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Purpose Total knee arthroplasty (TKA) rates have increased substantially in the recent decades worldwide, with Germany being one of the leading countries in the prevalence of TKA. The aim of this study was to provide an overview of treatment changes during the last decade and to project the expected burden of primary and revision TKA (rTKA) for the next 30 years. Methods Comprehensive nationwide data from Germany was used to quantify primary and revision TKA rates as a function of age and gender. Projections were performed with use of a Poisson regression models and a combination of exponential smoothing and autoregressive integrated moving average models on historical procedure rates in relation to official population projections from 2020 to 2050. Results The incidence rate of primary TKAs is projected to increase by around 43% to 299 per 100,000 inhabitants [95% CI 231–368], leading to a projected total number of 225,957 primary TKAs in 2050 (95% CI 178,804–276,442). This increase has been related to a growing number of TKA performed in male patients, with the highest increase modelled in patients between 50 and 65 years of age. At the same time, the annual total number of revision procedures is forecast to increase even more rapidly by almost 90%, accounting for 47,313 (95% CI 15,741–78,885; IR = 62.7 per 100,000, 95% CI 20.8–104.5) procedures by 2050. Those numbers are primarily associated with a rising number of rTKAs secondary to periprosthetic joint infection (PJI). Conclusions Using this country- specific forecast approach, a rising number of primary TKA and an even more rapidly growing number of rTKA, especially for PJI, has been projected until 2050, which will inevitably provide a huge challenge for the future health care system. As many other industrialized nations will face similar demographic and procedure-specific developments, these forecasts should be alarming for many health care systems worldwide and emphasize the tremendous need for an appropriate financial and human resource management in the future. Level of evidence Level III, prognostic study, economic and decision analysis.

Muscle and bone interact via physical forces and secreted osteokines and myokines. Physical forces are generated through gravity, locomotion, exercise, and external devices. Cells sense mechanical strain via adhesion molecules and translate it into biochemical responses, modulating the basic mechanisms of cellular biology such as lineage commitment, tissue formation, and maturation. This may result in the initiation of bone formation, muscle hypertrophy, and the enhanced production of extracellular matrix constituents, adhesion molecules, and cytoskeletal elements. Bone and muscle mass, resistance to strain, and the stiffness of matrix, cells, and tissues are enhanced, influencing fracture resistance and muscle power. This propagates a dynamic and continuous reciprocity of physicochemical interaction. Secreted growth and differentiation factors are important effectors of mutual interaction. The acute effects of exercise induce the secretion of exosomes with cargo molecules that are capable of mediating the endocrine effects between muscle, bone, and the organism. Long-term changes induce adaptations of the respective tissue secretome that maintain adequate homeostatic conditions. Lessons from unloading, microgravity, and disuse teach us that gratuitous tissue is removed or reorganized while immobility and inflammation trigger muscle and bone marrow fatty infiltration and propagate degenerative diseases such as sarcopenia and osteoporosis. Ongoing research will certainly find new therapeutic targets for prevention and treatment.

Purpose This study aimed to identify radiographic and demographic predictors influencing the intraoperative decision for cemented versus cementless humeral fixation in patients ≤ 80 years undergoing short-stem reverse shoulder arthroplasty (RSA). Methods A retrospective analysis was conducted on RSA cases between 02/2019 and 10/2024. Patients ≤ 80 years were stratified into Group A (cementless fixation; n  = 209) or Group B (cemented fixation; n  = 58) based on intraoperative assessment of trial stem stability and bone quality. Preoperative variables included age, sex, body mass index (BMI), American Society of Anesthesiologists score (ASA), diagnosis, and radiographic parameters such as cortical bone thickness gauge (CBTg), average cortical thickness (CBTavg), acromiohumeral distance (AHD), and Hamada and Walch classifications. Multivariate logistic regression including age, sex, CBTavg, CBTg, and diagnosis was performed to identify independent predictors of cemented fixation. Results Patients in the cemented group were significantly older (74.0 ± 4.2 vs. 70.0 ± 6.1 years; p  < 0.05) and more often female (81% vs. 61%; p  < 0.05). Cortical bone measurements were significantly lower in the cemented group (CBTg: 0.25 ± 0.06 vs. 0.27 ± 0.06; CBTavg: 5.15 mm ± 1.23 mm vs. 6.42 mm ± 1.43 mm; both p  < 0.05). Multivariate analysis identified increasing age (OR: 1.1; p  < 0.05), female sex (OR: 2.8; p  < 0.05), and reduced CBTavg (OR: 0.6; p  < 0.05) as independent predictors of cemented fixation. Other variables such as BMI, ASA score, AHD, and CBTg did not show significant associations with fixation type. Conclusion Among all evaluated factors, lower CBTavg was the strongest independent predictor for the use of cemented humeral fixation in short-stem RSA. Its integration into preoperative planning may assist surgical decision-making and improve consistency in fixation strategy. Study design Level IV; retrospective case series.

This literature review discusses the use of antibiotic loaded polymethylmethacrylate bone cements in arthroplasty. The clinically relevant differences that have to be considered when antibiotic loaded bone cements (ALBC) are used either for long-term implant fixation or as spacers for the treatment of periprosthetic joint infections are outlined. In this context, in vitro findings for antibiotic elution and material properties are summarized and transferred to clinical use.

In vitro co-cultures of different primary human cell types are pivotal for the testing and evaluation of biomaterials under conditions that are closer to the human in vivo situation. Especially co-cultures of macrophages and mesenchymal stem cells (MSCs) are of interest, as they are both present and involved in tissue regeneration and inflammatory reactions and play crucial roles in the immediate inflammatory reactions and the onset of regenerative processes, thus reflecting the decisive early phase of biomaterial contact with the host. A co-culture system of these cell types might thus allow for the assessment of the biocompatibility of biomaterials. The establishment of such a co-culture is challenging due to the different in vitro cell culture conditions. For human macrophages, medium is usually supplemented with human serum (hS), whereas hMSC culture is mostly performed using fetal calf serum (FCS), and these conditions are disadvantageous for the respective other cell type. We demonstrate that human platelet lysate (hPL) can replace hS in macrophage cultivation and appears to be the best option for co-cultivation of human macrophages with hMSCs. In contrast to FCS and hS, hPL maintained the phenotype of both cell types, comparable to that of their respective standard culture serum, as well as the percentage of each cell population. Moreover, the expression profile and phagocytosis activity of macrophages was similar to hS.

Background Non-unions are a common complication following fractures. Although fractures of the foot and ankle are frequent, reliable data on the incidence and epidemiology of non-unions in these regions are lacking. Methods A nationwide retrospective analysis was conducted using inpatient data from the German Federal Statistical Office between 2014 and 2023. Fractures and non-unions of the foot and ankle were identified via ICD-10 coding, with two cohorts defined: fracture cases and non-union cases. Data were stratified by age and sex, and all co-coded secondary diagnoses were extracted and aggregated to identify the most frequent comorbidities. Temporal trends were assessed using linear regression, while age distributions were modelled with two-component Gaussian mixture models to capture distinct etiological subpopulations. Data processing, statistical analyses, and visualization were performed in R (Version 4.3) using Tidyverse packages. Results Between 2014 and 2023, 992,360 foot and ankle fractures and 20,268 non-unions of the foot and ankle were treated in hospitalized patients in German hospitals. Women were more frequently affected by both fractures and non-unions than men. The age distribution was bimodal, with peaks at 18–29 and 50–59 years in men, and at 50–79 years in women. The overall non-union rate was 2.0% and showed a declining trend over time. Age- and sex-specific differences were observed, with the highest non-union rate in women aged 40–49 years (3.2%). Comorbidities including obesity, allergies, depressive episodes, asthma, and sleep disorders were more prevalent in patients with non-unions compared to those with fractures. Conclusions Non-unions following fractures of the foot and ankle remain rare and have declined steadily over the past decade. Age- and sex-specific differences underscore the need for targeted prevention strategies.

The fate and behavior of bone marrow mesenchymal stem/stromal cells (BM-MSC) is bidirectionally influenced by their microenvironment, the stem cell niche, where a magnitude of biochemical and physical cues communicate in an extremely orchestrated way. It is known that simplified 2D in vitro systems for BM-MSC culture do not represent their naïve physiological environment. Here, we developed four different 2D cell-based decellularized matrices (dECM) and a 3D decellularized human trabecular-bone scaffold (dBone) to evaluate BM-MSC behavior. The obtained cell-derived matrices provided a reliable tool for cell shape-based analyses of typical features associated with osteogenic differentiation at high-throughput level. On the other hand, exploratory proteomics analysis identified native bone-specific proteins selectively expressed in dBone but not in dECM models. Together with its architectural complexity, the physico-chemical properties of dBone triggered the upregulation of stemness associated genes and niche-related protein expression, proving in vitro conservation of the naïve features of BM-MSC.

Articular cartilage is crucial for joint function but its avascularity limits intrinsic repair, leading to conditions like osteoarthritis (OA). Chondromodulin-I (Cnmd) has emerged as a key molecule in cartilage biology, with potential implications for OA therapy. Cnmd is primarily expressed in cartilage and plays an important role in chondrocyte proliferation, cartilage homeostasis, and the blocking of angiogenesis. In vivo and in vitro studies on Cnmd, also suggest an involvement in bone repair and in delaying OA progression. Its downregulation correlates with OA severity, indicating its potential as a therapeutic target. Further research is needed to fully understand the mode of action of Cnmd and its beneficial implications for managing OA. This comprehensive review aims to elucidate the molecular characteristics of Cnmd, from its expression pattern, role in cartilage maintenance, callus formation during bone repair and association with OA.

Background: Vitamin D deficiency represents a global health problem of enormous extent. It is estimated that around one billion people worldwide have inadequate vitamin D levels. This phenomenon is directly associated with negative impact on a variety of orthopaedic conditions. Further, there is now robust evidence that perioperative vitamin D levels in patients scheduled for total joint replacement (TJA) affect outcome and the healing process. To date, only few studies focus on vitamin D levels of patients scheduled for total arthroplasty of the upper extremity (shoulder and elbow). For this reason, the objective of this study is to determine the prevalence of vitamin D deficiency in this patient collective. Methods: In a monocentric cohort study, serum levels of 25-hydroxyvitamin D (25OHD) were measured preoperatively in all patients undergoing total shoulder or elbow arthroplasty. Demographic and perioperative data as well as comorbidities were recorded from medical records to assess for potential risk factors for hypovitaminosis D. Multivariate regression analyses were used to identify risk factors for vitamin D insufficiency and deficiency. Results: Collectively, 108 patients with total joint replacement of the upper extremity were included over a period of twelve months. Notably, 28.7% (31/108) of patients reported a regular intake of vitamin D supplements. 62.3% (19/31) of those had sufficient vitamin D levels, while 38.7% (12/31) had insufficient and further 6% (2/31) deficient vitamin D levels (<20 ng/mL). Remarkably, 87% of patients that did not report a regular vitamin D intake (n = 77) showed low serum vitamin D levels. In particular, 63.6% (49/77) were vitamin D deficient, 23.4% (18/77) vitamin D insufficient and only 13% of patients had vitamin D serum levels above or equal to 30 ng/mL that are considered sufficient (mean serum 25(OH)D = 36.4 ng/mL for vitamin D substitution vs. 18.4 ng/mL for no substitution; p < 0.0001). Moreover, vitamin D levels varied between seasons, with the lowest levels recorded in spring (OR = 4.32, p = 0.044) and the highest levels in summer (p = 0.005 vs. spring). Conclusion: Patients undergoing total shoulder or elbow arthroplasty have an increased risk profile for hypovitaminosis D (vitamin D supplementation had 94% lower odds of being deficient; OR = 0.06, p = 0.001). Seasonal circumstances at the point of arthroplasty seem to be a key risk factor for low vitamin D levels. For this reason, it would be advisable to consider preoperative serum vitamin D level measurement as an integral part of the regularly performed preoperative care.

BackgroundHip resurfacing (HR) is an alternative to conventional total hip arthroplasty (THA) for the treatment of osteoarthritis (OA) in very active, young male patients. However, there is no study in the literature that has proven its benefits for high-impact sport over standard primary THA. The aim of the current study was to investigate the return to sport and function level of male patients after THA vs. HR.Materials and methodsThis prospective study is based on a telephone questionnaire for general health and sports activities. 40 HRs were matched with 40 THAs based on preoperative University of California Arthroplasty Score (UCLA), BMI, age at time of surgery and age at follow-up. The mean follow-up period was 56 months (range 24–87 months).ResultsHR patients showed a significantly higher High-activity arthroplasty score (HAAS) (14.9 vs. 12.9, p < 0.001) and Lower extremity activity scale (LEAS) (15.9 vs. 14.1, p < 0.001) and reached significantly higher values in the Hip cycle score (HCS) (44.7 vs. 35.7 p = 0.037) and Impact score (IS) (40.9 vs. 29.6, p < 0.002) than THA patients. No significant differences were found in the HOOS function section (91.4 vs. 90.3, p = 0.803) and the Pain numeric rating scale (NRS)-11 (0.6 vs. 0.9 p = 0.169). Patients with HR had a slightly higher Harris hip score (HHS) (97.8 vs. 95.6, p = 0.015)ConclusionThe current study suggests that young male patients are able to engage in higher activity levels after HR compared to standard THA.