Search

In diesem Beitrag wird der Fall einer 29-jahrigen Patientin geschildert, die an einem ausgepragtem Genu recurvatum in Folge einer spastisch-dystonen Bewegungsstorung litt. Durch die Fehlstellung im Kniegelenk war sie in ihrer Selbststandigkeit deutlich limitiert, eigenstandiges Gehen war ihr kaum moglich. Nach der operativen Versorgung mittels dorsaler Kapselrekonstruktion und Flexionsosteotomie des distalen Femurs zeigte sich initial eine vollstandig korrigierte Hyperextension. Vierzehn Wochen postoperativ war eine Rezidiv-Hyperextension von 15° aufgetreten. Dennoch resultierte fur die Patientin eine deutlich verbesserte Lebensqualitat und Mobilitat. Gegebenenfalls ist in Fallen eines derart ausgepragten multifaktoriellen Genu recurvatum eine knocherne Uberkorrektur anzustreben, um ein Rezidiv zu vermeiden.

In addition to the blast furnace converter route, electric steel production in the electric arc furnace (EAF) is one of the two main production routes for crude steel. In 2019, the global share of crude steel produced via the electric steel route was 28%, which in numbers is 517 million metric tons of crude steel. The production and processing of steel leads to the output of a variety of by-products, such as dusts, fines, sludges and scales. At the moment, 10&ndash, 67% of these by-products are landfilled and not recycled. These by-products contain metal oxides and minerals including iron oxide, zinc oxide, magnesia or alumina. Apart from the wasted valuable materials, the restriction of landfill space and stricter environmental laws are additional motivations to avoid landfill. The aim of the Fines2EAF project, funded by the European Research Fund for Coal and Steel, is to develop a low-cost and flexible solution for the recycling of fines, dusts, slags and scales from electric steel production. During this project, an easy, on-site solution for the agglomeration of fine by-products from steel production has to be developed from lab scale to pilot production for industrial tests in steel plants. The solution is based on the stamp press as the central element of the agglomeration process. The stamp press provides the benefit of being easily adapted to different raw materials and different pressing parameters, such as pressing-force and -speed, or mold geometry. Further benefits are that the stamp press process requires less binding material than the pelletizing process, and that no drying process is required as is the case with the pelletizing process. Before advancing the agglomeration of by-products via stamp press to an industrial scale, different material recipes are produced in lab-scale experiments and the finished agglomerates are tested for their use as secondary raw materials in the EAF. Therefore, the tests focus on the chemical and thermal behavior of the agglomerates. Chemical behavior, volatilization and reduction behavior of the agglomerates were investigated by differential thermogravimetric analysis combined with mass spectroscopy (TGA-MS). In addition, two melts with different agglomerates are carried out in a technical-scale electric arc furnace to increase the sample size.

Purpose To examine the measurement properties of the German International Knee Documentation Committee Subjective Knee Form (IKDC-SKF) in knee disorder patients. Methods Three hundred twelve consecutive patients undergoing surgery for anterior cruciate ligament, meniscus and/or cartilage injuries completed the IKDC-SKF, Lysholm Score, Tegner Activity Scale, and Short Form-12 Health Survey before and 6 months post-surgery. IKDC-SKF measurement properties were calculated and patients were also asked to rate the relevance/comprehensibility of the questionnaire items. Results Reliability was good with high Cronbach’s alpha and intraclass correlation coefficients, and standard error of measurement values of 4.4 to 6.0. The smallest detectable change (SDC) ranged from 12.3 to 16.7 points. Validity was good with 90% of all hypotheses confirmed. Confirmatory factor analysis did not show adequate fitting indices within the model. Over half of the items were rated as essential, and all were well comprehended. The majority of hypotheses for responsiveness were confirmed. No floor and ceiling effects were observed. The area under the curve ranged from 0.82 to 0.89 and the minimal important difference was smaller than the SDC. Conclusions The German IKDC-SKF is a reliable outcome measure with good hypotheses testing and responsiveness, but its MIC and structural/content validity need further analysis.

Patient expectations are an issue which is attracting increased interest in outcome research for knee surgery procedures. So far, research into patient expectations has mainly focused on the procedure and postoperative functional improvements. The purpose of this study was to identify patient expectations in the perioperative setting.This was a single-center prospective study. A 17-item questionnaire (ordinal answer scale) about patients' perioperative expectations was developed and completed by patients undergoing elective joint-preserving knee surgery. The study covered a period of 3 months and included all patients consecutively undergoing knee surgery. Subgroup analysis was performed for gender, age and type of insurance.111 consecutive patients completed the questionnaire on admission. Significant preferences for one answer option were found for 13 out of 17 items. Patients considered it "unimportant" whether or not the physician wore a white coat during the consultation and "very important" that the first medical consultation after the patient was discharged from hospital was with the surgeon who had performed their operation. A concise explanation of the surgical procedure using images, talking to the surgeon the day before surgery and immediately after surgery, having their wound personally inspected by the surgeon, and, finally, the availability of the surgeon by phone were regarded as "important". There were no differences in patient responses between the different subgroups.Patients expect a high personal commitment and availability of the surgeon during the entire perioperative setting, starting from the first consultation and continuing during follow-up examinations.Patientenerwartungen sind in der Ergebnisforschung für Knieoperationen von zunehmendem Interesse. Bisher konzentrierte sich die Forschung der Erwartungshaltung hauptsächlich auf Operationen und postoperative Funktionsverbesserungen. Der Zweck dieser Studie bestand darin, die Patientenerwartungen an die perioperativen Rahmenbedingungen zu ermitteln.Prospektive Single-Center-Studie. Ein 17-Punkte-Fragebogen (ordinale Antwortskala) zur perioperativen Patientenerwartung wurde entwickelt und nach entsprechender Bearbeitung durch Patienten, welche sich einer elektiven gelenkerhaltenden Knieoperation unterzogen, ausgewertet. Die Analyse dauerte 3 Monate und umfasste alle Patienten, welche sich in dieser Zeit einer Operation unterzogen. Es wurden Subgruppenanalysen nach Geschlecht, Alter und Art der Versicherung durchgeführt.111 aufeinanderfolgende Patienten füllten den Fragebogen nach der Aufnahme aus. Bei 13 von 17 Elementen wurden signifikante Präferenzen für eine Antwortoption gefunden. Die Patienten hielten es für „unwichtig“, dass der Arzt einen weißen Kittel zur Beratung trug und „sehr wichtig“ war, dass die erste ärztliche Beratung nach der Entlassung aus dem Krankenhaus vom Chirurgen persönlich durchgeführt wurde. Die Erklärung des Operationsvorgangs anhand von Bildern, ein Gespräch mit dem Chirurgen am Tag vor der Operation und direkt nach der Operation, die persönliche Wundkontrolle durch den Chirurgen und schließlich die telefonische Verfügbarkeit des Chirurgen wurden als „wichtig“ angesehen. Beim Vergleich der verschiedenen Untergruppen gab es keine Unterschiede im Antwortverhalten.Die Patienten erwarten ein hohes persönliches Engagement und eine hohe Verfügbarkeit des Chirurgen im gesamten perioperativen Umfeld – von der ersten Konsultation bis zur Nachuntersuchung.

Background:Chondral and osteochondral lesions are being detected with increasing frequency. For large-diameter lesions, cell-based treatment modalities are speculated to result in the best possible outcome.Purpose:To prospectively evaluate the 2-year clinical and radiological results after the treatment of chondral and osteochondral knee joint lesions by a single-step autologous minced cartilage procedure.Study Design:Case series; Level of evidence, 4.Methods:From February 2015 to June 2016, a total of 27 consecutive patients suffering from chondral or osteochondral lesions of the knee joint were treated using a single-step autologous minced cartilage procedure. All patients underwent preoperative and postoperative magnetic resonance imaging for the collection of AMADEUS (Area Measurement and Depth and Underlying Structures) and MOCART (magnetic resonance observation of cartilage repair tissue) scores. Clinical analysis was conducted by a numeric analog scale (NAS) for pain and knee function before the intervention and at 12 and 24 months postoperatively.Results:A total of 12 female and 15 male patients (mean age, 28.7 years) were evaluated for a mean of 28.2 ± 3.8 months. The mean cartilage defect size encountered intraoperatively was 3.1 ± 1.6 cm2. There was a significant decrease in pain from 7.2 ± 1.9 preoperatively to 1.8 ± 1.6 ( P < .001) at 2-year follow-up. Knee function improved from a mean of 7.2 ± 2.0 preoperatively to 2.1 ± 2.3 ( P < .001) at 2 years after surgery. The mean preoperative AMADEUS score was 57.4 ± 21.4. Postoperatively, the mean MOCART score was 40.6 ± 21.1 at 6-month follow-up. No correlation was observed between the clinical data and the MOCART or AMADEUS scores.Conclusion:Overall, the findings of this study demonstrated that patients undergoing a single-step autologous minced cartilage procedure had a satisfactory outcome at 2-year follow-up. As a result, the single-step autologous minced cartilage procedure does represent a possible alternative to standard autologous chondrocyte implantation. Longer follow-up and larger cohorts are required to define the benefits of this procedure.

Background Recently, the AMADEUS (Area Measurement And DEpth Underlying Structures) grading system has been introduced to evaluate and grade osteochondral lesions prior to cartilage surgery. The AMADEUS score has not been connected to clinical data in order to test a potential clincial impact. Purpose To examine the correlation between the AMADEUS score and preoperative patient-reported outcome measurements (PROMs). Study design Case series Methods Patients treated with matrix-induced autologous chondrocyte implantation (MACI) were included in the study, unless exclusion criteria like BMI > 35, prior extensive meniscectomy or ongoing inflammatory arthritis were present. Preoperative magnetic resonance (MR) examinations were graded according to the standardized AMADEUS protocol. The final AMADEUS score was correlated with preoperative patient-reported outcome measurements (PROMs), including the IKDC (International Knee Documentation Committee), the Lysholm score, the Short-Form-12 (SF-12) score, and the Core Outcome Measures Index (COMI) score. Results A total of 50 patients with a mean age of 33.6 ± 11.5 years, a mean BMI of 25.1 ± 4.9, and a mean defect size of 2.3 ± 1.5 cm2 were included in the study. More severe cartilage defects, indicated by the AMADEUS grade (R = 0.35, p = 0.01) and the AMADEUS score (R = − 0.36, p = 0.01) as well as larger chondral defects (R = 0.32, p = 0.03) show a moderate correlation with the higher COMI scores. No correlative capacity was demonstrated for the AMADEUS score and the IKDC, Lysholm, and Tegner activity scores as well as for its subscales. Conclusion There is a moderate correlation of the COMI and the AMADEUS score in patients treated with matrix-induced autologous chondrocyte implantation (MACI). All other patient-reported outcome measurement scores (PROMs) show no evidence of an association to the magnetic resonance-based AMADEUS score. Clinical relevance The clinical and scientific implication of the COMI score as a PROM tool can be recommended when working with the AMADEUS score and patients undergoing MACI.

Background: Transplantation of autologous minced cartilage is an established procedure to repair chondral lesions. It relies on the migration of chondrocytes out of cartilage particles into a biomaterial. So far, there is no efficient way to finely mince cartilage. No consensus exists on the nature of the biomaterial to be used to promote chondrocyte migration. Purpose/Hypothesis: This study aimed to investigate the potential clinical use of a custom-made mincing device as well as a possible alternative biomaterial to fibrin glue. The device was tested for its effect on chondrocyte viability and on subsequent chondrocyte migration into either a fibrin or a collagen gel. We hypothesized that device mincing would allow finer cutting and consequently more cell migration and that the gelation mechanism of the collagen biomaterial, which uses the clotting of platelet-rich plasma, would enhance matrix production by outgrown chondrocytes. Study Design: Controlled laboratory study. Methods: Cartilage from 12 patients undergoing knee arthroplasty was taken from the femoral condyles and subsequently either hand minced or device minced. The viability and the degree of outgrowth were quantified with live/dead assay on the generated cartilage particles and on the gels in which these particles were embedded, respectively. Matrix deposition in the biomaterials by the outgrown cells was investigated with histology. Results: The device allowed rapid mincing of the cartilage and produced significantly smaller pieces than hand mincing. The initial chondrocyte viability in cartilage particles dropped by 25% with device mincing as compared with no mincing. However, the viability in hand-minced, device-minced, and unminced samples was no longer different after 7 and 28 days in culture. Outgrowth scores were similar among the 3 groups. Fibrin and collagen biomaterials equally supported chondrocyte outgrowth and survival, but neither promoted matrix deposition after in vitro culture. Conclusion: The outgrowth potential, the viability after 28 days in culture, and the matrix deposition were not different between the mincing techniques and the tested biomaterials, yet device mincing is faster and results in significantly smaller cartilage particles. Clinical Relevance: Device mincing could become the standard method to mince cartilage for second-generation cartilage repair techniques., Orthopaedic Journal of Sports Medicine, 7 (9), ISSN:2325-9671

Applied Sciences 9(19), 3946 (2019). doi:10.3390/app9193946 special issue: "Extractive Metallurgy from Metallurgical Waste or by-Products / Special Issue Editors: Dr. Davide Mombelli, Politecnico di Milano, Dipartimento di Meccanica ; Prof. Carlo Mapelli, Politecnico di Milano, Dipartimento di Meccanica", Published by MDPI, Basel

Football is currently the most popular sporting activity in the world. Multiple reports have shown that a high incidence of osteoarthritis is found in football players. Evidence clearly shows that traumatic injury significantly predisposes players for such pathophysiology. Injuries are frequent in amateur as well as professional football players, with knee and ankle accounting for the most severe injuries. Many professional athletes lose playing time due to injuries and many are forced into early retirement. Posttraumatic osteoarthritis is a common finding among ex-football players with numbers well above the normal population. Today’s surgical techniques are advanced and capable of restoring the joint to a certain extent. However, a restitution ad integrum is reached only in very rare cases. Professional football players that return to play after serious injuries perform their extremely strenuous activity on morphologically compromised joints. Incomplete rehabilitation and pressure to return to play after an injurious event clearly put the athlete at an even higher risk for joint degeneration. Prevention strategies, improved surgical management, strict rehabilitation, as well as future aspects such as early suppression of inflammation, personalized medicine, and predictive genomics DNA profiling are needed to reduce incidence and improve the health perspectives of football players.

© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Purpose: Studies comparing the outcome of spine surgery with that of large-joint replacement report equivocal findings. The patient-reported outcome measures (PROMs) used in such studies are typically generic and may not be sufficiently sensitive to the successes/failures of treatment. This study compared different indices of “success” in patients undergoing surgery for degenerative disorders of the lumbar spine, hip, or knee, using a validated, multidimensional, and joint-specific PROM. Methods: Preoperatively and 12 months postoperatively, 4594 patients (3937 lumbar spine, 368 hip, 269 knee) undergoing first-time surgery completed a PROM that included the Core Outcome Measures Index (COMI) for the affected joint. The latter comprises a set of single items on pain, function, symptom-specific well-being, quality of life, and disability—all in relation to the specified joint problem. Other single-item ratings of treatment success were made 12 months postoperatively. Results: In multiple regression analyses, controlling for confounders, the mean improvement in COMI at 12 months was greatest for the hip patients and lowest for those with degenerative spinal deformity (= the statistical reference group) (p

Articular cartilage defects at the knee joint are identified and treated with increasing frequency. Autologous chondrocytes may have the strongest potential to generate high-quality repair tissue within the defective region. Autologous chondrocyte implantation is not available in every country. We present a surgical technique where the surgeon can apply autologous chondrocytes in a one-step procedure to treat articular cartilage defects at the knee joint.

Existing cryptographic realizations of privacy-friendly authentication mechanisms such as anonymous credentials, minimal disclosure tokens, self-blindable credentials, and group signatures vary largely in the features they offer and in how these features are realized. Some features such as revocation or de-anonymization even require the combination of several cryptographic protocols. The variety and complexity of the cryptographic protocols hinder the understanding and hence the adoption of these mechanisms in practical applications. They also make it almost impossible to change the underlying cryptographic algorithms once the application has been designed. In this paper, we aim to overcome these issues and simplify both the design and deployment of privacy-friendly authentication mechanisms. We define and unify the concepts and features of privacy-preserving attribute-based credentials (Privacy-ABCs), provide a language framework in XML schema, and present the API of a Privacy-ABC system that supports all the features we describe. Our language framework and API enable application developers to use Privacy-ABCs with all their features without having to consider the specifics of the underlying cryptographic algorithms-similar to as they do today for digital signatures, where they do not need to worry about the particulars of the RSA and DSA algorithms either.

Background The Core Outcome Measure Index (COMI) is a very short outcome instrument used in spine patients. The aim of this study was to examine the utility of a knee version of the COMI in patients undergoing total knee arthroplasty (TKA) by assessing the reproducibility, construct and discriminant validity, and responsiveness. Methods Preoperatively, 224 patients completed the Oxford Knee Score (OKS), EuroQoL (EQ-5D) and the COMI-Knee; 189 (84) % also completed the questionnaires at follow-up and 73 patients completed preoperatively the COMI-knee twice. Results The weighted kappa values for the COMI-knee single items ranged from 0.80 to 0.89 and the ICC for the COMI-knee (composite score), 0.86. The absolute SEM for COMI-knee was 0.4 points, i.e. four percent of the maximum value (10 points) and six percent of the average value (6.6 points). The Area Under the Curve derived from the Receiver Operating Characteristic method for the COMI-knee was 0.97 (95% CI, 0.93 to 0.99), with a cut-off value for indicating a “good” result of 2.3 (100% specificity, 87% sensitivity). Correlations between the COMI-knee and the OKS were − 0.72 at baseline and − 0.87 at six months. The correlations between the change scores for the COMI-knee and the change scores for the OKS and EQ5D index were 0.77 and 0.69, respectively. Conclusions The measurement properties of the COMI-knee satisfy international quality criteria and hence support its use in assessing patients undergoing TKA.

16 Monate nach auswartiger vorderer Kreuzbandersatzplastik stellte sich ein 26-jahriger Patient wegen persistierender Schmerzen und Bewegungseinschrankung trotz Physiotherapie vor. Bei der Untersuchung, u. a. mit einer Magnetresonanztomografie, zeigte sich eine ausgedehnte Chondrolyse mit rapidem Progress. Wie war es dazu gekommen?

Patella baja is a severe complication seen after trauma, prolonged immobilization and surgery. Several surgical methods have been described to proximalize the patella without a change in the patella tendon length. Yet, patella tendon shortening and thickening can be regarded as the hallmark pathology. As such, we describe a technique for the lengthening of the patellar tendon to pathoconformly address underlying patella baja. The technique is reproducible and gives the possibility of an early postoperative mobilization to prevent re-baja—a typical complication after patella baja surgery.

Background Osteochondrosis dissecans is a disorder of the subchondral bone potentially affecting the adjacent articular cartilage. There remains disunity with regard to treatment methods. Case presentation We present the case of a 21-year-old Swiss woman who presented with clinically symptomatic bilateral osteochondrosis dissecans lesions at both medial femoral condyles. She underwent sequential surgical intervention and was prospectively monitored using clinical scores and magnetic resonance imaging. Her left knee was treated with an open refixation of the osteochondrosis dissecans lesion with two 2.0 mm screws in combination with a cancellous bone graft and subchondral drilling since the cartilage of the osteochondrosis dissecans lesion was intact. On her right knee, she underwent open removal of the defective bone and cartilage, cancellous bone graft with subchondral drilling and coverage with a bilayered collagenous membrane (autologous matrix-induced chondrogenesis technique) since the cartilage of the osteochondrosis dissecans lesion was not intact. At final follow-up 12 months after surgery her Lysholm score had improved from 79 to 95 on her left side and from 74 to 78 on her right. Magnetic resonance imaging displayed good integration of the cancellous bone graft with a slight irregularity at the articular surface on her left side (magnetic resonance observation of cartilage repair tissue (MOCART) 75). The magnetic resonance imaging of her right knee depicted satisfying bony reconstitution with yet more irregularity at the joint surface (magnetic resonance observation of cartilage repair tissue 65) in comparison to her left femoral condyle. Conclusions In cases of failed conservative treatment of osteochondrosis dissecans lesions of the knee joint surgery should be taken into consideration. Considering this case, we believe that the focus should be the preservation of the cartilaginous layer whenever possible or at least replacement with high quality replacement tissue, such as autologous chondrocyte implantation.

PURPOSE: Performing total knee replacement, accurate alignment and neutral rotation of the femoral component are widely believed to be crucial for the ultimate success. Contrary to absolute bone referenced alignment, using a ligament balancing technique does not automatically rotate the femoral component parallel to the transepicondylar axis. In this context we established the hypothesis that rotational alignment of the femoral component parallel to the transepicondylar axis (0° ± 3°) results in better outcome than alignment outside of this range. METHODS: We analysed 204 primary cemented mobile bearing total knee replacements five years postoperatively. Femoral component rotation was measured on axial radiographs using the condylar twist angle (CTA). Knee society score, range of motion as well as subjective rating documented outcome. RESULTS: In 96 knees the femoral component rotation was within the range 0 ± 3° (neutral rotation group), and in 108 knees the five-year postoperative rotational alignment of the femoral component was outside of this range (outlier group). Postoperative CTA showed a mean of 2.8° (±3.4°) internal rotation (IR) with a range between 6° external rotation (ER) and 15° IR (CI 95). No difference with regard to subjective and objective outcome could be detected. CONCLUSION: The present work shows that there is a large given natural variability in optimal rotational orientation, in this study between 6° ER and 15° IR, with numerous co-factors determining correct positioning of the femoral component. Further studies substantiating pre- and postoperative determinants are required to complete the understanding of resulting biomechanics in primary TKA.

The clinical and radiographic results of 174 female and 86 male Innex (Zimmer, Warsaw, Indiana) mobile bearing total knee arthroplasty systems (245 patients) were evaluated, with particular emphasis on gender-related differences at five-year follow-up. Pre-operative Knee Society (KS) function and total scores were lower in women than in men. All KS scores showed a significant improvement at follow-up, but women still obtained lower KS function scores than men. Self-reported function was significantly better for male knees. No gender differences were observed for component alignment, while the occurrence of radiolucent lines, endosteal cavitations, and wear was significantly greater in male knees. Male Innex mobile bearing knees exhibited better clinical function and satisfaction than their female peers at five-year follow-up, despite inferior radiographic findings and higher revision rates.

BackgroundThere is a lack of detailed information concerning patients’ sports and recreational activities after unicompartmental knee arthroplasty.HypothesisPatients treated by unicompartmental knee arthroplasty will be able to return to sports and activity.Study DesignCase series; Level of evidence, 4.MethodsThe authors surveyed 83 patients by postal questionnaires to determine their sporting and recreational activities at a mean follow-up of 18 ± 4.6 months (range, 12-28) after unicompartmental knee arthroplasty. For data analysis, patients were divided into groups of women and men, and older and younger patients (those above and below the median age of the group). The authors also assessed the state of general health (SF-36) of the patients at the time of the survey and compared the results with those of a matched (for age and side-diagnoses) reference population.ResultsBefore surgery, 77 of 83 patients were engaged in an average of 5.0 sports and recreational disciplines; postoperatively, 73 (88%) participated in an average of 3.1 different sports disciplines, resulting in a return to activity rate of 95%. The frequency of activities (sessions per week) was 2.9 preoperatively and remained constant at the time of survey (2.8). The group of older patients (mean age 73.0 y) revealed a significantly higher frequency than the group of younger patients (mean age 57.8 y). The minimum session length decreased from 66 minutes before surgery to 55 minutes after surgery. The most common activities after surgery were hiking, cycling, and swimming. Several high-impact activities, as well as the winter disciplines of downhill- and cross-country skiing had a significant decrease in participating patients. The majority of the patients (90.3%) stated that surgery had maintained or improved their ability to participate in sports or recreational activities. The patients generally scored very high on the SF-36 compared with the matched reference population. Higher SF-36 values in the physical-related domains correlated with an increased level of activity (r = 0.425). The preoperative body mass index showed a weak, negative correlation with the postoperative extent of activities (r = —0.282).ConclusionThe majority of patients returned to sports and recreational activity after unicompartmental knee arthroplasty. However, the numbers of different disciplines patients were engaged in decreased as well as the extent of activities. The activities in which most patients participated were primarily low- or midimpact. The patients scored higher on the SF-36 than age-related norms, which might be due to the patient-selection process for unicompartmental knee arthroplasty and geographical differences.

Mobile devices are increasingly used in security-sensitive contexts such as physical access control and authorization of payment transactions. In this paper we contribute a mechanism to verify whether a mobile device currently resides within a geographical area at a given time, thus enabling the use of the location as an additional authentication factor. Trustworthiness, privacy, and practicability are central to our mechanism. In particular, to provide trustworthy location information, our mechanism uses the location of the phone as detected by the Mobile Network Operator instead of relying on the location detected by the phone itself, which can be manipulated. We have followed a privacy-by-design approach to ensure that sensitive information, e.g., location and subscriber data, are only revealed to parties with a need to know. Privacy safeguards are realized using anonymous credentials, an established privacy-enhancing technology. Finally, our mechanism is practical and has little requirements on the mobile phone beyond the ability to run computations on anonymous credentials, as well as Internet and mobile network connectivity. These requirements are fulfilled by most smartphones in the market.

Although knee joint arthroscopy is one of the most frequently performed surgical procedures worldwide, there is no consensus on how to apply a drain in the joint if it is decided to use one. Therefore we describe a simple technique to safely apply a drain intra-articularly under full arthroscopic control, avoiding placement of the drain through the arthroscopic portal.

One of the main objectives of the ABC4Trust project was to define a common, unified architecture for Privacy-ABC systems to allow comparing their respective features and combining them into common platforms. The chapter presents an overview of features and concepts of Privacy-ABCs and introduces the architecture proposed by ABC4Trust, describing the layers and components as well as the highlevel APIs. We also present the language framework of ABC4Trust through an example scenario. Furthermore, this chapter investigates integration of Privacy-ABCs with the existing Identity Management protocols and also analyses the required trust relationships in the ecosystem of Privacy-ABCs.

In this chapter we present the Cryptographic Engine which provides the cryptographic functionality used in the ABC Engine, such as issuance or presentation of credentials. We first describe the architecture of the Cryptographic Engine, explain the building blocks it uses, and explain how they are bound together. We then describe the cryptographic primitives that the library uses to instantiate those building blocks.

Many Internet users today use an electronic social network service (SNS) to share data with their friends. Most SNSs let users restrict access to their shared data, e.g., to particular groups of friends, or to users satisfying other criteria based on their attributes or relationships. Usually, however, such access control restrictions can only be applied to resources hosted on the SNS itself. In this paper, we present protocols to enable SNS users to protect access to resources that are hosted on external service providers (SPs). Our mechanisms preserve the users' privacy in the sense that (1) the SP does not learn the SNS-identities of users that share or access the resource, nor does it learn anything about the access policy that protects it, (2) the SNS does not obtain any information about the resource, and in particular, does not obtain a link to it, and (3) the SP cannot change the policy set by the owner of the resource, or test the policy on users who never requested access to the resource. We give formal definitions of these security requirements and present a cryptographic protocol based on group signatures that provably fulfills them. We also discuss to what extent our requirements can be fulfilled using the standard OAuth authorization protocol while making only minor changes to the SNS infrastructure.

Existing cryptographic realizations of privacy-friendly authentication mechanisms such as anonymous credentials, minimal disclosure tokens, selfblindable credentials, and group signatures vary largely in the features they offer and in how these features are realized. Some features such as revocation or de-anonymization even require the combination of several cryptographic protocols. These differences and the complexity of the cryptographic protocols hinder the deployment of these mechanisms for practical applications and also make it almost impossible to switch the underlying cryptographic algorithms once the application has been designed. In this paper, we aim to overcome this issue and simplify both the design and deployment of privacy-friendly authentication mechanisms. We define and unify the concepts and features of privacy-preserving attribute-based credentials (Privacy-ABCs) and provide a language framework in XML schema. Our language framework enables application developers to use Privacy-ABCs with all their features without having to consider the specifics of the underlying cryptographic algorithms—similar to as they do today for digital signatures, where they do not need to worry about the particulars of the RSA and DSA algorithms either.

Classical authentication mechanisms have various drawbacks such as the weak security properties they achieve, users' privacy, service providers' data quality, and the necessary protection of the collected data. Credential-based authentication is a first step towards overcoming these drawbacks. When used with anonymous credentials, the personal data disclosed can be reduced to the minimum with respect to a business purpose while improving the assurance of the communicated data. However, this privacy-preserving combination of technologies is not used today. One reason for this lack of adoption is that a comprehensive framework for privacy-enhancing credential-based authentication is not available. In this paper we review the different components of such an authentication framework and show that one remaining missing piece is a translation between high-level authentication policies and the cryptographic token specification level. We close this gap by (1) proposing an adequate claim language specifying which certified data a user wants to reveal to satisfy a policy and by (2) providing translation algorithms for generating the anonymous credentials (cryptographic tokens) providing the data to be revealed. For the latter we consider the Identity Mixer and the U-Prove technologies, where we provide detailed translation instructions for the former.

This chapter describes how users’ privacy preferences and services’ privacy policies are matched in order to decide whether personal data can be shared with services. Matching has to take into account data handling, i.e. does services handle collected data in a suitable way according to user expectations, and access control, i.e. do the service that will be granted access to the data comply with user expectations. Whereas access control describes the conditions that have to be fulfilled before data is released, data handling describes how the data has to be treated after it is released. Data handling is specified as obligations that must be fulfilled by the service and authorisations that may be used by the service. An important aspect of authorisation, especially in light of the current trend towards composed web services (so-called mash-ups), is downstream usage, i.e., with whom and under which data handling restrictions data can be shared.

Privacy protection tools can be characterised by the number of parties that have to cooperate so that the tools work and achieve the desired effect [Pfi01]: Some privacy protection tools can be used stand-alone, without the need for the cooperation of other parties. Others require that the communication partners use the same tools. Some tools only function when being supported by an appropriate infrastructure that quite often is currently not in place.

This chapter presents the results of the research on how the current standards for access control policies can be extended. In particular, Section 18.1 illustrates how privacy issues can be effectively tackled by means of a credential-based access control that includes anonymous credentials. Section 18.2 shows how the expressivity of policy languages can be exploited to introduce ontologies that model credential taxonomies and the relations among them, with a particular stress on the support for delegation mechanisms. Section 18.3 investigates the privacy issues that arise in those access control systems that are enriched with a dialog framework that enables servers to publish their policies. Finally, Section 18.4 maps these proposals onto a set of possible extensions of the architecture of the current de facto standard in access control policy languages: XACML.

Whereas access control describes the conditions that have to be fulfilled before data is released, usage control describes how the data has to be treated after it is released. Usage control can be applied to digital rights management, where the data are usually copyright-protected media, as well as in privacy, in which case the data are privacy-sensitive personal information. An important aspect of usage control for privacy, especially in light of the current trend towards composed web services (so-called mash-ups), is downstream usage, i.e., with whom and under which usage control restrictions data can be shared. In this work, we present a two-sided XML-based policy language: on the one hand, it allows users to express in their preferences in a fine-grained way the exact paths that their data is allowed to follow, and the usage restrictions that apply at each hop in the path. On the other hand, it allows data consumers to express in their policies how they intend to treat the data, with whom they intend to share it, and how the downstream consumers intend to treat the data.

In this paper we describe extensions to the access control industry standards XACML and SAML to enable privacy-preserving and credential-based access control. Rather than assuming that an enforcement point knows all the requester’s attributes, our extensions allow the requester to learn which attributes have to be revealed and which conditions must be satisfied, thereby enabling to leverage the advantages of privacy-preserving technologies such as anonymous credentials. Moreover, our extensions follow a credential-based approach, i.e., attributes are regarded as being bundled together in credentials, and the policy can refer to attributes within specific credentials. In addition to defining language extensions, we also show how the XACML architecture and model of evaluating policies can be adapted to the credential-based setting, and we discuss the problems that such extensions entail.

In open scenarios, where servers may receive requests to access their services from possibly unknown clients, access control is typically based on the evaluation of (certified or uncertified) properties, that clients can present. Since assuming the client to know a-priori the properties she should present to acquire access is clearly limiting, servers should be able to respond to client requests with information on the access control policies regulating access to the requested services. In this paper, we present a simple, yet flexible and expressive, approach for allowing servers to specify disclosure policies, regulating if and how access control policies on services can be communicated to clients. Our approach allows fine-grain specifications, thus capturing different ways in which policies, and portions thereof, can be communicated. We also define properties that can characterize the client view of the access control policy.

Three centers' experience with 93 comminuted humeral head fractures were clinically (Constant score) and radiologically (Neer) analyzed. The results revealed fundamental differences between the various types of fractures depending on the number of fragments. For three-part fractures open reduction and internal fixation (mean Constant scores 83 and 91 points, respectively) or conservative treatment (78 points) seem to be indicated. The prognosis for four-part fractures is determined largely by the vascular supply of the head fragment with a high risk of humeral head osteonecrosis. For this reason primary prosthetic replacement (mean Constant score, 74 points compared with 54 points for conservative treatment and 52 points for open reduction) should be recommended for this type of fracture. In conclusion, we stress the importance of fracture type directing the therapeutic modality.