Search results for "Lag"
showing 10 items of 3124 documents
EMG-Assisted Muscle Force Driven Finite Element Model of the Knee Joint with Fibril-Reinforced Poroelastic Cartilages and Menisci.
2019
Abnormal mechanical loading is essential in the onset and progression of knee osteoarthritis. Combined musculoskeletal (MS) and finite element (FE) modeling is a typical method to estimate load distribution and tissue responses in the knee joint. However, earlier combined models mostly utilize static-optimization based MS models and muscle force driven FE models typically use elastic materials for soft tissues or analyze specific time points of gait. Therefore, here we develop an electromyography-assisted muscle force driven FE model with fibril-reinforced poro(visco)elastic cartilages and menisci to analyze knee joint loading during the stance phase of gait. Moreover, since ligament pre-st…
Magnetic resonance chondro-crassometry (MR CCM): a method for accurate determination of articular cartilage thickness?
1996
A method for the assessment of articular cartilage thickness based on MRI is presented and its accuracy and reproducibility tested. Six specimens of human patellae were imaged, using a fat-suppressed FLASH 3D sequence, and sectioned with a high-precision band saw. The regional distribution of articular cartilage thickness was determined from the MR images and from the anatomical sections (intervals of 0.5 mm). With image analysis 50-90% of the image points were found to lie within exactly the same thickness interval in corresponding patterns, and less than 17% deviated more than 0.5 mm. More than 85% of all pixels were reproducible with MRI after new positioning of the joint. No influence o…
Repeatability of patellar cartilage thickness patterns in the living, using a fat-suppressed magnetic resonance imaging sequence with short acquisiti…
1998
A fast, reproducible, and noninvasive method is required for quantifying cartilage thickness clinically and for studying the deformation of articular cartilage during and after mechanical loading in vivo. The objective of the current investigation was to test the repeatability of regional distribution patterns of patellar cartilage thickness in the living on the basis of a fat-suppressed magnetic resonance imaging sequence with a short acquisition time and three-dimensional digital data processing. The knees of eight healthy volunteers were transversally imaged with a fat-suppressed FLASH-3D (fast low angle shot) sequence (acquisition time: 4 minutes and 10 seconds). In each case, the joint…
Traumatic damage to the cartilage influences outcome of anatomically reduced acetabular fractures: A medium-term retrospective analysis
2011
We reviewed 77 patients with an acetabular fracture, treated operatively through a non-extensile approach after an average time of 45 months. The ilioinguinal approach was chosen in 41, the Kocher-Langenbeck approach in 36 patients. Following the Letournel classification, the most frequent lesions were posterior wall (26%), two-column (22.1%) and anterior column (14.3%) fractures. Subchondral impaction, intra-articular fracture fragments and fracture comminution, called modifiers, could be identified in the preoperative CT-data of 38 patients (49.4%). Patients were operated after an average of 4 days. Average hospital stay was 19 days. Sciatic nerve and peroneal nerve palsy were registered …
Determination of knee joint cartilage thickness using three-dimensional magnetic resonance chondro-crassometry (3D MR-CCM)
1996
The objective of this article was to analyze the accuracy and precision with which the quantitative distribution of articular cartilage can be determined in the knee joint using MRI. A three-dimensional (3D) technique that accounts for the out-of-plane deviation of the interface normal in strongly curved joint surfaces (3D MR-CCM) has been developed for cartilage thickness measurements. Eight cadaveric knee-joint specimens and six volunteers were imaged using a fat-suppressed gradient-echo sequence at a resolution of 2 x 0.31 x 0.31 mm3. Cartilage volumes and topographical thickness maps were obtained and compared with those derived from anatomical sections by image analysis. The deviation …
Importance of Patella, Quadriceps Forces, and Depthwise Cartilage Structure on Knee Joint Motion and Cartilage Response During Gait
2015
In finite-element (FE) models of the knee joint, patella is often omitted. We investigated the importance of patella and quadriceps forces on the knee joint motion by creating an FE model of the subject's knee. In addition, depthwise strains and stresses in patellar cartilage with different tissue properties were determined. An FE model was created from subject's magnetic resonance images. Knee rotations, moments, and translational forces during gait were recorded in a motion laboratory and used as an input for the model. Three material models were implemented into the patellar cartilage: (1) homogeneous model, (2) inhomogeneous (arcadelike fibrils), and (3) random fibrils at the superficia…
Non-invasive determination of cartilage thickness throughout joint surfaces using magnetic resonance imaging.
1997
Abstract Data on articular cartilage thickness in the living are important for the design of computer models, aimed at preoperatively assessing the effect of surgical procedures on joint contact and load transmission, and for the calculation of cartilage material properties from its deformational behavior as determined during arthroscopy. A non-invasive method for measuring cartilage thickness in living subjects is, however, not available. A technique based on magnetic resonance imaging has therefore been tested for assessing articular cartilage thickness throughout joint surfaces. The accuracy is determined by comparing cartilage thickness maps obtained from three patellar specimens with a…
CD10 and HHF35 actin in the differential diagnosis between Collagenous Spherulosis and Adenoid-Cystic Carcinoma of the breast
2012
Collagenous Spherulosis (CS) and Adenoid-Cystic Carcinoma (AdCC) of the breast consist of cribriform proliferations of epithelial and myoepithelial cells with an immunophenotypic overlap of some myoepithelial markers, such as p63 and smooth muscle actin (SMA). To our knowledge, CD10 and HHF35 actin have not been assessed in the differential diagnosis of these two breast lesions. We performed an immunohistochemical study on 6 cases of CS and 9 cases of AdCC. We found CD10, muscle-specific actin (HHF35), Estrogen and Progesterone receptors (ER and PR) to be strongly expressed in CS, but not in AdCC; C-kit was diffusely positive in AdCC and scanty in CS; SMA, p63 and Cytokeratine 5/6 (CK5/6) w…
Pregnancy in primary sclerosing cholangitis
2011
Background There is a paucity of data on fertility or pregnancy in patients with primary sclerosing cholangitis (PSC). Objective To assess fertility in PSC by comparing the number of children in a large cohort of PSC patients to healthy controls and to investigate the outcome of pregnancy, as well as the influence of pregnancy on the disease course. Design Case series. Setting Germany. Participants 229 PSC patients and 569 healthy controls were evaluated for the number of children. 17 patients with PSC and at least one pregnancy, or who received a diagnosis of PSC within 6 months after delivery, were included in the more detailed analysis. Main outcome measures Number of children per patien…
The obsolescent renal glomerulus ? Collapse, sclerosis, hyalinosis, fibrosis
1977
By light and electron microscopical examination it is shown that four structural components can contribute to obsolescent glomeruli: capillary basement membranes, enriched mesangium matrix, “vascular” hyalin and collagen fibers. Each of these components can bring about glomerular damage alone. One non-reactive form — a glomerular collapse with only basement membrane remnants — can be separated from three reactive forms: the accumulation of mesangium matrix (sclerosis or matrix-sclerosis), deposition of vascular hyalin (hyalinosis in the narrow sense), and fiber development within the former urinary space (fibrosis or fibro-sclerosis). The use of the term “fibrinoid” in place of the descript…