly.

Fig 2a Craniocaudal radiographic view demonstrating the abnormal position of the gleannoid cavity relative to the humeral head. The indentation in the humeral head is easily recognizable (The gleannoid rim is positioned in the indentation).

Fig 2b Lateral radiographic projection depicting both shoulder joints (the subluxated one is positioned on the left side of the x-ray). The subluxated left joint does not show a radiographic joint space, compared the normal right joint.

Previous experience of the senior author with this type of treat-ment has allowed small horses to bear weight on the limb in a standing position with a mechanical gait anomaly.

Surgical techniqueInduction of anesthesia and administration of broad-spectrum perioperative antibiotics was routine and the animal was po-sitioned in right lateral recumbency on the operating table. Following aseptic skin preparation and draping, the skin was opened along the cranial edge of scapula and extended over the glenoid tubercle distally to the mid-humerus region. After splitting the brachiocephalicus muscle longitudinally, the bi-ceps brachii muscle was identified and its tendon of origin at the supraglenoid tubercle was isolated and transected allowing

1 2a 2b

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access to the shoulder joint (Fig 3). The articular damage created by the glenoid rim was readily visible on the humeral head. After removing the articular cartilage from the humeral head and the glenoid cavity, the surpascapular nerve was identified. The joint was subsequently realigned in a neutral position. A 16 hole broad veterinary LCP 3.5 was contoured to the cranial aspect of the scapula and proximal half of the humerus and affixed to the scapula with six locking head screws and five into the humerus. Over the glenoid joint three transarticular 3.5mm cortex screws were inserted in position screw technique to allow them to angulate away form each other (Fig 4). One locking head screw crossed the joint as well.

A 50mg Garamycin sponge (Syntacoll GmBH, Saal, Germany) was placed next to the plate and the incision closed. Because the surgery site could not be covered with a bandage, a stent bandage consisting of a gauze sponge was sutured over the skin incision site using a 0 monofilament synthetic suture material (Biosyn). The postoperative radiograph revealed good position of the joint and proper seating of the implants (Fig 5).

The stallion recovered without complications and subsequently started to use the limb more and more during the remainder of its stay at the clinic. Daily physiotherapy was applied during its stay at the clinic. Ten days postoperatively the staples were removed and the following day the animal was released from the hospital. Six weeks after the surgery the stallion uses its limb during trot and canter on the field and is feeling just fine.

DiscussionShoulder joint arthrodesis is a rare surgical intervention in Minishetties with mixed success1. This maybe due to trans-action of the biceps tendon origin which allows proper plate position on the humerus. This type of approach has not been described and it is foreseeable that it would be associated with a considerable amount of pain during ambulation as the soft

References

1. Semevolos SA, Watkins JP, Auer JA (2003) Scapulohumeral arthrodesis in miniature horses, Vet Surg; 32:416–420.

2. Auer JA (1996) Principles of Fracture Treatment. In: Auer JA, Stick JA (eds) Equine Surgery. 3rd ed. St. Louis, Mo: Elsevier Saunders; 1000–1029

Fig 3 The biceps tendon is transected (left) and a Penrose drain marks the suprascapular nerve. In the center of the picture the whitish articular cartilage is recognized.

Fig 4 The LCP is in place showing the cortex screws inserted across the joint.

Fig 5 The lateral postoperative radiograph shows the plate applied to the cranial surface of the distal scapula and the proximal humerus. The screws are of adequate length.

Joerg A AuerEquine Department, Vetsuise FacultyUniversity of Zurich, Zurich, [email protected]

Annina WidmerEquine Department, Vetsuise FacultyUniversity of Zurich, Zurich, [email protected]

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tissues over the plate scar allowing increasing postoperative function. This type of recovery could be observed in this Min-ishetty stallion, despite fact that the follow-up was somewhat short. The light weight of the animal and the relatively small forces acting on the surgery site are also possible explanations for the good result. The broad LCP 3.5 is a very stiff plate with slightly staggered holes to allow screws in alternating positions so as to avoid interference between the screws that crossed the joint as well as the use of cortex screws. Lag screw technique was deemed to be unnecessary, again because of the angles the screws were inserted relative to each other.

Although in equine osteosynthesis it is customary to fill every plate hole with a screw2, the use of the locking system may make it possible to soften this absolute rule.

The outcome of the case is very encouraging but only time will tell if the procedure will also be feasible for bigger horses.

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Lalgadh, Dhanusha, Nepal

— AO/SEC Course on Nonoperative Fracture Treatment November 01–30, 2009

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