bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction between intrinsic knee mechanics and the knee extensor mechanism
Authors: Draganich L. F. , Andriacchi T. P. , Andersson G. B. J. 
Published: February 2005

AbstractThe ability of the quadriceps muscles to extend the knee was studied relative to the intrinsic mechanical features of the knee joint. The quadriceps mechanical efficiency changed by nearly 50% between 0 and 90° of knee flexion. The peak efficiency occurred at ∼20° of knee flexion. The mechanical efficiency of the quadriceps was dependent on the movement of the net anteroposterior (AP) tibiofemoral contact center of pressure, the change in patellar ligament angle, and the change in the quadriceps‐to‐ligament force transfer ratio. The average net AP tibiofemoral contact center of pressure moved posteriorly on the tibial plateau as the knee flexed from 0 to 90°. The excision of both cruciate ligaments reversed the posteriorly directed movement of the net AP tibiofemoral contact center of pressure at flexion angles from 60 to 90°, resulting in a reduction in extension moment.
Limb lengthening by epiphyseal distraction. An experimental study in the caprine femur
Authors: Steen Harald , Fjeld Terje O. , Rönningen Helge , Langeland Norvald , Gjerdet Nils R. , Bjerkreim Ingjald 
Published: February 2005

AbstractEpiphyseal distraction of the left distal femur was accomplished in 10 goats (aged 3–4.5 months). A modified Hoffmann external fixation device was used as a unilateral distraction frame. A distraction rate of 1.5 mm/day was applied for 5.5 weeks. Epiphysiolysis occurred after 3–7 days of distraction. After the lengthening procedure, the growth plate had reduced in height in eight animals on radiographic examination. In two animals the growth plate was fused. Three animals were killed at 4 (Group 1) and 8 (Group 2) weeks and four animals at 16 (Group 3) weeks after the end of the distraction period. The gain in leg length obtained by distraction was reduced owing to growth retardation in the distal femur of the operated limb. The average final lengthening was 24.9, 19.4, and 13.4% in Groups 1,2, and 3, respectively. Femur and tibia from both sides were tested mechanically in torsion. Only one femur fractured in the elongation area. All but one elongated femur fractured in the area of the diaphysis subjected to distractional force. The torsional strength of the elongated femur compared with control was reduced to ∼50% in all groups. The corresponding torsional strength of the tibia on the elongated extremity compared with control was reduced to ∼75% in all groups. The difference in relative strength of femur compared with that of tibia was statistically significant. This finding can be explained by a stress‐protective effect on the femur in the distraction area caused by the external device.
Pin tract infections: A canine model
Authors: Respet Patrick J. , Kleinman Paul G. , Meinhard Bruce P. 
Published: February 2005

AbstractThe purpose of this study was to examine three issues: the relationship between the length of time of skeletal pin insertion and bacterial infection, the connection between skin organisms and the intramedullary infecting agent, and the length of time necessary for the medullary canal to sterilize itself after pin removal. Skeletal pins were inserted in a group of dogs, and a direct correlation was found between the duration of time that the pins remained in the bone and positive intramedullary cultures. The infecting agent in 88% of the medullary cultures was also cultured from the skin. In a second group of dogs, the pins remained in place for 1, 2, 3, or 4 weeks, respectively. The pins were removed, and the pin tracts were permitted to heal for varying periods of time. The medullary canals were then cultured. No medullary canal was infected when the pin tracts were allowed to heal for ≥3 weeks. Therefore, if pin tracts are allowed to heal for at least 3 weeks prior to performance of osteosynthesis, the chances of deep infection are probably lessened.
Stresses in plated long‐bones: The role of screw tightness and interface slipping
Authors: Beaupré Gary S. , Carter Dennis R. , Orr Tracy E. , Csongradi John 
Published: February 2005

AbstractUsing a three‐dimensional finite element model of a plated long bone, we studied the influence of screw tightness, sliding frictional interfaces, and loading magnitude on the stresses within the plated bone. The model incorporated frictional interface elements that allowed stress‐free separation under tensile loading to occur between the plate and bone and between the screw heads and the plate. The applied loading simulated both static preloads created by tightening the screws that secure the plate to the bone and physiologic loads created by activity. Initial screw tightening with plate application created regions of bone hydrostatic compressive stress that may be partly responsible for ischemia under the plate. The inclusion of frictional interfaces resulted in a nonlinear relationship between physiologic load and bone strain that was dependent on screw tightness. This nonlinear response correlated well with the results of previous in vitro studies showing that slippage between the plate and the bone can occur at physiologic load levels. The results showed that the effect of such slippage can be at least as important as plate meterial, rigidity, and placement in determining the degree of stress shielding. The results also indicated that previous plated bone models that assumed tight interfaces may have overestimated the extent of mechanical stress shielding.
Biomplant surfaces: Binding of fibronectin and fibroblast adhesion
Authors: Cannas Mario , Denicolai Fernando , Webb Lawrence X. , Gristina Anthony G. 
Published: February 2005

AbstractThe adhesion of baby hamster kidney 21C/13 fibroblasts to surfaces of passivated titanium, carbon fibers, bioactive glasses B5 and B6, fibronectin‐precoated passivated titanium, and fibronectin‐precoated B6 was quantified. The order of adhesive cell avidity for the uncoated surfaces was passivated titanium (greatest), B6 and carbon fibers (intermediate), and B5 (least). Precoating with fibronectin enhanced the adhesive characteristics of fibroblasts on passivated titanium and B6 by 74% and 118%, respectively.
Mathematical analysis of computed carpal models
Authors: Belsole Robert J. , Hilbelink Don R. , Llewellyn J. Anthony , Stenzler Stephen , Greene Thomas L. , Dale Mark 
Published: February 2005

AbstractThe computed carpal models from digital computed tomography (CT) data obtained in this study compare favorably to natural anatomy. A new application of algebraic analysis of this data provides mathematical markers from which to calculate the position and orientation of each carpal bone. When the origin of the spatial coordinates of a carpal bone is transferred to the centroid of the bone, the data can be treated as three‐dimensional pattern vectors describing its surface. It is then possible to calculate vectors that are the principal axes of the geometry. These axes provided references that were used to calculate position and orientation of the carpal bones in three wrist specimens. Comparisons of volumes, surface areas, and sizes and proportions of five computed images of each carpal bone from two of these wrists demonstrate the reliability of the technique. The analysis of CT scans of ceramics with known boundaries allows an estimation of its accuracy. The technique is well suited to the future study of normal wrist kinematic and pathological conditions.
Epiphyseal replacement using developing tissue donors in a murine model: A combined histologic and radiographic study
Authors: Zaleske David J. , Floyd Waldo E. , Hallett Joseph , Kushner David , Jupiter Jesse , Trahan Carol , Ehrlich Michael G. , Mankin Henry J. 
Published: February 2005

AbstractEpiphyseal transplantation has long been a goal of orthopaedic surgeons. While microvascular surgery has raised hopes that this goal could be achieved, factors other than blood supply also appear capable of affecting the function of the epiphysis. Basic reserch into the biology of the epiphysis appears to be required. This would be faciliated with a model of epiphyseal transplantation using a small mammal. The purpose of this experiment was to develop such a model in the mouse. Developing CD1 mouse or Lewis rat limb tissue was used to replace knee tissue that had been resected from CD1 postnatal mouse hosts. Donor tissue ranged from 14‐day embryonic mouse to 9‐day postnatal mouse or 18‐ and 19‐day fetal rat, which has a gestation similar to the mouse. The murine tissue is known to be avascular prior to the sixth postnatal day. The limbs were analyzed radiographically and histologically. The results show that epiphyseal replacement could be studied using developing tissue donors in a murine model. The results suggest that donor tissue prior to vascularization and tissue combinations with the least developmental time mismatch (the least heterochronicity) produced relatively the best, although still abnormal epiphyses.
Lectin‐binding histochemistry of intracellular and extracellular glycoconjugates of the reserve cell zone of growth plate cartilage
Authors: Farnum Cornelia E. , Wilsman Norman J. 
Published: February 2005

AbstractThe distribution of intracellular and extracellular lectin‐binding glycoconjugates of the reserve cell zone of growth plate cartilage was studied in the distal radial growth plate of 4‐week‐old Yucatan swine using a postembedment method on Epon‐embedded sections. Direct comparisons were made to articular, tracheal, and auricular cartilages not involved in endochondral ossification. All patterns of lectin binding that in the growth plate were restricted to the reserve cell zone were also patterns characteristic of tracheal, articular, and auricular cartilages. These included: (a) pericellular binding with peanut agglutinin (PNA) without prior digestion with neuraminidase; (b) pericellular binding with wheat germ agglutinin (WGA) at 24 h; (c) intracellular cytoplasmic binding to concanavalin A (CON‐A), Lens culinaris agglutinin (LCA), and Lotus tetragonobolus agglutinin (LTA) after periodic acid oxidation; and (d) a lack of pericellular binding with CON‐A and ricin agglutinin 1 (RCA‐1) after periodic acid oxidation. We conclude that reserve zone chondrocytes lack specific phenotypic markers as defined by lectin‐binding affinity that are found in the cellular zones of the growth plate that undergo calcification and vascularization. The reserve zone has identical lectin‐binding affinities to the three structural cartilages used as controls. One interpretation of these results is that the reserve zone may not be involved directly in endochondral ossification, but may have a structural function in growth plate cartilage.
Effect of irrigation and tourniquet application on aminoglycoside antibiotic concentrations in bone
Authors: Millan Michael Mac , Petty William , Hendeles Leslie 
Published: February 2005

AbstractPreoperative antibiotics are an important measure taken to prevent infection in joint replacement surgery. The local availability of these antibiotics in the operative site is absolutely necessary to ensure adequate prophylaxis against contaminant bacteria. Because pulsatile‐lavage rapid‐recovery systems have become a routine technique of bone preparation in joint reconstruction, we chose to study the effect of these systems on local antibiotic concentrations. We further investigated the effect of irrigation with and without use of a limb tourniquet. For our study, we obtained 23 bone specimens in 16 patients undergoing joint reconstruction (14) or amputation (2). The patients were classified into one of four groups based on whether a tourniquet was applied during the procedure and whether the bone specimens were irrigated. In addition, matched blood samples were obtained to establish that therapeutic serum levels were achieved. Nine patients contributed 13 bone specimens, which underwent vigorous irrigation in vitro. None of these specimens had detectable levels of antibiotics, regardless of whether a tourniquet was used. Seven patients yielded 10 bone specimens, which were not irrigated. Five of these seven patients had detectable levels of antibiotics. In addition, the specimens from limbs without tourniquets had levels that averaged 0.51 μg/ml while those with tourniquets averaged below 0.2 μg/ml. Therefore, the use of vigorous irrigation in bone preparation has a significant deleterious effect on the local presence of previously administered systemic antibiotics. This effect is compounded if the operative site is isolated from continuous blood flow by use of a tourniquet. We therefore recommend that additional measures be taken to ensure that adequate antibiotic levels are present. Two methods that may have efficacy are application of antibiotic‐containing irrigants or antibiotic‐impregnated polymethylmethacrylate.
Analysis of experimental immune synovitis cartilage using monoclonal antibodies reactive to rabbit proteoglycan
Authors: Yoo Jung U. , Kresina Thomas F. , Malemud Charles J. , Goldberg Victor M. 
Published: February 2005

AbstractThis study details the macromolecular changes in cartilage involving proteoglycan molecules in an animal model of rheumatoid arthritis. In experimental chronic immune synovitis, fluorescein‐conjugated mouse IgG and three monoclonal antibodies (MAbs 2G2, 2E9, and 6C9) portraying differing fine antigenic specificity for rabbit cartilage proteoglycan monomer were utilized to detail alterations in cartilage proteoglycan. In normal and IgG immune animals, fluorescein isothiocynate (FITC)‐conjugated MAbs 2G2 and 2E9 stained cellular/pericellular (C/PC) region intensely. FITC‐MAb 2G2 stained cartilage interterritorial matrix as well. FITC‐MAb 6C9 stained only C/PC area lightly but did not stain matrix. A marked decrease in staining intensity with FITC‐MAb 2G2 was noted in cartilage sections derived from animals with immune synovitis. A corresponding increase in staining of cartilage was noted with FITC‐MAb 6C9. The augmented staining of articular cartilage with FITC‐MAb 6C9 was most prominent in femoral condyle tissue sections, which corresponded to the cartilaginous area, with the greatest severity in gross pathology. There was a slight augmentation of staining with FITC‐MAb 2E9, especially in the C/PC area of medial/femoral cartilage. In addition, the animals with immune synovitis showed abortive cartilage repair exemplified by the presence of chondrocyte cloning (up to 20 cells) which correlated with increased FITC‐MAb 2G2 staining. The differential MAb staining patterns of cartilaginous tissues obtained utilizing FITC‐conjugated monoclonal antibodies with known fine antigenic specificity indicates a modulation of proteoglycans involving predominantly core protein epitopes in the articular cartilage of animals with chronic immune synovitis.
Chondrons extracted from canine tibial cartilage: Preliminary report on their isolation and structure
Authors: Poole C. Anthony , Flint Michael H. , Beaumont Brent W. 
Published: February 2005

AbstractWe report on the morphology and structure of single and multiple chondrons isolated from homogenized samples of fresh and fixed canine tibial cartilage. Phase contrast, Nomarski, and scanning electron microscopy observations show each chondron to be composed of a chondrocyte and its pericellular matrix enclosed within a “felt‐like” pericellular capsule. The extraction of intact chondrons from cartilage homogenates confirms the structural validity of chondron concept and emphasizes the intrinsic mechanical strength of the capsule. Frayed collagen fibers radiate from multiple chondron columns suggesting a shear‐resistant, structural interrelationship between capsular components and type II collagen fibers. Future development of chondron extraction procedures could provide a unique model with which to study the structure, biochemistry, and function of articular cartilage chondrocytes and their pericellular microenvironment.
Residual muscular swelling after repetitive eccentric contractions
Authors: Fridén Jan , Sfakianos Peter N. , Hargens Alan R. , Akeson Wayne H. 
Published: February 2005

AbstractThis investigation illustrates the morphological changes that take place following eccentric exercise and correlates those changes with intramuscular pressure readings. Eight healthy male subjects were asked to exercise their right lower leg anterior compartment eccentrically and their left concentrically. Four hundred submaximal contractions were performed in each exercise regimen over a 20‐min period against a load corresponding to 15% of the individual's maximal dorsiflexion torque. Tissue fluid pressures were measured by the slit catheter technique before, during, and after exercise and 48 h later. Needle biopsies of both anterior tibialis muscles were also taken 48 h after completion of the exercise regimens. Overall morphology of the specimens revealed a greater cross‐sectional fiber area (both type 1 and type 2) in the eccentrically exercised muscle as compared with the concentrically exercised muscle. Scant evidence of infiammation (only 1 of 8 of the “eccentric” muscle samples) and no fiber necrosis was observed. Fiber type proportions were equal on both sides and type 1 fiber biased (70%). Extremely large type 2 fibers were found in 4 of 8 subjects from the eccentric specimens. This incidence correlated significantly with the length of the time to return to resting pressure after eccentric exercise (r = 0.93, p < 0.001). The percentage of water content was significantly higher in the eccentrically exercised muscle. Based on these findings, we conclude that muscle fiber swelling is a predominant feature following eccentric exercise and is directly associated with delayed muscle soreness.
Contact pressures in chondromalacia patellae and the effects of capsular reconstructive procedures
Authors: Huberti Helmut H. , Hayes Wilson C. 
Published: February 2005

AbstractWe measured patellofemoral contact areas and pressures using pressure sensitive film in ten human cadaver knees exhibiting degenerative lesions of patellar cartilage. We studied a flexion range from 20° to 90° and compared contact pressures before and after capsular reconstructive procedures. With an intact, normal capsule. localized lesions of grade I–II exhibited a 50% reduction in pressure (from 3.4 ± 0.7 MPa to 1.6 ± 0.9 MPa) directly over the lesion. Grade III–IV lesions exhibited a loss of contact pressure greater than 90%. This reduction in pressure appears to result from a loss of stiffness in the low grade cartilage lesions and from a loss of cartilage thickness in higher grade lesions. Highly localized peak pressures were also observed on the normal cartilage bordering the lesions. Capsular reconstructive procedures (medial plication, lateral release, and bilateral release) did not result in consistent pressure reductions or in the creation of more uniform pressure distribution. In particular, lateral capsular release, a popular surgical procedure, resulted in no change in three knees and four different pressure patterns in the other seven knees.
EMG profiles of knee joint musculature during walking: Changes induced by anterior cruciate ligament deficiency
Authors: Limbird Thomas J. , Shiavi Richard , Frazer Mardon , Borra Henry 
Published: February 2005

AbstractA tear of the anterior cruciate ligament (ACL) disrupts the delicate balance of static stabilizers of the knee, leading to significant alterations in joint kinematics. Little is known about the dynamic compensatory responses of the patient to these kinematic alterations. This lack of quantitative information on the muscle synergy patterns has limited the surgeon's ability to evaluate various operative and rehabilitative techniques. Twelve subjects with documented ACL deficiency for a least 1 year and 15 normal participants were studied. Each subject was asked to walk at free and fast speeds on a 12 m walkway. The right and left foot contact patterns and the linear envelopes from the surface electromyogram (EMG) patterns of the gastrocnemius, medial and lateral hamstrings, rectus femoris, and vastus lateralis were measured. Significant differences were found in the muscle synergy patterns during walking. During the swing‐to‐stance transition, the ACL‐deficient subjects showed significantly less activity in the quadriceps and gastrocnemius muscles and more activity in the biceps femoris than in the normal group. During early swing, the vastus lateralis is more active than normal, and during midstance and terminal stance, the hamstrings appear to be less active than normal subjects. These dynamic compensatory mechanisms suggest that use of the hamstring tendons in reconstructive procedures may alter important compensatory mechanisms about the knee joint. Application of dynamic EMG techniques to the study of reconstructive procedures should provide additional information that will assist the clinician in the rational choice of a surgical procedure.
Analysis and measurement of neck loads
Authors: Moroney Sean P. , Schultz Albert B. , Miller James A. A. 
Published: February 2005

AbstractTo examine the loads imposed on the structures of the neck by the performance of physical tasks, a biomechanical model of the neck was constructed. The model incorporated 14 bilateral pairs of muscle equivalents crossing the C4 level. A double linear programming optimization scheme that minimized maximum muscle contraction intensity and then vertebral compression force while equilibrating external loads was used to calculate the muscle contraction forces required and the motion segment reactions produced by task performance. To test model validity, 14 healthy adult subjects performed a series of isometric tasks requiring use of their neck muscles. These tasks included exertions in attempted flexion, extension, and left and right lateral bending and twisting. Subjects exerted maximum and submaximum voluntary efforts. During the performance, surface myoelectric activities were recorded at eight locations around the periphery of the neck at the C4 level. Calculated forces and measured myoelectric activities were then linearly correlated. Mean measured voluntary neck strengths in 10 male subjects were as large as 29.7 Nm. Four female subjects developed mean strengths that were approximately 60%–90% of those of the males. In both sexes, neck muscle strengths were approximately one order of magnitude lower than previously measured lumbar trunk strengths. Mean calculated neck muscle contraction forces ranged to 180 N. Mean calculated compression forces on the C4‐5 motion segment ranged to 1164 N, lateral shear forces ranged to 125 N, and anteroposterior shear forces ranged to 135 N. Correlation coefficients between the calculated muscle forces and the measured myoelectric activities were as large as 0.85 in some muscles, but generally were smaller than this.
Symmetry of the canine femur: Implications for experimental sample size requirements
Authors: Sumner Dale R. , Turner Thomas M. , Galante Jorge O. 
Published: February 2005

AbstractThe purpose of this study was to determine the degree of bilateral variability in cross‐sectional geometric properties of the adult canine proximal femur and to use these data to deterrmine minimum detectable treatment effects in paired and independent experimental designs. Thirteen paris of canine femora were sectioned at nine locations and 16 cross‐sectional geometric properties were determined for each section location. The canine femur was found to be bilaterally symmetrical. For a given sample size, the magnitude of the detectable treatment effect was (a) smaller for diameters than for areas and area moments of inertia and (b) smaller within the middiaphysis than proximally. The data from this study can be used to estimate sample size requirements for experiments in which the treatment effect is determined by using the contralateral femur as a control. It was found that an increase from 3 to 7 animals would have a much greater effect on improving the sensitivity of an experiment than would an increase from 7 to 11 animals.