RESUMEN
Swelling behavior is an electrochemical mechanical property of articular cartilage. It plays an important role in weight bearing and joint lubrication. In this study, the altered transient and inhomogeneous swelling behavior of the degenerated articular cartilage was observed and quantified in situ using ultrasound. Three groups of bovine patellar articular cartilage samples (n = 10 x 3) were obtained and digested by trypsin for 10, 20 and 30 min respectively to mimic different levels of degeneration. The osmotic-free shrinkage and swelling behavior induced by changing the concentration of the bathing saline solution from 0.15 M to 2 M and then back to 0.15 M were characterized using high-frequency ultrasound (central frequency = 35 MHz) before and after digestion. It was found that the degenerated cartilage specimens showed a weaker shrinkage-swelling behavior compared with the normal cartilage samples. However, no significant differences in the peak shrinkage or swelling strains were observed between different groups. The absolute values of the peak shrinkage strain significantly (p < 0.05) decreased by 45.4%, 42.1% and 50.6% respectively after the trypsin digestion for 10, 20 and 30 min, but such significance was not demonstrated for the peak swelling strains. Due to the potential alterations in the collagen-PG matrix during trypsin digestion, the correlation between the swelling strain and the shrinkage strain of the degenerated samples changed slightly in comparison with the normal samples. The proposed ultrasound method has been successfully used to measure the transient and inhomogeneous swelling behavior of the degenerated articular cartilage and has the potential for the characterization of osteoarthritis.
Asunto(s)
Cartílago Articular/diagnóstico por imagen , Cartílago Articular/metabolismo , Proteoglicanos/deficiencia , Animales , Cartílago Articular/citología , Bovinos , Presión Osmótica , Tripsina/metabolismo , UltrasonografíaRESUMEN
Biomimetic apatite/collagen composite coating, previously reported particularly with regard to its fabrication, characterization and interaction with osteoblast-like cells, has been investigated in this study to understand the response of human mesenchymal stem cells (hMSC) to such surface. PLLA films and PLLA films with apatite coating were compared with PLLA films with apatite/collagen composite coating. The hMSC morphology in response to such conditions was first observed using fluorescence microscopy. To further understand such cell-material interactions at a molecular level, integrin expression, actin assembly and vinculin-positive focal adhesion plaques were examined. Our results demonstrated that spreading of stem cells on the apatite/collagen composite surface was determined best among the three types of surfaces, followed by the apatite surface and then the PLLA control. Integrin expression on the apatite/collagen surface was higher than those on the apatite surface and PLLA surface. Immunostaining for vinculin and actin suggested that the composite coating on PLLA enhanced the formation of focal adhesion.
Asunto(s)
Apatitas/química , Técnicas de Cultivo de Célula/métodos , Colágeno/química , Ácido Láctico/química , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/fisiología , Polímeros/química , Ingeniería de Tejidos/métodos , Adhesión Celular , Tamaño de la Célula , Células Cultivadas , Humanos , PoliésteresRESUMEN
To investigate the methods to improve the cell-material interaction of devices or tissue engineering scaffolds made of poly(L-lactic acid) (PLLA) polymer, apatite and apatite/collagen composite coatings were formed on PLLA films within 24 h through accelerated biomimetic processes. In vitro investigation using Saos-2 osteoblast-like cells through cell culture was conducted to assess the biological performance of these biomimetic coatings. The cell morphology on three types of surfaces, viz., PLLA film, PLLA film with the apatite coating, and PLLA film with the apatite/collagen composite coating, was studied using scanning electron microscopy (SEM). Cell viability was estimated using the MTT assay. The differentiated cell function was assessed by measuring the alkaline phosphatase (ALP) activity. The results obtained indicated that the biomimetic apatite and apatite/collagen composite coatings could significantly enhance the proliferation and differentiation of osteoblast-like cells. The apatite/collagen composite coating appears to be promising for the surface modification of PLLA-based devices with much improved interactions with osteoblastic cells.
Asunto(s)
Apatitas/química , Materiales Biocompatibles/química , Biomimética , Colágeno/química , Ácido Láctico/química , Osteoblastos/citología , Polímeros/química , Fosfatasa Alcalina/metabolismo , Adhesión Celular , Técnicas de Cultivo de Célula/instrumentación , Proliferación Celular , Diseño de Equipo , Humanos , Ensayo de Materiales , Osteoblastos/metabolismo , Poliésteres , ViscosidadRESUMEN
Articular cartilage is a biological weight-bearing tissue covering the bony ends of articulating joints. Negatively charged proteoglycan (PG) in articular cartilage is one of the main factors that govern its compressive mechanical behavior and swelling phenomenon. PG is nonuniformly distributed throughout the depth direction, and its amount or distribution may change in the degenerated articular cartilage such as osteoarthritis. In this paper, we used a 50 MHz ultrasound system to study the depth-dependent strain of articular cartilage under the osmotic loading induced by the decrease of the bathing saline concentration. The swelling-induced strains under the osmotic loading were used to determine the layered material properties of articular cartilage based on a triphasic model of the free-swelling. Fourteen cylindrical cartilage-bone samples prepared from fresh normal bovine patellae were tested in situ in this study. A layered triphasic model was proposed to describe the depth distribution of the swelling strain for the cartilage and to determine its aggregate modulus H(a) at two different layers, within which H(a) was assumed to be linearly dependent on the depth. The results showed that H(a) was 3.0+/-3.2, 7.0+/-7.4, 24.5+/-11.1 MPa at the cartilage surface, layer interface, and deep region, respectively. They are significantly different (p<0.01). The layer interface located at 70%+/-20% of the overall thickness from the uncalcified-calcified cartilage interface. Parametric analysis demonstrated that the depth-dependent distribution of the water fraction had a significant effect on the modeling results but not the fixed charge density. This study showed that high-frequency ultrasound measurement together with triphasic modeling is practical for quantifying the layered mechanical properties of articular cartilage nondestructively and has the potential for providing useful information for the detection of the early signs of osteoarthritis.
Asunto(s)
Cartílago Articular/diagnóstico por imagen , Cartílago Articular/fisiopatología , Ultrasonido , Animales , Fenómenos Biomecánicos , Bovinos , Edema/fisiopatología , Modelos Biológicos , Modelos Teóricos , Presión Osmótica , Rótula/citología , UltrasonografíaRESUMEN
BACKGROUND/AIMS: Quantitative and objective technique to assess radiation-induced tissue fibrosis is important for clinicians to estimate the efficiency of radiotherapeutic schemes. It has been widely reported that ultrasonic properties are sensitive to changes of acoustic scatterers in biological tissues. Therefore, measurement of ultrasonic properties may serve as a potential assessment technique for irradiated skins. The aim of the present study is to investigate the reliability of such measurement so as to evaluate its potentials for future clinical applications. METHODS: Ultrasonic parameters including attenuation slope (beta), integrated attenuation (IA) and integrated backscatter (IBS) were measured for the frequency range of 10-25 MHz from echographic signals of the forearm and neck dermis of 20 normal subjects in vivo. The intra- and inter-rater reliability of measurement was assessed in 10 normal subjects using intra-class correlation coefficients (ICC) and Bland-Altman test. RESULTS: The intra- and inter-rater measurement was demonstrated to be reliable as indicated by high ICC values generally larger than 0.80. In addition, the ultrasonic parameters could successfully differentiate the skins in the neck and forearm regions. CONCLUSION: The measurement provided reliable information on the ultrasonic properties of the skins and could be potentially applied to comparative clinical trials to assess the late effects of radiotherapy on skins.
Asunto(s)
Interpretación de Imagen Asistida por Computador/métodos , Fenómenos Fisiológicos de la Piel/efectos de la radiación , Piel/diagnóstico por imagen , Terapia por Ultrasonido/métodos , Ultrasonografía/métodos , Adulto , Estudios de Factibilidad , Femenino , Humanos , Masculino , Dosis de Radiación , Radiometría/métodos , Reproducibilidad de los Resultados , Dispersión de Radiación , Sensibilidad y Especificidad , SonicaciónRESUMEN
An innovative computer-aided method to plan and execute long bone fracture reduction using Dynafix unilateral external fixator (EF) is presented and validated. A matrix equation, which represents a sequential transformation from proximal to distal ends, was derived and solved for the amount of rotation and translation required at each EF joint to correct for a displaced fracture using a non-linear least square optimization method. Six polyurethane-foam models of displaced fracture tibiae were used to validate the method. The reduction accuracy was quantified by calculating the residual translations (xr, yr, zr), the residual displacement (dr), and the residual angulations (alphar, betar, gammar) based on the X-Y-Z Euler angle convention. The experiment showed that the mean+/-S.D. of alphar, betar, gammar, xr, yr, zr and dr were 1.57+/-1.14 degrees, 1.33+/-0.90 degrees, 0.71+/-0.70 degrees, 0.98+/-1.85, 0.80+/-0.67, 0.30+/-0.27, and 0.50+/-0.77 mm, respectively, which demonstrated the accuracy and reliability of the method. Instead of adjusting the fixator joints in-situ, our method allows for off-site adjustment of the fixator joints and employs the adjusted EF as a template to guide the surgeons to manipulate the fracture fragments to complete the reduction process. Success of this method would allow surgeons to perform fracture reduction more objectively, efficiently and accurately yet reduce the radiation exposure to both the involved clinicians and patients and lessen the extent of periosteum and soft tissue disruption around the fracture site.
Asunto(s)
Huesos/fisiología , Simulación por Computador , Fracturas Óseas/fisiopatología , Modelos Biológicos , Fijadores Externos , Fracturas Óseas/cirugía , Humanos , Cirugía Asistida por ComputadorRESUMEN
A primary function of external fixator is to stabilize the fracture site after fracture reduction. Conventional fracture reduction method would result in fixator configurations deviated from its neutral configuration. How the non-neutral configurations would affect the biomechanical performance of unilateral external fixators is still not well-documented. We developed a finite element model to predict the fixation stiffness of the Dynafix unilateral external fixator at arbitrary configurations under compression, torsion, three-point, and four-point bending. Experimental testing was done to validate the model using six Dynafix unilateral external fixators in neutral and particular non-neutral configurations. Effects of loading directions on bending stiffness were also studied. It appeared that the model succeeded in revealing the relative stiffness of the neutral and non-neutral configuration in all the loading conditions. Our results also demonstrated that bending stiffness could vary substantially for different loading directions and the principle loading directions could be very different for different fixator configurations. Therefore, a more logical way to compare the bending stiffness is to identify the principle loading directions of each fixator configuration and used their maximum and minimum bending stiffness as comparison criteria. Given that fixator configurations could substantially change the stiffness properties of the bone-fixator system, computer simulation with finite element modeling of this kind will provide useful clinical information on the rigidity of certain configurations in stabilizing the fracture site for bone healing.
Asunto(s)
Análisis de Falla de Equipo , Fijadores Externos , Fijación de Fractura/instrumentación , Modelos Teóricos , Simulación por Computador , Elasticidad , Estrés Mecánico , Resistencia a la Tracción , Soporte de PesoRESUMEN
This paper describes the development of a miniaturized wearable vital sign monitor which is aimed for use by elderly at home. The development of a compound sensor for pulse rate, motion, and skin temperature is reported. A pair of infrared sensor working in reflection mode was used to detect the pulse rate from various sites over the body including the wrist and finger. Meanwhile, a motion sensor was used to detect the motion of the body. In addition, the temperature on the skin surface was sensed by a semiconductor temperature sensor. A prototype has been built into a box with a dimension of 2 x 2.5 x 4 cm3. The device includes the sensors, microprocessor, circuits, battery, and a wireless transceiver for communicating data with a data terminal.
Asunto(s)
Técnicas Biosensibles/instrumentación , Servicios de Atención de Salud a Domicilio , Monitoreo Ambulatorio/instrumentación , Movimiento , Pulso Arterial , Anciano , Tecnología Biomédica/instrumentación , Temperatura Corporal , Humanos , Informática Médica/instrumentación , TelemedicinaRESUMEN
A cross-sectional study was conducted to investigate the foot arch function of Chinese children. A total of 2715 children, 1246 girls, and 1369 boys, 4-18 years of age were recruited from kindergartens, primary, and secondary schools. The dynamic footprints of the children were collected using a portable pressure-sensing mat. The Contact Force Ratio (CFR, i.e. the ratio of the mid-foot loading to the total loading of the contacted foot, with the toes ignored) of each age group was calculated. In general, the CFR decreased from 4 to 10 years and plateaued at 10-12 years and then increased until 15-16 years. An abnormal low arch foot was defined as the foot that had a CFR value larger than the corresponding age mean plus one standard deviation. The cut-off CFR values of each age group were calculated. With the exception of the 17 years age group, which consisted of a relatively small number of subjects, the percentage of low arch subjects of all the other age groups ranged from 15 to 20%.
Asunto(s)
Desarrollo Infantil/fisiología , Pie Plano/prevención & control , Pie/anatomía & histología , Marcha/fisiología , Adolescente , Factores de Edad , Análisis de Varianza , Peso Corporal , Niño , Preescolar , China/epidemiología , Estudios de Cohortes , Estudios Transversales , Femenino , Pie Plano/diagnóstico , Pie Plano/epidemiología , Deformidades Adquiridas del Pie/prevención & control , Humanos , Masculino , Probabilidad , Valores de Referencia , Medición de Riesgo , Sensibilidad y Especificidad , Factores SexualesRESUMEN
Research in elasticity imaging typically relies on 1-10 MHz ultrasound. Elasticity imaging at these frequencies can provide strain maps with a resolution in the order of millimetres, but this is not sufficient for applications to skin, articular cartilage or other fine structures. We developed a prototype high resolution elastomicroscopy system consisting of a 50 MHz ultrasound backscatter microscope system and a calibrated compression device using a load cell to measure the pressure applied to the specimen, which was installed between a rigidly fixed face-plate and a specimen platform. Radiofrequency data were acquired in a B-scan format (10 mm wide x 3 mm deep) in specimens of mouse skin and bovine patellar cartilage. The scanning resolution along the B-scan plane direction was 50 microm, and the ultrasound signals were digitized at 500 MHz to achieve a sensitivity better than 1 microm for the axial displacement measurement. Because of elevated attenuation of ultrasound at high frequencies, special consideration was necessary to design a face-plate permitting efficient ultrasound transmission into the specimen and relative uniformity of the compression. Best results were obtained using a thin plastic film to cover a specially shaped slit in the face-plate. Local tissue strain maps were constructed by applying a cross-correlation tracking method to signals obtained at the same site at different compression levels. The speed of sound in the tissue specimen (1589.8+/-7.8 m s(-1) for cartilage and 1532.4+/-4.4 m s(-1) for skin) was simultaneously measured during the compression test. Preliminary results demonstrated that this ultrasound elastomicroscopy technique was able to map deformations of the skin and articular cartilage specimens to high resolution, in the order of 50 microm. This system can also be potentially used for the assessment of other biological tissues, bioengineered tissues or biomaterials with fine structures.
Asunto(s)
Microscopía/instrumentación , Microscopía/métodos , Sistema Musculoesquelético/diagnóstico por imagen , Ultrasonografía/instrumentación , Ultrasonografía/métodos , Animales , Biofisica/métodos , Calibración , Cartílago Articular/diagnóstico por imagen , Cartílago Articular/patología , Bovinos , Elasticidad , Estudios de Factibilidad , Procesamiento de Imagen Asistido por Computador , Ratones , Ratones Desnudos , Modelos Estadísticos , Rótula/diagnóstico por imagen , Rótula/patología , Dispersión de Radiación , Piel/diagnóstico por imagen , Piel/patología , UltrasonidoRESUMEN
The traditional theory on subtalar joint neutral position and intrinsic foot deformities for the evaluation and treatment of foot and ankle disorders has been the basis for foot orthotics for many years. Although clinical evaluations have suggested a relationship between subtalar pronation and a variety of lower limb problems, such as shin splints and anterior knee pain, recent research has raised serious concerns about the reliability and validity of the assessment and intervention methods. Results of recent studies in foot biomechanics suggest that the orthosis design to control foot alignment should stabilise the medial apical bony structure of the arch to control the first ray mobility and transmit load through the lateral support structures of the foot, locking the calcaneocuboid joint and decreasing strain in the plantar aponeurosis. The concept of "posting" according to a measured foot deformity is de-emphasised. Reliable foot impression procedures are required to provide appropriate orthotic design and thus management. A prone lying position manipulated foot impression method using polycaprolactone based low temperature thermoplastic material was introduced. Ten (10) subjects were recruited to participate in the reliability tests, which were conducted by 2 orthotists specialized in foot orthotics. Results showed high intrarater and interrater reliability of the measured forefoot width and the navicular height. The reliability of the forefoot-rearfoot relationship was demonstrated by the small variance of the root mean square calculation. Subsequently orthotic intervention can be done in a more consistent manner.
Asunto(s)
Pie/anatomía & histología , Aparatos Ortopédicos , Sulfato de Calcio , Niño , Diseño de Equipo , Humanos , Reproducibilidad de los Resultados , Soporte de PesoRESUMEN
Recent commercially available miniature sensors have the potential to improve the functions of functional electrical stimulation (FES) systems in terms of control, reliability and robustness. A new control approach using a miniature gyroscope and an accelerometer was studied. These sensors were used to detect the linear acceleration and angular velocity of residual voluntary movements on upper limbs and were small and easy to put on. Five healthy subjects and three cervical spinal cord injured subjects were recruited to evaluate this controller. Sensors were placed on four locations: the shoulder, upper arm, wrist and hand. A quick forward-and-backward movement was employed to produce a distinctive waveform that was different from general movements. A detection algorithm was developed to generate a command signal by identifying this distinctive waveform through the detection of peaks and valleys in the sensor's signals. This command signal was used to control different FES hand grasp patterns. With a specificity of 0.9, the sensors had a success rate of 85-100% on healthy subjects and 82-97% on spinal cord injured subjects. In terms of sensor placement, the gyroscope was better as a control source than the accelerometer for wrist and hand positions, but the reverse was true for the shoulder.
Asunto(s)
Terapia por Estimulación Eléctrica/métodos , Fuerza de la Mano , Paraplejía/rehabilitación , Traumatismos de la Médula Espinal/rehabilitación , Adulto , Algoritmos , Vértebras Cervicales , Humanos , Movimiento (Física)RESUMEN
The equilibrium depth-dependent biomechanical properties of articular cartilage were measured using an ultrasound-compression method. Ten cylindrical bovine patella cartilage-bone specimens were tested in compression followed by a period of force-relaxation. A 50 MHz focused ultrasound beam was transmitted into the cartilage specimen through a remaining bone layer and a small hole at the centre of a specimen platform. The ultrasound echoes reflected or scattered within the articularcartilage were collected using the same transducer. The displacements of the tissues at different depths of the articular cartilage were derived from the ultrasound echo signals recorded during the compression and the subsequent force-relaxation. For two steps of 0.1 mm compression, the average strain at the superficial 0.2 mm thick layer (0.35 +/- 0.09) was significantly (p < 0.05) larger than that at the subsequent 0.2 mm thick layer (0.05 +/- 0.07) and that at deeper layers (0.01 +/- 0.02). It was demonstrated that the compressive biomechanical properties of cartilage were highly depth-dependent. The results suggested that the ultrasound-compression method could be a useful tool for the study of the depth-dependent biomechanical properties of articular cartilage.
Asunto(s)
Cartílago Articular/diagnóstico por imagen , Cartílago Articular/fisiología , Ultrasonografía/instrumentación , Ultrasonografía/métodos , Soporte de Peso/fisiología , Animales , Bovinos , Elasticidad , Diseño de Equipo , Homeostasis/fisiología , Técnicas In Vitro , Rótula/diagnóstico por imagen , Rótula/fisiología , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Estrés MecánicoRESUMEN
This is a preliminary investigation to detect the body sway and postural changes of patients with AIS under different spatial images. Two pairs of low-power prismatic eye lenses (Fresnel prisms) with 5 dioptre and 10 dioptre were used. In the experiment, the apices of the prisms were orientated randomly at every 22.5 degrees from 0 degrees to 360 degrees to test changes. Four patients with mean age of 11 and Cobb's angle of 30 degrees were recruited and the results showed that the low-power prisms at specific orientations (157.5 degrees and 180 degrees) could cause positive postural changes (2.1 degrees-2.7 degrees reduction of angle of trunk mis-alignment) measured by 3-D motion analysis. This might be used for controlling their scoliotic curves by induced visual bio-feedback. Apart from this laboratory test, a longitudinal study is necessary to investigate the long-term effect of the prisms at different powers and orientations (under both static and dynamic situations) on the patient's posture, spinal muscular activities, vision, eye-hand coordination, psychological state and other daily activities before it becomes an alternative management of AIS.
Asunto(s)
Biorretroalimentación Psicológica/métodos , Postura , Escoliosis/fisiopatología , Escoliosis/terapia , Percepción Espacial , Adolescente , Niño , Anteojos , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Proyectos PilotoRESUMEN
A tendon transfer technique is proposed for the reconstruction of the paralyzed shoulders secondary to brachial plexus injury. This innovative technique does not require bone-to-bone or tendon to-bone fixation, and attempts to overcome other clinical limitations such as those due to insufficient length of donor muscle. The approach is referred to as the reflected long head biceps (RLHB) technique. The long head of biceps tendons is utilized as a bridging tendon graft. Two surgical alternatives, namely the through-deltoid (TD) pathway and the sub-deltoid (SD) pathway, were studied. The moment arms of the transferred tendons were assessed and reported. The TD technique yielded a larger moment than the SD technique. In the plane 30 degrees anterior to the scapular plane, the average moment arms were 3.8cm TD and 3.0cm SD at zero elevation. Such differences tended to further widen with increasing elevation. At 80 degrees elevation, the moment arms became 3.2cm TD and 1.2cm SD. The results supported the clinical feasibility of this RLHB tendon transfer approach.
Asunto(s)
Neuropatías del Plexo Braquial/complicaciones , Parálisis/fisiopatología , Parálisis/cirugía , Articulación del Hombro/fisiopatología , Articulación del Hombro/cirugía , Transferencia Tendinosa/métodos , Anciano , Anciano de 80 o más Años , Brazo/fisiopatología , Brazo/cirugía , Plexo Braquial/lesiones , Cadáver , Humanos , Técnicas In Vitro , Persona de Mediana Edad , Músculo Esquelético/fisiopatología , Músculo Esquelético/cirugía , Parálisis/etiología , Sensibilidad y Especificidad , TorqueRESUMEN
A review is presented on the state-of-the-art methods for geometric and biomechanical assessments of residual limb tissues. Residual limb assessments are needed throughout different stages of prosthetic management, namely preamputation, residual limb maturation, prosthetic design, prosthetic fitting, and subsequent follow-ups. Geometric assessments include the monitoring of the volumetric change as the residual limb matures after amputation. Geometric and biomechanical assessments of the residual limb are important considerations in prosthetic design. Quantitative geometric and biomechanical assessments are becoming more important in the development of a computer-aided system for prosthetic socket design. It is noted that, except for the external shape measurements of residual limbs, most of the instruments used in residual limb assessment are not particularly cost-effective for clinical applications in prosthetics. Further developments are needed to facilitate the incorporation of the internal geometric assessments and biomechanical assessments into the current computer-aided design systems for clinical prosthetics.
Asunto(s)
Muñones de Amputación , Miembros Artificiales , Fenómenos Biomecánicos , Diseño Asistido por Computadora , Humanos , Imagen por Resonancia Magnética , VibraciónRESUMEN
An ultrasound-compression system has been developed for the study of the layered biomechanical properties of articular cartilage. Cartilage specimens harvested from the bovine patella groove, with and without trypsin digestion, were tested using this system. It was noted that a large ultrasound reflection can be detected in the interface of the trypsin digestion front. This ultrasound reflection signal was used to differentiate the deformations of different portions of the cartilage throughout its depth when a load was applied. The equilibrium compression moduli of the digested, undigested and entire portions of articular cartilage were measured. The modulus of the cartilage without any digestion was 660+/-230 kPa. After 1h digestion with 1 mg ml(-1) trypsin solution, the thickness of the digested portion was 0.50+/-0.06m, and the modulus of the entire cartilage layer changed to 125+/-42kPa. The moduli of the digested and undigested portions were 58+/-24 kPa and 470+/-31 kPa, respectively. Similar results were obtained for the cartilage with trypsin digestion for 2 h.
Asunto(s)
Cartílago Articular/efectos de los fármacos , Cartílago Articular/fisiopatología , Tripsina/farmacología , Animales , Cartílago Articular/diagnóstico por imagen , Bovinos , Elasticidad/efectos de los fármacos , Técnicas In Vitro , Rótula , Estrés Mecánico , UltrasonografíaRESUMEN
The sensorimotor performance of the knee joint in 31 subjects who had undergone unilateral anterior cruciate ligament reconstruction at least 5 months previously was tested under three bracing conditions, 1) the DonJoy Legend brace, 2) a mechanical placebo brace, and 3) no brace, in random order. The accuracy of the subjects' ability to reproduce specified knee joint angles was tested as well as the isokinetic performance of their knee muscles at 60 and 180 deg/sec. The results showed that subjects with the brace or placebo brace performed similarly in reproducing the knee joint positions, but both groups performed better than the subjects without a brace. Isokinetic tests revealed no difference among the three groups in extensor and flexor peak torque production at 60 deg/sec or total work done by the extensors and flexors at 60 and 180 deg/sec. These results suggest that knee bracing can improve the static proprioception of the knee joint, but not the muscle contractile function, in subjects with anterior cruciate ligament reconstruction under isokinetic testing conditions. The finding of similar performances for joint angle reproduction in the brace and placebo brace groups suggests that the apparent improvement in proprioception with knee bracing was not due to the mechanical restraining action of the brace.
Asunto(s)
Ligamento Cruzado Anterior/fisiología , Ligamento Cruzado Anterior/cirugía , Tirantes , Articulación de la Rodilla/fisiología , Contracción Muscular/fisiología , Propiocepción/fisiología , Adulto , Femenino , Humanos , Masculino , Análisis Multivariante , Trasplante AutólogoRESUMEN
Upper-limb orthotic systems have been designed for restoring the upper-limb functions of individuals with disabilities resulting from spinal cord injury (SCI), stroke and muscular dystrophy. These systems employ either functional electrical stimulation or external power. It is proposed that, instead of time-consuming and complicated monitoring using sensors and motion analysis, a software simulator with both angular displacement and acceleration parameters can facilitate the design of a control strategy for an orthosis. Reaching movements of three cervical SCI subjects are used to verify the simulator. A motion analysis system is used to measure the range of motion and joint angles during hand reaching. Results indicate that quaternion and spline curve techniques are suitable for interpolation of the hand reaching movements. The information needed for good simulation only compress the shoulder and elbow joint angles in a few key postures. Stimulated acceleration signals on the upper-arm segment have a high correlation coefficient (> 0.9) and a small root mean squared error (< 0.11 g) with a real bi-axial accelerometer.
Asunto(s)
Brazo/fisiopatología , Simulación por Computador , Modelos Biológicos , Trastornos del Movimiento/fisiopatología , Vértebras Cervicales , Humanos , Aparatos Ortopédicos , Programas Informáticos , Traumatismos de la Médula Espinal/fisiopatologíaRESUMEN
3D visualization and virtual reality are important trend in the development of modern science and technology, and as well in the studies on biomedical engineering. This paper presents a computer procedure developed for 3D visualization in biomedical applications. The biomedical models are constructed in slice sequences based on polygon cells and information interaction is realized on the basis of OpenGL selection mode in particular consideration of the specialties in this field such as irregularity in geometry and complexity in material etc. The software developed has functions of 3D model construction and visualization, real-time modeling transformation, information interaction and so on. It could serve as useful platform for 3D visualization in biomedical engineering research.