Terms Of Biomechanics Research Articles

How does scleral buckling affect the anterior segment of the eye?

Abstract Purpose To describe the modifications produced in the anterior segment of the eye after placing an encircling scleral buckling (SB) in terms of corneal morphology, biomechanics and intraocular pressure. Methods A prospective study of 15 eyes with rhegmatogenous retinal detachment who underwent pars plana vitrectomy combined with a scleral buckle (PPV/SB), and 12 eyes with vitreous hemorrhage treated with PPV alone. We measured preoperatively and 1‐month after surgery the corneal biomechanical properties using the Ocular Response Analyzer (ORA), including corneal hysteresis (CH), corneal resistance factor (CRF), intraocular pressure (IOPg), and corneal compensated IOP (IOPcc). Moreover, we defined the corneal morphology by 4 parameters provided by the topographer Orbscan IIz: mean corneal power (dioptres), standard deviation, thinnest point (µm), and anterior chamber depth (ACD) (mm). Results Mean CH values were significantly diminished following PPV/SB (p=0.003). We found no significant changes in CRF. IOPg and IOPcc mean values were significantly increased only in the PPV/SB group (p=0.019 and p=0.010, respectively) but not in PPV group (p=0.715 and p=0.273, respectively). In PPV/SB group, IOPcc mean values were significantly higher than IOPg before (p=0.001) and after surgery (p=0.003), but not in the other group. None of the morphological parameters were modified after surgery in any of the two study groups (p>0.05) Conclusion Anterior segment morphology was not modified after placing a SB. Corneal biomechanical properties showed a reduction in CH, probably due to a vascular constriction and reduction of the eye compliance. PPV might be considered a less invasive approach for the repair of noncomplex retinal detachments than PPV/SB.

Bone mineral density and microarchitecture in participants of a 105-day experiment in isolated environment

A study on the bone system state in healthy volunteers has been performed before and after 105-day experiment in hermetically isolated environment (the Mars-105 experiment) using dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). The values of bone mineral density (BMD), volumetric bone mineral density (VBMD), and bone structural characteristics of distal segments in radius and tibia have been evaluated. No significant DXA changes have been revealed in segments of skeleton critically important in terms of biomechanics. Microarchitectural deterioration (a decrease in the trabecula number and increase in the bone tissue heterogeneity) has been found using the pQCT technique in the radius of the majority of subjects. A VBMD decrease has been revealed for both cortical and trabecular bones in tibia, along with an unexpected trabecular bone improvement in the form of an increase in the trabecula quantity and decrease in bone tissue heterogeneity. Comprehensive studies, including estimation of projective and volumetric bone mineral densities (the bone mineral content) and bone structural characteristics (bone quality) are required to have a clear view on the changes in the bone system under the conditions of a simulation experiment.

Patellofemorale Diagnostik

Patellofemoral complaints are probably the most frequently encountered overstress symptoms of the knee in orthopedic consultations. New pathologies have recently been recognized in terms of evolution, biomechanics and clinical appearance and detailed knowledge is consistently increasing. The clinical implications for a physical examination have, however, not yet been elucidated for all pathologies. The clinical history and a detailed physical examination are the first steps in a successful therapy. This article presents a structured overview of clinical tests and their significance for routine practice.

Simulation and Numerical Parameter Identification of a Biologically Inspired Bipedal Robot with Passive Elements

The goal of the project is to investigate the influence of elastic mechanisms on technical, bipedal locomotion. In particular, the paper presents the parameter identification for a biologically inspired two-legged robot model. The simulation model consists of a rigid body model equipped with rubber straps. The arrangement of the rubber straps is based on the arrangement of certain muscle groups in a human being. The parameters of the elastic elements are identified applying numerical optimisation. Thus two optimisation algorithms are investigated and compared with respect to robustness and computing time. Moreover, different objective functions are defined and discussed. The behaviour of the resulting configuration of the system is explored in terms of biomechanics.

Behandlungsalgorithmus der hämophilen Arthropathie des oberen Sprunggelenkes

SummaryThe upper ankle joint is one of the targetjoints of the haemophilic patient. Therefore, the secondary arthritis of the upper ankle joint is one of the most frequent forms of haemophilic arthropathy. It is a secondary form of arthritis not only because of chronic synovitis and cartilage injury resulting from chronic recurrent intraarticular bleeds, but also due to the misalignment of the joint and abnormal joint stress. The consequences are manifest even in young patients and finally lead to upper ankle joint arthritis. In such clinical situations, the upper ankle joint-arthroplasty is a viable alternative to arthrodesis. After several years of bleeding of the upper ankle joint many patients with haemophilia suffer from symptomatic arthritis. Open joint cleansing considerably improves mobility in the upper ankle joint and alleviates the pain in the talonavicular joint. However, the recovered mobility of the arthritic upper ankle joint also activates arthritis, associated with severe pain. With no contraindication to upper ankle joint replacement, a cement-free prosthesis can be implanted. Three months after surgery, the patients are mobile, with good foot rolling properties without orthopaedic aids and without pain in the upper joint ankle. Concludion: In terms of biomechanics the upper ankle joint-arthroplasty is a superior alternative to arthrodesis in haemophilia patients. In order to minimize the complication rate, their treatment should be restricted to specially equipped interdisciplinary centers with adequately trained and experienced surgeons as well as haemostaseologists.

Upper ankle joint prostheses in haemophilia patients

Secondary arthrosis of the upper ankle joint (talocalcanean joint) is one of the most frequent forms of haemophilic arthropathy. It is a secondary form of arthrosis not only because of chronic synovitis and cartilage injury resulting from chronic recurrent intraarticular bleeds, but also due to the misalignment of the joint and abnormal joint stress. The consequences are manifest even in young patients and finally lead to subtalar joint ankylosis with the biomechanical disorder of foot drop (talipes equinus). In such clinical situations, implantation of a subtalar joint endoprosthesis is a viable alternative to arthrodesis. A man (age: 52 years), suffering from severe haemophilia A (residual FVIII activity < 1 %), no inhibitor formation. The patient has a history of several years of painful ankylosis of the right ankle joint and minor talipes equinus, and suffers from symptomatic talonavicular arthrosis. Open joint cleansing considerably improved mobility in the upper ankle joint and alleviated the pain in the talonavicular joint. However, the recovered mobility of the arthrotic upper ankle joint also activated the patient's arthrosis, associated with severe pain. As there was no contraindication to upper ankle joint replacement, a cement-free prosthesis was implanted. Three months after surgery, the patient was mobile, with good foot rolling properties without orthopedic aids, and without pain in his upper joint ankle. In terms of biomechanics an upper ankle joint endoprosthesis is a superior alternative to arthrodesis in haemophilia patients. In order to minimize the complication rate, the treatment of haemophilia patients should be restricted to specially equipped interdisciplinary treatment centers with adequately trained and experienced surgeons as well as haemostaseologists.

Utilization of Multiple Restorative Materials in Full‐Mouth Rehabilitation: A Clinical Report

Many different restorative materials are currently available for use in modern dentistry. Clinicians and dental technicians should be able to choose the most suitable materials for each patient based on research, anecdotal evidence, clinical experience, as well as patient's expectations and desires. The purpose of this article is to share the challenges presented in full-mouth rehabilitation and to describe the considerations in selecting three different restorative materials to achieve a successful restoration in terms of biomechanics, function, and esthetics. Interdisciplinary treatment planning, knowledge of available restorative materials, sequencing treatment modalities, and adequate communication between all parties involved are key to a successful treatment outcome when pursuing full-mouth restorative rehabilitation.

The Experimental Study of Mechanics-Heating Effect to Sand-Therapy in the Uyghur Medicine

Purpose: Experiment research and theory analysis to the heat transmission and mechanics property about organism tissue. Method: Heat transmission and the dynamic change of temperature should be survey in the course of sand-therapy, then compare it with simulative result; workpieces were made, buried in different temperature and buried in the sand for 30 minutes, to test its biomechanics property and compare to group without buried in sand. Result: (1) The initial temperature field of the sand was not well mixed. (2) The test spot of the electric thermocouple was inaccuracies when test the temperature. (3) Every parameter of the mathematical model is taken from the bibliography, it may not fix actually to the parameter of the patient. (4) In the model, we did not consider several factors such as sweat transit in the sand. (5) There was some differentiation between parameter of the experiment such as temperature, humidity, wind speed in the natural environment. The very common disease such as rheumarthritis, lumbag and cervical vertebra degeneration brings huge pain to the patients. Medical treatments which are often used by the medical institutions can not obtain efficient results. But sand-therapy, a great part of Uyghur medicine, has obviously effects to these diseases [1, 2]. The sand-therapy provides positive effects in such diseases taking place in the hot sand in Turfan in Xingjiang where special climate, special environment and strong sunshine have. But this treatment is greatly effected by environment and climate and only can take place between July to September. Nowadays, there is little research about the sand-therapy both domestically and internationally, among them concentrated on influence of medical parameter of the human body and exploration to cure the disease mechanism. The sand-therapy is effected by calorific, magnetic and mechanics, etc., involving a lot of disciplines. Some scholars have carried on qualitative analysis to sand-therapy and other heat-therapy in terms of biomechanics [3,4], others have carried on thermal effects by experiment manner and analysis [5,6], still others analysis sand-therapy deeply by animal experiment[7,8,9]. This paper has carried on experiment and theoretical analysis to part of hot-strength effect of Uyghur medicine[10,11] and mechanics of bone tissue by temperature of sand-therapy[12,13], based on thermal-physical model of thermal transmitting among human body and sand and numerical simulation of temperature change in human body and sand in the course of sand-therapy[14].

Biomechanical and Physiological Analyses of a Luggage-Pulling Task

The purpose of this study was to identify the degree of physical stresses on two-wheeled carry-on luggage users in terms of biomechanics and work physiology. Based on 3D kinematics, a 3D inverse dynamic biomechanical model having fifteen segments was developed to evaluate a one-hand pulling task. Joint reaction forces, joint moments and physiological variables (energy expenditure and heart rate) were measured from four subjects who performed 32 luggage-pulling tasks on a doublewide treadmill in the configurations of handle height (100 cm and 110 cm), handle rotation (0 degrees and 90 degrees ), pole angle (0 degrees and 10 degrees ), wheel diameter (8 cm and 15 cm), load weight (15 kg or 23 kg), center of mass (low and middle), carpeting (no and yes), trial day (first and second) and subject height (short and tall). ANOVA revealed that wheel diameter, center of mass and subject height were highly associated with the physical stresses of luggage users, especially their right arm. Although the task seems light work, users should place heavy belongings at the bottom of luggage when packing and manufacturers should give a priority to large wheels for ergonomic design.

How useful is satellite positioning system (GPS) to track gait parameters? A review

Over the last century, numerous techniques have been developed to analyze the movement of humans while walking and running. The combined use of kinematics and kinetics methods, mainly based on high speed video analysis and forceplate, have permitted a comprehensive description of locomotion process in terms of energetics and biomechanics. While the different phases of a single gait cycle are well understood, there is an increasing interest to know how the neuro-motor system controls gait form stride to stride. Indeed, it was observed that neurodegenerative diseases and aging could impact gait stability and gait parameters steadiness. From both clinical and fundamental research perspectives, there is therefore a need to develop techniques to accurately track gait parameters stride-by-stride over a long period with minimal constraints to patients. In this context, high accuracy satellite positioning can provide an alternative tool to monitor outdoor walking. Indeed, the high-end GPS receivers provide centimeter accuracy positioning with 5–20 Hz sampling rate: this allows the stride-by-stride assessment of a number of basic gait parameters – such as walking speed, step length and step frequency – that can be tracked over several thousand consecutive strides in free-living conditions. Furthermore, long-range correlations and fractal-like pattern was observed in those time series. As compared to other classical methods, GPS seems a promising technology in the field of gait variability analysis. However, relative high complexity and expensiveness – combined with a usability which requires further improvement – remain obstacles to the full development of the GPS technology in human applications.

Stretching: Mechanisms and Benefits for Sport Performance and Injury Prevention

Stretching is usually performed before exercise in an attempt to enhance performance and reduce the risk of injury. Most stretching techniques (static, ballistic, and proprioceptive neuromuscular facilitation) are effective in increasing static flexibility as measured by joint range of motion, but the results for dynamic flexibility as measured by active and passive stiffness, are inconclusive. The mechanisms of various stretching techniques in terms of biomechanics and neurology, the effectiveness of the combination of stretching with other therapies such as heat and cold, and the effectiveness of stretching for performance and injury prevention are reviewed. The possible mechanisms responsible for the detrimental effects of stretching on performance and the minimal effects on injury prevention are considered, with the emphasis on muscle dynamic flexibility. Further research is recommended to explore the mechanisms and effects of alternative stretching techniques on dynamic flexibility, muscle soreness, sport performance, and rate of injury.

Muscle, adipose, and connective tissue variations in intrinsic musculature of the adult human tongue.

The purpose of this investigation was to identify the composition and organization of lingual tissues underlying the histostructural and biomechanical functions of the adult human tongue. The small-scale structures of three intrinsic muscle regions, their principal cells, structural complexities, and differences in underlying tissue composition were compared to other skeletal muscle systems and the results discussed in relation to lingual morphology. Analysis of pixel color distributions determined the percent area concentration of each stained tissue component. Results indicated that muscle content increased from anterior to posterior (p <.0001). Greater adipose (p =.005) and connective tissue (p <.002) concentrations occurred in anterior regions. Dense collagen sheaths and elastic fibers found anteriorly occurred with less magnitude in medial and posterior sites. The unique elastin, collagen, and adipose connective tissue distributions found in intrinsic sampling sites are discussed in terms of understanding lingual biomechanics in both normal and pathologic states.

Physiology of the semicircular canals after surgical plugging.

Inactivation of individual semicircular canals by surgical occlusion (plugging) of the slender duct has been used in basic studies to elucidate the role of individual canal inputs to vestibular-mediated control systems and in clinical applications to treat certain vestibular disorders. The procedure has been shown to be highly effective in blocking sensitivity of individual canals, at least for moderate angular motion stimuli. Effectiveness does not extend to stimuli involving high accelerations where a residual response persists even after complete occlusion of the duct. The residual can be quite large at high-stimulus frequencies where sensitivity to angular motion approaches that of patent canals. The overall physiological effect of canal plugging is reported here in terms of the frequency-dependent attenuation in gain and phase shift of primary afferents. Plug-canal responses are quantitatively described in terms of biomechanics of the deformable labyrinth.

Clinical application of controlled stress to the healing extensor tendon: a review of 112 cases.

The purposes of this article are to describe an early passive motion program for the healing extensor tendon and to report the results and trends noted in a review of 112 complex extensor tendon injuries treated with this therapeutic technique. The rationale for this technique is based on a review of the physiologic response of healing tendon to controlled stress. Clinical application is dependent on a biomechanical study of extensor tendon excursion, which allows the therapist to apply controlled stress to the healing tendon with precision. The early passive motion technique is considered in terms of physiology, biomechanics, clinical application, and results. The author concludes that early controlled passive motion for the complex extensor tendon injury in zones V, VI, VII, T IV, and TV is a safe and effective rehabilitation technique that reduces complications associated with extensor tendon injury and repair.

Evaluation of Job Physical Requirements to Aid in the Placement of Medically Restricted Workers

This presentation describes the application of ergonomic principles by one company and its medical department to aid in the placement of medically restricted employees. Job physical requirements are systematically defined in terms of biomechanics and energy expenditure parameters as are workers' physical limitations. The job and employee data are then used to promote the safe, healthful and efficient job placement of the employee. The job physical requirement data has also been valuable in the medical treatment of workers and in workplace redesign.