bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relation of intramuscular pressure to the force output and myoelectric signal of skeletal muscle
Authors: Körner L. , Parker P. , Almström C. , Andersson G. B. J. , Herberts P. , Kadefors R. , Palmerud G. , Zetterberg C. 
Published: February 2005

AbstractThe force output of the biceps brachii muscle during static isometric contractions was studied in 26 arms of 23 subjects in relation to the simultaneously recorded level of the electromyogram (EMG) and the intramuscular pressure (IMP). The EMG was picked up with wire electrodes and the IMP recorded through wick catheters or by infusion technique. The load at the wrist was monitored using a force transducer. A near linear relationship with correlation coefficients exceeding 0.96 was shown between the load on the wrist on the one hand and IMP and EMG on the other. The regression coefficients of the relation between the load and IMP or EMG varied considerably between individuals and between different measuring points in the same individual. In cases where the correlation between the wrist load on one hand and the IMP and EMG on the other was poor because of varying synergistic interaction between the flexor muscles, the EMG and IMP were always well correlated. This means that they change in the same way when the mechanical output of the muscle varies. This was also the case in three experiments where the IMP and EMG from all three elbow flexors were recorded while the subjects changed from a supinated to a pronated position supporting a constant load on the wrist. Considering these observations we present indirect evidence that IMP and the level of the EMG signal both are good estimators of isolated muscular force under isometric static conditions and over limited time.
Medullary osteogenesis with platinum cathodes
Authors: Dymecki S. M. , Black J. , Nord D. S. , Jones S. B. , Baranowski T. J. , Brighton C. T. 
Published: February 2005

AbstractStudies of electrical stimulation of osteogenesis with stainless steel electrodes have previously established a dose‐response relationship between current and bone growth. Examination of the effect of different geometric current densities resulted in the conclusion that very little electrode surface area was involved in stimulation and led to the design of a multiport “distributive” cathode. A series of experiments were performed to extend these results to wire and multiport platinum electrodes. As before, a current‐bone growth dose‐response relationship was found. Peak bone growth was greater than for stainless steel. However, peak bone growth occurred at 2.0 μA (versus 20 μA for stainless steel). Correlation studies suggest that small changes in cathodic potential affect bone growth more than similar size changes in current. Finally, the generally benign local host response to platinum suggests that platinum may be a suitable materials for chronic indwelling anodes for stimulation of osteogenesis.
Sequential technetium‐99m/gallium‐67 scintigraphic evaluation of subclinical osteomyelitis complicating fracture nonunion
Authors: Esterhai John , Alavi Abass , Mandell Gerald A. , Brown Jamie 
Published: February 2005

AbstractTwenty‐four patients with a history of post‐traumatic fracture nonunion underwent sequential 99mTc and 67Ga citrate scintigraphy in an attempt to differentiate between posttraumatic fracture nonunion and nonunion complicated by subclinical osteomyelitis. Neither technetium nor gallium studies alone nor in combination, with or without clinical correlation, could help delineate between fracture nonunion and nonunion complicated by subclinical osteomyelitis because of the increased technetium and gallium radioisotope uptake associated with the nonunion site.
Effect of freezing on histologic and biomechanical failure patterns in the rabbit capital femoral growth plate
Authors: Lee Kendrick E. , Pelker Richard R. 
Published: February 2005

AbstractTen pairs of proximal femora were harvested from 8‐week‐old New Zealand white rabbits. Experimental shear fractures were then created in vitro, and load‐displacement curves were recorded. One specimen from each animal was tested within 4 h of death, whereas the contralateral specimen was frozen for 10 to 20 days and thawed prior to testing. Histologic sections of the fractured specimens were studied. No statistically significant differences could be demonstrated between the fresh and the frozen/thawed specimens in either the histologic patterns or the shear load or stress to failure.
Guidelines for external fixation frame rigidity and stresses
Authors: Huiskes R. , Chao E. Y. S. 
Published: February 2005

AbstractUsing results from FEM analyses and experiments as references, analytical methods are applied to develop simple approximate formulas to relate frame rigidity, maximal pin stresses, and peak pin–bone stresses in external fracture fixation (EFF) configurations in axial loading to the most important frame, pin, and bone parameters. It is found that, in a realistic range, the parameters can be adapted to vary the frame rigidity from about 13 N/mm to 17,000 N/mm, thereby reducing the maximal stresses in the pins and at the pin–bone interface by a factor of 140. In particular, when compromises have to be established in the frame characteristics in order to ensure a flexible configuration and limit the stress values at the same time, the formulas presented can provide useful guidelines. The side‐bar separation and the pin modulus, in particular, can be adapted to decrease the rigidity, while only moderately increasing the stresses, thereby reducing chances for pin failure, pin–bone loosening, and pin‐tract infection. A nomogram is presented for a quick reference to estimated relations between frame characteristics, rigidity, and stresses. It is believed that this material may be of use in EFF design and applications in clinical and animal experimental trials.
Effect of fatigue on joint position sense of the knee
Authors: Skinner H. B. , Wyatt M. P. , Hodgdon J. A. , Conard D. W. , Barrack R. L. 
Published: February 2005

AbstractThis study was designed to test position sense of the knee joint before and after fatigue in order to determine whether muscle or capsular receptors are the primary sensors for joint position sense. Reproduction of passive positioning and detection of the onset of motion (kinesthesia) were employed to measure joint position sense. Eleven subjects underwent joint position sense measurement before and after a fatigue protocol. A significant worsening of reproduction of knee joint angle after fatigue was noted (p < 0.05). Threshold (kinesthesia) showed no statistically significant change after fatigue. A significant correlation of reproduction measurements and threshold measurements prior to fatigue (p < 0.01) demonstrated that the same neural mechanism is applicable in the rested state, but these variables did not correlate significantly after fatigue. There was a significant correlation between reproduction measurements before and after fatigue (p = 0.018), while no correlation was seen for the pre‐ and postfatigue threshold measurements, suggesting a change in the neural path after fatigue. Since both tests of joint position sense are affected by fatigue, we conclude that muscle receptors are a prominent, if not primary, determinant of joint position sense, and capsular receptors may have a secondary role. Reproduction ability is decreased, presumably through the loss of efficiency of muscle receptors. The threshold data suggest a change in the mechanism of appreciation after fatigue, possibly due to increased sensitivity of capsular receptors from muscle‐fatigue‐induced laxity.
The phenomenon of “Ligamentization”: Anterior cruciate ligament reconstruction with autogenous patellar tendon
Authors: Amiel David , Kleiner Jeffrey B. , Roux Richard D. , Harwood Frederick L. , Akeson Wayne H. 
Published: February 2005

AbstractReconstruction of the anterior cruciate ligament (ACL) with patellar tendon (PT) is a common procedure for the symptomatic ACL‐deficient knee. Questions regarding graft incorporation, viability, and nutrition of the transplanted tissue are of concern. This relates to the graft's response to its new intrasynovial milieu and new physical forces. These factors were studied in a rabbit model of ACL reconstruction using PT and were evaluated with histological and biochemical parameters with respect to time. A histological and biochemical metamorphosis of the grafted PT occurred in this study. Autografts demonstrated a gradual assumption of the microscopic properties of normal ACL; by 30 weeks postoperatively, cell morphology was ligamentous in appearance. Normally, type III collagen is not observed in PT, however, a gradual increase in its concentration was seen in the grafts; by 30 weeks its concentration (10%) was the same as in normal ACL. Similarly, glycosaminoglycans content increased from its normally low level in PT to that found in native ACL. Collagen‐reducible crosslink analysis demonstrated that grafted tissue changed from the normal PT pattern of low dihydroxylysinonorleucine (DHLNL) and high histidinohydroxymerodesmosine (HHMD) to the pattern seen in normal ACL (high DHLNL and low HHMD) by 30 weeks. These data suggest that when PT is placed in the anatomic and environmental milieu of the ACL, a “ligamentization” of the grafted tissue results; also the autograft initially depends on synovial fluid nutrition, as revascularization occurs after 6 weeks.
Electrical stimulation of human muscle studied using 31P‐nuclear magnetic resonance spectroscopy
Authors: Shenton David W. , Heppenstall R. Bruce , Chance Britton , Glasgow Steven G. , Schnall Mitchell D. , Sapega Alexander A. 
Published: February 2005

AbstractThis study used phosphorous nuclear magnetic resonance (31P‐NMR) spectroscopy to examine the metabolic demand resulting from electrical muscle stimulation (EMS) applied to human skeletal muscle. For each of six subjects, the forearm flexor muscle group was monitored with 31P‐NMR during both maximum voluntary and 6‐s EMS‐induced contractions. A simple protocol using a tourniquet was added in one subject to assess the role of blood flow in this model. Eight hertz (nontetanic) EMS showed less (p < 0.025) depletion of phosphocreatine (36%) than did tetanic 70‐Hz EMS (60%), voluntary isometric (66%), and voluntary isokinetic (68%). The results of the tourniquet studies suggested that the nontetanic EMS allowed relatively increased muscle blood flow and oxygen supply during contraction. Tetanic EMS provided a similar metabolic demand to that of conventional resistive exercise, as measured by 31P‐NMR spectroscopy.
Patellar surface strain
Authors: Goldstein Steven A. , Coale Edward , Weiss Arnold‐Peter C. , Grossnickle Mark , Meller Bruce , Matthews Larry S. 
Published: February 2005

AbstractWe measured longitudinal surface strains on the anterior patella at controlled simulated quadriceps loads, quadriceps angles, and knee flexion angles. We studied both the natural patella and patellas resurfaced with domed, bifaceted, and metal backed polyethylene components. Twelve matched pairs of fresh human cadaver knee specimens were tested. Midanterior longitudinal patellar strains were greatest at knee flexion angles at 45 to 60° of knee flexion. Alterations in quadriceps angle medially and laterally did not decrease recorded strain values significantly. Polyethylene patellar prostheses increased patellar strains but a bifaceted component or “total contact” design minimized this effect. Metal support for the prosthetic patella decreased the recorded surface strains. This study of patellar surface strain at the three midline locations provides experimental results that may prove useful for design and validation of analytic models of the patella. The study also suggests that patellar surface strain measures may provide a method for evaluating the effects of patellar prosthesis design and resurfacing procedures.
Clonal analysis of the population of chondrocytes from the swarm rat chondrosarcoma in agarose culture
Authors: Sun Deqing , Aydelotte M. B. , Maldonado B. , Kuettner K. E. , Kimura J. H. 
Published: February 2005

AbstractChondrocytes from the Swarm chondrosarcoma, a transplantable rat tumor, have been difficult to maintain in tissue culture for extended periods due to a time‐dependent alteration of the culture to a more fibroblastic pheno‐type. This feature precluded the use of these cultures to examine chronic conditions that may affect cell metabolism, and the homogeneity or heterogeneity of the tumor cells within the culture population could not be examined. Use of suspension culture in agarose stabilized the chondrocyte phenotype, permitting long‐term culture. Clones of tumor chondrocytes were established in agarose and were examined over 2–3 weeks for evidence that the cells were accumulating a proteoglycan‐rich extracellular matrix, as determined by positive staining by Alcian blue, and were undergoing cell division. Nearly 90% of the cloned cells exhibited a prominent extracellular matrix by day 7 of culture and greater than 99% did so by day 14. Cell division did not occur to any great extent until days 6–7 of culture. After this lag, the cells appeared to undergo logarithmic growth, with a cell generation time of about 12 days. By 20 days of culture, between 80 and 90% of the initial clones contained multiple cells, indicating that nearly all the cells were in, or had entered, the cell cycle. These results suggest that the chondrocytes from the rat chondrosarcoma form a homogeneous cell population with respect to their ability to synthesize an extracellular matrix and divide.
Augmentation of anterior cruciate ligament reconstruction in dogs with prostheses of different stiffnesses
Authors: Yoshiya Shinichi , Andrish Jack T. , Manley Michael T. , Kurosaka Masahiro 
Published: February 2005

AbstractThe purpose of this study was to investigate the biological and bio‐mechanical properties of anterior cruciate ligament (ACL) reconstruction augmented with Dacron prostheses of three different stiffnesses. The ACLs of 36 adult mongrel dogs were removed and the ligament was reconstructed. In 18 dogs, one knee was reconstructed with patellar tendon alone, and the contralateral knee with Dacron augmented patellar tendon. In the remaining 18 dogs, reconstruction was with Dacron augmented patellar tendon with Dacron alone being used for the contralateral control knee. Death was 3 months after surgery, and the reconstructions were examined biologically and biomechanically. The mechanical data were compared with immediate postoperative data obtained from 45 reconstructed fresh cadaveric knees. Tensile testing demonstrated that an increase in failure load was found when the implanted patellar tendon graft was compared with the cadaveric reconstruction. The strength of the Dacron augmented reconstruction showed little change while the Dacron alone graft decreased in strength during the period of implantation. No clear difference was found between the performance of augmentation devices of different stiffnesses. Microangiography showed that grafts were totally revascularized in patellar tendon alone, but not well revascularized in Dacron augmented patellar tendon and Dacron alone reconstruction. The presence of the Dacron appeared to have an adverse effect on revascularization.
Three‐dimensional spinal curvature in idiopathic scoliosis
Authors: Stokes Ian A. F. , Bigalow Llynda C. , Moreland Morey S. 
Published: February 2005

AbstractScoliosis is usually considered as a deformity of the spine in the frontal plane, without reference to curvatures in other planes. In this study, the three‐dimensional shape of the spine of 104 patients with untreated idiopathic scoliosis (5–55° Cobb) was studied by means of stereo radiographs to determine relationships between curvature of the spine in the frontal plane view, in the lateral view, and in the intermediate views. There was a weak but statistically significant correlation (r = 0.2) relating greater scoliosis with lesser kyphosis or greater lordosis. In the thoracic region, the sagittal plane spinal curvature was less than that measured in a population without scoliosis (mean difference, 7.72 ° 9.9°). Seventy‐four of 76 scolioses in the upper region of the spine with lateral curvature greater than 5° Cobb were kyphotic. Sixty‐four of 84 curves greater than 5° Cobb in the lower region were lordotic. Measuring curvatures in the plane of symmetry of the rotated apical vertebra altered these ratios to 69 of 76 kyphotic in the upper region and 68 of 84 lordotic in the lower region. The plane of maximum curvature of sections of the spine with scoliosis was not related to the plane of symmetry of the rotated apical vertebra, for in kyphotic regions of the spine the rotations of these two planes were in opposite directions. In all cases, the magnitudes of the rotations were quite different, i.e., by a factor of −0.22 for curves in thoracic region and by a factor of 0.24 for curves in the lumbar region. This implies that mechanical measures to correct this spinal deformity or to prevent progression should apply different rotations to the apex from those applied to the curve as a whole and, in opposite senses, in curves in kyphotic regions. There was no evidence of an abnormality of sagittal curvature of a magnitude to implicate it in the etiology or in the treatment.
Tensile properties of human knee joint cartilage. II. Correlations between weight bearing and tissue pathology and the kinetics of swelling
Authors: Akizuki Shaw , Mow Van C. , Muller Francisco , Pita Julio C. , Howell David S. 
Published: February 2005

AbstractThe nonequilibrium or kinetic swelling behavior of normal, fibrillated, and osteoarthritic (OA) (removed from total knee joint replacements) human knee joint cartilage has been measured using our isometric tensile apparatus (ITA). We found that large local variation exist in the manner with which human knee joint cartilage swells, including anisotropic effects, inhomogeneities, and dependence on local biochemical composition and pathological condition. The ITA provides three convenient biomechanical parameters—peak stress (s̀P), stress relaxation (s̀R), and diffusion coefficient (D)—to quantify the kinetics of swelling. We used these parameters to quantify and differentiate the kinetic swelling behavior of normal, fibrillated, and osteoarthritic cartilage, as well as the swelling behavior of cartilage from high and low weight‐bearing areas. Also, these kinetic swelling parameters correlated very well, though by varying degrees, with such biochemical measures as collagen/proteoglycan ratio, hexosamine content/wet weight, and hydroxyproline content/dry weight, providing important insight into the mechanisms and processes involved during the course of swelling. Hence, the kinetic swelling behavior of cartilage should be used to provide important information not obtainable from equilibrium swelling studies.
Accuracy and reproducibility of instrumented knee‐drawer tests
Authors: Edixhoven Ph. , Huiskes R. , De Graaf R. , Van Rens Th. J. G. , Slooff T. J. 
Published: February 2005

AbstractInstrumented devices for knee‐drawer tests have become popular in orthopaedics relatively recently. The objective of the present study was to document the effects of several parameters on the accuracy and reproducibility of anterior‐posterior (AP) drawer measurements. An instrumented knee‐drawer tester for AP laxity evaluations was constructed, based on the differential displacement method, measuring shifts of the tuberosity relative to the patella. The accuracy of the AP‐shift was determined with the parallel use of a highly accurate roentgen stereo photogrammetric (RSP) measurement system on two postmortem leg specimens. The effects of relative motion between patella and femur were negligible. In addition to AP shifts, significant knee flexion and tibial rotations occurred, although the foot and the thigh were fixed as well as possible. The differential displacement method was effective in circumventing this problem. The accuracy of the AP shift was >10%. The reproducibility of the AP drawer parameters (shifts and compliances) was determined in normal subjects and patients. Tests were made to evaluate the effects of different observers, time sequences, and different days. In addition, effects of muscle relaxation were studied. Overall, the shift parameters at different forces were found to be reproducible to between 5 and 15%. The slopes (compliances) of the laxity curves, at different forces, were found to be reproducible to between 20 and 40%. The reproducibility was principally affected by deviations in the subject positioning procedure.
Mechanical behavior of the human lumbar spine. I. Creep analysis during static compressive loading
Authors: Keller T. S. , Spengler D. M. , Hansson T. H. 
Published: February 2005

AbstractThe in vitro viscoelastic “creep” behavior was examined in 18 cadaveric human lumbar motion segments subjected to static axial compressive loads. Axial deformation was followed for 30 min under constant applied load. Compressive material constants (moduli and viscosity coefficients) were then determined for each intervertebral disc using a linerization method based on a Taylor series expansion of experimental data for the “three parameter” viscoelastic creep model. The degree of disc degeneration and bone mineral content (BMC) were also assessed. Good correlation between the experimentally determined and model predicted strain values were found, with the average error <1%. We found that motion segments from older and more degenerated lumbar discs were less stable and had lower material constants than segments from younger and less degenerated discs. Material constants and BMC correlated closely, suggesting that an interdependency of disc and vertebral body properties exists. No correlation between the creep characteristics and disc height, disc area, segment level, or sex were noted.
Tendon synovial cells secrete fibronectin in vivo and in vitro
Authors: Banes Albert J. , Link G. William , Bevin A. G. , Peterson Hugh D. , Gillespie Yancy , Bynum Donald , Watts Susan , Dahners Lawrence 
Published: February 2005

AbstractThe chemistry and cell biology of the tendon have been largely overlooked due to the emphasis on collagen, the principle structural component of the tendon. The tendon must not only transmit the force of muscle contraction to bone to effect movement, but it must also glide simultaneously over extratendonous tissues. Fibronectin is classified as a cell attachment molecule that induces cell spreading and adhesion to substratum. The external surface of intact avian flexor tendon stained positively with antibody to cellular fibronectin. However, if the surface synovial cells were first removed with collagenase, no positive reaction with antifibronectin antibody was detected. Analysis of immunologically stained frozen sections of tendon also revealed fibronectin at the tendon synovium, but little was associated with cells internal in tendon. The staining pattern with isolated, cultured synovial cells and fibroblasts from the tendon interior substantiated the histological observations. Analysis of polyacrylamide gel profiles of 35S‐methionine‐labeled proteins synthesized by synovial cells and internal fibroblasts indicated that fibronectin was synthesized principally by synovial cells. Fibronectin at the tendon surface may play a role in cell attachment to prevent cell removal by the friction of gliding. Alternatively, fibronectin, with its binding sites for hyaluronic acid and collagen, may act as a complex for boundary lubrication.