AO Foundation

Wangen, Switzerland

AO Foundation

Wangen, Switzerland
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Reinhold M.,Innsbruck Medical University | Audige L.,AO Foundation | Schnake K.J.,Center for Spinal Surgery and Neurotraumatology Friedberger | Bellabarba C.,University of Washington | And 2 more authors.
European Spine Journal | Year: 2013

Purpose: The AO Spine Classification Group was established to propose a revised AO spine injury classification system. This paper provides details on the rationale, methodology, and results of the initial stage of the revision process for injuries of the thoracic and lumbar (TL) spine. Methods: In a structured, iterative process involving five experienced spine trauma surgeons from various parts of the world, consecutive cases with TL injuries were classified independently by members of the classification group, and analyzed for classification reliability using the Kappa coefficient (κ) and for accuracy using latent class analysis. The reasons for disagreements were examined systematically during review meetings. In four successive sessions, the system was revised until consensus and sufficient reproducibility were achieved. Results: The TL spine injury system is based on three main injury categories adapted from the original Magerl AO concept: A (compression), B (tension band), and C (displacement) type injuries. Type-A injuries include four subtypes (wedge-impaction/split-pincer/incomplete burst/complete burst); B-type injuries are divided between purely osseous and osseo-ligamentous disruptions; and C-type injuries are further categorized into three subtypes (hyperextension/translation/separation). There is no subgroup division. The reliability of injury types (A, B, C) was good (κ = 0.77). The surgeons' pairwise Kappa ranged from 0.69 to 0.90. Kappa coefficients κ for reliability of injury subtypes ranged from 0.26 to 0.78. Conclusions: The proposed TL spine injury system is based on clinically relevant parameters. Final evaluation data showed reasonable reliability and accuracy. Further validation of the proposed revised AO Classification requires follow-up evaluation sessions and documentation by more surgeons from different countries and backgrounds and is subject to modification based on clinical parameters during subsequent phases. © 2013 Springer-Verlag Berlin Heidelberg.

Floerkemeier S.,Hannover Medical School | Staubli A.E.,Private Clinic Sonnmatt Luzern | Schroeter S.,BG Unfallklinik Tubingen | Goldhahn S.,AO Foundation | Lobenhoffer P.,Sports Clinic Germany
International Orthopaedics | Year: 2014

Purpose: Nicotine abuse and obesity are well-known factors leading to common post-operative complications. However, their influence on the outcome after high tibial osteotomy is controversial. Thus, the aim of this study was to evaluate their effect on the clinical outcome with particular regard to bone non-union and local complications. Methods: The functional outcome after open-wedge high tibial osteotomy using the TomoFix® plate was assessed by means of the 12-item Oxford knee score in a multicentre study. In addition the intra- and post-operative complications were determined. Results: Of 533 eligible patients, 386 were interviewed after a mean follow-up of 3.6 years. The median Oxford knee score was 43 points (max. 48 points). Six per cent of these patients experienced at least one local post-operative complication. Patients with a body mass index (BMI) of up to 25 and between 25 and 30 had a higher mean score by 3.5 and 1.8 points, respectively, compared with those having a BMI of more than 30 showing a score of 37.5. No correlation was observed between smoking and the functional outcome. Smoking habits, BMI, the absolute patient weight and the interaction term between smoking and BMI were not significant with reference to the complication rate. Conclusions: This study reveals favourable mid-term results after high tibial osteotomy in varus osteoarthritis even in patients who smoked and obese patients. The indication in patients with a BMI above 30 should be handled with care due to the slightly inferior outcome, although the complication rate was not increased in these patients. © 2013 Springer-Verlag Berlin Heidelberg.

Kralinger F.,Innsbruck Medical University | Blauth M.,Innsbruck Medical University | Goldhahn J.,ETH Zurich | Kach K.,Kantonsspital Winterthur | And 3 more authors.
Journal of Bone and Joint Surgery - American Volume | Year: 2014

Background: There is biomechanical evidence that bone density predicts the mechanical failure of implants. The aim of this prospective study was to evaluate the influence of local bone mineral density on the rate of mechanical failure after locking plate fixation of proximal humeral fractures. Methods: We enrolled 150 patients who were from fifty to ninety years old with a closed, displaced proximal humeral fracture fixed with use of a locking plate from July 2007 to April 2010. There were 118 women and thirty-two men who had a mean age of sixty-nine years. Preoperative computed tomography (CT) scans were done to assess bone mineral density of the contralateral humerus, and dual x-ray absorptiometry of the distal end of the radius of the unaffected arm was conducted within the first six weeks postoperatively. At follow-up evaluations at six weeks, three months, and one year postoperatively, pain, shoulder mobility, strength, and multiple functional and quality-of-life outcome measures (Disabilities of the Arm, Shoulder and Hand [DASH] questionnaire; Shoulder Pain and Disability Index [SPADI]; Constant score; and EuroQuol-5D [EQ-5D]) were done and standard radiographs were made. We defined mechanical failure as all complications related to bone quality experienced within one year. Results: After locking plate fixation, fifty-three (35%) of 150 patients had mechanical failure; loss of reduction and secondary screw loosening with perforation were common. CT assessments of local bone mineral density showed no difference between patients with and without mechanical failure (89.82 versus 91.51 mg/cm3, respectively; p = 0.670). One-year DASH, SPADI, and Constant scores were significantly better for patients without mechanical failure (p ≤ 0.05). Conclusions: We did not find evidence of an association between bone mineral density and the rate of mechanical failures, which may suggest that patients with normal bone mineral density are less prone to sustain a proximal humeral fracture. Future studies should target other discriminating factors between patients with and without mechanical failure. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

Stefan U.,Innsbruck Medical University | Stefan U.,AO Foundation | Michael B.,Innsbruck Medical University | Michael B.,AO Foundation | And 2 more authors.
Bone | Year: 2010

Background and purpose: In the development of new strategies for fracture fixation, new methods have to be tested biomechanically under in vitro conditions before clinical trials can be performed. The gold standard for laboratory evaluations is fresh-frozen specimen. As the availability of fresh-frozen specimens is limited and since their use bears infectious risks, specimens treated with various chemical embalming fluids are also used. These preservation methods may alter the mechanical properties of the specimens used. Therefore, the aims of the present study were to determine the effects of three different preservation methods (formalin fixation (FO), Thiel-fixation (TH), and alcohol-glycerine fixation (AG)) on the elastic and postyield mechanical properties of cortical bone and to compare these properties to those of fresh-frozen (FF) specimens. Materials and methods: Cylindrical cortical specimens (diameter 3. mm, length 60. mm) were obtained from human femurs (n= 48) and bovine tibiae (n= 40). Before specimen immersion in different fixation fluids, bone mineral density (BMD) as well as the initial Young's modulus was determined. The Young's modulus was determined in a nondestructive bending test, and measurements were repeated after 6. months of immersion in fixative solution. Subsequent to the nondestructive test, a destructive 3-point bending test was conducted to assess the postyield and fracture properties. Results: The BMD as well as the initial Young's modulus showed no significant differences between the four test groups. After 6. months in fixative solution, the Young's modulus was significantly lowered in human Thiel specimens and only showed minor changes in formalin- and alcohol-glycerine-treated specimens. The plastic energy absorption of human and bovine specimens was altered significantly. Formalin as well as alcohol-glycerine fixation yielded a significant decrease in plastic energy absorption, whereas Thiel fixation significantly increased the plastic energy absorption. Discussion/conclusion: Because of the significantly altered plastic mechanical properties of cortical bone, the use fresh-frozen bone specimens is recommended in biomechanical studies investigating failure loads of orthopaedic implants. The use of embalmed specimens should be restricted to pilot tests. © 2010 Elsevier Inc.

Audige L.,AO Foundation | Cornelius C.-P.,Ludwig Maximilians University of Munich | Ieva A.D.,Medical University of Vienna | Prein J.,University of Basel
Craniomaxillofacial Trauma and Reconstruction | Year: 2014

Validated trauma classification systems are the sole means to provide the basis for reliable documentation and evaluation of patient care, which will open the gateway to evidence-based procedures and healthcare in the coming years. With the support of AO Investigation and Documentation, a classification group was established to develop and evaluate a comprehensive classification system for craniomaxillofacial (CMF) fractures. Blueprints for fracture classification in the major constituents of the human skull were drafted and then evaluated by a multispecialty group of experienced CMF surgeons and a radiologist in a structured process during iterative agreement sessions. At each session, surgeons independently classified the radiological imaging of up to 150 consecutive cases with CMF fractures. During subsequent review meetings, all discrepancies in the classification outcome were critically appraised for clarification and improvement until consensus was reached. The resulting CMF classification system is structured in a hierarchical fashion with three levels of increasing complexity. The most elementary level 1 simply distinguishes four fracture locations within the skull: mandible (code 91), midface (code 92), skull base (code 93), and cranial vault (code 94). Levels 2 and 3 focus on further defining the fracture locations and for fracture morphology, achieving an almost individual mapping of the fracture pattern. This introductory article describes the rationale for the comprehensive AO CMF classification system, discusses the methodological framework, and provides insight into the experiences and interactions during the evaluation process within the core groups. The details of this system in terms of anatomy and levels are presented in a series of focused tutorials illustrated with case examples in this special issue of the Journal. Copyright © 2014 by AO Foundation.

Hasler C.,University of Basel | Sprecher C.M.,AO Foundation | Milz S.,AO Foundation
Spine | Year: 2010

Study Design: A comparative study on growth of the sheep and human spine. Objective: To validate the immature sheep spine as model for the growing human spine and to yield a database for planning and interpretation of future animal experiments. Summary Of Background Data: With the current change of paradigm to nonfusion strategies for pediatric spine deformities, experimental surgery on spines of growing goats, sheep, and pigs has gained importance as preclinical proof-of-concept test. However, despite the proceeding use of animals, there is a lack of knowledge regarding the growth of the sheep spine and the relation to the human spine. Methods: Thoracic and lumbar cadaver spines were harvested from 50 Swiss alpine sheep. Specimens were obtained from newborn, 1, 3, 6, 9 and 12, 15 and 18 months old female sheep. Direct spondylometry yielded vertebral body heights, widths, and depths and spinal canal size, which were compared to pooled data on human spine growth retrieved from the literature. Results: Sheep spine growth ceases at age 15 to 18 months, which corresponds to a time-lapse model of human growth. Main growth occurs within the first 3 to 6 months of life, as opposed to human spines with maximal growth during the first 4 years and puberty. The relation between sheep and human vertebral shape is continuously changing with growth: at birth, sheep vertebrae are twice as tall, but equally wide and deep. At skeletal maturity, height is 15% to 25% bigger in sheep, but width 15% to 30% and depth 30% to 50% are smaller. Conclusion: The immature sheep spine offers fast effects if growth-modulating interventions are performed within the first 3 to 6 months of age. The differences in vertebral shapes and further distinctions between human and sheep spines such as biomechanics, facet anatomy, and rib cage morphology have to be considered when interpreting results after experimental surgery. © 2010 Lippincott Williams & Wilkins.

Dror I.,University College London | Schmidt P.,AO Foundation | O'Connor L.,Northwestern University
Medical Teacher | Year: 2011

As new technology becomes available and is used for educational purposes, educators often take existing training and simply transcribe it into the new technological medium. However, when technology drives e-learning rather than the learner and the learning, and when it uses designs and approaches that were not originally built for e-learning, then often technology does not enhance the learning (it may even be detrimental to it). The success of e-learning depends on it being 'brain friendly', on engaging the learners from an understanding of how the cognitive system works. This enables educators to optimize learning by achieving correct mental representations that will be remembered and applied in practice. Such technology enhanced learning (TEL) involves developing and using novel approaches grounded in cognitive neuroscience; for example, gaming and simulations that distort realism rather than emphasizing visual fidelity and realism, making videos interactive, training for 'error recovery' rather than for 'error reduction', and a whole range of practical ways that result in effective TEL. These are a result of e-learning that is built to fit and support the cognitive system, and therefore optimize the learning. © 2011 Informa UK Ltd All rights reserved.

Businger A.,Trauma Unit | Ruedi T.P.,Trauma Unit | Ruedi T.P.,AO Foundation | Sommer C.,Trauma Unit
Injury | Year: 2010

The most widely accepted treatment for comminuted fractures of the radial head is either the excision or open reduction and internal fixation. The purpose of the present study is to evaluate the value of an 'on-table' reconstruction technique in severely comminuted fractures of the radial head. In this study, two patients with a Mason type-III and four patients with a Mason type-IV radial-head fracture were treated with 'on-table' reconstruction and fixation using low-profile mini-plates. After a mean follow-up of 112 months (47-154 months), the mean elbow motion was 0-6-141° extension flexion with 79° of pronation and 70° of supination. The mean Broberg and Morrey functional rating score was 97.0 points, the Mayo Elbow Performance Index was 99.2 points and the mean Disabilities of the Arm, Shoulder, and Hand (DASH) Outcome Measure score was 1.94 points. One patient had symptoms of degenerative changes, with a slight joint-space narrowing. There were no radiographic signs of devitalisation at final examination. Comminuted fractures of the radial head, which would otherwise require excision, can be successfully treated with an 'on-table' reconstruction technique. © 2009 Elsevier Ltd. All rights reserved.

Oestern H.-J.,AO Foundation | Garg B.,All India Institute of Medical Sciences | Kotwal P.,All India Institute of Medical Sciences
Clinical Orthopaedics and Related Research | Year: 2013

Background: Road traffic accidents are among the leading causes of death worldwide in individuals younger than 45 years. In both India and Germany, there has been an increase in registered motor vehicles over the last decades. However, while the number of traffic accident victims steadily dropped in Germany, there has been a sustained increase in India. We analyze this considering the sustained differences in rescue and trauma system status. Questions/purposes: We compared India and Germany in terms of (1) vehicular infrastructure and causes of road traffic accident-related trauma, (2) burden of trauma, and (3) current trauma care and prevention, and (4) based on these observations, we suggested how India and other countries can enhance trauma care and prevention. Methods: Data for Germany were obtained from federal statistical databases, German Automobile Club, and German Trauma Registry. Data from India were available from the Ministry of Road Transport and Highways. We also performed a standardized literature search of PubMed for India and Germany using the following key words: "road traffic accidents", "prevention", "prehospital trauma care", "trauma system", "trauma registry", "trauma centers", and "development of vehicles." Results: The total number of registered motor vehicles increased 473-fold in India and 100-fold in Germany from 1951 to 2011. The number of road traffic deaths increased in both countries until 1970, but thereafter decreased in Germany (3606 in 2012) while continuing to increase in India (142,485 in 2011). The differences between Germany and India relate to the relative sizes and populations of the countries (1:9 and 1:15, respectively), and differences in prevention and prehospital care (nationwide versus big cities) and hospital trauma systems (nationwide versus exceptional). Conclusions: Improvement requires attention to three major issues: (1) prevention through infrastructure, traffic laws, mandatory licensing; (2) establishment of a prehospital care system; and (3) establishment of regional trauma centers and a trauma registry. © 2013 The Association of Bone and Joint Surgeons®.

Joeris A.,University of Bern | Audige L.,AO Foundation | Ziebarth K.,University of Bern | Slongo T.,University of Bern
International Orthopaedics | Year: 2012

Purpose: Osteotomies of the proximal femur and stable fixation of displaced femoral neck fractures are demanding operations. An LCP Paediatric Hip Plate™ was developed to make these operations safer and less demanding. The article focuses on the surgical technique and critically analyses the device. Methods: Between 2006 and 2008, 30 hips in 22 patients underwent surgery. Patients' demographics, perioperative details, postoperative outcome and complications were retrospectively collected and analysed. Results: Patients' diagnoses included persistent congenital hip dysplasia (n = 4), neuropathic hip dysplasia (n = 9), idiopathic ante/retroversion (n = 8), femoral neck fracture (n = 3), Perthes' disease (n = 2), deformity after slipped capital femoral epiphysis (SCFE), congenital femoral neck pseudarthrosis, deformity after pelvic tumour resection and malunion following proximal femoral fracture (one each). In 21 of 22 patients, the postoperative radiographs showed corrections as planned. Two cases had to be revised for screw loosening. Intraoperative handling using the plate was excellent in all cases. Conclusions: In our case series of 30 hip operations, the LCP Paediatric Hip Plate™ was shown to be safe and applicable in the clinical setting with excellent results and a low complication rate. We consider that the LCP Paediatric Hip Plate™ is a valuable device for correction of pathological conditions of the proximal femur and for fixation of displaced femoral neck fractures in children. Larger studies should be carried out to better quantify the risk of clinically relevant complications. © 2012 Springer-Verlag.

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