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Results for “Musculoskeletal System”

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At least 937 records · Page 52Linked to original sources

PubMed2000

Adaptive neural network control of cyclic movements using functional neuromuscular stimulation.

In this study, we evaluated the performance of an adaptive feedforward controller and its ability to automatically develop and customize stimulation patterns for use in functional neuromuscular stimulation (FNS) systems. Results from previous experiments using the pattern generator/pattern shaper (PG/PS) controller to generate isometric contractions demonstrated its ability to adjust stimulation patterns to account for recruitment nonlinearities and muscle dynamics. In this study, the PG/PS controller was tested under isotonic conditions. This evaluation required the PG/PS controller to account for muscle length-tension and force-velocity properties as well as limb dynamics. The performance of the adaptive controller was also compared with that of a proportional-derivative (PD) feedback controller. The PG/PS controller is composed of a neural network system that adaptively filters a periodic signal to produce a muscle stimulation pattern for generating cyclic movements. We used computer-simulated models to determine controller parameters for the PG/PS and PD controller that perform well across a variety of musculoskeletal systems. The controllers were then experimentally evaluated on both legs of two subjects with spinal cord injury. Results indicated that the PG/PS controller was able to achieve and maintain better tracking performance than the PD controller. This study indicates that the PG/PS control system may provide an effective mechanism for automatically customizing stimulation patterns for individuals using FNS systems.

Algorithms↗

PubMed1997

Incidence of long-term sick-listing in an urban area of Sweden and its relationship with demographic data of the population.

By checking the card indexes of seven out of twelve Social Insurance Offices covering 66% of the total wage-earning population in the city of Göteborg the patients recorded for 90 days of continuous sick-listing were classified into four diagnostic categories according to the doctor's certificate: "non-specific pain" and "specific pain" of the musculoskeletal system, "other pain" and "non-pain" diagnoses. The overall yearly incidence of 90 days' sick-listing averaged 5.4%. A significant correlation was found between the incidence of 90 days' sick-listing due to "non-pain" and musculoskeletal pain diagnoses and the proportion of demographic characteristics of the areas. The hypothesis of presuming the highest association between non-specific pain diagnoses and demographic factors was rejected.

Child↗

PubMed1999

The role of rehabilitation in the treatment of balance disorders.

The vestibular system registers changes in head position, gravity, vibration, acceleration and deceleration. This information is then transmitted to the central nervous system, where additional information from the visual and auditory systems, muscles, tendons, joints and skin, serve to regulate and maintain the equilibrium and orientation of the system. Vision plays the most obvious part in continual monitoring of the environment. Distances, speeds of linear and angular movement, and changes of direction, can all be estimated with experience and be integrated in the central nervous system with those received by other sensory systems. Light touch and pressure receptors in the skin detect bodily contact with the environment and are an essential source of data in walking, cycling, motoring, flying and other activities. Proprioception provides data regarding the instantaneous mechanical disposition of the musculoskeletal system as it relates to the force of gravity acting upon it. The functional recovery that occurs after unilateral vestibular lesions is referred to as "vestibular compensation" and consists of all the processes of neurological reorganization that allow recovering balance after a unilateral vestibular lesion. Exercises are particularly useful in helping patients to overcome disturbances, associated with balance disorders. The purpose of these selected exercises is to build up a tolerance mechanism in the brain, which will compensate for the unequal balance of the two ears.

Exercise↗

PubMed2004

Anterior chest pain: musculoskeletal considerations.

The clinical symptom of anterior chest pain generally elicits a long list of diagnoses. When cardiac and pleural conditions are excluded, conditions that affect the musculoskeletal system become important considerations. Many of these conditions have characteristic imaging features that allow accurate diagnosis. In others, the imaging findings can be instrumental in directing the appropriate course of action. This article reviews the imaging features of a number of musculoskeletal entities that present with anterior chest pain including traumatic, rheumatologic, inflammatory, infectious, and neoplastic conditions.

Chest Pain↗

PubMed2004

Combined finite-element and rigid-body analysis of human jaw joint dynamics.

The jaw joint plays a crucial role in human mastication. It acts as a guidance for jaw movements and as a fulcrum for force generation. The joint is subjected to loading which causes tensions and deformations in its cartilaginous structures. These are assumed to be a major determinant for development, maintenance and also degeneration of the joint. To analyze the distribution of tensions and deformations in the cartilaginous structures of the jaw joint during jaw movement, a dynamical model of the human masticatory system has been constructed. Its movements are controlled by muscle activation. The articular cartilage layers and articular disc were included as finite-element (FE) models. As this combination of rigid-body and FE modeling had not been applied to musculoskeletal systems yet, its benefits and limitations were assessed by simulating both unloaded and loaded jaw movements. It was demonstrated that joint loads increase with muscle activation, irrespective of the external loads. With increasing joint load, the size of the stressed area of the articular surfaces was enlarged, whereas the peak stresses were much less affected. The results suggest that the articular disc enables distribution of local contact stresses over a much wider area of the very incongruent articular surfaces by transforming compressive principal stress into shear stress.

Bite Force↗

PubMed1989

A double-blind randomised multicentre study with tenoxicam, piroxicam and diclofenac sodium retard in the treatment of ambulant patients with osteoarthritis and extra-articular rheumatism.

In a randomised, double-blind comparative study involving a total of 1,630 out-patients, tenoxicam (a new non-steroidal anti-inflammatory drug belonging to the oxicam group), piroxicam and diclofenac retard were tested for their efficacy and tolerability in the treatment of osteoarthritis (OA) and extra-articular rheumatism (EAR). Single doses of 20 mg tenoxicam, 20 mg piroxicam or 100 mg diclofenac sodium retard were administered daily. Tenoxicam was found to be as effective as piroxicam and diclofenac sodium retard in the treatment of degenerative and extra-articular rheumatic disorders of the musculo-skeletal system. When baseline values were compared with values obtained at all subsequent examinations, all evaluation parameters for all three substances showed improvement. In analyses of the frequency, degree of severity and type of undesired effects, tenoxicam proved to be superior to the reference drugs. This was particularly evident from an improved gastrointestinal and central nervous system (CNS) tolerance and a lower rate of withdrawal from treatment. Tenoxicam has a favourable risk/benefit ratio and can be recommended for the treatment of chronic pain due to inflammation resulting from degenerative and extra-articular rheumatic disorders of the musculoskeletal system.

Aged↗

PubMed2001

Musculoskeletal causes of chest pain.

BACKGROUND: Chest pain is a common presenting problem to general practitioners and accident and emergency departments. Such a symptom generates anxiety in both patients and their medical attendants, for fear that this symptom represents a life threatening event. Numerous investigations often ensue, adding to the physical and financial burden on an already stressed health system. Musculoskeletal causes of chest pain are common but frequently overlooked. OBJECTIVE: This article aims to outline some of the more common musculoskeletal problems which may present as chest pain, and to present a practical approach to their diagnosis and management. DISCUSSION: It is estimated that somewhere in the vicinity of 20-25% of noncardiac chest pain has a musculoskeletal basis. Careful history taking to identify red flag conditions differentiates those who require further investigation. Historical features suggesting a musculoskeletal cause include pain on specific postures or physical activities. A musculoskeletal diagnosis can usually be confirmed by clinical examination alone, the key to which is reproducing the patient's pain by either a movement or more specifically palpation over the structure that is the source of the pain. Confirming the diagnosis, explanation and reassurance allay anxiety. Management strategies include manual therapy, the provision of analgesia and anti-inflammatory agents, either topically, orally or by injection. Focal injection of local anaesthetic alone may also be a useful diagnostic and therapeutic tool.

Adult↗

PubMed2003

Stability of bipedal stance: the contribution of cocontraction and spindle feedback.

The aim of this study is to assess the contribution of cocontraction and spindle feedback to local stability during bipedal stance. To that aim, an existing nonlinear state space model of the human musculoskeletal system is linearized in a reference equilibrium state. The maximal real part of the eigenvalues of the linearized system matrix A and the low-frequency joint stiffness are used as a measure of local stability. Muscle properties, as represented in a Hill-type muscle model, are shown to improve the behavior, the improvement being larger at high cocontraction. However, even at maximal cocontraction the low-frequency joint stiffness generated by the muscle properties is insufficient to yield a locally stable system. It follows that feedback is necessary to ensure local stability. In this study, the potential contribution of spindle feedback is investigated by optimizing the feedback gains for contractile element length and velocity for each muscle. It is found that in the case of time-delayed negative feedback, it is impossible to stabilize the system on the basis of spindle feedback. When positive time-delayed feedback is allowed, a barely stable system is obtained. When the time delays are removed, the feedback gains can be chosen such that a locally stable system is obtained, indicating the limitations imposed by the presence of time delays. Finally, it is shown that for small perturbations the response of the linear system to an arbitrary perturbation is similar to that of the nonlinear system, indicating the validity of the approach used. It is concluded that the combination of muscle properties and time-delayed spindle feedback is insufficient to obtain a system with reasonable local stability.

Feedback↗

PubMed1998

Musculoskeletal ultrasonography.

This article introduces ultrasound in the evaluation of the musculoskeletal system. An emphasis is placed on currently accepted applications, and examples are included to illustrate pathologic conditions. Topics of current investigations are also presented. The efficacy of ultrasound, combined with its inaccessibility and low cost, has earned it an important role in musculoskeletal imaging.

Connective Tissue↗

PubMed2004

Musculoskeletal disorders associated with HIV infection and AIDS. Part II: non-infectious musculoskeletal conditions.

This section of a two-part series on musculoskeletal disorders associated with HIV infection and AIDS reviews the non-infectious musculoskeletal conditions. In the first part, the infectious conditions were reviewed. The non-infectious conditions include polymyositis, drug-induced myopathy, myositis ossificans, adhesive capsulitis, avascular necrosis, bone marrow abnormalities, and hypertrophic osteoarthropathy. Inflammatory and reactive arthropathies are more prevalent in HIV-positive individuals, and a separate section is dedicated to these conditions, including Reiter's syndrome, psoriatic arthritis, HIV-associated arthritis, painful articular syndrome, and acute symmetric polyarthritis. Lastly, we include a discussion of HIV-related neoplastic processes that affect the musculoskeletal system, namely Kaposi's sarcoma and non-Hodgkin's lymphoma.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Computerized baropodometry in obese patients.

BACKGROUND: Few studies have investigated the influence of obesity on the structural and functional performance of the feet, and its potential implications for the musculoskeletal system. Computerized baropodometric analysis (CPA) is a new investigation for the center of pressure, plantar surface area and plantar pressure while standing on the platform of a specialized apparatus. CPA is relevant to gait and posture, and may be important as well for postoperative musculoskeletal disorders. We investigated the biomechanical dysfunctions of foot pressure by means of CPA in bariatric and non-bariatric subjects. METHODS: Subjects (n=67, 71.6% females, age 40.8 +/- 13.8 years, BMI 31.4 +/- 11.0 kg/m(2)) included obese (BMI 30.0-60.0 kg/m(2), n=27), overweight (BMI 25.0-29.9 kg/m(2), n=12) and normal-weight controls (BMI 20.0-24.9 kg/m(2), n=28) of equivalent age and gender. Variables included center of pressure location, plantar ground contact area and pressure, and pressure patterns (maximum and average) in different regions of the foot, during quiet standing on the platform of the baropodometer. RESULTS: A significant increase was detected for peak pressure on forefoot and plantar ground contact area in the obese group, compared to control and overweight cases, during quiet standing. CONCLUSION: Excessive forefoot pressure and enlarged support area were a consequence of obesity, mirroring the efforts of the obese subject to acquire a wider and stronger support base. Although this is originally a physiological change, it may result in maladaptative and degenerative musculoskeletal consequences. Re-education exercises may be advised, in combination with bariatric surgery in the morbidly obese, aiming at restoration of normal gait and posture, as well as at minimization of stress damage to bones and joints in the axial skeleton.

Adult↗

PubMed1993

The pial ligaments of the anterior spinal artery and their stretch receptors. A spinal cord distraction-sensing system?

The pial sheath of the anterior spinal artery displays a system of ligaments that course along the ventral surfaces of the anterior spinal artery and its medullary feeder arteries on the lower half of the spinal cord. Frequently, discrete ligamentous straps extend from these anterior spinal artery ligaments to the sheath of an anterior spinal nerve root to reinforce the general cauda equina pial connections to this system. Microscopy of ligament sections revealed that numerous Golgi-type neurofascicular receptors were oriented longitudinally among the ligament fascicles and associated with well-myelinated nerves. As this type of mechanoreceptor has been known only in association with stretch reflex mediation in the musculoskeletal system, it appeared likely that these anterior spinal artery ligaments and their homologous type of receptors may be implicated in sensing distraction of the thoracolumbar spinal cord and protectively modifying the actions of the involved spinal musculature.

Aged↗

PubMed2003

Melanocortin-4 receptor messenger ribonucleic acid expression in rat cardiorespiratory, musculoskeletal, and integumentary systems.

We determined melanocortin-4 receptor (MC4-R) mRNA ontogeny in the rat using in situ hybridization and a rat MC4-R riboprobe and showed numerous peripheral sites of expression for MC4-R. The developing heart showed MC4-R mRNA expression as early as embryonic day (E) 14. In the lungs of E16-E20 fetuses, the cells surrounding developing bronchi expressed relatively strong in situ signal. Muscles associated with the respiratory system such as diaphragm and intercostal muscle expressed MC4-R mRNA as early as E14. Occipital and tongue muscles, in particular the genioglossus, showed diffuse signal at E15-E20. In the eye, a discrete signal was detected in an outer neuroblastic layer which may correspond to retina or extraocular muscle. Developing limb buds expressed relatively strong signal at E14, whereas skull bone and joint capsules of the paw of the forelimb showed signal at E18-E20. Using RT-PCR and ribonuclease protection assays, we determined that MC4-R mRNA is also expressed in adult rat heart, lung, kidney, and testis. The expression of the MC4-R in cardiorespiratory, musculoskeletal, and integumentary systems supports functional roles for the MC4-R in addition to its roles in appetite, weight control, and regulation of linear growth.

Animals↗

PubMed2003

Musculoskeletal disorders in diabetes mellitus: an update.

Diabetes mellitus (DM) is associated with several musculoskeletal disorders. The incidence of DM and the life expectancy of the diabetic patient have both increased, resulting in the increased prevalence and clinical importance of musculoskeletal alterations in diabetic subjects. The exact pathophysiology of most of these musculoskeletal disorders remains obscure. Connective tissue disorders, neuropathy, vasculopathy or combinations of these problems, may underlie the increased incidence of musculoskeletal disorders in DM. The development of musculoskeletal disorders is dependent on age and on the duration of DM; however, it has been difficult to show a direct correlation with the metabolic control of DM. Most of these disorders can be diagnosed clinically, but some radiological examination may help, especially in differential diagnosis. No specific treatment is available, and treatments used in the general population are also recommended for diabetic subjects. Infectious complications affecting the musculoskeletal system are common in DM subjects, and these, possibly life-threatening, complications should be systematically discussed.

Diabetes Complications↗

PubMed1992

Electromagnetic field effects on cells of the immune system: the role of calcium signaling.

During the past decade considerable evidence has accumulated demonstrating that nonthermal exposures of cells of the immune system to extremely low-frequency (ELF) electromagnetic fields (< 300 Hz) can elicit cellular changes that might be relevant to in vivo immune activity. A similar responsiveness to nonionizing electromagnetic energy in this frequency range has also been documented for tissues of the neuroendocrine and musculoskeletal system. However, knowledge about the underlying biological mechanisms by which such fields can induce cellular changes is still very limited. It is generally believed that the cell membrane and Ca(2+)-regulated activity is involved in bioactive ELF field coupling to living systems. This article begins with a short review of the current state of knowledge concerning the effects of nonthermal levels of ELF electromagnetic fields on the biochemistry and activity of immune cells and then closely examines new results that suggest a role for Ca2+ in the induction of these cellular field effects. Based on these findings it is proposed that membrane-mediated Ca2+ signaling processes are involved in the mediation of field effects on the immune system.

Animals↗

PubMed1993

Prevention, clinical, and pathophysiological research on vibration syndrome.

In the 1950s, introduction of portable power tools into the production process of many industries began on a large scale around the world and resulted in many cases of occupational vibration syndrome after the 1960s. There was an urgent need to undertake preventive steps, medical assessment and therapy throughout the world. At the end of 1964, our investigation began in Japanese national forests, and then in mining and stone quarries. Our research and efforts resulted in a comprehensive system for prevention of vibration syndrome in the Japanese national forest industry. It has presented a good model of prevention for other industries in Japan. Clinical and pathophysiological research on vibration syndrome in the 1960s and 1970s clarified disturbances of the peripheral circulatory, nervous, and musculoskeletal systems. From the mid-1970s, neurophysiological, neurochemical, and clinical research on vibration syndrome in relation to the autonomic nervous system developed. Our studies contributed to the advancement of research in this field. More in-depth study is needed to determine the role of the autonomic nervous system in vibration syndrome.

Humans↗

PubMedDate not supplied

Long-term musculoskeletal disorders and work career in 55-year-old workers.

The purpose of the present study was to describe the associations between long-term disorders of musculoskeletal system and work career in elderly workers. The data were obtained by a postal questionnaire and clinical examinations. The study group consisted of 778 elderly urban persons, who were 55 years old and who lived in the city of Oulu in northern Finland. Long-term musculoskeletal disorders were reported by 62% of the women and 57% of the men. The high prevalence of musculoskeletal disorders was significantly associated with heavy physical work. However, job mobility and declining work career were correlated with the occurrence of long-term musculoskeletal disorders in women whereas advanced work career was connected with a low prevalence of long-term musculoskeletal disorders.

Chronic Disease↗

PubMed1996

Musculoskeletal symptoms among dentists in a dental school.

A cross-sectional study of symptoms from the musculoskeletal system among employees in a school of dentistry was performed. A questionnaire was answered by 139 dentists, dental auxiliaries and office workers, e.g. 68% of the employees. The answers from the dentists were compared to the answers from all the other employees. No significant differences in musculoskeletal symptoms between the dentists and the other employees were found. Female dentists reported more musculoskeletal symptoms than did male dentists. No difference was found comparing the occurrence of musculoskeletal symptoms among female dentists and females in the reference group. This indicates that the symptoms are not related to the work as a dentist, but to female working conditions in general or to factors outside work.

Adult↗