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At least 145 records · Page 8Linked to original sources

PubMed1992

Coordination of the leg muscles in backlift and leglift.

Net joint moments are often used to quantify the loading of structures (e.g. the intervertebral disc at L5S1) during lifting. This quantification method is also used to evaluate the loading of the knee, for instance, to determine the effect of backlifting as opposed to leglifting. However, the true loading of the joint as derived from net joint moments can be obscured by a possible co-contraction of antagonists. To unravel the mechanisms that determine the net joint moments in the knee, the leglift was compared to the backlift. Although a completely different net knee moment curve was found when comparing the two lifting techniques, it appeared to be closely related to the ground reaction force vector and its orientation with respect to the joint centre of rotation (R > 0.995). This close relation was established by co-contraction of both flexors and extensors of the knee. Furthermore, a close relation appeared to exist between the joint moment difference between hip and knee and the activity difference between rectus femoris muscle and hamstring (R = 0.72 and 0.83 in leglift and backlift, respectively). The knee-ankle joint moment difference and the activity of the gastrocnemius showed a close relation as well (R = -0.89 and 0.96 in leglift and backlift, respectively). These relations can be interpreted as a mechanism to distribute net moments across joints. It is concluded that during lifting tasks the intermuscular coordination is aimed at coupling of joint moments, such that the ground reaction force points in a direction that provides balance during the movement. The use of net joint moments as direct indicators for joint loading (e.g. knee) seems, therefore, questionable.

Adult↗

PubMed2003

Fibroblast apoptosis and caspase-8 activation in aseptic loosening.

The presence of apoptosis has been investigated in the interface membranes collected during revision surgery of loosened total hip joint arthroplasty (THAs). Terminal deoxyrobonucleotidyl transferase (TdT) assay for apoptotic DNA fragmentation quantification revealed a statistically significant presence of apoptosis in aseptic samples, obtained from both cementless (2.37+/-0.6%) and cemented (12.01+/-1%) prosthesis compared to septic samples where apoptosis was almost absent. Activated caspase-8 immunostaining was almost undetectable in septic samples, while in the aseptic samples active caspase-8 was present weakly in the cementless samples (1.35+/-0.22%) and strongly in the cemented ones (9.0+/-0.40%). The caspase-8 cytoplasmatic staining allowed the morphological recognition of positive cells both as fibroblast-like and immunocompetent cells. In aseptic cemented samples fibroblast-like cells were the most represented subpopulation in the caspase-8 positive population scored (76.6%) compared to the immunocompetent cells (23.4%). Caspase-8 activation is an upstream event in the apoptotic pathway triggered by the activation of cytokines receptors such as TNF-alpha receptor 1 (TNFR-1), and the presence of caspase-8 activation in fibroblast-like cells in the aseptic interface membranes of THAs suggests a possible TNF-alpha dependent apoptosis.

Apoptosis↗

PubMed2000

Morphology of young and old cervical spine intervertebral disc tissues.

The intervertebral disc of the cervical spine undergoes degenerative changes during the aging process. Although many studies have reported the qualitative changes in the disc, methodology to quantify these changes is lacking. The present study was designed to quantify the geometrical variations of the nucleus pulposus, annulus fibrosus and uncovertebral joints. The age groups of specimens were classified as juvenile, adult and aged. Fresh intervertebral discs with adjacent vertebral bodies of the lower cervical spine of primates were isolated. The specimens were sectioned sequentially in a coronal plane. Sections were stained with Hematoxylin and Eosin, Verhoeff's, Safranin O, and Trichrome methods to distinguish the nucleus, annulus and uncovertebral joints. Histological images were examined using light microscopy and processed using a computer imaging program to trace the boundaries of the disc components. Dorsal-to-ventral depth and medial-to-lateral width of the nucleus pulposus, and its relative location to the annulus pulposus were also obtained. In the juvenile and adult discs, the nucleus appeared as a light opaque region with scattered notochordal cells with a clear distinction from the annulus region. In contrast, in the aged discs, the nucleus appeared as a dense region of amorphous, irregular collagen materials with less distinction from the annulus region. With the progression of aging, the dorsal-to-ventral depth of the nucleus decreased considerably compared to medial-to-lateral width. The uncovertebral joints were clear in the adult discs. The joints were less distinct in the aged discs and their size decreased. Quantification of three-dimensional geometrical variations will assist in better defining the disc tissue in the mathematical models.

Aging↗

PubMed1979

[Examination of leg volume of patients for determining the therapeutic effect of 1-phenylephrine hydrochloride (author's transl)].

Distorsions and other injuries of a more or less grave kind are often found in combination with exudative processes. The anti-exudative effect of adequate drugs has so far been tested only on the rat paw oedema. As results gained from animal tests cannot immediately be applied to man, tests with human subjects were carried out. With a device by Diebschlag it has become possible to fulfil the demands of a simple but still exact measuring process for quantification of leg volumes. 12 subjects with a distorsion of the ankle joint were treated with a gel (active substance: 1-phenylephrine HCl) which reduces the volue of the leg and with a similar placebo gel, and the effects of both treatments were compared and examined. The analysis of data yielded statistically highly significant values for the effectivity of the active substance gel.

Adult↗

PubMed1999

Measurement of anterior-to-posterior translation of the glenohumeral joint using the KT-1000.

STUDY DESIGN: Single-group repeated measures. OBJECTIVES: To adapt an existing arthrometer to allow simple quantification of glenohumeral translation and to assess the arthrometer's reliability. BACKGROUND: The measurement of glenohumeral translation is an integral part of the clinical examination of the shoulder. However, no objective and reliable measure for glenohumeral translation has been reported. METHODS AND MEASURES: The KT-1000 Knee Ligament Arthrometer was used to measure the amount of anterior-to-posterior (AP) translation of the humeral head at the glenohumeral joints of 28 (16 women and 12 men) nonimpaired undergraduate university students (age 22.1 +/- 2.9 years). Two assessments were made (20 minutes apart), by a single tester, of the dominant and nondominant shoulders of each participant. RESULTS: Anterior-to-posterior translation varied from 10 to 32 mm (20.9 +/- 4.9). The test-retest reliability of the KT-1000 when measuring the nondominant shoulders was good (ICC [intraclass correlation coefficient] 0.76), and it was moderate (ICC = 0.67) when measuring the dominant shoulders. The reliability findings were influenced by large amounts of random error. Analysis by ANOVA showed that compared to women (dominant shoulder, 22.6 +/- 4.6 mm; nondominant, 23.8 +/- 4.2 mm), men showed significantly less glenohumeral translation (dominant, 17.1 +/- 3.7 mm; nondominant, 18.3 +/- 3.7 mm). CONCLUSIONS: The KT-1000 arthrometer has the potential to provide therapists with a clinically viable method of measuring glenohumeral translation.

Adult↗

PubMed2004

[Distinguishing pleural transudates and exudates through the quantification of biochemical parameters].

OBJECTIVES: 1) to evaluate the possibility of distinguishing pleural transudates and exudates through the joint determination of 26 biochemical parameters in pleural effusion and in plasma (including the determination of high molecular weight proteins, acute phase reactants, and proinflammatory citokines), and 2) to formulate a logistic regression equation for optimizing the classification efficiency, comparing the equation obtained with Light's criteria. PATIENTS AND METHODS: All diagnostic thoracocentesis carried out in La Rioja Autonomous Community during a 22-month period were evaluated. The 245 clinical records were evaluated periodically along a minimum of 2 years, after the discharge of the patients. In pleural effusion and in plasma the following were quantified: total proteins, LDH, glucose, amylase, cholesterol, albumin, cholinesterase, phosphatase alkaline, urea, beta2-microglobulin, IgG, IgM, alpha2-macroglobulin, C reactive protein, transferrin, alpha1-antitrypsin, serum amyloid A protein, interleukin 1-beta, interleukin 6, tumoral necrosis factor-alpha, and lysozyme. In addition, the cellularity, polymorphonuclear elastase and adenosine deaminase were evaluated in pleural fluid. RESULTS: The LDH pleural effusion/plasma ratio was the individual parameter that showed higher area under the receiver operating characteristic curve for the separation of pleural transudates and exudates. Interleukin 6 and tumoral necrosis factor-alpha showed pleural effusion/plasma ratios higher than the unit, which suggests an in situ citokines production. An predictive logistic regression equation was obtained that incorporates only LDH and cholesterol ratios, including the diuretic treatment of the patient at the time of thoracocentesis, which did not modify the protein concentrations in pleural effusion. Except for LDH ratio, the logistic regression equation showed an area under the receiver operating characteristic curve higher than that of all the evaluated individual parameters, with a sensitivity of 95% and a specificity of 85% (70% for the Light's criteria). CONCLUSIONS: LDH ratio is the best individual parameter for distinguishing pleural transudates and exudates. The additional evaluation of cholesterol ratio and of the diuretic state of the patient make possible to improve the clinical efficiency of this classification. The quantification of high molecular weight proteins, acute phase reactants and citokines does not contribute additional significant information.

Adult↗

PubMedDate not supplied

A quantitative method for evaluating results of treating Legg-Perthes syndrome.

A new quantitative method of analyzing hip joint architecture in Legg-Perthes syndrome is presented. Outlines of the bony femoral head and acetabular configuration as seen on the anteroposterior (AP) view were traced on a digitizer. Computer analysis provided measures of joint congruity, containment, and femoral head shape. The method's ability to distinguish pathologic from normal hips and to trace the course of the bony deformity of the hip joint was demonstrated in a group of 14 patients. Interobserver reliability was established. The method provides an objective quantification of treatment results and a reliable means for comparison of data between groups of patients.

Child↗

PubMed2002

[Early diagnosis of chronic polyarthritis with conventional roentgen imaging].

Radiographs used to be the gold standard of imaging techniques in rheumatoid arthritis. New imaging techniques allow more detailed examinations of soft tissue changes, the predominant features of early RA. This could change the place of radiography especially in this phase of the disease. The best available radiographic technique is necessary to capture the changes of early RA. Radiographs of both hands and feet are needed for early diagnosis and standardized follow-up. Extent and distribution of indirect signs of arthritis (soft tissue swelling and juxtaarticular osteoporosis) vary with disease activity but can provide important information also for the differential diagnoses. Inter-reader reliability of these changes is low, thus, questioning the validity of these findings. Direct signs of arthritis (erosions and joint space narrowing) are more easy to detect and are used for the quantification of the long-term disease course, in clinical studies, as proof for the disease modifying property of an intervention. Direct signs of arthritis are also found in other diseases, so they are not exclusive signs of RA. Nevertheless a typical radiographic finding in early RA is highly specific and is the most important risk factor for a poor prognosis. Therefore, it serves as the basis for therapeutic decisions, e.g., for an early aggressive treatment. As long as there are no data that the findings with the new imaging techniques are as relevant for prognosis, radiographs cannot be replaced in early RA.

Arthritis, Psoriatic↗

PubMed2026

Which radiographic plane should be used to quantify the distal tibia angle on weightbearing CT images?

BACKGROUND: Precise quantification of distal tibial alignment is essential for planning corrective osteotomies and ankle joint replacement surgery. The lateral distal tibial angle (LDTA) is the principal radiographic parameter used for this purpose. While LDTA is increasingly measured on weightbearing cone-beam CT (WBCT) using two-dimensional coronal slices, the optimal measurement plane remains unclear. METHODS: In this retrospective comparative study, full-leg WBCT scans of patients scheduled for supramalleolar osteotomy (n = 20; mean age 47 ± 12.8 years) were analyzed. LDTA was measured on three coronal planes of the distal tibial plafond (anterior edge, mid-dome, posterior edge) and compared with semi-automated three-dimensional (3D) tibial alignment measurements as the reference standard. RESULTS: Mid-dome LDTA showed no significant difference from the 3D reference (p > 0.05) and demonstrated excellent agreement. Anterior measurements significantly overestimated LDTA, while posterior measurements underestimated it (both p < 0.05), with only fair agreement. CONCLUSION: LDTA should be measured at the mid-dome of the distal tibial plafond on WBCT to ensure accurate and reproducible alignment assessment. LEVEL OF EVIDENCE: Level III - Retrospective Comparative Study.

Humans↗

PubMed2006

Can the patellar tendon moment arm be predicted from anthropometric measurements?

The purpose of this study was to examine the relations between patellar tendon moment arm length and several relevant anthropometric characteristics of 22 healthy men. The patellar tendon moment arm length was measured using magnetic resonance imaging with two different methods: (1) measurement of patellar tendon moment arm length (d(PT)) with respect to the tibiofemoral contact point (d(PTCP)) and (2) measurement of d(PT) with respect to the intersection point of the anterior and posterior cruciate ligament (d(PTIP)). Pearson correlation coefficients and a stepwise linear regression analysis were used to examine the relationships between the d(PT) and anthropometric measurements taken. Furthermore, a Student's t-test was used to determine differences between the d(PTCP) and d(PTIP) values. Only knee circumference was a significant d(PTCP) predictor (P < 0.05) but with a very low R2 (0.139). None of the anthropometric parameters examined was found to be a significant d(PTIP) predictor. The correlation coefficients ranged from -0.04 to 0.42. The d(PTIP) values were significantly higher (by 0.84-1.89 cm) than the d(PTCP) values (P < 0.05). These results are in disagreement with previous in vitro findings that d(PT) variance may be explained by knee joint size differences. Hence, existing imaging-based methodologies remain necessary for accurate quantification of the patellar tendon moment arm.

Adult↗

PubMed1996

Quantitative assessment of the synovial membrane in the rheumatoid wrist: an easily obtained MRI score reflects the synovial volume.

Determination of the synovial membrane volume in the rheumatoid arthritis (RA) wrist by gadolinium-DTPA-enhanced MRI is introduced. Moreover, dynamic imaging and an MRI score of synovial hypertrophy, based on gradings in six regions, are evaluated as substitutes of the time-consuming volume calculations. Twenty-six RA wrists were examined. Synovial membrane volumes ranged from 1 to 20 ml (median 9 ml). Synovial hypertrophy scores were highly correlated to synovial volumes (Spearman r = 0.88; P < 10(-8) for uncorrelated values). The volumes and scores were significantly higher in wrists with joint swelling and/or joint tenderness than in wrists without these signs (Mann-Whitney, both P < 0.05). Suboptimal slice selection made dynamic imaging uninformative. MRI allows quantification of the synovial volume in the rheumatoid wrist. The volume is related to clinical signs of inflammation, but may also give information about the cumulated synovial proliferation in the joint. An easily obtained score of synovial hypertrophy reflects the synovial volume and may thus be a useful marker of synovial involvement.

Adult↗

PubMed2006

Muscle activation assessment: effects of method, stimulus number, and joint angle.

Activation capacity has traditionally been assessed using the interpolated twitch technique (ITT) and central activation ratio (CAR). However, the quantitative agreement of the two methods and the physiological mechanisms underpinning any possible differences have not been fully elucidated. The aim of this study was to compare and assess the sensitivity of the ITT and CAR to potential errors introduced by (1) evoking inadequate force, by manipulating the number of stimuli, and (2) neglecting differences in series elasticity between conditions, by manipulating joint angle. Ten subjects performed knee extension contractions at 30 degrees and 90 degrees knee-joint angles during which the ITT and CAR methods were applied using 1, 2, 4, and 8 electrical stimuli. Joint angle influenced the ITT outcome with higher values taken at 90 degrees (P < 0.05), while the number of stimuli influenced the CAR outcome with a higher number of stimuli yielding lower values (P < 0.05). For any given joint angle and stimulus number, the CAR method produced higher activation values than the ITT method by 8%-16%. Therefore, in the quantification of voluntary drive with the ITT and CAR methods consideration should be given not only to the number of stimuli applied but also to the effect of series elasticity due to joint-angle differences, since these factors may differently affect the outcome of the calculation, depending on the approach followed.

Adult↗

PubMed2003

Procollagen II C propeptide level in the synovial fluid as a predictor of radiographic progression in early knee osteoarthritis.

OBJECTIVE: To investigate the prognostic value of procollagen type II carboxy-terminal propeptide (PIICP) level in synovial fluid in relation to early tibiofemoral joint osteoarthritis (OA). METHODS: Data were collected on 172 women (age 40 to 59 years) who had knee pain and tibiofemoral joint OA in the early stage. Standing semiflexed knee radiographs were obtained by fluoroscopy at baseline and at four year follow up and a computerised, magnification corrected measurement system was applied to measurement of minimal joint space width in the tibiofemoral compartment. Synovial fluid sampling was performed at baseline and at the four year follow up. Levels of PIICP in the synovial fluid were measured by enzyme immunoassay. The outcome measures were assessed by radiographic joint space narrowing (JSN) in the tibiofemoral joints over four years. Multiple linear regression analyses were used to examine the relation between radiographic JSN and synovial fluid level of PIICP. RESULTS: The number of women available at both baseline and at four year follow up was 110. The average of radiographic JSN over four years was 0.53 mm (range 0.00-2.01). Body mass index showed a slightly positive association with baseline PIICP level. In multiple linear regression analyses adjusted for age and body mass index, radiographic JSN over four years had a direct positive correlation with baseline PIICP level (r=0.395; 95% confidence interval (95% CI) 0.231 to 0.529; p<0.001). CONCLUSION: In a four year prospective study of women, quantification of synovial fluid PIICP was able to predict subsequent radiographic progression in early tibiofemoral joint OA.

Adult↗

PubMed2003

Quantification of T cell receptor rearrangement excision circles to estimate thymic function: an important new tool for endocrine-immune physiology.

Although the thymus constitutes a target organ for most protein and steroid hormones, it has been quite difficult to determine the precise control exerted in vivo by the endocrine system upon thymic function. The biological role of the thymus is to ensure the generation of a diversified population of peripheral T cells able to respond to non-self-antigens but nevertheless tolerant to self-antigens. For a long time, thymic function could not be monitored, as a consequence of the absence of adequate technology to differentiate recent thymic emigrants from naive T cells. The generation of T cell receptor (TCR) diversity occurs in the thymus through recombination of gene segments encoding the variable parts of the TCR alpha and beta chains. During these processes, by-products of the rearrangements are generated in the form of TCR excision circles (TRECs). As these molecules are lost upon further cell division, their quantification is actually considered as a very valuable tool to estimate thymic function. The most appropriate TREC is deltaRec-Psi(J)alpha TREC or signal joint TREC resulting from deltaRec-Psi(J)alpha rearrangement (TCRD deletion) that occurs late during thymopoiesis, before V(alpha)-J(alpha) rearrangement. Here we describe how TREC quantification is a powerful and reliable method to evaluate the impact of hormones and endocrine disorders upon thymic function.

Aged↗

PubMed1986

Assessment of inflammation in the rheumatoid knee joint: correlation between clinical, radioisotopic, and thermographic methods.

Standard clinical methods of assessing joint inflammation are being supplemented increasingly by radioisotopic and thermographic studies. However, the correlation between these different methods has not been firmly established. In the quantification of synovitis by infrared thermography we have shown that the heat distribution index (HDI) based on thermal pattern is more reliable and is less affected by diurnal variations in joint temperature than the commonly used thermographic index, which is based on average skin temperature values. In 20 patients with rheumatoid arthritis whose knees were being treated with intra-articular steroid we obtained 184 serial paired observations over a period of 24 weeks for clinical assessment, HDI, and 99mTc pertechnetate uptake. We found significant correlations (p less than 0.001) between the three methods of assessment (except for pain and HDI (p = 0.116)).

Adult↗

PubMedDate not supplied

Radiographic changes of the revascularized femoral head.

Twenty-two necrotic femoral heads in young adults were radiologically followed-up after grafting with vascularized bone by comparing the preoperative and the postoperative state of the hip joint. Three parameters were observed and followed; the flattening of the femoral head; the degree of osteoarthrosis of the joint; and the degree of incorporation of the graft into the recipient bone. The results, expressed by index figures, showed that the femoral head flattened during the first two years postoperatively; that the maximal incorporation occurred during the same period of time; and that the appearance of postoperative osteoarthrosis was slow during the first year and increased subsequently. This numerical characterization of radiological findings allows systematic individual analysis after revascularization of the femoral head with bone grafts. It is also suited for comparisons between patients, between series of patients and of various treatment techniques. Furthermore, this quantification provides a numerical index that seems to correlate with the outcome of the treated hip joint.

Adult↗

PubMed2003

Cine phase-contrast magnetic resonance imaging as a tool for quantification of skeletal muscle motion.

In recent years, biomechanics researchers have increasingly used dynamic magnetic resonance imaging techniques, such as cine phase contrast (cine PC), to study muscle and bone motion in vivo. Magnetic resonance imaging provides a non-invasive tool to visualize the anatomy and measure musculoskeletal tissue velocities during joint motion. Current application of cine PC magnetic resonance imaging in biomechanics includes study of knee joint kinematics, tendon strain, and skeletal muscle displacement and shortening. This paper article reviews the use of cine PC magnetic resonance imaging for quantification of skeletal muscle motion. The imaging studies presented examine the relative motion of the knee flexor and extensor muscles after orthopedic surgery and examine the uniformity of shortening within the biceps brachii muscle. The current challenges and limitations of using cine PC magnetic resonance imaging in biomechanics research are addressed as well as opportunities for future studies of skeletal muscle motion using dynamic magnetic resonance imaging.

Biomechanical Phenomena↗

PubMed1998

Quantification of cocontraction in spastic cerebral palsy.

Antagonist cocontraction was hypothesized to limit net moment production in children with spastic diplegic cerebral palsy (CP). A second hypothesis was that concontraction would vary with joint angle. To test these hypotheses, surface EMG activity and moment data from the quadriceps and hamstrings muscle groups were obtained from children with CP and compared with normally developing children during isometric flexion and extension exertions. A biomechanical model was developed to predict individual moments produced by the agonist and antagonist muscle groups. Concontraction was defined as the percentage of the net moment that was negated by the antagonist moment. The model performed well in predicting the measured moment as illustrated by high R2 correlation coefficients and low prediction errors. The mean maximum moment produced was greater in normally developing children than children with CP in both flexion and extension. Antagonist cocontraction during extension was greater in children with CP (12.2 +/- 14.4%) than in normally developing children (4.9 +/- 3.8%), implying that antagonist cocontraction is one explanation for the observed extension weakness in children with CP. However, during flexion, cocontraction was not significantly different between the two groups. Cocontraction differed significantly with joint angle in both groups during flexion and in the normally developing children during extension. Although quantifying coactivation based on EMG activity alone produced similar results, it underestimated the effect of the antagonist. The quantification of cocontraction has potential applications for characterizing spastic muscle dysfunction and thereby improving clinical outcomes in children with CP.

Adolescent↗