Cartilage matrix is a composite of discrete, but interacting suprastructures, i.e. cartilage fibers with microfibrillar or network-like aggregates and penetrating extrafibrillar proteoglycan matrix. ...The biomechanical function of the proteoglycan matrix and the collagen fibers are to absorb compressive and tensional loads, respectively. Here, we are focusing on the suprastructural organization of collagen fibrils and the degradation process of their hierarchical organized fiber architecture studied at high resolution at the authentic location within cartilage. We present electron micrographs of the collagenous cores of such fibers obtained by an improved protocol for scanning electron microscopy (SEM). Articular cartilages are permeated by small prototypic fibrils with a homogeneous diameter of 18 ± 5 nm that can align in their D-periodic pattern and merge into larger fibers by lateral association. Interestingly, these fibers have tissue-specific organizations in cartilage. They are twisted ropes in superficial regions of knee joints or assemble into parallel aligned cable-like structures in deeper regions of knee joint- or throughout hip joints articular cartilage. These novel observations contribute to an improved understanding of collagen fiber biogenesis, function, and homeostasis in hyaline cartilage.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Monolayer graphene exhibits exceptional electronic and mechanical properties, making it a very promising material for nanoelectromechanical devices. Here, we conclusively demonstrate the ...piezoresistive effect in graphene in a nanoelectromechanical membrane configuration that provides direct electrical readout of pressure to strain transduction. This makes it highly relevant for an important class of nanoelectromechanical system (NEMS) transducers. This demonstration is consistent with our simulations and previously reported gauge factors and simulation values. The membrane in our experiment acts as a strain gauge independent of crystallographic orientation and allows for aggressive size scalability. When compared with conventional pressure sensors, the sensors have orders of magnitude higher sensitivity per unit area.
Purpose
Patient-based and psychological factors do influence outcome in patients undergoing total knee arthroplasty (TKA). The purpose was to investigate if preoperative psychological factors ...influence the subjective and objective outcomes 6 weeks, 4 months and 1 year after TKA. Our hypothesis was that there is a significant influence of psychological factors on clinical outcome scores before and after TKA.
Methods
A prospective, longitudinal, single-cohort study investigating the correlation of depression, control beliefs, anxiety and a variety of other psychological factors with outcomes of patients undergoing TKA was performed. A total of 104 consecutive patients were investigated preoperatively using the Beck`s depression inventory, the State-Trait Anxiety Index, the questionnaire for assessment of control beliefs and the SCL-90R inventory. The Knee Society Clinical Rating System (KSS) and the WOMAC were used. Analysis of TKA position was performed on radiographs according to Ewald et al. Correlation of psychological variables with outcomes was performed (
p
< .05).
Results
Self-efficacy did not influence clinical scores. More depressed patients showed higher pre- and postoperative WOMAC scores, but no difference in amelioration. KSS scores were not influenced. Patients with higher State and Trait Anxiety Indexes had higher WOMAC and lower KSS scores before and after the operation, but most significant correlations were <0.3. Several SCL-90 dimensions had significant correlations with pre- and postoperative clinical scores, but not with their amelioration. The SCL-90 subscore for somatization and the overall SCL-90 significantly correlated with the WOMAC, KSS before and after TKA.
Conclusions
Depression, anxiety, a tendency to somatize and psychological distress were identified as significant predictors for poorer clinical outcomes before and/or after TKA. Standardized preoperative screening and subsequent treatment should become part of the preoperative work-up in orthopaedic practice.
Level of evidence
Prognostic prospective, Level I.
Purpose
Trochleoplasty and reconstruction of the medial patellofemoral ligament (MPFL) are among the most commonly performed surgical treatments in patients with patellofemoral instability. The ...primary purpose of the study was to perform a systematic literature review on trochleoplasty in the treatment of patients with patellofemoral instability. The secondary purpose was to compare the outcomes with those seen in patients treated after reconstruction of the MPFL.
Methods
A standardised search on search engines was performed. All observational and experimental studies dealing with trochleoplasty were then obtained and reviewed in a consensus meeting. Fifteen articles out of 1543 were included and analysed using the CASP appraisal scoring system. Twenty-five studies on MPFL reconstruction were obtained for comparison. The clinical and radiological outcomes were statistically analysed.
Results
Both treatment groups showed significant improvement in outcomes from pre- to post-operatively. The mean post-operative Kujala and the Lysholm scores significantly increased in both groups when compared to preoperatively (trochleoplasty group: Kujala 61.4–80.8 and Lysholm 55.5–78.5; MPFL group: Kujala 46.9–88.8 and Lysholm 59.9–91.1). Post-operatively a positive apprehension test was found in 20 and 8 % of the trochleoplasty and MPFL groups, respectively. No significant differences in redislocation (2 %) and subluxation (5–6 %) rates were found.
Conclusions
This systematic review showed that both trochleoplasty and MPFL reconstruction are able to deliver good clinical outcomes with stable patellofemoral joints.
Level of evidence
III.
The pathological changes in osteoarthritis--a degenerative joint disease prevalent among older people--start at the molecular scale and spread to the higher levels of the architecture of articular ...cartilage to cause progressive and irreversible structural and functional damage. At present, there are no treatments to cure or attenuate the degradation of cartilage. Early detection and the ability to monitor the progression of osteoarthritis are therefore important for developing effective therapies. Here, we show that indentation-type atomic force microscopy can monitor age-related morphological and biomechanical changes in the hips of normal and osteoarthritic mice. Early damage in the cartilage of osteoarthritic patients undergoing hip or knee replacements could similarly be detected using this method. Changes due to aging and osteoarthritis are clearly depicted at the nanometre scale well before morphological changes can be observed using current diagnostic methods. Indentation-type atomic force microscopy may potentially be developed into a minimally invasive arthroscopic tool to diagnose the early onset of osteoarthritis in situ.
Automatic wire bonding is a highly mature, cost-efficient and broadly available back-end process, intended to create electrical interconnections in semiconductor chip packaging. Modern production ...wire-bonding tools can bond wires with speeds of up to 30 bonds per second with placement accuracies of better than , and the ability to form each wire individually into a desired shape. These features render wire bonding a versatile tool also for integrating wires in applications other than electrical interconnections. Wire bonding has been adapted and used to implement a variety of innovative microstructures. This paper reviews unconventional uses and applications of wire bonding that have been reported in the literature. The used wire-bonding techniques and materials are discussed, and the implemented applications are presented. They include the realization and integration of coils, transformers, inductors, antennas, electrodes, through silicon vias, plugs, liquid and vacuum seals, plastic fibers, shape memory alloy actuators, energy harvesters and sensors.
The purpose of our study was to evaluate the clinical value of hybrid SPECT/CT for the assessment of patients with painful total knee arthroplasty (TKA).
Twenty-three painful knees in patients ...following primary TKA were assessed using Tc-99m-HDP-SPECT/CT. Rotational, sagittal and coronal position of the TKA was assessed on 3D-CT reconstructions. The level of the SPECT-tracer uptake (0-10) and its anatomical distribution was mapped using a validated localization scheme. Univariate analysis (Wilcoxon-Mann-Whitney, Spearmean's-rho test, p < 0.05) was performed to identify any correlations between component position, tracer uptake and diagnosis.
SPECT/CT imaging changed the suspected diagnosis and the proposed treatment in 19/23 (83%) knees. Progression of patellofemoral OA (n = 11), loosening of the tibial (n = 3) and loosening of the femoral component (n = 2) were identified as the leading causes of pain after TKA.Patients with externally rotated tibial trays showed higher tracer uptake in the medial patellar facet (p = 0.049) and in the femur (p = 0.051). Patients with knee pain due to patellofemoral OA showed significantly higher tracer uptake in the patella than others (p < 0.001).
SPECT/CT was very helpful in establishing the diagnosis and guiding subsequent management in patients with painful knees after TKA, particularly in patients with patellofemoral problems and malpositioned or loose TKA.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective: Developing robotic tools that introduce substantial changes in the surgical workflow is challenging because quantitative requirements are missing. Experiments on cadavers can provide ...valuable information to derive workspace requirements, tool size, and surgical workflow. This work aimed to quantify the volume inside the knee joint available for manipulation of minimally invasive robotic surgical tools. In particular, we aim to develop a novel procedure for minimally invasive unicompartmental knee arthroplasty (UKA) using a robotic laser-cutting tool. Methods: Contrast solution was injected into nine cadaveric knees and computed tomography scans were performed to evaluate the tool manipulation volume inside the knee joints. The volume and distribution of the contrast solution inside the knee joints were analyzed with respect to the femur, tibia, and the anatomical locations that need to be reached by a laser-cutting tool to perform bone resection for a standard UKA implant. Results: Quantitative information was determined about the tool manipulation volume inside these nine knee joints and its distribution around the cutting lines required for a standard implant. Conclusion: Based on the volume distribution, we could suggest a possible workflow for minimally invasive UKA, which provides a large manipulation volume, and deducted that for the proposed workflow, an instrument with a thickness of 5-8 mm should be feasible. Significance: We present quantitative information on the three-dimensional distribution of the maximally available volume inside the knee joint. Such quantitative information lays the basis for developing surgical tools that introduce substantial changes in the surgical workflow.
Background
Alumina particles from the grit blasting of Ti-alloy stems are suspected to contribute to aseptic loosening. An alumina-reduced stem surface was hypothesized to improve osseointegration ...and show comparable short-term outcomes to those of a standard stem.
Methods
In this prospective, double-blind, randomized trial, 26 standard (STD) and 27 experimental new technology (NT) stems were implanted. The latter were additionally treated by acid etching and ice blasting to remove alumina particles from the grit-blasting process. Follow-up occurred at 12 and 24 months. Bone mineral density (BMD) around the stem was measured by a dual-energy x-ray absorptiometry device (DEXA). Radiographs were reviewed for alterations. Clinical scoring comprised the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Harris Hip Score (HHS). Survival rates were calculated up to 50 months.
Results
Lower mean BMD and more severe cortical hypertrophies were found in the NT group. At 12 months, radiolucent lines were observed mostly in the metaphyseal zone for both groups, with a progression tendency in the NT group at 24 months. At 12 months, pain scores and the WOMAC total and physical activity scores were significantly lower in the NT group, without any differences thereafter. The number of NT stem revisions amounted to 6 (24%) and 11 (41%) at 24 and 50 months, respectively.
Conclusion
In the NT group, unexpected catastrophic failure rates of 41% caused by early aseptic loosening were noted within 50 months. Compared with the STD stems, NT stems lead to poor clinical and radiographic results.
Level of evidence
: II.
Trial Registration
: NCT05053048.
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