A Review of the Combination of Experimental Measurements and Fibril-Reinforced Modeling for Investigation of Articular Cartilage and Chondrocyte Response to Loading.

A review of the combination of experimental measurements and fibril-reinforced modeling for investigation of articular cartilage and chondrocyte response to loading.

Comput Math Methods Med. 2013; 2013: 326150
Julkunen P, Wilson W, Isaksson H, Jurvelin JS, Herzog W, Korhonen RK

The function of articular cartilage depends on its structure and composition, sensitively impaired in disease (e.g. osteoarthritis, OA). Responses of chondrocytes to tissue loading are modulated by the structure. Altered cell responses as an effect of OA may regulate cartilage mechanotransduction and cell biosynthesis. To be able to evaluate cell responses and factors affecting the onset and progression of OA, local tissue and cell stresses and strains in cartilage need to be characterized. This is extremely challenging with the presently available experimental techniques and therefore computational modeling is required. Modern models of articular cartilage are inhomogeneous and anisotropic, and they include many aspects of the real tissue structure and composition. In this paper, we provide an overview of the computational applications that have been developed for modeling the mechanics of articular cartilage at the tissue and cellular level. We concentrate on the use of fibril-reinforced models of cartilage. Furthermore, we introduce practical considerations for modeling applications, including also experimental tests that can be combined with the modeling approach. At the end, we discuss the prospects for patient-specific models when aiming to use finite element modeling analysis and evaluation of articular cartilage function, cellular responses, failure points, OA progression, and rehabilitation. HubMed – rehab


Correlations between brain activity and components of motor learning in middle-aged adults: an fMRI study.

Front Hum Neurosci. 2013; 7: 169
Wadden K, Brown K, Maletsky R, Boyd LA

Implicit learning may be shown by improvements in motor performance, which occur unconsciously with practice and are typically restricted to the task that was practiced. The purpose of this study was to examine behaviorally relevant brain activation associated with change in motor behavior during sequence-specific motor learning of a perceptuomotor continuous tracking (CT) task in middle-aged adults. To gain further insight into the neural structures associated with change in motor behavior, overall improvement in tracking (root mean square error; RMSE) was decomposed into two components-temporal precision and spatial accuracy. We hypothesized that individual differences in CT task performance would be evident in unique networks of brain activation that supported overall tracking behavior as well-temporal and spatial tracking accuracy. A group of middle-aged healthy individuals performed the CT task, which contains repeated and random segments for seven days. Functional magnetic resonance imaging (fMRI) data was collected on the first and seventh day while the participants performed the task. Subjects did not gain explicit awareness of the sequence. To assess behaviorally-relevant changes in the blood oxygenation level-dependent (BOLD) response associated with individual sequence-specific tracking performance, separate statistical images were created for each participant and weighted by the difference score between repeated and random performance for days 1 and 7. Given the similarity of performance for random and repeated sequences during early practice, there were no unique networks evident at day 1. On Day 7 the resultant group statistical fMRI image demonstrated a positive correlation between RMSE difference score and bilateral cerebellar activation (lobule VI). In addition, individuals who showed greater sequence-specific temporal precision demonstrated increased activation in the precentral gyrus, middle occipital gyrus, and putamen of the right hemisphere and the thalamus, cuneus, and cerebellum of the left hemisphere. Activation of this neural network further confirms its involvement in timing of movements as it has been previously associated with task performance when individuals are instructed to emphasize speed over accuracy. In the present study, behavioral performance was associated with neural correlates of individual variation in motor learning that characterized the ability to implicitly learn a sequence-specific CT task. HubMed – rehab


Management of complications in long-term ?LVAD support.

Int J Artif Organs. 2013 May 8; 0
Schweiger M, Vierecke J, Potapov1 E, Krabatsch T

Introduction: Management of complications in long-term LVAD support like aortic regurgitation, progressive decline of right ventricular function, or pump thrombosis are challenging.?Methods and Results: After 2.5 years on a HeartMate II left ventricular assist device (LVAD) a 59-year-old patient was admitted to hospital due to severe hemolysis caused by a partial occlusion and thrombosis caused by a shift of the LVAD inflow cannula towards the lateral wall of the left ventricle (LV). Preoperative assessment revealed additional severe aortic regurgitation and impaired right ventricular (RV) function (severe tricuspid regurgitation, RV ejection fraction 25%, central venous pressure ?14 mmHg). After LVAD device exchange and aortic valve replacement (AVR) RV failure occurred and a temporary right ventricular assist device (RVAD) was employed. RVAD explantation was feasible ?21 days after surgery. The patient was discharged to a rehabilitation center.?Discussion: In this case, LVAD exchange with concomitant AVR and temporary RVAD efforts saved the patient’s life and restored a good quality of life. HubMed – rehab


Exercise in the prevention and rehabilitation of breast cancer?

Wien Klin Wochenschr. 2013 May 8;
Volaklis KA, Halle M, Tokmakidis SP

Breast cancer is the most common type of cancer among women worldwide. Several epidemiological studies have shown an inverse relationship between the risk of breast cancer and physical activity levels, whereas exercise training has been recognized as a significant means in the rehabilitation process of breast cancer survivors. The relative risk reduction of breast cancer for women who engaged in moderate to vigorous physical activity for 3-5 days peek week ranged between 20-40?%. Furthermore, several studies demonstrated a 24-67?% reduction in the risk of total deaths and 50-53?% reduction in the risk of breast cancer deaths in women who are physically active after breast cancer diagnosis compared with sedentary women. Breast cancer survivors should be encouraged to participate in rehabilitation programs in order to obtain numerous physiological and psychological benefits. These include reductions in fatigue and improvements in immune function, physical functioning, body composition, and quality of life. Based on recent scientific evidence, a complete rehabilitation program for patients with breast cancer should combine both strength and aerobic exercise in order to maximize the expected benefits. HubMed – rehab