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At least 271 records · Page 15Linked to original sources

PubMed2001

In situ complement activation by polyethylene wear debris.

A frequent long-term complication of total joint arthroplasty is aseptic loosening, the end result of wear debris accumulation, synovitis, and osteolysis about the implant-bone or cement-bone interface. Complement, an effector system in plasma, synovial fluid, and tissue, has powerful chemotactic, inflammatory, and osteoclast-activating potentials. This study explored the complement-activating ability of polyethylene, a material used in joint implants. In vitro hemolytic assays using sheep red blood cells (E(sh)), human serum, and particulate polyethylene suggested alternative pathway complement activation, as well as polyethylene adsorption of activated complement components. These results were confirmed by enzyme-linked immunosorbent assay (ELISA) quantification of activated complement factors Bb and C3b. In situ double antibody immunoperoxidase staining for factors Bb, C3a, iC3b, and SC5-9 in synovial tissue from revision hip specimens showed localized alternative pathway activation and component adsorption. These results introduce a likely role for complement activation in particle-mediated recruitment, proliferation, and activation of macrophages during early events in osteolysis and implant loosening.

Biocompatible Materials↗

PubMed2005

[Soft tissue management in knees with varus deformity. Computer-assisted sequential medial ligament release].

BACKGROUND: Knees with severe varus deformities and contractures of the medial and lateral collateral ligaments and the posterior capsule require special soft tissue management to gain a stable knee over the full range of movement. The introduction of navigation systems into knee surgery has now made precise measurement of the leg axis and gap size possible. METHODS: Ten knee joints received a computer-assisted total knee replacement (Ci navigation system DePuy) I-Orthopaedics, Munich). The change of the leg axis and the size of the mediolateral gaps were measured and documented when performing a standardized medial ligament release sequence. RESULTS: We found a significant effect after each release step regarding the change of the leg axis as well as the gap width (p<0.001). The highest effect was seen for the 6-cm capsule release in extension and the release of the medial collateral ligament in 90 degrees flexion. CONCLUSION: Implementation of computer-assisted navigation facilitates visualization and quantification of the effect of the sequential medial soft tissue release in total knee arthroplasty.

Arthroplasty, Replacement, Knee↗

PubMed2006

Neuromuscular mechanisms and anthropometric modifications in the initial stages of independent gait.

The gait acquisition is an important milestone of motor development. Structural modifications observed during this period add complexity to the process, and the child needs to use appropriate neuromuscular strategies to walk independently. The objective of this study was to document the longitudinal modifications in neuromuscular mechanisms and in functional anthropometric measures during independent gait acquisition in typically developing children. Twelve children were followed for 2 months after gait acquisition, with its initial period documented by the standardized test Alberta Infant Motor Scale. Quantification of the EMG signals of six muscles in the right lower limb allowed the calculation of the co-contraction indexes (CCI) considering pairs of antagonistic muscles, representing the hip, knee and ankle joints. The CCIs were summed up to yield a total index. Anthropometric measures were transformed into gravitational torque (mLg) values for stance and swing phases of gait. Statistical analyses included repeated measures ANOVA models with one factor (week post-acquisition) for the dependent variables mLg and normalized CCI (CCI/mLg). A significant increase was observed in the mLg during the period evaluated both in stance and swing phases (p=0.0001). In addition, there was a decrease in the value of the normalized hip and total CCIs in both phases of gait (p<0.05). The results revealed changes in the neuromuscular mechanisms used by typical children to deal with the demands involved in the process of gait acquisition.

Analysis of Variance↗

PubMed1992

The response of 99Tcm-methylene diphosphonate and 99Tcm-hexametazime-labelled neutrophils to intra-articular steroid injection in rheumatoid arthritis.

The synovial and bone uptake of tracer in the knees of patients with rheumatoid arthritis (RA) was quantified using 99Tcm-hexamethyl propylene amine oxime-labelled leucocytes and 99Tcm-methylene diphosphonate (MDP), respectively. Significant neutrophil migration and MDP uptake occurred in the knees of patients with RA irrespective of the disease duration. In all but one patient neutrophil migration was reduced after intra-articular steroid injection. The change in MDP uptake after steroid injection was variable. There was a significant correlation between the percentage reduction in neutrophil migration and pain score, while the latter correlated poorly with the change in MDP uptake. The quantification of the neutrophil component of the inflammatory process is a sensitive index for monitoring RA activity and response to pharmacological interventions, while quantitative bone scintigraphy should not be employed to monitor changes in joint inflammation in patients with RA.

Aged↗

PubMedDate not supplied

Selection of an animal model for implant fixation studies: anatomical aspects.

A number of different animal models have been employed by investigators to study the biology of the bone-cement interface as it relates to the problem of hip implant loosening in humans. This study compares to the human three species (baboon, dog, and sheep) currently under use as experimental animal models from an anatomical point of view. A number of parameters, important for the dimensional design of a femoral prosthesis, loads at the hip joint and its subsequent performance, were used for comparing external and internal femoral anatomy. The baboon and dog femora were found to be most similar to the human femur in their external anatomy. The quantification of cancellous bone distribution within the medullary canal revealed that, of the species studied, the sheep femur provided the least support to the prosthesis. The results suggest that the dog and baboon are anatomically appropriate for studying hip implant biomechanics experimentally. Thus, from an anatomical point of view, the current extensive use of the dog as an experimental animal appears appropriate.

Animals↗

PubMed2002

Keratan sulfate epitopes exhibit a conserved distribution during joint development that remains undisclosed on the basis of glycosaminoglycan charge density.

Changes in glycosaminoglycan (GAG) content and distribution are vital for joint development. However, their precise character has not been established. We have used immunohistochemistry (IHC) and "critical electrolyte" Alcian blue staining to assess such changes in developing chick and rabbit joints. IHC showed chondroitin sulfate labeling in chick epiphyseal cartilage but not in interzones. In contrast, prominent labeling for keratan sulfate (KS) was restricted to chick cartilage-interzone interfaces. In rabbit knees, KS labeling was also prominent at presumptive cavity borders, but weak in interzone and cartilage. Selective pre-digestion produced appropriate loss of label and undersulfated KS was undetectable. Quantification of Alcian blue staining by scanning and integrating microdensitometry showed prominent hyaluronan-like (HA-like) interzone staining, with chondroitin sulfate and weaker KS staining restricted to epiphyseal cartilage. Hyaluronidase decreased HA-like staining in the interzone. Surprisingly, keratanases also reduced HA-like but not sulfated GAG (sGAG-like) staining in the interzone. Chondroitinase ABC had little effect on HA-like staining but decreased sGAG staining in all regions. Rabbit joints also showed HA-like but not KS staining in the interzone and strong chondroitin sulfate-like staining in epiphyseal cartilage. Our findings show restricted KS distribution in the region close to the presumptive joint cavity of developing chick and rabbit joints. Alcian blue staining does not detect this moiety. Therefore, it appears that although histochemistry allows relatively insensitive quantitative assessment of GAGs, IHC increases these detection limits. This is particularly evident for KS, which exhibits immunolabeling patterns in joints from different species that is consistent with a conserved functional role in chondrogenesis.

Alcian Blue↗

PubMed1999

System identification of tendon reflex dynamics.

Patellar tendon reflexes were evaluated in 12 healthy adult subjects using several measures of the reflex responses and of the system input-output relationship. A hand-held instrumented hammer was used to tap the patellar tendon and to elicit the reflex response. Tendon reflex dynamics were estimated using the recorded tapping force (as input) and the quadriceps muscle electromyogram and knee joint extension torque signals (as output). A dome-shaped rubber pad was mounted onto the most sensitive spot on the patellar tendon, where it served as a tapping target, and helped to reduce the reflex variability significantly (p < 0.01). The input-output properties of the system relating the reflex torque to the tapping force were characterized using several measures: the tendon reflex gain (Gtr), contraction rate (Rc), and half-relaxation rate (Rhr). Reflex loop delay (t(d)) was estimated using the delay from the onset of tapping force to the onset of reflex torque. We determined that these system parameters provided significantly more repeatable and consistent characterization of tendon reflexes than did reflexive torque or EMG signals alone (p < 0.025). The input-output relationship relating the EMG signals of the stretched muscle to the tapping force was also identified to help characterize neuromuscular dynamics of tendon reflexes. The observed sensitivity and consistency of the reflex system measures suggest that with appropriate simplification of the instrumentation, these methods may prove useful in routine clinical practice, and may allow more precise quantification of the tendon jerk than is currently feasible with standard clinical tests.

Adult↗

PubMed1998

[Intraoperative monitoring of the function of the peroneal nerve in knee joint operations].

Operations on the knee are known to be associated with postoperative neurological complications. There is no consensus opinion on the causes of these complications. The aim of the present study was to develop a method for the intraoperative monitoring of the function of the common peroneal nerve. This was done as to identify intraoperative factors that might be responsible for reversible and irreversible neurological deficits. Computer-aided neuromonitoring is based on online digitizing of the surface EMG of the anterior tibial muscle. An algorithm continuously modifies the amplitude to determine the motor threshold. The method described has been used in 18 patients undergoing high tibial osteotomy. In 10 of the 18 patients, the nerve is rendered completely non-excitable after an average tourniquet application time of 59 min. This non-excitability was reversed on release of the tourniquet. In the remaining 8 patients, excitability was maintained throughout the ischaemic period, which did not exceed 60 minutes in any of the cases. Our method enables accurate quantification of the neural function throughout the entire operation, and convincingly documents the influence of ischaemia on peripheral nerve block.

Electromyography↗

PubMed1993

[Tensile strength of various anchor systems in surgical correction of instability of the shoulder joint].

Commercially available fixation devices used for reattachment of capsuloligamentous tissue to the glenoid rim were tested until they failed in 42 human cadaveric shoulders, and compared to the tension strength of the standard Bankart procedure and that of the intact anterior capsule. The bone quality in the glenoid was measured by quantitative computed tomography, which allowed selective quantification of cortical and cancellous quantification of cortical and cancellous bone. The mean load at failure perpendicular to the bone surface varied from 90 to 115 N and was lower than in the standard Bankart procedure (127 N). All suture anchors demonstrated similar holding strength with the exception of an absorbable wedge (P < 0.05). Due to reduced mineral content in the inferior part of the glenoid, the fixation strength of all suture anchors was significantly decreased. In more than 20% a tension load of 100 N caused the suture anchor to pull out, but in general the fixation strength was limited by the suture attachment and the quality of the soft tissues. These data together with the first clinical results of 49 cases of anterior instability operated on between 1988 and 1992 allow the conclusion to be made that this modification will provide sufficient stability for early mobilization after surgical repair.

Adult↗

PubMed1991

The quantification of EMG normalization error.

Electromyography (EMG) and normalized EMG have been accepted as methods of quantifying the activity level of a muscle. Normalized EMG, in conjunction with the EMG/force relationship and muscle cross-sectional area data, allows researchers to estimate the amount of muscle force exerted across a joint. An accurate description of this muscle force is a critical input to models designed to describe the risk of injury of a task. In order to be able to make statements about the relative intensity of an EMG signal, researchers who use normalization procedures take a given EMG activity level, at a known joint angle, and relate it to some reference activity level obtained at that particular joint angle. However, there have been studies where the EMG activity of an unrestricted dynamic task, such as walking, cycling, performing an occupational task, etc., has been normalized with respect to an EMG value taken during a single maximum voluntary contraction performed at one reference joint angle. This practice will render inaccurate results because at different joint angles there are changes in the portion of the muscle within the viewing area of the electrode, as well as changes in the length/tension relationship of the muscle which would cause changes in the maximum EMG value. The present study was an attempt to quantify the errors associated with normalization relative to a reference EMG value collected at an arbitrary joint position. Four subjects performed a series of controlled trunk extension exertions. As they performed these exertions the EMG activities were collected for eight trunk muscles. The task EMG values that resulted were then: (1) all normalized with respect to the maximum EMG at a single arbitrary trunk angle and (2) each normalized with respect to that specific trunk angle's maximum EMG. The results show that for the primary trunk extensors (erector spinae) large errors (greater than 75%) resulted from normalization using a single reference point and the magnitude of these errors followed consistent patterns within subjects as a function of trunk angle.

Back Pain↗

PubMed1993

Quantification of the locomotion of Dutch Warmblood foals.

To get an in-depth insight into the ontogeny of the equine locomotor apparatus, the locomotion of 28 Dutch Warmblood foals was recorded at the walk, trot and canter on a treadmill using a CODA-3 apparatus. A great similarity in joint angle-time diagrams was found, although considerable differences in kinematic gait parameters of individual foals could be detected. These results contribute to an objective comparison of the locomotor performance of foals.

Animals↗

PubMed2002

Osmotic loading to determine the intrinsic material properties of guinea pig knee cartilage.

Few methods exist to study cartilage mechanics in small animal joints due to the difficulties associated with handling small tissue samples. In this study, we apply an osmotic loading method to quantify the intrinsic material properties of articular cartilage in small animal joints. Cartilage samples were studied from the femoral condyle and tibial plateau of two-month old guinea pigs. Swelling strains were measured using confocal fluorescence scanning microscopy in samples subjected to osmotic loading. A histochemical staining method was developed and calibrated for quantification of negative fixed charge density in guinea pig cartilage. Site-matched swelling strain data and fixed charge density values were then used with a triphasic theoretical model for cartilage swelling to determine the uniaxial modulus of the cartilage solid matrix. Moduli obtained in this study (7.2 MPa femoral condyle; 10.8 MPa, tibial plateau) compare well with previously reported values for the tensile moduli of human and other animal cartilages determined from uniaxial tension experiments. This study provides the first available data for material properties and fixed charge density in cartilage from the guinea pig knee and suggests a promising method for tracking changes in cartilage mechanics in small animal models of degeneration.

Animals↗

PubMed2004

Osteonecrosis: etiology, diagnosis, and treatment.

PURPOSE OF REVIEW: This review provides an update of the recent progress in etiology, pathogenesis, diagnosis, and treatment of osteonecrosis. RECENT FINDINGS: Concerning pathogenesis, there is evidence that there is a genetic predilection for those who are exposed to the two leading etiologic associations for osteonecrosis: corticosteroids and alcohol. Studies concerning the treatment of osteonecrosis indicate that most preservative (ie, joint-sparing) procedures available today have better results in the precollapse stages of the disease and in smaller lesions. Therefore, researchers continue to develop and modify diagnostic techniques, particularly relating to MRI, for the identification and quantification of osteonecrotic lesions. Advances concerning bone grafting and arthroplasty procedures have resulted in improved clinical outcomes for this patient population. The future treatment of osteonecrosis may involve genetic or cell-based therapies. SUMMARY: Although progress has been made, considerably more research is needed before we fully understand this disease. Hopefully, such research will lead to effective measures for saving the femoral head or, better yet, preventing osteonecrosis.

Humans↗

PubMed1981

Quantitative nephelometric determination of Haemophilus influenzae antigen in body fluids.

Nephelometry, an immunological technique widely used for the quantification of blood proteins, was adapted to provide a quantitative method of detecting Haemophilus influenzae capsular antigen in body fluids. Using specific antiserum directed against H. influenzae capsular antigen, samples of serum, cerebrospinal fluid, urine, and joint fluid from 38 cases of H. influenzae infections were analyzed. The results were compared for reliability to counterimmunoelectrophoresis, a widely used diagnostic tool. The nephelometric technique has the same advantages of speed and specificity as counterimmunoelectrophoresis and provides the clinician and researcher with a quantitative method that is as reliable as the qualitative counterimmunoelectrophoresis procedure. The method allowed directly quantitative readouts on patient specimens, with no necessity for serial dilutions or densitometric readings.

Antigens, Bacterial↗

PubMed2005

Quantification of local and global benefits from air pollution control in Mexico City.

Complex sociopolitical, economic, and geographical realities cause the 20 million residents of Mexico City to suffer from some of the worst air pollution conditions in the world. Greenhouse gas emissions from the city are also substantial, and opportunities for joint local-global air pollution control are being sought. Although a plethora of measures to improve local air quality and reduce greenhouse gas emissions have been proposed for Mexico City, resources are not available for implementation of all proposed controls and thus prioritization must occur. Yet policy makers often do not conduct comprehensive quantitative analyses to inform these decisions. We reanalyze a subset of currently proposed control measures, and derive cost and health benefit estimates that are directly comparable. This study illustrates that improved quantitative analysis can change implementation prioritization for air pollution and greenhouse gas control measures in Mexico City.

Air Pollution↗

PubMed2003

Identification, quantification and isolation of mesenchymal progenitor cells from osteoarthritic synovium by fluorescence automated cell sorting.

OBJECTIVE: Identification, quantification and isolation of subpopulations with characteristics of mesenchymal progenitor cells (MPC) from the synovial membrane (SM) from patients with osteoarthritis (OA). METHOD: Cells from the SM of patients with end stage OA who underwent total knee joint replacement were enzymatically isolated. One aliquot was directly analyzed by fluorescence automated cell sorting (FACS) using various combinations of surface markers of bone marrow MPC (CD9, CD44, CD54, CD90, and CD166). Remaining cells were cultivated on plastic, expanded over several passages, analyzed by FACS again and tested for their osteo- and chondrogenic potential. The differentiation was analyzed by immuno-/histochemistry and by RT-PCR for the expression of lineage related marker genes. RESULTS: Using FACS analysis we could show that the relative proportion of subpopulations expressing triplicate combinations of CD9, CD44, CD54, CD90 and CD166 in the SM from OA patients varies between 3 and 10%. Upon cultivation their relative amount markedly increased to values between 24 and 48%. Within the heterogeneous cell populations it was possible to induce osteogenic and chondrogenic differentiation. Initial sorting for CD9/CD90/CD166 triplicate positive cells proved that this subpopulation contains cells with multipotency for mesenchymal differentiation and thus characteristics of MPC. CONCLUSION: Our results show that SM from OA patients contains cells that express typical combinations of MPC surface markers and have the potency of osteogenic and chondrogenic differentiation. Their relative enrichment during in vitro cultivation and the possibility of cell sorting to get more homogenous populations offer interesting perspectives for possible future therapeutic applications.

Aged↗

PubMed1996

Relation between the instrumental activities of daily living and physical fitness tests in elderly women.

A cross-sectional study was conducted to quantitatively evaluate the relationship between the instrumental activities of daily living (IADL) and various physical fitness tests in elderly women living at home. The study focused on the total population of those women aged 65 years and over living in Y Town, Hyogo Prefecture, Japan, who visited a nursing home for day services. A total of 128 subjects were divided into two groups: dependent in IADL group (n = 49) and independent in IADL group (n = 79). The magnitude of the relation was evaluated by the odds ratio (OR). The following tests showed a significant decrease in IADL: knee-raising test [age-adjusted OR = 4.23, 95% confidence interval (CI) 1.81-9.87], height (age-adjusted OR = 4.09, 95% CI 1.75-9.56), grip strength (age-adjusted OR = 3.68, 95% CI 1.57-8.60), sit-and-reach test (age-adjusted OR = 2.76, 95% CI 1.20-6.34), and standing on one leg with closed eyes (age-adjusted OR = 2.56, 95% CI 1.09-5.97). Multivariate analysis using Hayashi's quantification method I indicated that knee-raising was the test most highly correlated with decreased IADL. These results suggest that measurement of knee-raising ability, muscle strength of the lower extremities and flexibility of hip joint could be the most useful factors to assess the level of instrumental self-support ability.

Activities of Daily Living↗

PubMed1995

[The Pain Perception Scale--a differentiated and change-sensitive scale for assessing chronic and acute pain].

Presented is a diagnostic instrument to assess chronic and acute pain, that allows multifaceted and standardized quantification of pain experience. This tool--the Pain Experience Scale ("Schmerzempfindungsskala"--SES)--measures two dimensions of subjectively felt pain, the affective characterization as well as modes of sensory characterization of pain. Applications range from degenerative or inflammatory joint and back pain to headache/migraine, neuropathias and other pain-related diseases (age 16 to 80 years). Completion, evaluation, and interpretation are done easily. Scale development had comprised 3 steps of research for obtaining a model of invariant structure and homogenous factors. Scale analyses demonstrated the instrument's reliability, and numerous studies illustrated the validity of the scale. They showed that factorial, convergent and discriminant validity can be regarded as given. Moreover, the scale proved to be sensitive in experimental pain studies. Additionally, specific patterns of scores could be observed validly for 18 different groups of disease/pain. Special efforts were invested to show its sensitivity to change in the course of pains. Here, the Pain Experience Scale proved to be suitable in postoperative pain, drug-based pain therapies, different psychological pain management approaches, physiotherapeutic prevention, and a multimodal treatment programme of a specialized pain clinic. In German-speaking countries, the SES has been in use for several years as a well-proven instrument in medical care, clinical research as well as field evaluation.

Acute Disease↗