Enhancing Cranio-Maxillofacial Fracture Care in Low- and Middle-Income Countries: A Systematic Review.

Background: Cranio-maxillofacial (CMF) injuries represent a significant challenge in low- and middle-income countries (LMICs), exacerbated by inadequate infrastructure, resources, and training. This systematic review aims to evaluate the current strategies and solutions proposed in the literature to improve CMF fracture care in LMICs, focusing on education, patient transfer, and off-label solutions. Methods: A comprehensive literature search was conducted using PubMed/Medline from January 2000 to June 2023. Studies were selected based on the Preferred Reporting Items for Systematic Review and Meta-analysis Statement (PRISMA). Solutions were categorized into three main areas: education (digital and on-site teaching, fellowships abroad), patient transfer to specialized clinics, and off-label/non-operative solutions. Results: Twenty-three articles were included in the review, revealing a consensus on the necessity for enhanced education and training for local surgeons as the cornerstone for sustainable improvements in CMF care in LMICs. Digital platforms and on-site teaching were identified as key methods for delivering educational content. Furthermore, patient transfer to specialized national clinics and innovative off-label techniques were discussed as immediate solutions to provide quality care despite resource constraints. Conclusions: Effective CMF fracture care in LMICs requires a multifaceted approach, prioritizing the education and training of local healthcare professionals, facilitated patient transfer to specialized centers, and the adoption of off-label solutions to leverage available resources. Collaborative efforts between international organizations, local healthcare providers, and educational institutions are essential to implement these solutions effectively and improve patient outcomes in LMICs.

Three-Dimensional Osseointegration Patterns of Cementless Femoral Stems: An ex Vivo Study with High-Resolution Imaging and Histological Evaluation.

BACKGROUND: Osseointegration is essential for the long-term survival of cementless femoral stems and is dependent on periprosthetic bone quality and correct implantation technique. The aim of this study was to evaluate the 3-dimensional long-term fixation patterns of, and bone microarchitecture around, cementless hip stems. METHODS: Four specimens with varying degrees of bone quality and fixation characteristics from body donors who had received Alloclassic Zweymüller hip stems during their lifetime (mean time in situ at the time of death: 12.73 years) were evaluated with use of radiographs, high-resolution computed tomography (CT) scans, and hard-tissue histology. The CT voxel size was 85 µm, and the following parameters were calculated: total bone volume, total bone volume fraction, trabecular bone volume, trabecular bone volume fraction, cortical bone volume, cortical bone volume fraction, and cortical thickness. Bone-implant contact and canal fill index values for each Gruen zone of the specimens were calculated with use of histological samples. RESULTS: Femoral stems with apparently good cortical contact on clinical radiographs showed higher values for cortical bone volume, trabecular bone volume, and cortical thickness in the high-resolution CT analysis than femoral stems with apparently weak cortical contact on clinical radiographs. Based on the histological evaluation, the mean bone-implant contact ranged from 22.94% to 57.24% and the mean canal fill index ranged from 52.33% to 69.67% among the specimens. CONCLUSIONS: This study demonstrated different osseointegration patterns of cementless femoral stems on the basis of radiographs, high-resolution CT scans, and histological evaluation. Femora with high cortical bone volume and cortical thickness were associated with higher canal fill indices, whereas femora with low cortical bone volume and cortical thickness had lower canal fill indices and showed a characteristic corner-anchorage pattern. CLINICAL RELEVANCE: Osseointegration patterns and thus the long-term survival of cementless femoral stems are dependent on cortical bone volume and cortical thickness.

Evaluation of temperature of a full ceramic total knee arthroplasty during MRI examinations.

BACKGROUND: A diagnosis by magnetic resonance imaging (MRI) is often necessary before surgery of degenerative spine diseases. This can lead to a possible conflict with an inserted implant of the hip or knee. Heat generation or movement could be caused by the magnetic field. The aim of this study is to investigate temperature development in vitro in a 1.5T MRI of a ceramic knee arthroplasty. METHODS: A full ceramic, complete metal-free non-constrained primary total knee arthroplasty is investigated. Temperature change was measured between platinum resistors before and after each MRI sequence by change of resistance. The knee implant was placed in a plastic container after the sensors were attached. Then the container was completely filled with ultrasound gel. To document any possible movement of the implant, a grid was placed under the container to document the position of the implant before and after the scans. RESULTS: A total of four standard knee sequences were performed. The temperature at sites 1 to 5 per implant was always documented in the as-is state before MRI and then after each sequence. A total of 5 temperature measurement points were taken per implant. It was found that there were extremely small temperature variations. These were always in the range of less than 1°C. There was no case of movement of the implant triggered by the MRI scan. CONCLUSIONS: The experimental investigations carried out here showed homogeneous results with this experimental setup. It is concluded that, at least in vitro, that this ceramic knee implant can be used in MRI examinations without heating or movement.

Scoliosis: Brace treatment - from the past 50 years to the future.

OBJECTIVE: This paper deals with scoliosis treatment over the past 50 years. The review of the literature from the point of view of the current formation of opinion. From conservative forms of treatment, the pendulum has swung to surgical measures. To visualize this temporarily rejection of conservative treatment is the goal of this article. MATERIALS AND METHODS: A review of the literature over the last 50 years was performed from the perspective of current opinion, this with a pinch of personal experience in bracing and scoliosis surgery since 1972. The MESH terms (scoliosis, idiopathic scoliosis, adolescent idiopathic scoliosis) are presented in their number in a flow diagram and the publications on conservative therapies (brace, physiotherapy) are compared to surgical therapies (surgery).Opinions of "eminences" in the 1980s have been replaced by the rules of evidence-based medicine (EBM) at end of the 1990s. This transition will be visualized in the graph of PubMed statistics. In a statement, the future scoliosis treatment is derived from history. RESULTS: The total number of publications shows a ratio of brace to surgery of 13.9% and physiotherapy to surgery of 6.7% for the MESH terms "scoliosis". When "scoliosis" is supplemented with "idiopathic", the brace to surgery ratio changes from 24.5% and physiotherapy to surgery 8.2%. Focusing on adolescent scoliosis the addition of "adolescent" changes the brace to surgery ratio from 24.8% and physiotherapy to surgery 8.1%. In the total number of publications, "adolescent idiopathic scoliosis" is treated by 25.26%. The patient numbers of our own scoliosis outpatient clinic (1482 patients) over the last 15 years show a ratio of brace (Cobb angle 20°-50° brace-indication) to surgery (Cobb angle >50° indication to surgery) of 1 to 0.06. The scientific focus on surgical therapy is evident from the figures of PubMed mentioned. The number of conservative publications shows a depression in the 1990s. In the remainder of this article, opinion-forming developments are outlined and supported by literature citations, responsible for the recovery of publications on conservative scoliosis treatment. New technologies provide additional treatment options. CONCLUSIONS: In this sense, brace therapy is a success story with a future in the digital world of AI (artificial intelligence), mathematical model calculations, and production perhaps from the 3D printer. The central message from the history of the last 50 years is: "The scientific review of treatment results is essential for the further acceptance of brace treatment."

An Indication-Based Concept for Stepwise Spinal Orthosis in Low Back Pain According to the Current Literature.

BACKGROUND: The current literature is not conclusive for spinal orthosis treatment in low back pain. Therefore, two questions have to be answered: Does the current literature support the indication of spinal orthosis treatment in low back pain? Which treatment concept can be derived from the result? METHOD: The 30 highest-rated literature citations (PubMed: best match, 30 December 2021) dealing with low back pain and spine orthosis were included in the study. Excluded were all articles related to Kinesio Taping, scoliosis, physical exercise, or dealing with side effects and unrelated to treatment effect. Thus, the literature list refers only to "low back pain and spine orthoses". These articles were analyzed according to the PRISMA criteria and divided according to "specific diagnosis", when the cause of pain was explained (group A), or when "specific diagnosis is not given" (group B). The articles were also distinguished by the information about the orthosis. Articles with biomechanical information about the function of the orthoses were called "diagnosis-based orthosis" (group C). All other articles were part of the group "unspecific orthotic treatment" (group D). The results were compared to each other in terms of effectiveness. According to anatomical causes, a concept of orthosis selection depending on diagnosis of low back pain for clinical practice was developed. The risk of bias lies in the choice of the MESH terms. The synthesis of the results was a clinical treatment concept based on findings from the current literature. RESULTS: The literature citations with 1749 patients and 2160 citations of literature were processed; 21 prospective clinical or biomechanical studies and 9 review articles were included. The combination of literature citations according to "specific diagnosis" (group A) and "diagnosis based orthosis" (group C) was very likely to lead to a therapeutic effect (seven articles). No positive effect could be found in four articles, all dealing with postoperative treatment. When "specific diagnosis is not given" (group B) and combined with "unspecific orthotic treatment" (group D), therapy remained without measurable effect (15 articles). An effect was described in four articles (three biomechanical studies and one postoperative study). In review articles, according to specific diagnosis, only one article dealt with fractures and another with stenosis. In all review articles where specific diagnosis was not given, no effect with spine orthoses could be found. Using this knowledge, we created a clinical treatment concept. The structure was based on diagnosis and standardized orthoses. According to pain location and pathology (muscle, intervertebral disc, bone, statics, postoperative) the orthoses were classified to anatomical extent and the mechanical limitation (bandage, bodice, corset, orthosis with shoulder straps and erecting orthosis). CONCLUSION: The effectiveness of spinal orthoses could not be deduced from the current literature. The most serious limitation was the inconsistency of the complaint and the imprecise designation of the orthoses. INTERPRETATION: Articles with a precise allocation of the complaint and a description of the orthosis showed a positive effect. The treatment concept presented here is intended to provide a basis for answering the question concerning the effectiveness of spinal orthoses as an accompanying treatment option in low back pain.

Thickness accuracy of virtually designed patient-specific implants for large neurocranial defects.

The combination of computer-aided design (CAD) techniques based on computed tomography (CT) data to generate patient-specific implants is in use for decades. However, persisting disadvantages are complicated design procedures and rigid reconstruction protocols, for example, for tailored implants mimicking the patient-specific thickness distribution of missing cranial bone. In this study we used two different approaches, CAD- versus thin-plate spline (TPS)-based implants, to reconstruct extensive unilateral and bilateral cranial defects in three clinical cases. We used CT data of three complete human crania that were virtually damaged according to the missing regions in the clinical cases. In total, we carried out 132 virtual reconstructions and quantified accuracy from the original to the generated implant and deviations in the resulting implant thickness as root-mean-square error (RMSE). Reconstructions using TPS showed an RMSE of 0.08-0.18 mm in relation to geometric accuracy. CAD-based implants showed an RMSE of 0.50-1.25 mm. RMSE in relation to implant thickness was between 0.63 and 0.70 mm (TPS) while values for CAD-based implants were significantly higher (0.63-1.67 mm). While both approaches provide implants showing a high accuracy, the TPS-based approach additionally provides implants that accurately reproduce the patient-specific thickness distribution of the affected cranial region.

Prospective Mid-Term Results of a Completely Metal-Free Ceramic Total Knee Endoprosthesis: A Concise Follow-Up of a Previous Report.

BACKGROUND: Hypersensitivity reactions are suspected to cause premature aseptic loosening in susceptible patients after total knee arthroplasty. In response, metal-free implants have been developed. The aim of this prospective, observational midterm study was the assessment of a completely metal-free ceramic knee replacement system as a concise follow-up of a previous report. METHODS: Thirty-eight patients, with anamnestic suspected or documented allergy to the metal used in prosthetic alloys, participated in this 4-year follow-up of the metal-free BPK-S (Peter Brehm) total knee replacement system with ceramic femoral and tibial components. Clinical assessment included Knee Society Score (KSS), Oxford Knee Score, Euro Quol-5D-Visual Analogue Scale (EQ-5D-VAS), and perioperative or postoperative complications and need for revision. The position of the implant, signs of loosening, and leg alignment were assessed radiographically. RESULTS: All postoperative clinical scores improved significantly from baseline to 48-month follow-up examination. The Oxford Knee Score improved from 39 to 15 points. The KSS improved from 99 to 195 points (the KSS knee score 42.5 to 96 and the KSS function score 60 to 100). The EQ-5D improved from 12 to 7 points; the EQ-VAS improved from 52.5 to 97 points. No allergic reactions could be detected. Radiologically, a median preoperative varus deformity of 5° improved to 0° at 4-year follow-up. Radiolucent lines appeared around uncemented areas with no clinical symptoms. CONCLUSION: The fully metal-free BPK-S Integration ceramic knee replacement system exhibits excellent immuno-allergological compatibility, offering a safe option for patients with prior hypersensitivity reactions to metallic materials. Full cementation of all components is recommended to avoid radiolucent lines around the implant.

Silicone soft socket system for the treatment of geriatric transtibial amputees.

BACKGROUND: Outfitting geriatric amputees with a suitable prosthesis is a demanding task. The aim of this study was to determine the effect of prostheses outfitted with a silicone suspension interface system on a large group of transtibial amputees regarding walking distance, satisfaction of use and duration of daily use. METHODS: The study included 75 mostly geriatric transtibial amputees fitted with a rigid total contact socket with a silicone interface system called an Icelandic roll-on silicone socket (ICEROSS, Ossur, Reykjavik, Iceland). At follow-up 54 patients remained for assessment. Ambulatory performance was measured by first categorizing the patients into four subgroups regarding their walking capacity: 0-50 m, 50-100 m, 100-500 m and >500 m. The alteration in patient mobility was measured at admission, discharge and follow-up. Satisfaction and duration of daily use as well as use of walking aids were collated with a standard questionnaire. RESULTS: Between admission and discharge, patients showed significant improvement (p = <0.001) in walking distances. The walking distance diminished again between time of discharge and follow-up (p = <0.001). The parameters satisfaction with device and duration of daily use showed no significant differences and the same applied to male and female subjects. CONCLUSIONS: Geriatric transtibial amputees fitted with prostheses attached via a silicone suction socket system showed significant improvements in walking distances and a high rate of satisfaction with the device. There were no statistically significant gender-specific differences among users of the ICEROSS system.

Extracorporeal shock wave therapy: an update.

Extracorporeal shock wave therapy (ESWT) is a safe therapy and there are only a few side effects known (such as pain during ESWT and minor haematomata), but no severe complications are to be expected if it is performed as recommended.Contraindications are severe coagulopathy for high-energy ESWT, and ESWT with focus on the foetus or embryo and focus on severe infection.The effect mechanism of ESWT is still a component of diverse studies, but as far as we can summarize today, it is a similar process to a cascade triggered by mechano-transduction: mechanical energy causes changes in the cellular skeleton, which provokes a reaction of the cell core (for example release of mRNA) to influence diverse cell structures such as mitochondria, endoplasmic reticulum, intracellular vesicles, etc., so the enzymatic response leads to the improvement of the healing process.The usage of ESWT should be taught, to improve the outcome. Courses should be organized by national societies, since the legal framework conditions are different from one country to another.In this update the musculoskeletal indications are addressed (mainly bone and tendons): pseudoarthrosis, delayed fracture healing, bone marrow oedema and osteonecrosis in its early stages, insertional tendinopathies such as plantar fasciitis and Achilles tendon fasciitis, calcifying tendonitis of the rotator cuff, tennis elbow, and wound healing problems. Cite this article: EFORT Open Rev 2020;5:584-592. DOI: 10.1302/2058-5241.5.190067.

Rotating Hinge Implants in Knee Arthroplasty. / Achsgeführte Implantate in der Endoprothetik des Kniegelenkes.

Due to demographic transition an increasing number of primary knee arthroplasty is expected. A consequence is a rise in frequency in revision knee arthroplasty. Rotating hinge prostheses are a development of former hinge prostheses, due to changes in implant design the outcome of modern rotating hinge implants clearly improved in comparison to former models. Interpretation of outcome in present literature is difficult due to the small number of cases and the heterogeneous indications. Nevertheless the use of rotating hinge knee prostheses in primary and revision arthroplasty is associated with good clinical outcomes, when indicated appropriately.

[Timing of kyphoplasty influences the outcome: a prospective study]. / Der Zeitpunkt der Kyphoplastie beeinflusst das Ergebnis: eine prospektive Analyse.

The aim of this prospective study was to evaluate the efficiency of early versus delayed treatment of vertebral fractures by balloon kyphoplasty with regard to fracture age. A total of 106 patients (37 male and 69 female) with 128 vertebral body fractures, an average age of 67.5 years (21 to 92) and a body mass index of 26.4 (16 to 40.4) were recorded. All fractures were evaluated radiologically and clinically. Pain intensity (visual analogue scale 0-10), analgesics consumption (WHO steps 1 to 3) and the relevant surgery data (operating time, cement consumption, complications) were recorded. 37 A 1.1, 43 A 1.2, 43 A 1.3, 4 A 3.1 and 1 A 2.3 classifications were collected. Fracture age in days was less than 23 days in 75 patients; the mean time of surgery was 43 minutes. Analgesics consumption was reduced from 1.8 ±â€Š0.8 preoperatively to 1.0 ±â€Š0.6 postoperatively. A significant improvement was found in pain intensity, which fell significantly from 8.2 ±â€Š0.9 preoperatively to 3.9 ±â€Š0.8 postoperatively. In relation to fracture age and pain intensity, a significantly higher pain reduction was achieved with timing of kyphoplasty between 0 and 23 days. Here, pain intensity decreased to 2.5 ±â€Š0.5 postoperatively, compared with 4.5 ±â€Š0.4 for fractures treated later. Fracture age had no influence on vertebral body alignment or improvement of the kyphotic angle. In summary, it can be stated that balloon kyphoplasty is a sufficient method to treat vertebral body fractures, to improve the kyphotic angle and reduce pain significantly.

CD28 and CD57 define four populations with distinct phenotypic properties within human CD8+ T cells.

After repeated antigen exposure, both memory and terminally differentiated cells can be generated within CD8+ T cells. Although, during their differentiation, activated CD8+ T cells may first lose CD28, and CD28- cells may eventually express CD57 as a subsequent step, a population of CD28+ CD57+ (DP) CD8+ T cells can be identified in the peripheral blood. How this population is distinct from CD28- CD57- (DN) CD8+ T cells, and from the better characterized non-activated/early-activated CD28+ CD57- and senescent-like CD28- CD57+ CD8+ T cell subsets is currently unknown. Here, RNA expression of the four CD8+ T cell subsets isolated from human PBMCs was analyzed using microarrays. DN cells were more similar to "early" highly differentiated cells, with decreased TNF and IFN-γ production, impaired DNA damage response and apoptosis. Conversely, increased apoptosis and expression of cytokines, co-inhibitory, and chemokine receptors were found in DP cells. Higher levels of DP CD8+ T cells were observed 7 days after Hepatitis B vaccination, and decreased levels of DP cells were found in rheumatoid arthritis patients. More DP and DN CD8+ T cells were present in the bone marrow, in comparison with PBMCs. In summary, our results indicate that DP and DN cells are distinct CD8+ T cell subsets displaying defined properties.

Visualization of intervertebral disc degeneration in a cadaveric human lumbar spine using microcomputed tomography.

Gross features of disc degeneration (DD) that are associated with back pain include tears in the anulus fibrosus, structural changes of the endplates, and a collapse of the anulus. The aim of this study is the detailed visualization and microstructural characterization of DD using microcomputed tomography (µCT) and a dedicated image post-processing pipeline. In detail, we investigate a cadaveric spine that shows both types of DD between L1 and L2 and between L2 and L3, respectively. The lumbar spine was obtained from a male donor aged 74 years. The complete specimen was scanned using µCT with an isometric voxel size of 93 µm. Subsequently, regions of interest (ROI) were prepared featuring each complete intervertebral disc including the adjacent endplates. ROIs were then additionally scanned with a voxel size of 35 µm and by means of magnetic resonance imaging. The collapsed endplate of the superior L2 showed explicit signs of an endplate-driven degeneration, including bony endplate failures. In contrast, the intervertebral disc between L2 and L3 showed indications of an annulus-driven DD including severe disc height loss and concentric tears. Using µCT we were able to visualize and quantify bone and cartilage features in DD. We showed that in both cases a suite of structural changes accompanies cartilage degeneration, including microstructural bony adaptions to counteract changes in the biomechanical loading regimen.

Minimally Invasive AC Joint Reconstruction System (MINAR®) in Modified Triple-Button Technique for the Treatment of Acute AC Joint Dislocation.

Acute acromioclavicular (AC) joint dislocation is a frequent sports injury with more than 100 different operation methods described. A total of 65 patients with an acute AC joint dislocation were treated with the modified MINAR® system between 2009 and 2013. Clinical outcome, horizontal and vertical instability, as well as concomitant intraarticular injuries were assessed. We used Zanca, stress and axial X-rays for radiological assessment. A Constant score of 95 (±8.8), University of California Los Angeles Shoulder score (UCLA) of 31 (±4.9), Disabilities of Arm, Shoulder and Hand (DASH) of 9.1 (±14.3), and Visual Analogue Scale (VAS) of 0.9 (±0.126) was found. A total of 30 patients (59%) had no signs of reduction loss, nine patients (18%) a slight loss, 11 patients (22%) a partial loss, and one patient (2%) a total loss. No significant influence on the clinical scores could be shown. The postoperative coracoclavicular (CC) distance negatively affected the Constant (p = 0.007) and UCLA scores (p = 0.035). A longer time interval to surgery had a negative influence on all scores (p ≤ 0.001). We could not find any signs of persistent horizontal instability or intraarticular injuries at follow-up. The MINAR® system promises satisfactory functional and radiological results. When setting the correct indication, patients benefit from an early operation. No persisting horizontal instability was observed following suturing of the AC capsule and the delta fascia.

Peripheral antibody concentrations are associated with highly differentiated T cells and inflammatory processes in the human bone marrow.

BACKGROUND: Antigen-experienced immune cells migrate back to the bone marrow (BM), where they are maintained in BM survival niches for an extended period. The composition of T cell subpopulations in the BM changes with age, leading to an accumulation of highly differentiated T cells and a loss of naïve T cells. While innate immune cells are also affected by age, little is known about interactions between different adaptive immune cell populations maintained in the BM. In this study, the phenotype and function of innate and adaptive immune cells isolated from human BM and peripheral blood (PB) was analysed in detail using flow cytometry, to determine if the accumulation of highly differentiated T and B cells, supported by the BM niches, limits the maintenance of other immune cells, or affects their functions such as providing protective antibody concentrations. RESULTS: Total T cells increase in the BM with age, as do highly differentiated CD8+ T cells which no longer express the co-stimulatory molecule CD28, while natural killer T (NKT) cells, monocytes, B cells, and naïve CD8+ T cells all decrease in the BM with age. A negative correlation of total T cells with B cells was observed in the BM. The percentage of B cells in the BM negatively correlated with highly differentiated CD8+CD28- T cells, replicative-senescent CD8+CD57+ T cells, as well as the CD8+CD28-CD57+ population. Similar correlations were seen between B cells and the frequency of highly differentiated T cells producing pro-inflammatory molecules in the BM. Interestingly, plasma concentrations of diphtheria-specific antibodies negatively correlated with highly differentiated CD8+CD57+ T cells as well as with exhausted central memory CD8+ and CD4+ T cells in the BM. A negative impact on diphtheria-specific antibodies was also observed for CD8+ T cells expressing senescence associated genes such as the cell cycle regulator p21 (CDKN1A), KLRG-1, and elevated levels of reactive oxygen species (ROS). CONCLUSION: Our data suggest that the accumulation and maintenance of highly differentiated, senescent, and exhausted T cells in the BM, particularly in old age, may interfere with the survival of other cell populations resident in the BM such as monocytes and B cells, leading to reduced peripheral diphtheria antibody concentrations as a result. These findings further highlight the importance of the BM in the long-term maintenance of immunological memory.

Human bone marrow adipocytes display distinct immune regulatory properties.

BACKGROUND: The bone marrow (BM) is a major reservoir of resting memory T cells and long-lived plasma cells, capable of providing protection against recurrent infections. Whether the age-related accumulation of adipose tissue in the BM affects the functionality and maintenance of memory cells is not well understood. METHODS: For the first time, we compare human femur marrow adipose tissue (fMAT) and subcutaneous white adipose tissue of the thigh (tsWAT) obtained from the same donors. Therefore, we used microarrays for comparative global gene expression analysis, and employed assays to analyse parameters of adipocyte biology, inflammation and oxidative stress. FINDINGS: We show that fMAT adipocytes differ significantly from tsWAT adipocytes regarding specific gene expression profiles including inflammatory responses and adipogenesis/adipocyte phenotype. Concomitant with considerably lower levels of CD36, a membrane-associated protein important for long-chain fatty acid uptake that is used as maturation marker, fMAT adipocytes are smaller and contain less triglycerides. fMAT adipocytes secrete similar levels of adiponectin and leptin as tsWAT adipocytes, and express increased levels of pro-inflammatory molecules concomitant with an elevated generation of reactive oxygen species (ROS) and impaired function of plasma cells in the BM. INTERPRETATION: Our findings suggest that fMAT is a unique type of adipose tissue containing small adipocytes with lower CD36 protein and triglyceride levels than tsWAT but high adipokine secretion. Moreover, fMAT adipocytes secrete high levels of pro-inflammatory cytokines, contributing to inflammation and impairment of plasma cell function in the BM, suggesting that fMAT has more immune regulatory functions than tsWAT.

Non-Destructive Testing of Ceramic Knee Implants Using Micro-Computed Tomography.

BACKGROUND: Because of the accumulated numbers and the increasing rate of knee replacement surgeries larger numbers of revision cases are likely. Although the success rate of knee arthroplasties is high, complications like the loosening of the implant necessitate subsequent treatments. Therefore, new concepts such as metal-free ceramic implants are necessary, for example, using zirconium dioxide (ZrO2). Several studies showed that the strength of ceramic ZrO2 implants is equivalent to cobalt-chromium components. METHODS: Non-destructive testing remains challenging due to the high density (6 g/cm³) of ZrO2. In this feasibility study, we investigated 8 tibial and 8 femoral implants respectively using an industrial X-ray micro-computed tomography (XCT) system at a voxel size of 100 µm. We established a non-destructive testing protocol for ceramic knee implants optimizing scanning parameters and sample orientation using CT simulations. Finally, we used an iterative artifact reduction procedure for beam hardening correction. RESULTS: The results show that corrected image data enable the non-destructive inspection of high-density components. In this sample, none of the investigated components show any internal defects like pores or cracks. In general, XCT is a major imaging method that is able to provide a 3-dimensional representation of higher dense objects that allows the inspection of metal or ceramic knee implants. Even though we established an optimized scanning routine for tibial and femoral ceramic components, it is not possible to completely eliminate scanning artifacts of XCT. CONCLUSION: Altogether, after visual inspection, none of the beam-hardening corrected XCT data sets for femoral and tibial implants showed any defects, that is, no inclusions, cracks, or pores were detected. XCT test is therefore an essential addition to the fatigue testing since it is the only non-destroying testing method.

Finite Element Analysis and Biomechanical Testing of the New MiniMIS Short Stem. / Finite-Elemente-Analyse und biomechanische Testung des neuen MiniMIS-Kurzschafts.

INTRODUCTION: In hip arthroplasty a trend towards short stem prostheses is observed. The aim of this study is to investigate the finite element analysis and biomechanical fatigue performance of a new short stem prosthesis. METHODS: A finite element analysis was used to simulate the stresses during neck and stem loading according to the ISO standards. Numerical analysis with applied forces of up to 6 kN were performed in the vertical direction on a femoral neck-preserving stem (MiniMIS). During experimental testing, 10 million cycles with a maximum load of 5.34 kN using the worst case of a XL ceramic head (36 mm) were applied. This was followed by a Locati test, where the load was increased until failure of the stem. RESULTS: For all stems, stress values below the limits according to the ISO 5832-3 standard (yield strength of 800 N/mm2) were calculated by the finite element analysis. In the biomechanical tests, the total number of 10 million cycles with a maximum load of 5.34 kN was reached in all cases without any visible signs of implant damage. The estimated load to failure after stem testing was 2.16 kN (required by ISO 7206-4: 1.2 kN) and after neck testing > 9.35 kN (required by ISO 7206-6: 5.4 kN). SUMMARY: The presented finite element calculation and subsequent biomechanical testing show that the design of this stem meets the essential mechanical requirements given by the ISO and a material failure is not expected in all variants tested under the applied boundary conditions.

Fcµ receptor as a Costimulatory Molecule for T Cells.

Fc receptor for IgM (FcµR)-deficient mice display dysregulated function of neutrophils, dendritic cells, and B cells. The relevance of FcµR to human T cells is still unknown. We show that FcµR is mostly stored inside the cell and that surface expression is tightly regulated. Decreased surface expression on T cells from elderly individuals is associated with alterations in the methylation pattern of the FCMR gene. Binding and internalization of IgM stimulate transport of FcµR to the cell surface to ensure sustained IgM uptake. Concurrently, IgM accumulates within the cell, and the surface expression of other receptors increases, among them the T cell receptor (TCR) and costimulatory molecules. This leads to enhanced TCR signaling, proliferation, and cytokine release, in response to low, but not high, doses of antigen. Our findings indicate that FcµR is an important regulator of T cell function and reveal an additional mode of interaction between B and T cells.

Immunological and morphological analysis of heterotopic ossification differs to healthy controls.

BACKGROUND: Formation of lamellar bone in non-osseus tissue is a pathological process called heterotopic ossification. It is the aim of this study to analyse the morphology and immunological status of patients with heterotopic ossification compared to individual healthy persons. METHODS: Human bone marrow and blood samples were obtained from 6 systemically healthy individuals and 4 patients during resection of heterotopic ossification from bone at hip arthroplasty. Bone was fragmented and treated with purified collagenase. Immunofluorescence surface staining was performed and analyzed with flow cytometry. Microcomputed tomography scanning was done performed at a resolution of 11 and 35 µm isometric voxel size respectively using a two different cone beam X-computer tomography systems and a microfocus X-ray tube. Subsequently the volume data was morphometrically analysed. RESULTS: The monocytes, stem cells, stroma cells and granulocytes progenitor cells were strongly reduced in the heterotopic ossification patient. Additionally a significant reduction of stromal stem cells cells and CD34 positive stem cells was observed. The frequency of NK-cells, B cells and T cells were not altered in the patients with heterotopic ossification compared to a healthy person. Micromorphometric parameters showed a lower content of mineralized bone tissue compared to normal bone. Mean trabecular thickness showed a high standard deviation, indicating a high variation in trabecular thickness, anisotropy and reducing bone strength. CONCLUSIONS: This work shows altered immunological distribution that is accompanied by a low decrease in bone volume fraction and tissue mineral density in the heterotopic ossification sample compared to normal bone. Compared to healthy subjects, this might reflect an immunological participation in the development of this entity.