Arbeitsgemeinschaft Für Osteosynthesefragen Research Articles

Return to Sports Activity After Tibial Plateau Fractures

Background: Tibial plateau fractures requiring surgery are severe injuries. For professionals, amateurs, and recreational athletes, tibial plateau fractures might affect leisure and professional life. Hypothesis: Athletic patients will be affected in their sporting activity after a tibial plateau fracture. Despite a long rehabilitation time and program, physical activity will change to low-impact sports. Study Design: Case series; Level of evidence, 4. Methods: A total of 89 consecutive patients (age range, 14-76 years) were included in the study and were surveyed by a questionnaire. Inclusion criteria were surgical treatment of tibial plateau fractures between 2003 and 2009 with a minimum follow-up of 24 months. The sporting activity was determined at the time of injury, 1 year postoperatively, and at the time of the survey at an average of 52.8 months postoperatively. The clinical evaluation included the Lysholm score, the Tegner activity scale, the activity rating scale (ARS), and a visual analog scale (VAS) for pain perception. Fractures were classified and analyzed using both the Arbeitsgemeinschaft für Osteosynthesefragen (AO) and the Schatzker classifications. Results: At the time of injury, 88.8% of all patients were engaged in sports compared with 62.9% 1 year postoperatively and 73.0% at the time of the survey. Of the professional or competitive athletes (n = 11 at the time of injury), only 2 returned to competition at the time of the survey. The number of different sporting activities declined from 4.9 at the time of injury to 3.6 at the time of the survey (P < .001). The sports frequency and the activity duration per week, being 2.8 sessions and 4.5 hours at the time of injury, respectively, declined to 2.4 sessions and 3.8 hours (P < .001 and P = .007, respectively) at the time of the survey, respectively. The Lysholm score (98.7 points before accident) and the VAS for pain perception (0.2 before accident) illustrated significant declines to 76.6 points for the Lysholm score and 2.6 for the VAS (P < .001 and P < .001, respectively) at the time of the survey. The high-energy traumas, Schatzker IV to VI, had significant worse results in the clinical scores compared with the low-energy traumas (Lysholm, P < .001; Tegner, P = .027). Conclusion: The majority of patients could not return to their previous level of activity, and for patients playing competitive sports, this injury can be a career ender. Overall, we noticed a postinjury shift toward activities with less impact. However, at the time of the survey, 73% of all patients were engaged in sports.

Factors associated with the decision for operative versus non-operative treatment of displaced proximal humerus fractures in the elderly

BackgroundIn the management of displaced proximal humerus fractures in the elderly, wide variation has been documented. However, no prior study has investigated the factors that currently lead surgeons to treat patients with surgical fixation, arthroplasty or non-operative management. The purpose of this study was to identify the factors associated with treatment selection in the management of displaced proximal humerus fractures in individuals over the age of 60 years. To this end, we conducted a retrospective review of all such injuries that presented to our two level-I trauma centres between 2006 and 2009. Patients and methodsFrom our prospectively collected trauma database, we identified 229 displaced proximal humerus fractures that met all inclusion and exclusion criteria. Data were collected on patient-, fracture- and surgeon-related characteristics that were plausibly related to the decision for treatment. The choice of management was recorded, and logistic regression was used to identify factors associated with the decision for treatment. ResultsIn the multivariate analysis, the predictors of operative intervention as opposed to non-operative treatment were younger patient age (p=0.038), associated orthopaedic injuries requiring surgery (p=0.012), higher Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification (p=0.012), translation-type displacement (p=0.0012) and associated glenohumeral dislocation (p=0.0006). In addition, shoulder and upper extremity specialists were found to choose operative intervention significantly more frequently than orthopaedic trauma specialists (49.1% vs. 26.1%, adjusted relative risk (RR) 1.96, p=0.012). Factors associated with the decision for arthroplasty as opposed to fixation were higher Charlson score (p=0.045), higher Neer classification (p=0.012), and higher AO classification (p=0.0097). ConclusionsIn this study of displaced proximal humerus fractures in the elderly, the decision for surgery was influenced by the patient's age, the presence of associated orthopaedic injuries, the severity of the fracture and the presence of an associated glenohumeral dislocation. In addition, treatment by a shoulder or upper extremity specialist (as opposed to an orthopaedic trauma specialist) was associated with a higher likelihood of operative intervention. Further investigation into the resultant clinical outcomes is required to determine whether the use of these characteristics to select operative candidates is appropriate and beneficial for patients.

The origins of the AO Foundation

In 1958, a group of Swiss general and orthopedic surgeons established the AO (Arbeitsgemeinschaft für Osteosynthesefragen). Their mission was to transform fracture treatment in Switzerland, which at that point in time included prolonged bed rest in traction and subsequent application of a cast or splint, often resulting in poor functional results and lifelong disability. The “core group” of founders consisted of Maurice E. Müller, Hans Willenegger, Martin Allgöwer, and two other early members, Robert Schneider and Walter Bandi. Today, the AO Foundation (which was officially established in 1984) is a medically guided, global network with over 10,000 surgeons, in more than 100 countries. It is the world’s leading educational and research organization for trauma and musculoskeletal treatment and reflects a global knowledge network and interdisciplinary teamwork.

The Implementation of a Pilot Femur Fracture Registry at Komfo Anokye Teaching Hospital: An Analysis of Data Quality and Barriers to Collaborative Capacity‐Building

Trauma registries are essential for injury surveillance and recognition of the burden of musculoskeletal injury in low- and middle-income countries (LMICs). The purpose of this study was to pilot a femur fracture registry at Komfo Anokye Teaching Hospital (KATH) to assess data quality and determine the barriers to research partnering in LMICs. All patients admitted to KATH with a fracture of the femur, or Arbeitsgemeinschaft für Osteosynthesefragen (AO) class 31, 32, 33, were entered into a locally designed, electronic femur fracture database. Patients' characteristics and data quality were assessed by using descriptive statistics. Orthopedic trauma research barriers and opportunities were identified from key informants at the research site and supporting site. Ninety-six femur fracture patients were enrolled into the registry over a 5-week period. The majority of patients resided in the Ashanti region surrounding the hospital (78 %). Most participants were involved in a road traffic crash (58 %) and physiologically stable with a Cape Triage Score of yellow upon admission (84 %). AO class 32 femur fractures represented the majority of femur fractures (78 %). Median times from injury to admission, admission to surgery, and surgery to discharge were 0, 5, and 10 days, respectively. Data quality analysis showed that data collected at admission had higher rates of completion in the database relative to data collected at various follow-up time points. Data and data quality analyses highlighted characteristics of femur fracture patients presenting to KATH as well as the technological, administrative support, and hospital systems-based challenges of longitudinal data collection in LMICs.

Patterns of triangular fibrocartilage complex (TFCC) injury associated with severely dorsally displaced extra-articular distal radius fractures

The aim of the study was to examine triangular fibrocartilage (TFCC) injury patterns associated with unstable, extra-articular dorsally displaced distal radius fractures. Twenty adult patients with an Arbeitsgemeinschaft für Osteosynthesefragen (AO), type A2 or A3, distal radius fracture with an initial dorsal angulation greater than 20° were included. Nine had a tip fracture (distal to the base) of the ulnar styloid and 11 had no such fracture. They were all openly explored from an ulnopalmar approach and TFCC injuries were documented. Eleven patients also underwent arthroscopy and intra-articular pathology was recorded. All patients had TFCC lesions of varying severity, having an extensor carpi ulnaris subsheath avulsion in common. Eighteen out of 20 also displayed deep foveal radioulnar ligament lesions, with decreasingly dorsal fibres remaining. The extent of this foveal injury could not be appreciated by radiocarpal arthroscopy. Severe displacement of an extra-articular radius fracture suggests an ulnar-sided ligament injury to the TFCC. The observed lesions concur with findings in a previous cadaver study. The lesions follow a distinct pattern affecting both radioulnar as well as ulnocarpal stabilisers.

One-third tubular-hook-plate osteosynthesis for olecranon osteotomies in distal humerus type-C fractures: A preliminary report of results and complications

IntroductionDistal humerus fractures are rare and challenging to treat. Anatomic reduction of the articular surface and stable osteosynthesis are mandatory for satisfactory results. The transolecranon approach allows superior visualisation of the joint. However, controversy exists regarding how best to fix the osteotomy. The purpose of the present study was to investigate the eligibility of a one-third tubular hook plate for osteosynthesis of olecranon osteotomies in distal humerus type-C fractures. Patients and methodsA consecutive series of 34 patients who were treated through an olecranon osteotomy and underwent fixation using a one-third tubular hook plate were identified. Thirty-one patients (17 females, 14 males) with a median age of 50 years (14–87, standard deviation (SD) 18.3) were available for a comprehensive assessment after a mean of 12.3 months (6–20, SD 3.7). Using the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification, six (19.4%) fractures were categorised as type C2 and 25 (80.6%) were categorised as C3. Physical and radiological examinations were performed. The Mayo Elbow Performance Score (MEPS) and the Disabilities of the Arm, Shoulder and Hand score (DASH) were evaluated. ResultsMean extension–flexion ROM was found to be 102° (50–145°, SD 25). Pronation and supination were only slightly compromised. The mean MEPS was 87.2 points (50–100, SD 12.4). Fourteen patients (45.2%) were rated as excellent, and 15 (48.4%) were rated as good. One patient was rated fair, and one patient was rated as poor, respectively. Mean DASH score was 24.4 points (0–65, SD 20.3). Complications regarding the osteotomy occurred in seven patients (22.5%). Revision surgery was necessary in five cases (16%). At follow-up, all osteotomies went on to union. Mild joint degeneration (Broberg I) was found in 10 patients (32.2%). Implant removal was carried out in 15 patients (48.4%). ConclusionBased on this study, the osteosynthesis of olecranon osteotomies using a one-third tubular hook plate can be regarded as a safe procedure with a low complication rate. The implant needed is widely available and cost-efficient, in contrast to specially designed plates or nails.

Predictive factors for functional outcome and failure in angular stable osteosynthesis of the proximal humerus

Introduction Angular stable osteosynthesis has become the gold standard in the operative treatment of proximal humeral fractures. The aim of this article is to determine the indications for osteosynthesis versus primary arthroplasty based on clinical and radiological parameters. Methods A total of 368 surgically treated proximal humeral fractures were reviewed. Preoperative X-rays were used to evaluate the displacement and vascularity of the humeral head (according to the Hertel criteria) and the AO (Arbeitsgemeinschaft für Osteosynthesefragen) fracture type. Postoperative X-rays were analysed to assess the quality of the reduction, the reconstruction of the medial hinge and the displacement of the tuberosities. Follow-up X-rays were used to evaluate healing progress, the occurrence of avascular necrosis, loss of reduction and implant related failures. The American Shoulder and Elbow Surgeons score (ASES score) was used to evaluate the functional outcome. Correlations between a set of variables, type of treatment and eventual outcome were verified in both univariate and multivariate settings, with the significance rate set at p < 0.05. Results In total, 307 shoulders were evaluated. Mean follow-up was 4.3 years and showed a 15.3% failure rate, a 23.8% re-operation rate and a mean ASES score of 75.3. Better results were noted in patients who were younger at the time of surgery. More displaced fractures, AO type C fractures, varus fracture configuration and reduced head vascularity all led to a worse outcome. Anatomical reduction correlated with better results. Articular fractures had better results when treated with a plate. Conclusion Surgical treatment of proximal humeral fractures remains difficult, with a failure rate of 15.3% and a re-operation rate of 23.8% at 4.3 years. A significantly displaced varus articular fracture in the older patient results in the worst outcome.

A quantitative analysis of tension band plating of the femur diaphysis

To measure quantitatively the strains in the concave and convex sides of a femur to substantiate the Arbeitsgemeinschaft für Osteosynthesefragen (AO) tension band principle. Eight cadaveric fresh-frozen femurs were cleaned of soft tissue and prepared for mounting the strain gages (Vishay, Raleigh, NC). The student strain gages were mounted at the anterior, lateral and medial surfaces of a femur. They were loaded at 100, 250, 500, 1,000 and 1,500 N axial forces in a mechanical testing machine (Instron Model 4202, Norwood, MA) and the micro strains were measured for intact and after fixation of a simulated fracture by an eight hole broad 4.5 mm stainless steel compression plate (Synthes LCP). In order to simulate the fracture conditions, where all eight screw holes might not be filled, three different arrangements were tested: 8 screws, 4 screws and 2 screws. The microstrains under different loads were analyzed by Analysis of Variance (ANOVA) with Holm-Sidak multiple comparison method. At the same gage location micro strains were not significantly different between the intact, and the femur fixated by 8, 4 and 2 screws. For intact bones at 1,500 N the strain ratio between the tension to compression sides was -0.21 proximally and -0.04 distally. The comparison of these strain ratios at different loads did not show any significant differences at p = 0.05 and power of 0.8. The data showed a trend validating the tension band principle as tensile strains lowered and compressive strains increased after placement of the plate.

The Treatment of Supracondylar Humeral Fractures With Elastic Stable Intramedullary Nailing (ESIN) in Children

Supracondylar humeral fractures are the most common elbow fractures in children. In case of displacement and instability, the standard procedure is closed reduction and percutaneous Kirschner wire fixation. As Kirschner wire fixation requires postoperative cast immobilization, does not allow early mobilization, and is associated with the risk of damage of the ulnar nerve, innovative techniques should be evaluated. Therefore, the aim of the study was to assess both radiologic and functional outcome of supracondylar humeral fractures treated by elastic stable intramedullary nailing (ESIN) in a large pediatric cohort. Retrospective review of children who underwent closed reduction and ESIN of displaced supracondylar humeral fractures in our institution between 2001 and 2009. One hundred twenty-seven children (mean age 6.1 y) with types II (60.6%), III (23.6%), and IV (15.7%) fractures according to the Arbeitsgemeinschaft für Osteosynthesefragen (AO) Pediatric Comprehensive Classification were included. One hundred and eighteen patients (92.9%) had healing of fracture without any limitation in range of motion and 9 patients (7.1%) had some minor degree of long-term functional deficit (7 children with flexion and 2 with extension deficit). Two children had clinical cubitus varus deformity. No iatrogenic damage to the ulnar nerve occurred and no secondary reduction or a change of surgical strategy was necessary. Postoperative radiologic evaluation showed antecurvation in 1 case, recurvation in 3 cases, as well as cubitus varus deformity and rotation deformity in 1 child each. Antegrade ESIN is a technique suitable for all types of supracondylar humeral fractures with good functional results. The advantages include the avoidance of iatrogenic ulnar nerve injury, low rates of cubitus varus, cast-free treatment, and the possibility to evaluate clinical motion at all times postoperatively. Although biased toward milder forms of supracondylar fractures, our data clearly suggest that if closed reduction is possible, intramedullary nailing in these children is more than an alternative to Kirschner wire fixation as the standard procedure. IV.

Treatment of Linear Mandibular Fractures Using a Single 2.0-mm AO Locking Reconstruction Plate: Is a Second Plate Necessary?

To prospectively evaluate the use of a single Arbeitsgemeinschaft für Osteosynthesefragen (AO) 2.0-mm locking reconstruction plate for linear noncomminuted mandibular fractures without the use of a second plate. We analyzed the clinical and radiologic data of 45 patients with 74 fractures (21 single fractures, 22 double fractures, and 2 triple fractures). Fracture locations were the symphysis (n = 35, 47.3%), body (n = 15, 20.3%), and angle (n = 24, 32.4%). We recorded the mechanism of injury, time between admission to the hospital and surgery, gender and age, temporary maxillomandibular fixation and its duration, and the surgical approach. Postsurgical complications that were recorded as minor did not require surgical intervention, whereas major complications required further surgical intervention. All patients had satisfactory fracture reduction and a successful treatment outcome without major complications. Ten patients (22.2%) developed minor complications. The present study has demonstrated that treating linear noncomminuted mandibular fractures with a single AO 2.0-mm locking reconstruction plates is associated with no major complications and sound bone healing in all patients.

The stepped hybrid plate for carpal panarthrodesis

SummaryIn the 1990s, the AO (Arbeitsgemeinschaft für Osteosynthesefragen) Hand Study Group developed several anatomically bent plates (standard and short) for wrist panarthrodesis in humans. However, only straight plates have been used for carpal panarthrodesis (CP) in animals to date. The primary purpose of this study was to determine if precontoured plates are more anatomical for CP in dogs. Measurement of several of the bones that are implicated in CP, as well as the relationship between their surfaces and the surface of a straight plate, were performed in a radio-graphic and computed tomographic cadaveric study. Axial and transverse measurements taken at different levels of the metacarpal bones 2, 3 and 4 were also included. The second objective of this study was to develop a more anatomical CP plate according to the results obtained. The measurements and images obtained in this study show that, as in human orthopaedics, bent or stepped plates are more anatomically correct than straight plates for CP in dogs.

The classification systems for tibial plateau fractures: How reliable are they?

The aim of the study was to assess the inter-observer reliability and intraobserver reproducibility of three different classification systems for tibial plateau fractures. Four observers of various levels of experience classified 50 tibial plateau fractures. The same observers repeated the classification of the same fractures after an interval of 8 weeks. Inter- and intra-observer variability was assessed using the mean kappa co-efficient and the mean percentage of agreement. For inter-observer reliability, the mean kappa co-efficient values for Arbeitsgemeinschaft für Osteosynthesefragen (AO), Schatzker and Hohl and Moore classifications were 0.36, 0.47 and 0.14, respectively. The mean percentage of agreement was 0.52, 0.59 and 0.34, respectively. For intra-observer reliability kappa-values were 0.80, 0.91 and 0.76 and the mean percentage of agreement was 0.88, 0.93 and 0.85 in the same order. Our results show that none of the classification systems were ideal. The Schatzker classification system was superior to the AO and the Hohl and Moore systems both in terms of inter-observer reliability and intra-observer reproducibility. However, there is a need for developing a more comprehensive approach to judge the classification systems.

Surgical treatment of AO type C distal humeral fractures: Internal fixation with a Y-shaped reconstruction (Lambda) plate

Although surgical repair is considered the standard treatment for intraarticular distal humeral fractures, most investigators have assessed its results using dual-plate fixation in 2 planes. The purpose of this study was to determine the functional outcome of open reduction and internal fixation of these complex fractures using Y-shaped reconstruction plates. We identified 17 patients who had operative treatment for Arbeitsgemeinschaft Für Osteosynthesefragen (AO) type 1, 3-C fractures using a Y-shaped Lambda plate (Zimmer, Warsaw, IN). Patients were recalled for follow-up that included recording of a complete history, physical examination, radiographic evaluation, and completion of a limb-specific questionnaire. The mean duration of follow-up was 37.3 months. The average loss of extension was 13 degrees , and the average arc of flexion-extension was 112 degrees . As determined by the Mayo Elbow Performance Index, 6 were graded excellent; 8, good; 3, fair; and none, poor. Surgical repair of intraarticular distal humeral fractures by open reduction and internal fixation with a Lambda plate is an effective procedure that allows for stable osteosynthesis without loss of reduction or fixation as a basis for good functional outcome.

Assessment of Two Thoracolumbar Fracture Classification Systems as Used by Multiple Surgeons

The reproducibility and repeatability of modern systems for classification of thoracolumbar injuries have not been sufficiently studied. We assessed the interobserver and intraobserver reproducibility of the AO (Arbeitsgemeinschaft für Osteosynthesefragen) classification and compared it with that of the Denis classification. Our purpose was to determine whether the newer, AO system had better reproducibility than the older, Denis classification. Anteroposterior and lateral radiographs and computerized tomography scans (axial images and sagittal reconstructions) of thirty-one acute traumatic fractures of the thoracolumbar spine were presented to nineteen observers, all trained spine surgeons, who classified the fractures according to both the AO and the Denis classification systems. Three months later, the images of the thirty-one fractures were scrambled into a different order, and the observers repeated the classification. The Cohen kappa (kappa) test was used to determine interobserver and intraobserver agreement, which was measured with regard to the three basic classifications in the AO system (types A, B, and C) as well as the nine subtypes of that system. We also measured the agreement with regard to the four basic types in the Denis classification (compression, burst, seat-belt, and fracture-dislocation) and with regard to the sixteen subtypes of that system. The AO classification was fairly reproducible, with an average kappa of 0.475 (range, 0.389 to 0.598) for the agreement regarding the assignment of the three types and an average kappa of 0.537 for the agreement regarding the nine subtypes. The average kappa for the agreement regarding the assignment of the four Denis fracture types was 0.606 (range, 0.395 to 0.702), and it was 0.173 for agreement regarding the sixteen subtypes. The intraobserver agreement (repeatability) was 82% and 79% for the AO and Denis types, respectively, and 67% and 56%, for the AO and Denis subtypes, respectively. Both the Denis and the AO system for the classification of spine fractures had only moderate reliability and repeatability. The tendency for well-trained spine surgeons to classify the same fracture differently on repeat testing is a matter of some concern.

ASSESSMENT OF TWO THORACOLUMBAR FRACTURE CLASSIFICATION SYSTEMS AS USED BY MULTIPLE SURGEONS

Background: The reproducibility and repeatability of modern systems for classification of thoracolumbar injuries have not been sufficiently studied. We assessed the interobserver and intraobserver reproducibility of the AO (Arbeitsgemeinschaft für Osteosynthesefragen) classification and compared it with that of the Denis classification. Our purpose was to determine whether the newer, AO system had better reproducibility than the older, Denis classification. Methods: Anteroposterior and lateral radiographs and computerized tomography scans (axial images and sagittal reconstructions) of thirty-one acute traumatic fractures of the thoracolumbar spine were presented to nineteen observers, all trained spine surgeons, who classified the fractures according to both the AO and the Denis classification systems. Three months later, the images of the thirty-one fractures were scrambled into a different order, and the observers repeated the classification. The Cohen kappa (κ) test was used to determine interobserver and intraobserver agreement, which was measured with regard to the three basic classifications in the AO system (types A, B, and C) as well as the nine subtypes of that system. We also measured the agreement with regard to the four basic types in the Denis classification (compression, burst, seat-belt, and fracture-dislocation) and with regard to the sixteen subtypes of that system. Results: The AO classification was fairly reproducible, with an average kappa of 0.475 (range, 0.389 to 0.598) for the agreement regarding the assignment of the three types and an average kappa of 0.537 for the agreement regarding the nine subtypes. The average kappa for the agreement regarding the assignment of the four Denis fracture types was 0.606 (range, 0.395 to 0.702), and it was 0.173 for agreement regarding the sixteen subtypes. The intraobserver agreement (repeatability) was 82% and 79% for the AO and Denis types, respectively, and 67% and 56%, for the AO and Denis subtypes, respectively. Conclusions: Both the Denis and the AO system for the classification of spine fractures had only moderate reliability and repeatability. The tendency for well-trained spine surgeons to classify the same fracture differently on repeat testing is a matter of some concern.

Use of the AO veterinary mini ‘T’-plate for stabilisation of distal radius and ulna fractures in toy breed dogs

The use of the AO (Arbeitsgemeinschaft für Osteosynthesefragen) veterinary mini 'T'-plate for stabilisation of distal radius and ulna fractures in toy breed dogs was evaluated in a retrospective study. All of the 14 dogs in the study weighed 3.5 kg or less. The AO mini 'T'-plate was used as the final means of fixation in all cases. It was used as the primary form of stabilisation in ten dogs, and in four dogs it was used at revision surgery. In all cases, of the fractures healed. Return to function was graded 'as excellent' in six cases, 'good' in four and 'fair' in two. Two dogs were lost to long-term follow up. It was concluded that the AO veterinary mini 'T'-plate is a suitable choice of implant for stabilisation of distal radius and ulna fractures in toy breed dogs, especially when the distal fragment is very small.

Interrater reliability for the basic categories of the AO/ASIF's system as a frame of reference for classifying distal radial fractures.

This study is about agreement on the assignment into the three basic classes or categories (A, B, C) of the Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation's (AO/ASIF) classification system for distal radial fractures. A random sample of 124 distal radial fractures was classified by two experienced observers. Their agreement was calculated according to Cohen's kappa statistic. To investigate the possible bases for disagreement, all conflicting X-ray assessments were discussed in a consensus meeting. It appeared that the kappa value was .65 (good agreement) before the meeting; kappa rose to .86 (excellent agreement) after the consensus meeting. It appeared that the undisplaced fractures were a major source of disagreement. Further, the presence of articular involvement was an important issue. It was frequently noted that one observer classified the fracture as extraarticular (basic Class A), while the other observer chose classification as an intra-articular fracture (basic Class C) or vice versa. This phenomenon has been called the A/C reversal shift. It is concluded that radiological innovations might enhance agreement on articular involvement, and a separate category for undisplaced fractures should be defined in the Arbeitsgemeinschaft für Osteosynthesefragen (AO) system. However, agreement on relevant distinctive features and discussion of conflicting assessments may also be important in achieving excellent agreement.

INTERRATER RELIABILITY FOR THE BASIC CATEGORIES OF THE AO/ASIF'S SYSTEM AS A FRAME OF REFERENCE FOR CLASSIFYING DISTAL RADIAL FRACTURES

This study is about agreement on the assignment into the three basic classes or categories (A, B, C) of the Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation's (AO/ASIF) classification system for distal radial fractures. A random sample of 124 distal radial fractures was classified by two experienced observers. Their agreement was calculated according to Cohen's kappa statistic. To investigate the possible bases for disagreement, all conflicting X-ray assessments were discussed in a consensus meeting. It appeared that the kappa value was .65 (good agreement) before the meeting; kappa rose to .86 (excellent agreement) after the consensus meeting. It appeared that the undisplaced fractures were a major source of disagreement. Further, the presence of articular involvement was an important issue. It was frequently noted that one observer classified the fracture as extraarticular (basic Class A), while the other observer chose classification as an intra-articular fracture (basic Class C) or vice versa. This phenomenon has been called the A/C reversal shift. It is concluded that radiological innovations might enhance agreement on articular involvement, and a separate category for undisplaced fractures should be defined in the Arbeitsgemeinschaft für Osteosynthesefragen (AO) system. However, agreement on relevant distinctive features and discussion of conflicting assessments may also be important in achieving excellent agreement.

History of the AO and Its Global Effect on Operative Fracture Treatment

In 1958 a group of Swiss general and orthopaedic surgeons established the AO (Arbeitsgemeinschaft für Osteosynthesefragen) or the Association of the Study of Internal Fixation (ASIF) to strive to transform the contemporary treatment of fractures in Switzerland. This association was revolutionary in development of instruments and implants for operative fracture treatment. The first instructional course for teaching the use of these instruments and implants occurred in Davos, Switzerland, in the newly founded Laboratory of Experimental Surgery in 1960. Through a process of internal quality control (AO documentation) the clinical success of these new techniques and implants became evident. Operative fracture treatment gained acceptance throughout Europe and finally worldwide. AO/International (AOI) was founded in 1972 to expand education and the teaching programs for surgeons and operating personnel on an international basis. In 1984, the AO/ASIF Foundation was created with an AO Board of Trustees comprising 90 leading trauma surgeons from throughout the world. Continuous research, implant and instrument development, clinical documentation, and multifaceted educational opportunities are coordinated by the AO/ASIF Foundation to maintain its position as the international authority in the treatment of trauma. The medical community recognizes today the enormous positive global effect that this respected and ever changing organization has had by continually improving operative fracture treatment.

Total Posterior Vertebrectomy of the Thoracic or Lumbar Spine

A total vertebrectomy in the thoracic or lumbar spine via a posterior approach can provide optimal neural decompression in certain severely compromised terminal patients affected with a malignant metastatic spinal lesion. The Arbeitsgemeinschaft für Osteosynthesefragen (AO) internal fixator, accompanied by methyl methacrylate reconstruction of the anterior vertebral column, provides sufficient stabilization so that immediate ambulation with minimal external support is possible. This single operative procedure allows reduction of the iatrogenic trauma by avoiding an additional anterior exposure. Total posterior vertebrectomy has been performed successfully in a total of nine cases in this study. In three early cases the spine was stabilized with posterior transpedicular plate fixation. The six most recent cases in which the AO internal fixator was used have verified the effectiveness of this fixation system. A modification of this technique may be applied to certain primary benign or malignant spinal lesions by allowing appropriate tumor resection margins and anterior corticocancellous bone graft reconstruction.