bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intramuscular pressure and electromyography in four shoulder muscles
Authors: Järvholm Ulf , Palmerud Gunnar , Karlsson Dan , Herberts Peter , Kadefors Roland 
Published: February 2005

AbstractEstimations of shoulder muscle load are important in biomechanic and ergonomic research. We have studied shoulder muscle load in the trapezius (six subjects), deltoid (six subjects), infraspinatus (eight subjects), and supraspinatus (seven subjects) muscles with simultaneous intramuscular pressure (IMP) and intramuscular bipolar electromyography (EMG) recordings. For imposition of shoulder muscle load, the arm was positioned in abduction or flexion with different hand loads (0, 1, or 2 kg), or isometric force registrations were performed. The microcapillary infusion technique was used for IMP recordings. The IMP in the supra‐ and infraspinatus muscles were high compared with the trapezius and deltoid muscles in abducted arm positions. In all test situations, IMP and EMG gave a similar description of local muscle load. IMP at maximal voluntary contraction was highest in the supraspinatus and infraspinatus muscles. Both IMP and EMG in all four muscles showed an almost linear correlation to recorded isometric external force. The difference in IMP between shoulder muscles in the same arm position may be due to muscle anatomy, muscle function, and compliance of surrounding tissues. Because a high IMP may impede muscle blood flow, our findings may possibly explain the physiological stress on the rotator cuff muscles as compared with the deltoid and trapezius muscles in work with elevated arms.
Are leg electromyogram profiles symmetrical?
Authors: Pierotti Stephen E. , Brand Richard A. , Gabel Ronald H. , Pedersen Douglas R. , Clarke William R. 
Published: February 2005

AbstractElectromyographic (EMG) patterns reflect function of the neuromuscular system. Abnormality of a given pattern may be established by comparison with that of the contralateral (presumably normal) limb if one ensures a difference beyond normal degrees of symmetry. We studied EMG patterns in six homologous knee muscles during freely selected, slow, and fast gaits in normal subjects. EMG signals were electronically conditioned to produce linear envelopes; envelopes from at least eight cycles from each subject at each speed were ensemble averaged. Grand ensemble averages for each muscle and speed were assembled from all subjects for right and left muscles. Transformed correlation coefficients (r′) and variance ratios established the degree of similarity. All muscles exhibited a fair degree of symmetry (mean r′ = 0.797 − 0.953), but we saw exceptions. On rare occasion, muscles repeatedly exhibited monophasic signals on one side and biphasic on the other. With increasing speed, signals generally became more repeatable, but we occasionally saw monophasic patterns becoming biphasic or vice versa. Considerable caution is essential before presuming any given pattern is abnormal. To ensure that a given pattern is abnormal one could establish that the pattern lies outside some statistical limits for normal population pattern controlled for speed and outside statistical limits for normal symmetry. Alternatively, one could determine the level of statistical differences in EMG patterns associated with distinct differences in level of functional performance between normal subjects and patients.
Measurement reproducibility of two commercial knee test devices
Authors: Torzilli Peter A. , Panariello Robert A. , Forbes Andrew , Santner Thomas J. , Warren Russell F. 
Published: February 2005

AbstractObjective evaluation of patients' knee motion using mechanical devices, whether for diagnostic purposes or for assessing rehabilitative procedures, requires that these devices be reproducible, in order to avoid errors independent of the patients' condition. This study prospectively evaluates the reproducibility of two commercial knee test systems, the KT 1000 Knee Ligament Arthrometer and the Genucom Knee Analysis System, by performing repeated measurements on twenty normal men. Average knee motion, between‐subject variance, and within‐subject variance were determined by performing repeat tests on the same day and one week later. No significant difference was found between measurements taken on the two different test days, but the within‐subject variation was high. We found that larger applied forces or moments resulted in a larger variation in mean displacements. However, the percent variation about the mean (coefficient of variation) decreased with increasing applied loads. The coefficient of variation for the KT 1000 varied from 8 to 33% and for the Genucom, from 13 to 87%. On an individual basis, large variations were found in repeated measures for both devices. To minimize errors, we recommend that repeated tests be performed, higher forces and moments utilized, and specific flexion angles be used for each device and test. Even under these conditions, caution must be exercised when evaluating individual subjects.
An evaluation of three loading configurations for the in vitro testing of femoral strains in total hip arthroplasty
Authors: Finlay J. Bryan , Chess David G. , Hardie W. Robert , Rorabeck Cecil H. , Bourne Robert B. 
Published: February 2005

AbstractDespite recent advances in total hip arthroplasty, proximal femoral resorption and osteopenia remain problems. To analyze the proximal strain effects of three different loading conditions, strains produced in intact and postarthroplasty femora have been compared. Ten adult cadaveric femora of similar size, shape, and rigidity were tested. Ten strain‐gauge rosettes were positioned on each femur. To simulate the “single leg support” phase of gait, fixtures were developed to load the femora under three different configurations: the VS (vertical shaft) configuration, with a vertically orientated femur having rotational freedom proximally and distally; the ITB (iliotibial band) configuration of a femur with rotational freedom positioned 11° from the vertical, with a strain‐gauge adjustable metallic simulation of the lateral muscles of the thigh; and the ABD (abductor) configuration of a femur with rotational freedom positioned 11° from the vertical, with a strain‐gauge adjustable metallic simulation of the abductor muscles. Each femur was loaded ⩽600 N through the medial point, located at one sixth of the transcondylar distance. Strain patterns and magnitudes produced by the three loading configurations were quite different in both the intact and postarthroplasty femora. Both the ITB and the ABD configurations resulted in greater proximal medial compression and lateral tension than did the VS configuration. The magnitudes of the proximal strains were significantly greater in the ABD configuration (p < 0.05). Postarthroplasty femora showed similar proximal results. It is proposed that meaningful strain data for the physiologically loaded femur can be obtained only with simulations that include the forces produced by the iliotibial band. To overcome the indeterminate nature and biological variation in these forces, the studies have to consider a range of forces.
The biologic effects of implant materials
Authors: Galante Jorge O. , Lemons Jack , Spector Myron , Wilson Philip D. , Wright Timothy M. 
Published: February 2005

AbstractThe interaction between implant materials and the surrounding biological environment continues to be an area of intense research and clinical interest. This article presents the information presented in a symposium, held during the 36th Annual Meeting of the Orthopaedic Research Society, in which several important issues concerning the biologic effects of implant materials were discussed. These issues included the mechanisms by which implant materials are released to the surrounding tissues and the ways in which these tissues respond to implant materials. The problem of bone loss around cementless implants was discussed as a specific example of a biologic effect resulting in both bone remodelling and endosteal erosion.
The effects of ischemia on long bone vascular resistance
Authors: Davis Timothy R. C. , Wood Michael B. 
Published: February 2005

AbstractAn in vitro canine tibia model was used to assess the effects of 48 h of hypothermic (4°C) ischemia on bone vascular resistance and on responsiveness of intraosseous blood vessels to circulating norepinephrine. Three groups of bones were studied: Group I (n = 11), 48 h hypothermic ischemia; Group II (n = 11), 48 h hypothermic ischemia with pretreatment with allopurinol and oxypurinol; and Group III (n = 10), no ischemia. Resting vascular resistance in both ischemic groups (79 and 74 mmHg/ml/min) was significantly higher (p < 0.0001) than in the nonischemic group (22 mmHg/ml/min). Effects of norepinephrine on vascular resistance were significantly greater in both ischemic groups (p < 0.004). In all three groups, acetylcholine infusion attenuated the increases in perfusion pressure caused by norepinephrine. This demonstrates secretion of endothelial‐mediated relaxing factors (EDRF) and prostaglandin for up to 48 h of hypothermic ischemia. As no significant differences were detected between the two ischemic groups, this study failed to demonstrate any protective effect of xanthine oxidase inhibitors.
Response of cortical bone to local controlled release of sodium fluoride: The effect of implant insertion site
Authors: Anderson Paul A. , Copenhaver James C. , Tencer Allan F. , Clark John M. 
Published: February 2005

AbstractIn a previous experiment, sodium fluoride in a biodegradable polymer matrix was introduced into the femoral canal of the rabbit and bone formation was compared with contralateral controls. We noted significant bone formation, but only in the distal third of the periosteal surface of the femur. This experiment was performed to distinguish fluoride‐induced periosteal bone formation from that due to the reactive osteogenic changes associated with local injury caused by the process of implantation. A proximal approach on the right leg and a distal approach on the left were used for the insertion of the implants in rabbits. Femurs were removed after 30 days and tested for stiffness and load to failure. The cross‐sectional area of mineralized bone was determined at proximal, midshaft, and distal locations. Fluorescent bone tissue growth labels were injected at weekly intervals to measure the rate of new periosteal bone formation. The results were compared with a control group that received sham implants. Results showed no difference between measured properties in right and left femurs in the control group or in those exposed to fluoride. A significant increase was found in the fluoride group in load to failure, along with cross‐sectional area of mineralized bone, and periosteal growth rates compared with the control group, but no difference was seen in stiffness. No difference was detected between the response proximally and distally in the fluoride group regardless of the location of insertion. There were no detectable changes in serum fluoride level after implantation of the poly L‐lactic acid/sodium fluoride matrix. These results show that fluoride exerts its osteogenic effects equally at proximal, midshaft, and distal regions of diaphyseal bone and is uninfluenced by the site of local injury due to insertion of the implant.
Computational methods for analyzing the structure of cancellous bone in planar sections
Authors: Kuo Arthur D. , Carter Dennis R. 
Published: February 2005

AbstractConventional stereologic methods for expressing the orientation of anisotropic materials are limited to materials assumed to possess orthogonal directions of orientation. In many substances, including cancellous bone, this assumption is unsubstantiated. Presented here are two simple methods for characterizing the orientation of any anisotropic material within a plane. By modeling the substance as a series of lines oriented in particular directions, it is possible to arrive at either a “phase distribution” that expresses the degree of orientation distributed over a range of angles or a series of “primary orientations” that express the degree of orientation at a select number of angles, with an additional measure of the degree of isotropy. This characterization of anisotropy is highly dependent on such parameters as feature size, sample size, test line spacing, and test line width. Given the careful selection of these parameters, the new methods provide simple measures of orientation, which may prove useful in testing Wolff's trajectorial theory of the relationship between mechanical stresses and the orientation of cancellous bone.
The reliability of the mankin score for osteoarthritis
Authors: van der Sluijs J. A. , Geesink R. G. T. , van der Linden A. J. , Bulstra S. K. , Kuyer R. , Drukker J. 
Published: February 2005

AbstractFor the histopathological classification of the severity of osteoarthritic lesions of cartilage, the Mankin score is frequently used. A necessary constraint on the validity of this scoring system is the consistency with which cartilage lesions are classified. The intra‐ and interobserver agreement of the Mankin score was determined. The intra‐ and interobserver agreement of the 14‐point Mankin score was adequate. Between observers 95% of differences were less than ∼7 points. By a more strict definition of the elements of the Mankin score, the intraobserver differences were reduced only for some observers. The interobserver differences were only slightly reduced: between observers 95% of differences were less than ∼6 points. We found the Mankin score to be an adequate histopathological tool.
Rabbit knee immobilization: Bone remodeling precedes cartilage degradation
Authors: Lane Smith R. , Thomas K. D. , Schurman D. J. , Carter D. R. , Wong M. , van der Meulen M. C. 
Published: February 2005

AbstractThis study analyzed processes underlying osteoporosis and osteoarthrosis after short‐term immobilization of the right hind limb of postadolescent (2.8 kg) and mature (4.0 kg) rabbits. After 3 weeks, the lateral posterior aspect of the lateral tibial plateau and the lateral femoral condyle of the immobilized limb exhibited prominent subchondral vascular eruptions. Femoral metaphyseal bone density decreased 27 and 18% in the immobilized limbs of postadolescent and mature rabbits, respectively. Calcein green fluorescence increased 1.9‐fold (p < 0.001) in the metaphyseal trabeculae of immobilized femurs. With immobilization, sulfate incorporation into femoral cartilage glycosaminoglycan increased, although total cartilage glycosaminoglycan and hydroxyproline levels were unchanged. Thymidine incorporation into DNA increased four‐ to fivefold in tibial and femoral cartilage of the immobilized limb. In this study, bone loss and remodeling preceded erosive cartilage degradation.
A finite element study of the initiation of failure of fixation in cemented femoral total hip components
Authors: Harrigan T. P. , Kareh J. A. , O'Connor D. O. , Burke D. W. , Harris W. H. 
Published: February 2005

AbstractIn order to study initial mechanisms of failure in cemented femoral total hip components, an anatomically accurate three‐dimensional linear finite element model was constructed and verified against experimental strain measurements in the cement mantle. Good agreement was found between predicted and measured strains. The likelihood of failure initiation due to cement‐prosthesis debonding and crack initiation at voids was studied for loading conditions simulating both one‐legged stance and stair climbing. The “out of plane” forces involved in stair climbing appear to be the greatest threat to the fixation of total hip replacements. In stair climbing, cement‐prosthesis debonding and pore crack initiation were probable in the proximal anteromedial region of the cement mantle, and near the distal tip of the implant. The proximal stresses in stair climbing were higher than the distal stresses in either stair climbing or one‐legged stance.
Biochemically discrete zones of canine flexor tendon: Evaluation of properties with a new photographic method
Authors: Amadio Peter C. , Berglund Lawrence J. , An Kai‐Nan 
Published: February 2005

AbstractWe describe a photographic method that we have found useful for studying small strain fields within a larger zone of interest. We have used this method to document differences in material properties which correlate with zones of different biochemical makeup in the canine flexor digitorum profundus tendon. This method may be useful in analysis of experimental injury and wound healing in this model and may have application in evaluating material properties of soft tissue in other models as well.
The effects of pulsed electromagnetic fields on blood vessel growth in the rabbit ear chamber
Authors: Greenough C. G. 
Published: February 2005

AbstractA double‐blind, controlled trial of the effects of pulsed electromagnetic field on capillary growth in the rabbit ear chamber in adult New Zealand white rabbits has been performed. Three waveforms have been investigated. The first, a pulse burst waveform, produced a significant increase in the rate of growth of the vascular tissue within the chamber, but had no effect on macroscopic tissue maturation. The second and third, two different single pulse waveforms, had, in contrast, no significant effect on the rate of vascular growth and only an effect on vessel characteristics, with increased maturation of vessels using the second waveform. It is concluded that some of the observed effects of pulsed electromagnetic fields on tissue healing may be mediated through a primary effect on vascular growth.
The achilles functional index
Authors: Murrell George A. C. , Lilly Edward G. , Davies Helen , Best Thomas M. , Goldner Richard D. , Seaber Anthony V. 
Published: February 2005

AbstractThe literature regarding the management of spontaneous rupture of the Achilles tendon is controversial and confusing. The relative infrequency of the condition in any one center prohibits the completion of well‐designed clinical studies. Many of the disputes could be addressed and innovations tested if an appropriate animal model were available. We present a method for evaluating Achilles tendon function from measurements of the prints, preserved in bromphenol‐blue‐impregnated photocopying paper, of the hindfeet of walking rats. The stimulus for this study was derived from de Medinaceli's method for assessing the functional condition of rat sciatic nerves (de Medinaceli L, Freed WJ, Wyatt RJ: An index of the functional condition of rat sciatic nerve based on measurements made from walking tracks. Exp Neurol 77:634–643, 1982). Four variables were measured from these walking tracks, and comparsions between the damaged (experimental) and intact (normal) side were converted to proportional deficits. The relative contribution of each parameter to the overall deficit was determined by multiple linear regression analysis, and the variables were weighted accordingly to obtain an “Achilles Functional Index” (AFI). A sham operation produced no functional deficit, whereas animals subjected to a 0.5‐cm midsubstance Achilles tendon defect demonstrated a markedly impaired AFI. Animals with repaired transected Achilles tendons also demonstrated a significant, but less severly impaired AFI. The functional deficit in this repair group returned to control values by postoperative day 15, whereas animals with a defect remained impaired at day 15. Furthermore, an excellent correlation was found between the functional recovery and biomechanical properties (ultimate failure load) of the healing tendon (r = 0.94; p < 0.001). In summary, this method provides a relatively inexpensive, sensitive, and reproducible means of assessing the functional performance of the Achilles tendon after injury in the rat.
Microstructurally based model analysis of γ‐irradiated tendon allografts
Authors: Belkoff S. M. , Haut R. C. 
Published: February 2005

AbstractA mathematical model of the collagenous microstructure of tendon was used to analyze the mechanical responses of γ‐irradiated patellar tendon allografts and nonirradiated controls. The model was fit to tensile test response curves from 10 pairs of allografts. Donors ranged in age from 16–64 years (six males, four females). The model indicated a decrease in elastic modulus of irradiated tendon collagen. It also suggested a significant increase in the degree and range of collagen fiber crimping following γ irradiation. The model results agree with the literature and histological observations. The model fit the experimental response curves well and provided a structurally based, objective method of quantitatively studying the mechanical response of tendons and the consequences of irradiation sterilization.
Primary and coupled motions in the intact and the ACL‐deficient knee: An in vitro study in the goat model
Authors: Oster David M. , Grood Edward S. , Feder Seth M. , Butler David L. , Levy Martin S. 
Published: February 2005

AbstractQuadrupeds are commonly used as animal models to study healing of anterior cruciate ligament (ACL) reconstructions. While rabbits, dogs, goats, and sheep have been used, goats and sheep are increasingly being employed because of the larger joint size that facilitates surgery, ease of availability, and lower expense to maintain in the farm environment. In spite of this, little is known about the function of the ACL in controlling primary and coupled motions in the quadruped. We report here on the measurements of these motions in goats, with the application of anterior‐posterior forces, varus‐valgus moments, and internal‐external moments in the intact and ACL‐deficient knee. Sectioning the ACL caused significant increases in primary anterior translation, and in varus‐valgus and internal rotations. The increases in anterior translation were similar in amount and dependence on flexion angle to those seen in human knees. The increase in varus averaged 7° and did not depend on flexion angle, whereas the increase in valgus was significant only in the flexed knee. The increases in internal tibial rotation were greatest in extension, whereas the increases in external rotation were small and independent of flexion angle. When the ACL was cut, coupled internal rotation increased with an anterior force as well as a valgus moment. Large increases were seen in coupled anterior translation with the application of varus and valgus moments, whereas smaller increases were seen with internal and external moments. These findings demonstrate that the ACL restrains multiple motions in the goat knee. This study also provides baseline data for future studies of ACL reconstruction.