Search

Background:Postoperative knee instability is one of the major reasons accounting for unsatisfactory outcomes, as well as a major failure mechanism leading to total knee arthroplasty (TKA) revision. Nevertheless, subjective knee instability is not well defined clinically, plausibly because the relationships between instability and implant kinematics during functional activities of daily living remain unclear. Although muscles play a critical role in supporting the dynamic stability of the knee joint, the influence of joint instability on muscle synergy patterns is poorly understood. Therefore, this study aimed to understand the impact of self-reported joint instability on tibiofemoral kinematics and muscle synergy patterns after TKA during functional gait activities of daily living.Methods:Tibiofemoral kinematics and muscle synergy patterns were examined during level walking, downhill walking, and stair descent in eight self-reported unstable knees after TKA (3M:5F, 68.9 ± 8.3 years, body mass index [BMI] 26.1 ± 3.2 kg/m2, 31.9 ± 20.4 months postoperatively), and compared against 10 stable TKA knees (7M:3F, 62.6 ± 6.8 years, 33.9 ± 8.5 months postoperatively, BMI 29.4 ± 4.8 kg/m2). For each knee joint, clinical assessments of postoperative outcome were performed, while joint kinematics were evaluated using moving video-fluoroscopy, and muscle synergy patterns were recorded using electromyography.Results:Our results reveal that average condylar A-P translations, rotations, as well as their ranges of motion were comparable between stable and unstable groups. However, the unstable group exhibited more heterogeneous muscle synergy patterns and prolonged activation of knee flexors compared to the stable group. In addition, subjects who reported instability events during measurement showed distinct, subject-specific tibiofemoral kinematic patterns in the early/mid-swing phase of gait.Conclusions:Our findings suggest that accurate movement analysis is sensitive for detecting acute instability events, but might be less robust in identifying general joint instability. Conversely, muscle synergy patterns seem to be able to identify muscular adaptation associated with underlying chronic knee instability.Funding:This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

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.

Cartilage tissue has a very limited ability to regenerate. Symptomatic cartilage lesions are currently treated by various cartilage repair techniques. Multiple treatment techniques have been proposed in the last 30 years. Nevertheless, no single technique is accepted as a gold standard. Minced cartilage implantation is a newer technique that has garnered increasing attention. This procedure is attractive because it is autologous, can be performed in a single surgery, and is therefore given it is cost-effective. This narrative review provides an overview of the biological potential of current cartilage regenerative repair techniques with a focus on the translational evidence of minced cartilage implantation.

The in-plant recycling routes of side streams produced in electric arc furnace (EAF) steelmaking remain underexplored. Briquetting is an attractive technique to enable their recycle. Briquettes introduced into EAF must possess certain mechanical and chemical properties. However, no standard is available to determine the suitability of briquettes used in the EAF process. Herein, eight side streams are characterized, and used to produce seven different briquettes to be used in EAF. Briquettes tested consist of four self-reducing briquettes and three slag-forming briquettes produced using different recipes. The briquettes are subjected to several mechanical and thermal tests which reflect their intended use in EAF. The mechanical tests include compression and drop tests, and the thermal tests include optical dilatometry, thermogravimetric analysis (TGA)–derivative thermogravimetry (DTG)–mass spectrometry (MS), and full-scale briquette reduction tests. Moreover, melting trials are performed to assess the melting behavior of selected briquettes and their interaction with slag. Suitability of briquettes characteristics is assessed based on values from the literature and against reference ferroalloys and lime stones used in one of the steel plants. Two briquettes are deemed suitable for EAF use, while three briquettes are deemed unsuitable, and two briquettes are considered of limited use.

Purpose Despite practised for decades, the planning of osteotomy around the knee, commonly using the Mikulicz-Line, is only empirically based, clinical outcome inconsistent and the target angle still controversial. A better target than the angle of frontal-plane static leg alignment might be the external frontal-plane lever arm (EFL) of the knee adduction moment. Hypothetically assessable from frontal-plane-radiograph skeleton dimensions, it might depend on the leg-alignment angle, the hip-centre-to-hip-centre distance, the femur- and tibia-length. Methods The target EFL to achieve a medial compartment force ratio of 50% during level-walking was identified by relating in-vivo-measurement data of knee-internal loads from nine subjects with instrumented prostheses to the same subjects’ EFLs computed from frontal-plane skeleton dimensions. Adduction moments derived from these calculated EFLs were compared to the subjects’ adduction moments measured during gait analysis. Results Highly significant relationships (0.88 ≤ R2 ≤ 0.90) were found for both the peak adduction moment measured during gait analysis and the medial compartment force ratio measured in vivo to EFL calculated from frontal-plane skeleton dimensions. Both correlations exceed the respective correlations with the leg alignment angle, EFL even predicts the adduction moment’s first peak. The guideline EFL for planning osteotomy was identified to 0.349 times the epicondyle distance, hence deducing formulas for individualized target angles and Mikulicz-Line positions based on full-leg radiograph skeleton dimensions. Applied to realistic skeleton geometries, widespread results explain the inconsistency regarding correction recommendations, whereas results for average geometries exactly meet the most-consented “Fujisawa-Point”. Conclusion Osteotomy outcome might be improved by planning re-alignment based on the provided formulas exploiting full-leg-radiograph skeleton dimensions.

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.

Bei isolierter medialer Gonarthrose hat sich die unikondylare Kniearthroplastik (UKA) als operative Behandlung etabliert. Abweichungen der mechanischen Achse von der Norm konnen durch Mehrbelastung des Implantats oder des nichtbetroffenen Gelenkkompartiments das Resultat negativ beeinflussen. Die mediale oder laterale Gonarthrose mit ausgepragter juxtaartikularer koronarer Achsdeformitat kann daher nicht optimal mittels isolierter UKA behandelt werden. Der folgende Artikel geht auf die Technik einer kombinierten medialen UKA und einer medial aufklappenden hohen tibialen Osteotomie (HTO) bei medialer Gonarthrose mit proximaler tibialer Varusdeformitat ein. Praoperativ erfolgte eine radiologische Deformitatenanalyse nach Paley. Um eine ausreichende Knochenbrucke zwischen HTO und tibialer Prothesenkomponente zu gewahrleisten, wird die Osteotomie distaler als ublich angesetzt. Anschliesend wird die UKA durchgefuhrt. Das hierbei gewonnene autologe Knochenmaterial wird zur Auffullung des aufklappenden Osteotomiespalts verwendet und die Osteotomie schlieslich mit einer winkelstabilen 3,5-T-Platte fixiert. Die Nachbehandlung entspricht jener bei isolierter UKA, jedoch mit Teilbelastung von 15 kg fur 6 Wochen postoperativ. Die Technik der kombinierten UKA und HTO bei medialer Gonarthrose mit juxtaartikularer tibialer Deformitat stellt eine Alternative zur Knietotalprothese dar und bietet die Moglichkeit einer Indikationserweiterung fur die UKA. Fur eine abschliesende Beurteilung dieser Operationstechnik sind Vergleichsstudien notwendig. Das diesem Beitrag beigefugte Videomaterial veranschaulicht die Operationstechnik im Detail.

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.

This study examined the validity of the twitch interpolation technique for evaluating side-to-side asymmetries in quadriceps neuromuscular function. Fifty-six subjects with a wide range of asymmetries (19 healthy, 24 with unilateral and 13 with bilateral anterior cruciate ligament reconstruction) took part in the study. Supramaximal electrical paired stimuli were delivered to the quadriceps muscle during and immediately after a maximal voluntary contraction (MVC) of the knee extensors (twitch interpolation technique). MVC torque, voluntary activation and resting doublet-evoked torque were measured separately for the two sides, and percent side-to-side asymmetries were calculated for each parameter. MVC torque asymmetry was plotted against voluntary activation asymmetry and doublet-evoked torque asymmetry, and a multiple regression analysis was also conducted. Significant positive correlations were observed between MVC torque asymmetry and both voluntary activation asymmetry (r=0.40; p=0.002) and doublet-evoked torque asymmetry (r=0.53; p

© 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

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.

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?