SEARCH · PubMed Health

Results for “joint quantification”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources

PubMed2001

Automatic recognition of vertebral landmarks in fluoroscopic sequences for analysis of intervertebral kinematics.

Intervertebral kinematics closely relates to the functionality of the spinal segments. Direct measurement of the intervertebral kinematics in vivo is very problematic. The use of a fluoroscopic device can provide continuous screening of the lumbar tract during patient spontaneous motion, with an acceptable, low X-ray dose. The kinematic analysis is intended to be limited to planar motion. Kinematic parameters are computed from vertebral landmarks on each frame of the image sequence. Landmarks are normally selected manually in spite of the fact that this is subjective, tedious to perform and regarded as one of the major contributors to errors in the computed kinematic parameters. The aim of this work is to present an innovative method for the automatic recognition of vertebral landmarks throughout a fluoroscopic image sequence to provide an objective and more precise quantification of intervertebral kinematics. The recognition procedure is based upon comparing vertebral features in two adjacent frames by means of a cross-correlation index, which is also robust despite the low signal-to-noise ratio of the lumbar fluoroscopic images. To provide a quantitative assessment of this method a calibration model was used which consisted of two lumbar vertebrae linked by a universal joint. The reliability and accuracy of the kinematic measurements have been investigated. The errors are of the order of a millimetre for the localisation of the intervertebral centre of rotation and tenths of a degree for the intervertebral angle. Error analysis suggests that this method improves the accuracy of the intervertebral kinematic calculations and has the potential to automate the selection of anatomical landmarks.

Calibration↗

PubMed2005

Quantification of level of effort at the plantarflexors and hip extensors and flexor muscles in healthy subjects walking at different cadences.

The plantarflexor, hip extensor and hip flexor muscle groups contribute by their concentric action to generate most of the energy during level gait in healthy subjects. The goal of the present study was to determine, during the main energy generation phases, the relative demand of these three groups in 14 healthy subjects walking at four cadences (self-selected, 60, 80 and 120 steps/min). The muscular utilization ratio (MUR), that compares the net joint moment obtained during gait to the maximal potential moment (MPM) at each percentage of the gait cycle, was used to estimate the mechanical relative demand. The MPM values were obtained by regression equations developed from torque data measured with a Biodex dynamometric system. The results showed that the peak MURs increased with gait cadence. The peak values were not significantly different between sides for all cadences despite mean absolute lateral differences ranging from 7% to 10%. The mean peak MURs of both sides ranged from 51.3% to 62.6%, from 20.7% to 49.9% and from 14.9% to 42.5%, for the plantarflexors, hip flexors and hip extensors, respectively. Highly significant associations were found between the MURs and net moments (numerator of the MUR ratio), with Pearson coefficients (r) superior to 0.80 for all muscles groups. The association between the MURs and the maximal potential moments (denominator of MUR ratio) was lower (0.01<r<0.60). The results of this study indicated that the mechanical relative demand during gait increased with gait cadence. The plantarflexor MUR values were always the highest. However, when gait cadence increased, the MURs at the hip reached similar values of those of the ankle, which suggests that these muscles also work significantly at elevated gait cadences. The changes in the MUR values were mainly explained by changes in the net joint moments.

Adult↗

PubMed1996

Transient osteoporosis of the hip: a densitometric study.

Three new cases of transient osteoporosis of the hip are reported. Diagnosis was achieved by plain radiographs, bone scintiscan, magnetic resonance imaging and X-ray absorptiometry of proximal femurs. The densitometry showed at the Ward's triangle a mean reduction of bone mineral density in the affected side of 36%. All subjects were treated with i.v. clodronate for ten consecutive days with a complete recovery of femoral density within 4 months. X-ray absorptiometry allows a quantification of the demineralization process and can be useful in the long term evaluation of this entity.

Absorptiometry, Photon↗

PubMed1998

Effects of Temperature and Exposure Duration on Transfer of Cadmium Between Naturally Contaminated Sediments and Burrowing Mayfly Nymphs (Hexagenia rigida)

Burrowing mayfly nymphs (Hexagenia rigida) were exposed to naturally contaminated sediments collected from two stations along a metallic pollution gradient on the Lot River (France) using indoor microcosms. Bioaccumulation kinetics (0, 20, 40, and 60 days) of cadmium (Cd) and the combined effects of temperature (12, 18, and 24 degreesC) were evaluated by a complete experimental design, jointly with the analysis of growth rate of the nymphs, bioturbation, and total and dissolved Cd concentrations in the water column. Cadmium was transferred from the sediment to the organisms with uptake influenced by contamination levels of the sediments, exposure duration, and temperature. The two complementary criteria-Cd concentration and burden in the nymphs-clearly demonstrate the importance of the growth dilution on the quantification of Cd bioaccumulation at the whole organism level.

Journal Article↗

PubMed2004

Quantification of C2 cervical spine rotatory fixation by X-ray, MRI and CT.

Atlanto-axial rotatory displacement is known to be a cause of childhood torticollis and may as well be responsible for chronic neck pain after rear-end automobile collisions. The objective was to determine whether quantification of C2 malrotation is possible by plain radiographs in comparison to CT as the golden standard. MR imaging was evaluated as to whether it was of equal value in the detection of bony landmarks. C2 vertebra of five human cadaveric cervical spine specimens, ligamentously intact, were rotated using a Steinmann pin in steps of 5 degrees up to 15 degrees right and 15 degrees left. Plain radiographs, CT and MRI images were taken in each rotational step. Data were analyzed for quantification of C2 rotation by three independent examiners. A rotation of 5 degrees led to a spinous process deviation (SPD) from the midline of 3 mm as measured on an a.p. plain radiograph. A coefficient of rotation was calculated (1.62 degrees mm(-1)). Data analyzed by three examiners revealed a small coefficient of variation (0.03). MRI and CT measurements showed comparable results for the quantification of rotation; however, in both techniques the 15 degrees rotation was underestimated. Quantification of upper cervical spine malrotation was possible on plain radiographs using the SPD and a rotation coefficient. MRI and CT were equally successful in the assessment of C2 malrotation.

Adult↗

PubMed2003

Stress radiography for quantifying posterior cruciate ligament deficiency.

PURPOSE: The objective of this study was to evaluate the efficacy of different stress radiography techniques in quantifying a posterior cruciate ligament (PCL) lesion. TYPE OF STUDY: Prospective serial study. METHODS: Sixty patients with subacute or chronic PCL injuries, confirmed using magnetic resonance imaging (MRI) or arthroscopic evaluation, were enrolled in this study. The patients underwent a KT-2000 (Medmetric, San Diego, CA) examination and a series of stress radiographs that included a radiographic posterior drawer test with Telos (Telos, Weterstadt, Germany) at 90 degrees and 25 degrees of knee flexion, an active radiograph at 90 degrees of knee flexion, and an axial view radiograph. RESULTS: Stress radiography performed with Telos showed an average posterior tibial displacement of 11.54 +/- 4.93 mm and 7.97 +/- 3.16 mm at 90 degrees and 25 degrees, respectively. The active radiographs showed an average posterior tibial displacement of 11.48 +/- 5.14 mm. CONCLUSIONS: Stress radiographs were shown to be superior to arthrometric evaluation in quantifying posterior tibial translation. The techniques performed with the knee at 90 degrees of knee flexion allowed for greater posterior tibial displacement and, consequently, an easier quantification of the degree of ligament insufficiency. Stress radiographs performed through hamstring contraction gave the same results as those performed with Telos at 90 degrees of knee flexion.

Absorptiometry, Photon↗

PubMed1999

[Dynamic gait analysis. Means for quality assurance after surgically treated ankle joint fractures].

Forty-nine patients (mean age, 54 years) admitted for displaced ankle fractures were observed retrospectively to determine by clinical examination and measurement of plantar pressure distribution whether successful surgical treatment of ankle fractures had led to gait symmetry. The mean followup was 36 months (range, 19-54 months). The deviation in gait was quantified using peak pressure. Using a clinical score, most of the patients had satisfactory results. The plantar pressure distribution showed significant load asymmetries of patients with satisfactory results and those with non-satisfactory results. Dynamic gait analysis allows quantification of gait asymmetry and clinically non-visible gait disorder.

Aged↗

PubMed2000

Quantification of fingertip force reduction in the forefinger following simulated paralysis of extensor and intrinsic muscles.

Objective estimates of fingertip force reduction following peripheral nerve injuries would assist clinicians in setting realistic expectations for rehabilitating strength of grasp. We quantified the reduction in fingertip force that can be biomechanically attributed to paralysis of the groups of muscles associated with low radial and ulnar palsies. We mounted 11 fresh cadaveric hands (5 right, 6 left) on a frame, placed their forefingers in a functional posture (neutral abduction, 45 degrees of flexion at the metacarpophalangeal and proximal interphalangeal joints, and 10 degrees at the distal interphalangeal joint) and pinned the distal phalanx to a six-axis dynamometer. We pulled on individual tendons with tensions up to 25% of maximal isometric force of their associated muscle and measured fingertip force and torque output. Based on these measurements, we predicted the optimal combination of tendon tensions that maximized palmar force (analogous to tip pinch force, directed perpendicularly from the midpoint of the distal phalanx, in the plane of finger flexion-extension) for three cases: non-paretic (all muscles of forefinger available), low radial palsy (extrinsic extensor muscles unavailable) and low ulnar palsy (intrinsic muscles unavailable). We then applied these combinations of tension to the cadaveric tendons and measured fingertip output. Measured palmar forces were within 2% and 5 degrees of the predicted magnitude and direction, respectively, suggesting tendon tensions superimpose linearly in spite of the complexity of the extensor mechanism. Maximal palmar forces for ulnar and radial palsies were 43 and 85% of non-paretic magnitude, respectively (p<0.05). Thus, the reduction in tip pinch strength seen clinically in low radial palsy may be partly due to loss of the biomechanical contribution of forefinger extrinsic extensor muscles to palmar force. Fingertip forces in low ulnar palsy were 9 degrees further from the desired palmar direction than the non-paretic or low radial palsy cases (p<0.05).

Cadaver↗

PubMed1994

Quantification of articular cartilage in the knee with pulsed saturation transfer subtraction and fat-suppressed MR imaging: optimization and validation.

PURPOSE: To assess the reproducibility and accuracy of volumetric quantifications of articular cartilage in the knee determined with three-dimensional (3D) magnetic resonance (MR) imaging combined with pulsed saturation transfer subtraction (STS) or T1-weighted fat suppression (FS) imaging. MATERIALS AND METHODS: Eight osteoarthritic knees were imaged repeatedly with optimized STS and FS sequences. Cartilage volumes were determined from 3D reconstructions of FS and STS images and by means of water displacement of surgically retrieved tissue. RESULTS: Mean over- or underestimation of cartilage volume at STS and FS imaging was 0.40 mL +/- 0.11 (standard deviation) (8.2%) and 0.31 mL +/- 0.08 (5.9%), respectively. Intraobserver reproducibility error was 0.20-0.65 mL (3.6%-6.4%) for STS and 0.21-0.58 mL (4.2%-6.4%) for FS imaging. Interobserver error was less than 0.62 mL and 7.8%. CONCLUSION: Three-dimensional data analysis of MR images acquired with STS or FS allows accurate and reproducible volumetric quantification of articular cartilage in the knee.

Aged↗

PubMed2003

Identification and quantification of disease-related gene clusters.

MOTIVATION: DNA microarray technology and the completion of human and mouse genome sequencing programs are now offering new avenues for the investigation of complex genetic diseases. In particular, this makes possible the study of the spatial distribution of disease-related genes within the genome. We report on the first systematic search for clustering of genes associated with a polygenic autoimmune disease. RESULTS: Using a set of cDNA microarray chip experiments in two mouse models of rheumatoid arthritis, we have identified approximately 200 genes based on their expression in inflamed joints and mapped them into the genome. We compute the spatial autocorrelation function of the selected genes and find that they tend to cluster over scales of a few megabase pairs. We then identify significant gene clusters using a friends-of-friends algorithm. This approach should aid in discovering functionally related gene clusters in the mammalian genome.

Algorithms↗

PubMed1992

In vivo quantification of muscle contractility in humans: healthy subjects and patients with myotonic muscular dystrophy.

The purpose of this study was to use direct in vivo contractility measurements to assess muscle function in patients with myotonic muscular dystrophy (MMD). The tetanic and twitch responses and several time parameters of muscle contraction were obtained from nine MMD subjects and nine able-bodied, age-matched controls. After a routine nerve conduction study, in vivo contractility measurements were obtained by stimulating the ulnar nerve at the wrist and recording the isometric flexor function of the intrinsic muscles at the metacarpophalangeal joint of the index finger. A series of single stimuli, paired stimuli, and fused tetanic stimulations were generated during a 20-minute experimental protocol. A stable tetanus was produced at 50Hz for 1.2 seconds. M-wave and contractile data were recorded at 1,000Hz by digitization of the analog signal and storage by the microcomputer. The MMD patients were weaker than controls (p less than .05), as shown by the 39% reduction in tetanic tension and 57% reduction in twitch tension. The MMD patients also had a significant impairment in relaxing their muscles as shown by the 1,100% increase in half-relaxation time after contraction, even though there was no evidence of repetitive firing after cessation of stimulus. These data show that MMD patients exhibit failure of sarcolemmal activation, altered excitation-contraction coupling mechanisms, and failure of the contractile machinery. The myotonia is due in part, to some defect in the contractile machinery; it is not solely due to failure of sarcolemmal activation.

Adolescent↗

PubMed2001

Power Doppler sonography in the evaluation and follow-up of knee involvement in patients with juvenile idiopathic arthritis.

INTRODUCTION: This study was undertaken to evaluate the role of ultrasound (US), conventional color (CD) and power Doppler (PD) in the detection and quantification of inflammatory signs of the knee in children with juvenile idiopathic arthritis (JIA) and to correlate these findings with patient history, clinical, laboratory and radiological findings. PATIENTS AND METHODS: Thirty patients with JIA who had clinical signs of knee involvement as well as 15 healthy children as a control group where subjected to full clinical examination and laboratory investigations on the same day of US examination. The knee joints were evaluated with plain radiography, US, and color Doppler in 13 patients, while the remaining 17 were assessed with power Doppler. Fourteen patients were subjected to follow-up assessment. RESULTS: A highly significant difference in synovial thickening and cartilage thickness detected by US between JIA affected knees and those of controls (p < 0.0001). Knee effusion was demonstrated in 93% of patients. Synovial vessels were detected by Doppler in 76.7% of patients. A significant correlation was detected between the degree of vascularity detected by PD and knee score (p < 0.05), and JAFAR score (P < 0.05). On comparing the findings of the follow-up with those of the initial examination, a significant positive correlation was detected between the differences in the knee score and those in synovial thickness (p < 0.05), and with the vascularity scale detected by PD (p < 0.05). CONCLUSION: This study suggests the Doppler sonography as a non-invasive, low-cost, and readily available tool for the evaluation and follow-up of articular involvement in knees of JIA patients.

Adolescent↗

PubMed1992

Biomechanical analyses of rising from a chair.

Quantification of the biomechanical factors that underlie the inability to rise from a chair can help explain why this disability occurs and can aid in the design of chairs and of therapeutic intervention programs. Experimental data collected earlier from 17 young adult and two groups of elderly subjects, 23 healthy and 11 impaired, rising from a standard chair under controlled conditions were analyzed using a planar biomechanical model. The joint torque strength requirements and the location of the floor reaction force at liftoff from the seat in the different groups and under several conditions were calculated. Analyses were also made of how body configurations and the use of hand force affect these joint torques and reaction locations. In all three groups, the required torques at liftoff were modest compared to literature data on voluntary strengths. Among the three groups rising with the use of hands, at the time of liftoff from the seat, the impaired old subjects, on an average, placed the reaction force the most anterior, the healthy old subjects placed it intermediately and the young subjects placed it the least anterior, within the foot support area. Moreover, the results suggest that, at liftoff, all subjects placed more importance on locating the floor reaction force to achieve acceptable postural stability than on diminishing the magnitudes of the needed joint muscle strengths.

Adult↗

PubMedDate not supplied

[Material-specific wear of ceramic/ceramic sliding surfaces in revised hip endoprostheses--clinical and technological considerations].

After more than 8 years of "in-vivo"-experience with ceramic bearing surfaces in hip endoprostheses clinical and tribological aspects of damage-analysis in 29 cases of retrieved Al2O3 prostheses are performed. The balls and sockets are investigated in view of wear-quantification by relative metric determination and wear-quantification by SCAN-microscopy. In 2/3 of all cases the microstructure average grain standard was superelevated. As hypothesis of the destruction mechanism an avalanche-like acceleration of grain-excavations is discussed.

Adult↗

PubMed2001

[Imaging of oto-mandibular dysplasias].

The modern imaging opened a possibility of precise exploration of otomandibular dysplasias. The techniques of browsing by IRM and CT Scan and the software of image processing which is associated with these techniques (three-dimensional, superposition and removing of the anatomical structures) allow to carry out a true anatomical dissection of the whole of these malformative syndromes. The study of the skeletal anomalies gains by specifying the disorders of development of the various mandibular segments: temporomandibular joint, ramus and horizontal branch and also, all cranio-maxillar structures: orbital rim, cranial basis. Study of masticatory muscles shows an important damage correlated with skeletal troubles and performs a grading of morphological and functional gravity. This analytical study emphasizes some malformative axis: malar axis in cases of mandibulofacial dystosis, temporomandibular axis in hemifacial microsomia. Modern imaging can appreciate, by development of three-dimensional cephalometry, growth anomalies and quantification of post therapeutical results. At last usefulness of imaging appears in therapeutic modelisation and in the field of Computer-Aided Planning of surgical techniques of osteotomies and overall maxillaries distractions.

Ear↗

PubMed2006

Monitoring and assessment of oil pollution in the Danube River during the transnational Joint Danube Survey.

An extensive river basin monitoring exercise of 2581 km of the river Danube was carried out in 2001 under of the aegis of the transnational Joint Danube Survey (JDS). Water, suspended and bottom sediment, and biota samples were collected from 76 cross-sections in the Danube main stream and 22 major tributaries during the 39-day cruise, and analysed for chemical and biological variables. During the JDS, oil pollution was characterised with GC-FID and fluorescence measurements. Fluorescence fingerprints of the cyclohexane extracts of water, suspended and bottom sediment samples allowed characterization and quantification of the type and level of oil pollution. The results revealed that the oil pollution in the water varied in the range 1-300 microg/l. Gasoline type contamination was found at the higher concentration levels and diesel oil type in the lower concentrations. Oil contamination was similar in the suspended and bottom sediment (the less than 63 microm grain-size fraction) and varied between 2-140 mg/kg. A higher contamination level was found along the middle Danube reach. The highest concentrations were observed in the suspended sediment upstream of the Danube delta. Weathered crude oil characteristics were observed in the upper Danube basin, whereas between crude and diesel oil characteristics were dominant along most of the middle and the lower Danube reaches.

Environmental Monitoring↗

PubMed2001

Antibodies to PECAM-1 and glucocorticoids reduce leukocyte adhesion in adjuvant arthritis of the rat knee synovium in vivo.

OBJECTIVE AND DESIGN: To demonstrate the effect of monoclonal antibodies to the adhesion-molecule PECAM-1 (CD31) and of prednisolone on leukocyte adhesion in rat adjuvant arthritis. MATERIAL: Adjuvant arthritis was induced in male CD-rats (five groups of n = 6) 18 days prior to measurements. TREATMENT: Mouse-monoclonal antibody to rat CD-31 at 200 microg/kg or prednisolone at 24 mg/kg were administered i.v. 15 minutes prior to measurements. METHODS: Venules within the intact rat-knee synovium were focused by confocal laser scanning microscopy. Numbers of rolling and adherent leukocytes were assessed in vivo. RESULTS: Induction of arthritis significantly increased rolling and adherent leukocytes compared to healthy controls. Both monoclonal antibodies to PECAM-1 and prednisolone significantly reduced adherent, but not rolling leukocytes in arthritic animals. CONCLUSIONS: The method used is well suited for in vivo quantification of leukocyte adhesion under the influence of antiadhesive therapies. PECAM-1 might be an interesting target for novel therapies in rheumatoid arthritis.

Animals↗

PubMed2001

[Quantification of blood loss. How precise is visual estimation and what does its accuracy depend on?].

Estimation of blood loss is a difficult task. Apart from measuring the volume of the suctioned blood the anaesthetist has to make a visual estimate of blood shed on the floor, spread in the surgeons' gowns and gloves and hidden in drapes and sponges at nearly every operation. We were interested in how exact visual estimation of blood loss can be and what factors influence accuracy and precision of the visual estimate. In one OR we simulated typical blood loss scenes occurring during a mock hip joint replacement, using our normal customary equipment of drapes, sponges and containers. More than 8 litres of blood from autologous whole blood donations were partitioned with a graduated measure and syringes and were distributed around the OR in 22 locations in typical ways. 36 members of staff entered the OR one by one and all gave their 22 estimates. Results were analysed by repeated measures analysis of variance. Bias (accuracy) and variation error (precision) were calculated for individuals and groups of individuals. We found a broad deviation of the visual estimates and little coincidence with the actual values. Over- and underestimations by 2 or even 3 were rather common; underestimations were more frequent. We found a significant trend to overestimate diluted blood, even though these certain sites were known to exhibit diluted blood. On the other hand laparotomy pads and sponges fully saturated with blood as well as the simulation of the operative site were grossly underestimated. Age, sex and professional experience (!) did not influence the magnitude of estimation errors, but the professional groups'estimates differed: anaesthetists estimated slightly but significantly more than orthopedic or general surgeons. Obviously our capability to estimate lost blood volumes is more influenced by our belonging to a professional group than by our professional experience. Do we not learn by experience? Diluted blood is overestimated, whereas in some other typical scenes blood loss is grossly underestimated. Simulations such as this one may improve our estimation capabilities and thus result in better patient care in the OR.

Adult↗