Eine valide Risikoadjustierung ist in der Endoprothetik Voraussetzung, um die Behandlungsqualität zwischen Kliniken und Operateuren vergleichbar zu machen. Bestehende Modelle berücksichtigen überwiegend patientenspezifische Faktoren wie Alter oder Komorbiditäten. Hinsichtlich gelenkspezifischer Risikofaktoren für postoperative Komplikationen besteht bisher kein Konsens. Ziel dieser Studie war die Erarbeitung eines Expertenkonsensus zu klinisch relevanten gelenkspezifischen Risikofaktoren in der Knieendoprothetik. Ein dreistufiges modifiziertes Delphi-Verfahren wurde mit 14 deutschen Experten, die in Diagnostik und Therapie in der Knieendoprothetik eingebunden sind, durchgeführt. Auf Basis einer Literaturrecherche wurden 120 potenzielle Risikofaktoren identifiziert. In Runde 1 erfolgte deren Bewertung, in Runde 2 eine Fokussierung auf 70 gelenkspezifische Faktoren. In einer virtuellen Konsenssitzung (Runde 3) wurden die wichtigsten Faktoren verfeinert und priorisiert. Es konnten 12 gelenkspezifische Risikofaktoren identifiziert und nach Relevanz eingeordnet werden: septische Voroperationen, große Knochendefekte, einliegendes Fremdmaterial, Valgusfehlstellung > 10°, Varusfehlstellung > 15°, Streckdefizit > 10°, Flexion < 70°, Kellgren-Lawrence-Score < 3°, Patella baja, knöcherne Voroperation, Genu recurvatum > 10° sowie vorausgegangene Bandrekonstruktionen. Im Rahmen eines strukturierten Delphi-Konsensusverfahrens konnten erstmals 12 gelenkspezifische Risikofaktoren durch Experten im deutschsprachigen Raum definiert werden. Diese Risikofaktoren können bestehende Risikoadjustierungsmodelle ergänzen. Zukünftige Studien sollten ihre prognostische Validität prüfen und die Integration in Routinedatenregister (z. B. EPRD) sowie Qualitätssicherungsinstrumente evaluieren.

BACKGROUND AND PURPOSE:Total hip arthroplasty (THA) in young patients is rare but increasingly performed. We aimed to analyze implant survivorship and risk factors for revision in patients aged 30 years or less after THA based on the German Arthroplasty Registry (EPRD). METHODS:Kaplan-Meier survival analysis and Cox proportional hazard models were used to analyze the EPRD dataset from 2013 to 2023 for factors associated with increased risk of revision. The primary outcome was first revision operation. RESULTS:1,622 primary THAs in 1,452 patients were analyzed. The mean age was 26 years (range 11-30), 908 (56%) of whom were male. The most frequent diagnosis was secondary osteoarthritis (1,146, 72%), followed by osteonecrosis (357, 22%), and hip dysplasia (53, 3.2%). Of all THAs, 1,601 (99%) were uncemented, and 1,574 (97%) received ceramic heads. The average follow-up period was 3.7 years (range 0-10.6). 47 hips were revised with a cumulative revision rate (CRR) at 8 years of 4.6% (95% confidence interval [CI] 2.8-7.3). The most frequent revision cause was infection in 11 cases (0.7%). Increased revision risk was associated with pediatric hip disease for those with prior surgery for Perthes, HR 4.3 (CI 1.9-9.6), pelvic osteotomy HR 2.8 (CI 1.1-7.5), and a primary diagnosis of hip dysplasia, HR 3.4 (CI 1.3-8.5). CONCLUSION:Uncemented THA in young patients demonstrated a revision rate of 4.6% (CI 2.8-7.3), which we believe is a satisfactory mid-term survival. Patients with pediatric hip disease present the highest risk of revision.

BACKGROUND:Total knee arthroplasty (TKA) performed for post-traumatic osteoarthritis (PTOA) is associated with higher complication and revision rates than TKA for primary osteoarthritis (OA). This study aimed to compare implant survival and identify risk factors for revision in TKA performed for PTOA versus OA using registry data. METHODS:The TKA procedures from 2012 to 2022 in the German Arthroplasty Register (EPRD) were analyzed (n = 289,382). The incidence of PTOA was 2.4% (n = 6,982). Implants were categorized as unconstrained or constrained (varus-valgus stabilized or hinge). Kaplan-Meier survival analysis and multivariable Cox proportional hazards models were used to assess implant survival, adjusted revision risk, and independent risk factors for revision. RESULTS:A total of 10,341 complications were recorded, with PTOA showing a higher complication rate than OA (5.7 versus 3.5%; P < 0.001). Aseptic revision rates were higher for unconstrained TKA in PTOA (P < 0.001), but not for constrained TKA (P = 0.1), whereas septic revision rates were higher for PTOA with both implant designs (both P < 0.001). The most common reasons for revision were infection (19%) and instability (8%). After adjustment for age, sex, body mass index, weighted Elixhauser score, fixation method, patellar resurfacing, and hospital case volume, a 45% higher risk of revision was observed after TKA for PTOA compared with OA. Independent risk factors for revision in unconstrained TKA for PTOA included hospital volumes ≤ 200 annual cases and TKA without patellar resurfacing. CONCLUSIONS:An increased adjusted risk of revision was observed after TKA for PTOA compared with OA. While aseptic revision rates varied by implant constraint, septic revision rates were higher in PTOA independent of constraint. Lower hospital volume and the absence of patellar resurfacing in unconstrained implants further increased revision risk, whereas higher implant constraint was protective regarding the risk of aseptic revision.

BACKGROUND:Valid risk adjustment is a prerequisite in knee arthroplasty to enable fair comparisons of treatment quality across hospitals and surgeons. Existing models mainly consider patient-related factors such as age or comorbidities. Consensus on joint-specific risk factors for postoperative complications is currently lacking. OBJECTIVES:The aim of this study was to establish expert consensus on clinically relevant joint-specific risk factors in total knee arthroplasty (TKA). METHODS:A three-stage modified Delphi process was conducted with 14 German experts in the field of TKA. Based on a systematic literature search, 120 potential risk factors were identified. In the first round, all factors were rated; in the second round, the focus was narrowed to 70 joint-specific factors. In a final virtual consensus meeting (third round), the most relevant factors were refined and prioritized. RESULTS:Twelve joint-specific risk factors were identified and ranked: prior septic surgery, large bone defects, implanted foreign material, valgus malalignment > 10°, varus malalignment > 15°, extension deficit > 10°, flexion < 70°, Kellgren-Lawrence score < 3°, patella baja, prior bone surgery, genu recurvatum > 10°, and prior ligament reconstruction. CONCLUSIONS:Through a structured Delphi consensus process, 12 joint-specific risk factors were defined by a panel of German arthroplasty experts. These factors may meaningfully complement existing risk adjustment models. Future research should evaluate their predictive validity and integration into routine registries (e.g., EPRD) as well as quality assurance instruments.

The effect of femoral head length on implant survival in total hip arthroplasty (THA) has been little studied so far. Longer heads may increase taper corrosion and reflect intraoperative complexity. This study evaluated factors associated with the use of extra-long heads (≥ XL) and their impact on implant survival. We analyzed 562,001 primary THA from the German Arthroplasty Registry. Subgroup analyses were performed by hospital annual primary THA volume (≤ 250, 251–500, ≥ 501), surgical indication (primary osteoarthritis [OA] vs. femoral neck fracture [FNF]), and fixation method (cemented vs. cementless). Logistic regression identified factors associated with ≥ XL head use, and implant survival was compared between head lengths using Kaplan–Meier analysis in both subgroups and the overall cohort. The use of ≥ XL femoral heads decreased with increasing hospital volume (5.4

Abstract Purpose The benefit of patella resurfacing (PR) in primary total knee arthroplasty (TKA) remains debated. While outcomes appear similar, unsurfaced patellae show higher revision rates. Existing studies are limited by heterogeneous cohorts. This study assessed the risk of secondary PR in relation to the level of constraint and primary procedure complexity (idiopathic vs. posttraumatic osteoarthritis). Methods Using registry data, 258,669 primary TKAs without primary PR were analysed. Demographics, implant constraint and subsequent revisions were recorded. The primary endpoint was secondary PR (without additional femoral or tibial implant removal) over a follow‐up period of up to 8 years. Results Cruciate‐retaining (CR) designs showed the lowest revision risk (ca. 1%), whereas posterior‐stabilised (PS) designs showed the highest (ca. 2.0–2.5%, hazard ratio = 1.8 [95% confidence interval = 1.66–1.99], p < 0.001). The majority of secondary PR occurred within 4 years. No differences were found between idiopathic and posttraumatic groups. Conclusions Registry data indicate higher revision risk with PS versus CR designs, regardless of index surgery complexity. Level of Evidence Level III.

Background Obesity has been associated with increased revision rates in total hip arthroplasty (THA). There is ongoing discussion as to whether this justifies postponing or denying THA to these patients. This study was initiated to determine the influence of obesity on revision rates and mortality after primary elective THA in Germany. Methods The German Arthroplasty Registry (EPRD) provided data of 403,073 elective THAs with a valid body mass index (BMI) for analysis. Cumulative revision rates up to 7 years and 1-year mortality were calculated for BMI groups (nonobese, obesity grade 1, 2, and 3). Results Increased revision rates with rising BMI were found. The main differences in revision rates appeared within the first postoperative months. This was most distinctive for periprosthetic joint infections during the first year after surgery (0.7% in nonobese, 1.3% in grade 1, 2.1% in grade 2, and 4.2% grade 3 obesity). Similar effects were observed in cementless and cemented stems. Revision rates in morbidly obese patients were not influenced by hospital caseload. Age- and sex-standardized mortality was lower than expected in most groups, but also increasing with rising BMI. Conclusions Obesity increased the risk of revision following primary elective THA, particularly for periprosthetic joint infection in morbidly obese patients. However, the absolute risks of this potentially life-improving surgery may be acceptable for the patients affected. The potential risks and benefits should be weighed up individually for each patient, taking into account their BMI and any other risk factors they have. Level of Evidence Level III, Therapeutic Study.

Mit dem Ziel, die klinischen Ergebnisse der primären Kniegelenkendoprothetik weiter zu verbessern, werden wieder vermehrt die biomechanischen Aspekte des Kniegelenkes in den wissenschaftlichen Fokus gerückt. Neben der Implantatauswahl und der Alignmentphilosophie sind die individuellen anatomischen Voraussetzungen entscheidend für die Wiederherstellung einer natürlichen Gelenkkinematik, das Funktionsausmaß und die Stabilität von Knieendoprothesen. Biomechanische Messungen anhand instrumentierter Knieendoprothesen haben die Bedeutung der Achsausrichtung, sowie der mediolateralen Lastverteilung hervorgehoben. Auch der Stellenwert des patellofemoralen Alignments hat in den letzten Jahren nochmals zugenommen. Statische radiologische Beurteilungen können durch instrumentierte Ganganalysen ergänzt werden, um eine patientenspezifische Beurteilung der dynamischen Beinachse und die Einwirkung das Knieadduktionsmomentes zu detektieren. Des Weiteren liefern computergestützte Simulationen präzisere Informationen zur funktionellen, designspezifischen Belastung von Knieprothesen und deren spezifischen Kinematik. Kombinationen mit experimentellen Methoden, wie Kniekinematoren, können so komplexe Bewegungs- und Belastungsabläufe detaillierter untersuchen und letztlich individualisierte Therapie- und Rehabilitationskonzepte entwickeln. Zusätzlich können den Patienten spezifische kinematischen Phänotypen zugeordnet werden, um zukünftig die Behandlungsergebnisse und Patientenzufriedenheit nach erfolgter Knieendoprothetik zu verbessern. Außerdem können anatomische Voraussetzungen mithilfe von spezifischen muskuloskelettalen Modellen und Finite-Elemente-Analysen (FEA) simuliert werden, um so die Implantationsparameter zu optimieren und biomechanische Belastungen zu minimieren. Zukünftig kann durch die Integration von künstlicher Intelligenz und Machine Learning eine Verbesserung der patientenspezifischen Behandlungsstrategien im Rahmen der präoperativen Planung erfolgen. All diese Methoden erlauben detaillierte Analysen der biomechanischen Belastungen und ermöglichen eine präzisere Anpassung der Implantatpositionierung an individuelle anatomische Gegebenheiten. Langfristig müssen die vielversprechenden biomechanischen Forschungsergebnisse in größeren Studienpopulationen klinisch angewandt und analysiert werden.

BACKGROUND:This study aimed to evaluate the safety of primary total knee arthroplasty (TKA) in patients aged ≥ 90 years by assessing complication and mortality rates. Additionally, we compared these outcomes with those of younger patient groups and identified comorbidities associated with increased morbidity and mortality. METHODS:Data were obtained from a national arthroplasty registry. The study included 392,929 patients aged ≥ 60 years who underwent primary TKA for osteoarthritis. Of these, 1,284 patients were aged ≥ 90 years. Patients were divided into four age groups: (1) 60 to 69 years, (2) 70 to 79 years, (3) 80 to 89 years, and (4) ≥ 90 years. Minor and major complications and mortality during follow-up were recorded and compared across age groups and comorbidities; mortality was also compared with the general population using Federal Statistical Office data. RESULTS:Minor complications occurred in 58% (745 of 1,284) of cases in group 4, compared to 21% (29,867 of 144,978) in group 1 (P < 0.001), with postoperative anemia being the most common (38%). Major complications were significantly more frequent in nonagenarians (18%, 233 of 1,284) than in sexagenarians (5.2%, 7,524 of 144,978; P < 0.001). Overall mortality increased with age, occurring in 4.0, 9.6, 17, and 36% of patients in Groups 1 to 4, respectively. Kaplan-Meier estimates showed significantly higher mortality for patients who have minor and major complications. At 90 years, 1-year mortality was 9.1, 9.7, and 9.5% in men and 2.2, 7.2, and 15.4% in women for no, minor, and major complications, respectively, compared with 18.5 and 14.7% in the general population. CONCLUSIONS:Older age and comorbidities were associated with higher complication and mortality rates after TKA. Moreover, implant-related complications remain low, and with careful selection, nonagenarians can safely undergo TKA, given their lower 1-year mortality than the general population.

BACKGROUND:Since its foundation in 2010 by the German Society for Orthopaedics and Orthopaedic Surgery (DGOOC) and its establishment together with industry representatives (Bundesverband Medizintechnologie e. V.-BVMed) and the health insurance companies (AOK-Bundesverband eGbR, Verband der Ersatzkassen e. V. (vdek)), the German Arthroplasty Registry (EPRD) has developed rapidly in terms of size and quality of results. With over 3 million data records of hip and knee prostheses, it is now the world's third largest registry for arthroplasty. The product database of the EPRD and National Joint Registry (NJR) is becoming the global standard. 2023 was a record year in terms of recorded operations and scientific publications. The results of the EPRD are increasingly analysing and influencing everyday clinical practice in hip and knee arthroplasty in Germany. PROSPECTS:From 2025, all EPRD clinics will be able to use the Oxford Hip and Oxford Knee Score free of charge for their patients as Patient Reported Outcome Measures (PROMs). In 2025, the recording parameters will be expanded to include surgical approaches to the hip, navigation and robotics on the knee joint, as well as an optional infection module. In 2026, voluntary registration of the surgeon with surgeon level reporting will be possible. The EPRD and the Implantateregister Deutschland (IRD) are expected to exist in parallel from 2025, and cooperation is still being sought. Data collection should be as streamlined as possible without duplicate data entries. However, the EPRD will continue to work independently of the IRD with its more than 12 years of experience and over 3 million data sets and will continue to provide clinics and specialists with its analyses and publications in the future.

Das Endoprothesenregister Deutschland (EPRD) hat sich nach seiner Gründung 2010 durch die Deutsche Gesellschaft für Orthopädie und Orthopädische Chirurgie (DGOOC) und dem Aufbau gemeinsam mit der Vertretung der Industrie (Bundesverband Medizintechnologie e. V. [BVMed]) und der Krankenkassen (AOK-Bundesverband eGbR, Verband der Ersatzkassen e. V. [vdek]) rasant bezüglich Größe und Qualität der Ergebnisse weiterentwickelt. Inzwischen ist es mit über 3 Mio. erfassten Datensätzen von Hüft- und Knieprothesen das weltweit drittgrößte Register für Endoprothetik. Die Produktdatenbank des EPRD und National Joint Registry (NJR) wird zum weltweiten Standard. 2023 war ein Rekordjahr bezüglich erfasster Operationen und wissenschaftlicher Publikationen. Die Ergebnisse des EPRD analysieren und beeinflussen zunehmend den klinischen Alltag in der Hüft- und Knieendoprothetik in Deutschland. Ab 2025 können alle EPRD-Kliniken den Oxford Hip und Oxford Knee Score kostenfrei für ihre Patienten als „patient reported outcome measures“ (PROM) nutzen. 2025 werden die Erfassungsparameter um die operativen Zugänge an der Hüfte, die Navigation und Robotik am Kniegelenk sowie ein optionales Infektionsmodul erweitert. 2026 wird die freiwillige Erfassung des Operateurs möglich sein. Das EPRD und das Implantateregister Deutschland (IRD) werden ab 2025 voraussichtlich parallel bestehen, eine Kooperation wird unverändert angestrebt. Die Datenerfassung soll möglichst schlank ohne doppelte Dateneingabe ermöglicht werden. Das EPRD wird jedoch unabhängig vom IRD mit seiner über 12-jährigen Erfahrung und über 3 Mio. Datensätzen weiterarbeiten und die Kliniken und Fachkreise auch zukünftig mit seinen Analysen und Publikationen versorgen.

OBJECTIVES:To determine the influence of obesity on revision rates and mortality after primary elective hip and knee arthroplasty in Germany. MATERIALS AND METHODS:In the German Arthroplasty Registry (EPRD) there were 403,073 elective total hip arthroplasties (THA), 320,913 bicondylar total knee arthroplasties (TKA) and 48,480 unicondylar knee arthroplasties (UKA) with valid BMI available for analysis. Cumulative revision rates and 1‑year mortality was calculated for BMI groups. RESULTS:There were increased revision rates with increasing BMI, most distinctive for septic revisions in THA during the first year after surgery (non-obese 0.7%, obesity grade 1 1.3%, grade 2 2.1%, grade 3 4.2%). In TKA and UKA this increase was generally less pronounced. Age- and gender-standardized mortality was lower than expected in most groups, but also increasing with increasing BMI. CONCLUSION:The risk for revisions in obese patients is more distinctive in hip arthroplasty than in knee arthroplasty and is especially high in morbidly obese patients (BMI ≥ 40 kg/m2). Nonetheless, this risk may be acceptable for affected patients. Therefore, the possible benefits and risks of an arthroplasty should be weighed against each other and individually discussed with the patient.

Background:The use of antibiotic-loaded bone cement (ALBC) in primary total knee arthroplasty (TKA) is debated. Some argue that ALBC might only be justified in high-risk patients. This study assessed the effectiveness of ALBC vs. plain bone cement (PBC) in reducing risk of revision for periprosthetic joint infection (PJI) in TKA patients considered to have a high risk of infection. Methods:Cohort study of primary TKAs in 11 national or regional arthroplasty registries from 2010 to 2020. The 1-year risk of revision for PJI in TKAs with ALBC vs. PBC among patients with high American Society of Anesthesiologists (ASA) classification, body mass index (BMI), and/or diabetes was compared. Cumulative percent revision (1 minus Kaplan-Meier) based on 685,818 TKAs and Cox regression analyses (adjusted Hazard Rate Ratios [aHRRs]) were performed for TKAs with ALBC (reference) vs. PBC restricted to the following high-risk subgroups of patients: (1) ASA ≥3 (n = 335,612 vs. 35,997), (2) BMI ≥35 (n = 278,927 vs. 24,737), (3) ASA ≥3 and BMI ≥35 (n = 99,407 vs. 11,407), (4) diabetes (n = 38,341 vs. 21,838), and (5) ASA ≥3, BMI ≥35, and diabetes (n = 3,347 vs. 4,261). Advanced distributed meta-analyses were performed to combine all aggregate data and assess 1-year risk of revision for PJI. Results:Each registry reported a 1-year cumulative percent revision of ≤1.6% for PJI following TKAs both for ALBC and PBC in all high-risk subgroups. Similar 1-year risks of revision for PJI were found in TKAs with ALBC (reference) and PBC among patients with ASA ≥3 (aHRR: 1.09; 95% CI, 0.90-1.31); BMI ≥35 (1.06; 0.54-2.12); ASA ≥3 and BMI ≥35 (1.12; 0.83-1.50); diabetes (0.95; 0.74-1.20); and ASA ≥3, BMI ≥35, and diabetes (1.40; 0.86-2.29). Conclusions and Relevance:Similar 1-year revision risk of PJI was found for TKAs with ALBC vs. PBC in high-risk patients. Confirmation of the efficacy of ALBC in high-risk TKA patients needs to be evaluated in clinical trials. Level of Evidence:Level III. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:In order to optimise clinical outcomes after primary total knee arthroplasty (TKA), research has refocused on the knee joint's biomechanical characteristics. Beyond implant design and alignment philosophy, the restoration of natural joint kinematics, functional range of motion, and stability critically depends on patient-specific anatomical conditions. BIOMECHANICS:Instrumented TKA systems have demonstrated the significance of coronal alignment and mediolateral load distribution. Furthermore, patellofemoral joint alignment has gained attention as a determinant of postoperative success. While static radiographic assessments remain the gold standard, they can be meaningfully complemented by instrumented gait analysis to capture dynamic leg alignment and quantify the influence of the external knee adduction moment. Furthermore, computational simulations facilitate a more precise analysis of implant-specific loading conditions and kinematic behaviour. NEW METHODS:In combination with experimental approaches, such as in vitro kinematic testing, these tools facilitate a detailed evaluation of complex movement and load scenarios, thereby supporting the development of personalised therapeutic and rehabilitative strategies. Furthermore, the development of novel classifications of kinematic phenotypes holds great potential for the systematic categorisation of patients and the personalisation of interventions, with the aim of enhancing functional outcomes and satisfaction. The use of subject-specific musculoskeletal models and finite element analysis (FEA) permits the simulation of joint mechanics under individual anatomical constraints, thus contributing to the optimisation of implant positioning and the reduction of biomechanical load. In the future, the integration of artificial intelligence and machine learning into preoperative planning is expected to refine patient-specific treatment algorithms. PROSPECT:The clinical translation of these biomechanical insights will ultimately require validation in larger patient cohorts in order to substantiate their efficacy and long-term benefit.

BACKGROUND:The burden of osteoarthritis (OA) in multiple joints is high. For patients with bilateral knee OA there is no clear recommendation when to time the second surgery. The purpose of this study was therefore to compare revision and mortality rate in bilateral unicondylar and bicondylar knee arthroplasties after different strategies of surgical timing in bilateral knee OA from the German Arthroplasty Registry (EPRD). METHODS:Data from the German Arthroplasty Registry (EPRD) was used. Since 2012 a total of 15,154 patients had bilateral knee arthroplasty within one year. Patellofemoral arthroplasties and constraint total knee arthroplasties (TKA) were excluded. 1,144 TKA and 682 unicondylar arthroplasties (UKA) were simultaneously performed, 772 TKA and 292 UKA between 1 and 90 days (short interval) and 24,496 TKA and 2,922 UKA between 91 and 365 days (intermediate interval). Revision and mortality rates were analyzed up to 7 years after surgery. Cox regression was performed to evaluate the influence of different patient characteristics on these outcomes. RESULTS:The highest cumulative revision rate for any of the bilateral TKA was found for simultaneous surgery with 3.4% (95% CI 2.1-5.5). Lower risk for revision was seen in two-staged surgery in short interval (HR 0.42; 95% CI 0.20-0.90) and intermediate interval (HR 0.58; 95% CI 0.39-0.85). The cumulative one year mortality rate for TKA was comparable in all three groups with 0.8% for simultaneous TKA, 1.3% for short interval two-staged and 0.7% for intermediate interval. In UKA there were no differences between the groups regarding cumulative revision rate and mortality rate. CONCLUSION:TKA should be performed simultaneously in selected patients only, the two-staged procedure demonstrated lower revision risks. For UKA we found no differences in timing, simultaneous surgery seems to be a safe option. TRIAL REGISTRATION:Clinical trial number not applicable. LEVEL OF EVIDENCE:III.

Background: The use of antibiotic-loaded bone cement (ALBC) in primary total knee arthroplasty (TKA) is debated. Some argue that ALBC might only be justified in high-risk patients. This study assessed the effectiveness of ALBC vs. plain bone cement (PBC) in reducing risk of revision for periprosthetic joint infection (PJI) in TKA patients considered to have a high risk of infection. Methods: Cohort study of primary TKAs in 11 national or regional arthroplasty registries from 2010 to 2020. The 1-year risk of revision for PJI in TKAs with ALBC vs. PBC among patients with high American Society of Anesthesiologists (ASA) classification, body mass index (BMI), and/or diabetes was compared. Cumulative percent revision (1 minus Kaplan-Meier) based on 685,818 TKAs and Cox regression analyses (adjusted Hazard Rate Ratios [aHRRs]) were performed for TKAs with ALBC (reference) vs. PBC restricted to the following high-risk subgroups of patients: (1) ASA ≥3 (n = 335,612 vs. 35,997), (2) BMI ≥35 (n = 278,927 vs. 24,737), (3) ASA ≥3 and BMI ≥35 (n = 99,407 vs. 11,407), (4) diabetes (n = 38,341 vs. 21,838), and (5) ASA ≥3, BMI ≥35, and diabetes (n = 3,347 vs. 4,261). Advanced distributed meta-analyses were performed to combine all aggregate data and assess 1-year risk of revision for PJI. Results: Each registry reported a 1-year cumulative percent revision of ≤1.6% for PJI following TKAs both for ALBC and PBC in all high-risk subgroups. Similar 1-year risks of revision for PJI were found in TKAs with ALBC (reference) and PBC among patients with ASA ≥3 (aHRR: 1.09; 95% CI, 0.90-1.31); BMI ≥35 (1.06; 0.54-2.12); ASA ≥3 and BMI ≥35 (1.12; 0.83-1.50); diabetes (0.95; 0.74-1.20); and ASA ≥3, BMI ≥35, and diabetes (1.40; 0.86-2.29). Conclusions and Relevance: Similar 1-year revision risk of PJI was found for TKAs with ALBC vs. PBC in high-risk patients. Confirmation of the efficacy of ALBC in high-risk TKA patients needs to be evaluated in clinical trials. Level of Evidence: Level III . See Instructions for Authors for a complete description of levels of evidence.

Welchen Einfluss hat die Adipositas und deren Ausprägung auf Revisionsraten und Mortalität in der primären Hüft- und Knieendoprothetik in Deutschland? Im Endoprothesenregister Deutschland (EPRD) waren 403.073 elektive Hüft-TEP, 320.913 Standard-Knie-TEP und 48.480 unikondyläre Knieendoprothesen mit BMI verfügbar. Es erfolgte der Vergleich von Revisionen und 1‑Jahres-Mortalität über BMI-Gruppen. Mit steigendem BMI zeigten sich zunehmende Revisionsraten, in der Hüftendoprothetik insbesondere septische Revisionen innerhalb des 1. Jahres (nichtadipös 0,7

INTRODUCTION:Aseptic loosening and periprosthetic fractures are main reasons for revision after THA. Quite different from most other stem systems, Corail cementless hip stems show better survival rates than their cemented counterpart, which can possibly be explained by the use of a collar. The study aimed to investigate primary stability with standard and undersized hip stems both collared and collarless. MATERIALS AND METHODS:Primary stability of cementless, collared and collarless, femoral stems was measured in artificial bones using both undersized and standard size. After preconditioning, 3D micromotion was measured under cyclic loading at the bone-implant interface. RESULTS:The use of a collar resulted in higher micromotion within the same stem size but showed no statistically significant difference for both standard and undersized hip stems. The collared and collarless undersized stems showed no significant differences in 3D micromotion at the upper measuring positions compared to the standard stem size. Micromotion was significantly higher in the distal measuring positions, with and without collar, for the undersized stems (vs. standard collarless stem size). CONCLUSION:The key finding is that the collarless and collared Corail hip stems, within one stem size, showed no significant differences in primary stability. Undersized stems showed significantly higher micromotion in the distal area both with and without collar.

Die periprothetische Gelenkinfektion (PJI) ist eine Hauptursache für Revisionsoperationen nach totaler Knieendoprothese (TKA) und unikondylärem Kniegelenksersatz (UKA). Patienten- und krankenhausbezogene Risikofaktoren müssen bewertet werden, um PJI zu verhindern. Diese Studie identifiziert Einflussfaktoren und Unterschiede in den Infektionsraten zwischen den unterschiedlichen Implantattypen. Die Datengrundlage bildet das Deutsche Endoprothesenregister (EPRD). Septische Revisionen wurden mithilfe der Kaplan-Meier-Schätzungen berechnet, wobei septische Revisionsoperationen als primärer Endpunkt definiert wurden. Patienten mit gekoppelter und ungekoppelter TKA oder UKA wurden unter Verwendung des Holm-Mehrfach-Log-Rank-Tests und des Cox-proportionalen Hazard-Modells analysiert. Die 300.998 analysierten Fälle von Knieendoprothesen umfassten 254.144 (84,4

Purpose: Periprosthetic joint infection (PJI) is a major cause of revision surgery after total knee arthroplasty (TKA) and unicondylar knee arthroplasty (UKA). Patient- and hospital-related risk factors need to be assessed to prevent PJI. This study identifies influential factors and differences in infection rates between different implant types. Methods: Data were obtained from the German Arthroplasty Registry. Septic revisions were calculated using Kaplan-Meier estimates with septic revision surgery as the primary endpoint. Patients with constrained and unconstrained TKA or UKA were analysed using Holm's multiple log-rank test and Cox's proportional hazards ratio. The 300,998 cases of knee arthroplasty analysed included 254,144 (84.4%) unconstrained TKA, 9993 (3.3%) constrained TKA and 36,861 (12.3%) UKA with a maximum follow-up of 7 years. Results: At 1 year, the PJI rate was 0.5% for UKA and 2.8% for TKA, whereas at 7 years, the PJI rate was 4.5% for UKA and 0.9% for TKA (p < 0.0001). The PJI rate significantly increased for constrained TKA compared to unconstrained TKA (p < 0.0001). The PJI rate was 2.0% for constrained TKA and 0.8% for unconstrained TKA at 1 year and 3.1% and 1.4% at 7 years. Implantation of a constrained TKA (hazard ratio [HR] = 2.55), male sex (HR = 1.84), increased Elixhauser score (HR = 1.18-1.56) and implant volume of less than 25 UKA per year (HR = 2.15) were identified as risk factors for revision surgery; an Elixhauser score of 0 (HR = 0.80) was found to be a preventive factor. Conclusions: Reduced implant volume and constrained knee arthroplasty are associated with a higher risk of PJI. Comorbidities (elevated Elixhauser score), male sex and low UKA implant volume have been identified as risk factors for PJI. Patients who meet these criteria require specific measures to prevent infection. Further research is required on the potential impact of prevention and risk factor modification. Level of Evidence: Level III.