bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of extracellular matrix macromolecules from bovine synovial capsule
Authors: Kleftogiannis Fotini , Handley Christopher J. , Campbell Margaret A. 
Published: February 2005

AbstractSynovial capsule from the metacarpophalangeal joints of cattle was shown to be a highly collagenous tissue, with a hydroxyproline content of 100 ± 1 μg/mg dry weight and a water content of 70 ± 3.6%. Type‐I collagen made up 83% of the collagen present, and the remainder was type III. When incubated in explant culture, synovial capsule incorporated [3H]acetate into both glycoproteins and hyaluronan and [3H]acetate and [35S]sulfate into proteoglycans. The rate of synthesis of proteoglycans by synovial tissue was shown to be similar to that measured for collateral ligament from the same joint. Two populations of proteoglycans were observed to be synthesized by synovial capsule. More than 90% of the 35S‐labelled proteoglycans eluted with a Kav of 0.7 on Sepharose CL‐4B, and the remainder of the radiolabelled macromolecules eluted from the column with a Kav of less than 0.5. Analysis of the major population of proteoglycans showed it to consist of a dermatan sulfate‐containing proteoglycan with a core protein of 45,000 Da that had the same N‐terminal amino acid sequence as decorin.
Differential levels of synovial fluid aggrecan aggregate components in experimental osteoarthritis and joint disuse
Authors: Ratcliffe Anthony , Beauvais Paul J. , Saed‐Nejad Fatemeh 
Published: February 2005

AbstractThe levels of proteoglycan aggregate components (link protein, keratan sulfate epitope, and total sulfated glycosaminoglycan) were determined in the synovial fluid lavages of dogs with experimental osteoarthritis or disuse atrophy. A model of experimental osteoarthritis was created by transection of the anterior cruciate ligament of the right knee; studies were carried out 6 and 12 weeks after surgery. Joint disuse was studied at 4 and 8 weeks after initiation of the disuse. Recovery after disuse also was studied in joints that had 3 weeks of remobilization after 4 or 8 weeks of disuse. Synovial fluid lavages from the right knee joints of untreated animals were used as controls. The concentrations of keratan sulfate epitope, sulfated glycosaminoglycan, and link protein in the synovial fluid lavages at 6 and 12 weeks after transection of the anterior cruciate were elevated compared with the control values. Similar analysis of the fluid after disuse showed that the levels of keratan sulfate epitope and sulfated glycosaminoglycan were increased compared with the control levels and the levels after transection. However, the concentration of link protein in the fluid after disuse was not significantly different from the control level. The levels of keratan sulfate epitope and sulfated glycosaminoglycan in the synovial fluid lavages after disuse with recovery were high, but the levels of link protein remained low. The results indicate that the catabolism of proteoglycan aggregates in articular cartilage during early osteoarthritis and disuse is different. The determination of keratan sulfate epitope in synovial fluid lavages appears to provide a relatively general indication of proteoglycan catabolism, whereas increased levels of link protein may be more indicative of cartilage degeneration.
Fit of the uncemented femoral component and the use of cement influence the strain transfer to the femoral cortex
Authors: Jasty Murali , O'Connor Daniel O. , Henshaw Robert M. , Harrigan Timothy P. , Harris William H. 
Published: February 2005

AbstractTo determine whether the strain patterns produced in the femoral cortex after uncemented femoral arthroplasty are influenced by the fit of the component and whether these patterns are different from those of cemented components, cortical surface strains of cadaveric femurs subjected to loads simulating single‐limb stance were measured before and after the insertion of uncemented, collared, straight‐stemmed femoral components. The effects of press fit, loose fit, and precise fit of the components were evaluated and were contrasted to the strain patterns occurring after insertion of cemented femoral components. Strains varied markedly, depending on the fit of the stem of the uncemented femoral component within the isthmus. Nearly normal patterns of femoral strain were produced when the femoral stem was fit precisely at the isthmus, and the proximal femoral strains were similar to those of the intact state. In contrast, press fit and loose fit at the isthmus altered the strain patterns. The proximal medial axial strains were significantly reduced with press fit, to a mean of 39% of normal (p < 0.05), and increased with loose fit, to a mean of 141% of normal (p < 0.05). The prostheses fixed with cement showed a mean reduction in proximal medial axial strains to 33% of normal, which was comparable with press fit uncemented components even though the collar was well seated. Thus, our findings indicated that, in the immediate postoperative period, femoral strain patterns can be influenced by the fit of an uncemented component within the isthmus and by the use of cement.
Effects of intermittent administration of pamidronate on the mechanical properties of canine cortical and trabecular bone
Authors: Acito A. J. , Kasra M. , Lee J. M. , Grynpas M. D. 
Published: February 2005

AbstractThe mechanical properties of cortical and trabecular bones from beagles treated with the bisphosphonate pamidronate (administered intermittently 1 week every month for 3 months, at a dosage of 0.45 μmol/kg/day) were assessed. The mechanical properties of cortical bone were measured by four‐point bending tests on femoral quadrants, in order to measure their elastic modulus and ultimate stress. The structural properties of whole tibias were measured in torsion to determine the torsional stiffness and failure torque. The elastic modulus and maximum compressive stress of the trabecular bone samples were measured by compression tests of trabecular cores. Intermittent treatment with pamidronate did not change the pattern of mechanical properties that occurs naturally around the femur or the torsional stiffness and failure torque of the tibias. By contrast, pamidronate did significantly increase the modulus of elasticity (by 19%) and maximum compressive stress (by 33%) of vertically aligned cylindrical trabecular specimens taken from the vertebrae of the beagles.
Three‐dimensional knee joint movements during a step‐up: Evaluation after anterior cruciate ligament rupture
Authors: Jonsson Håkan , Kärrholm Johan 
Published: February 2005

AbstractThe three‐dimensional motions of the knee were analysed during closed kinetic chain knee extension in 13 patients with unilateral chronic injury of the anterior cruciate ligament. The patients ascended a platform, and serial stereophotogrammetric roentgenograms were exposed from about 100° of flexion to full extension. From a position of about 100° of knee flexion and 20° of internal rotation, the tibia rotated externally during the extension. Almost no tibial adduction or abduction was observed. The tibial intercondylar eminence translated laterally, distally, and anteriorly relative to the femur. In knees with absence of the anterior cruciate ligament, the intercondylar eminence had a more posterior position compared with the contralateral normal knees. The proximal tibia was used as a fixed reference segment to evaluate the anteroposterior translations of a central point in the femoral condyles. The femoral point was more anteriorly displaced in the injured than in the contralateral knees. This difference might reflect increased activity of the hamstrings in the injured knees, because it was most pronounced at 80° of flexion and decreased with increasing extension. In the sagittal plane, the mean helical axis was positioned close to the femoral insertion of the ligament at 80° of flexion and was displaced distally and anteriorly during extension. In the frontal plane, the axis had a transverse direction at 80° of flexion. At close to full extension, the axis was positioned distally in the lateral condyle and proximally in the medial condyle. In the horizontal plane, the helical axes ran slightly more anteriorly in the medial than in the lateral femoral condyle but changed inclination at close to full extension and became almost parallel to the transverse axis.
Tendons attached to prostheses by tendon‐bone block fixation: An experimental study in dogs
Authors: Gottsauner‐Wolf Florian , Egger Erick L. , Schultz Fredrick M. , Sim Franklin H. , Chao Edmund Y. S. 
Published: February 2005

AbstractTo develop a method of tendon attachment to a metallic endoprosthesis, we evaluated fixation strength, clinical function of the tendon, and morphological changes in an experimental model. The canine supraspinatus tendon was removed from the greater tubercle of the humerus and attached to a titanium prosthesis. In 12 animals, the bone block underlying the tendon insertion was preserved and attached in one limb; the soft part of the tendon was attached directly to the prosthesis in the contralateral limb. Fixation strength was evaluated after 16 weeks of in vivo implantation (12 specimens) and compared with the in vitro fixation strength (12 specimens) and with intact normal controls (six specimens from cadavera). Function of the tendon in vivo was evaluated by force‐plate analysis (at 3‐weeks intervals). All specimens were evaluated histologically. Sixteen weeks after surgery, the tendon‐bone block attachment was significantly stronger (mean, 16%) than the direct tendon attachment and not significantly different from the normal control, and the direct tendon attachment was significantly weaker (mean, 68%) than the normal control. There was significantly more weight‐bearing on the limbs with a tendon‐bone block attachment than on the limbs with a direct tendon attachment at both 3 and 6 weeks postoperatively. Both front legs showed increased weight‐bearing with time, but the differences were not statistically significantly. Anchorage by tissue ingrowth to the titanium prosthesis was found consistently–there was bone ingrowth in the tendon‐bone block attachments and fibrous tissue ingrowth in the direct tendon attachments. When a bone block was preserved, the strength and stiffness were comparable with those of a normal tendon insertion. This mechanical linkage was capable of transmitting muscle forces to the prosthesis and consequently to the limb.
Femoral abnormalities and vitamin D metabolism in X‐linked hypophosphatemic (Hyp and Gy) mice
Authors: Meyer Ralph A. , Meyer Martha H. , Gray Richard W. , Bruns M. Elizabeth 
Published: February 2005

AbstractX‐linked hypophosphatemia is a genetic bone disease in humans and mice. Two closely linked mutations in mice. Hyp and Gy. cause low plasma phosphate and a rachitic and osteomalacic bone disease. Because of the controversy as to whether Gy is a good model for X‐linked hypophosphatemia, the phenotypic severity of these two mutations was compared in both sexes and on two genetic backgrounds. The depression in plasma levels of phosphate was similar in all 10‐week‐old mutant mice. Male Hyp mice and heterozygous female Hyp mice were affected with similar severity in terms of reduced tail growth, shortened femora, reduced femoral mineral content, and abnormal mineral composition of the femoral matrix. In contrast, male Gy mice did not survive on the C57BL/6J background and were more severely affected than female Gy mice on the B6C3H background. The hybrid B6C3H background ameliorated the bone disease compared with the inbred C57BL/6J background for both mutant strains. There was no evidence of change in the plasma levels of 1.25‐dihydroxyvitamin D, duodenal level of vitamin D‐dependent calcium‐binding protein, or urinary level of calcium in these adult mutant mice. In summary, Gy mice have a sexual dimorphism not present in Hyp mice. These two genes may indicate the presence of multiple gene loci in the human disease, with multiple proteins involved in the pathophysiology of the bone disease.
Changes of cytoskeletal architecture and incorporation of 3H‐proline in contracted anterior cruciate ligament
Authors: Sonoda Masaki , Moriya Hideshige , Wada Yuichi , Shimada Yutaka 
Published: February 2005

AbstractChanges of cytoskeletal architecture and incorporation of 3H‐proline were investigated in contracted anterior cruciate ligaments with use of a model of contracture. In control ligaments, fibroblasts were shown by immunofluorescence microscopy to contain actin, vimentin, and myosin in their cytoplasm. Cytoskeletons were visualized by electron microscopy as a mesh network of microfilaments among cell organelles. In contracted anterior cruciate ligaments, fibroblasts were spindle‐shaped and their cytoplasm could not be observed clearly in sections stained with hematoxylin and eosin. Actin staining was distributed irregularly and extensively, whereas vimentin and myosin staining was not scattered so extensively. When compared electromyographically, the actin staining appeared in cytoplasmic pseudopods of the fibroblasts. It was thought that these cytoplasmic pseudopods contained mainly actin and little or no other cytoskeletal elements such as vimentin and myosin. In autoradiographs, contracted anterior cruciate ligaments were shown, with use of 3H‐proline, to experience a decrease in the number of labeled cells. On the basis of these findings of cytoskeletal rearrangement and of decreased incorporation of 3H‐proline, we hypothesized that fibroblasts of the anterior cruciate ligament had the capacity to change their character during knee immobilization and to play a role in ligament contracture.
Histomorphometric analysis of innervation of the anterior cruciate ligament in osteoarthritis
Authors: Amir Gail , Lowe Joseph , Finsterbush Alex 
Published: February 2005

AbstractThe aim of this study was to determine whether there are quantitative changes in the innervation of the anterior cruciate ligament in osteoarthritis. Eleven whole anterior cruciate ligaments were obtained at autopsy from cadavera of individuals with advanced osteoarthritis; five healthy ligaments were used as controls. The ligaments were transected and stained with hematoxylin and eosin, oil red O for fat, and a modification of Gairn's gold chloride method. The latter stain permits visualization of axons, mechanoreceptors, and free nerve endings that are not apparent on routine stains. The ratio of nerve tissue to periligamentous synovial tissue was determined histomorphometrically by the point‐counting method. The nerve tissue was located almost exclusively in the periligamentous synovial tissue. There was a statistically significantly greater area of nerve tissue (as a percentage of the total area) around the anterior cruciate ligaments in the osteoarthritic group than around the ligaments in the control group (p < 0.02). The nerve tissue was distributed evenly throughout the periligamentous synovial tissue in the specimens in both groups. A neurological role has been proposed for the anterior cruciate ligament in osteoarthritis. This study provides morphological evidence for neural pathology of the anterior cruciate ligament in subjects with osteoarthritis.
Cyclic compressive loading results in fatigue cracks in ultra high molecular weight polyethylene
Authors: Pruitt L. , Koo J. , Rimnac C. M. , Suresh S. , Wright T. M. 
Published: February 2005

AbstractWear damage to the articulating surfaces of total joint components made of ultra high molecular weight polyethylene is associated with a fatigue fracture mechanism, despite the fact that these surfaces are subjected to primarily compressive and compressive‐tensile cyclic stresses. The question arises as to whether fatigue cracks will form under such loading conditions. In this study, we experimentally demonstrated that fatigue cracks could be initiated and propagated in notched ultra high molecular weight polyethylene specimens subjected to fully compressive and compressive‐tensile cyclic loading. Under these loading conditions, growth of fatigue cracks was limited: the cracks arrested without catastrophic failure of the test specimens. The final length of the crack was dependent on the load ratio of the fatigue cycle; fatigue cracks propagated to greater lengths as the load ratio was increased.
Hamstrings and gastrocnemius co‐contraction protects the anterior cruciate ligament against failure: An in vivo study in the rat
Authors: Aune Arne Kristian , Nordsletten Lars , Skjeldal Sigmund , Madsen Jan Erik , Ekeland Arne 
Published: February 2005

AbstractAn anesthetized rat model was used to study the effects of muscle contraction on the ultimate tensile load and the energy absorption at failure of the anterior cruciate ligament. In both knees, the joint capsule and ligaments, except for the anterior cruciate ligament, were divided, and the menisci were removed with the aid of a stereomicroscope. The cruciate ligament of the right knee was tested in tension until failure by femorotibial distraction during contraction of the hamstrings and calf muscles induced by electrical stimulation of the ischiatic nerve. The cruciate ligament of the left knee, which was loaded to failure with nonstimulated (relaxed) muscles, served as the control. The mean ultimate tensile load during muscle contraction was 86 N compared with 53 N when tested with relaxed muscles (p < 0.001). The energy absorption at failure was 0.41 and 0.19 J during contraction and relaxation, respectively (p < 0.05). This study suggests that previous investigations evaluating the force and energy necessary to rupture the anterior cruciate ligament (with use of a femur‐anterior cruciate ligament‐tibia complex stripped of all soft tissues and without gastrocnemius‐hamstring muscle contractions) are incomplete and probably not representative of the in vivo situation.
Adhesiveness of human ligament fibroblasts to laminin
Authors: Sung K‐L. Paul , Steele Laura L. , Whittermore Darren , Hagan Jay , Akeson Wayne H. 
Published: February 2005

AbstractThe adhesiveness of fibroblasts from the human anterior cruciate and medial collateral ligaments to the laminin molecule was studied, with particular emphasis on the intrinsic differences between fibroblasts from the two ligaments. Cellular adhesion strength, adhesion area, laminin concentration, and seeding time were examined. Cell adhesion to laminin anchored with poly‐D‐lysine to a cleaned cover glass was measured with a micropipette micromanipulation system after seeding. The adhesion strength of fibroblasts from the anterior cruciate ligament to laminin was greater than and significantly different from that of fibroblasts from the medial collateral ligament, depending on the laminin concentration. Fibroblasts from the anterior cruciate ligament also exhibited an increase in adhesion strength, dependent on laminin concentration of as much as 30 μg/ml, at which the laminin receptors were thought to be saturated. Fibroblasts from the medial collateral ligament did not show such an increase except at laminin concentrations of 5–10 μg/ml. There was no significant difference in adhesion area between fibroblasts from the two ligaments except after 45 minutes at a laminin concentration of 40 μg/ml. For both, the adhesion to laminin showed little correlation to seeding time during periods of as long as 60 minutes. Measurements of adhesion area also failed to show a significant correlation to seeding time for fibroblasts from either ligament at laminin concentrations of 20 and 40 μg/ml. Adhesion strength normalized by adhesion area had no correlation to seeding time. With all times taken into account, however, normalized adhesion strength for fibroblasts from the anterior cruciate ligament was approximately two times greater than and significantly different from that for fibroblasts from the medial collateral ligament at laminin concentrations of 20 and 40 μg/ml. Fibroblasts from the anterior cruciate ligament adhere more strongly to laminin than do those from the medial collateral ligament. This study may prove useful in the understanding of fibroblast adhesion to the basal lamina within the extracellular matrix and may provide insight into the natural healing processes of the anterior cruciate and medial collateral ligaments.
Immobilization of the knee joint alters the mechanical and ultrastructural properties of the rabbit anterior cruciate ligament
Authors: Newton Peter O. , Woo Savio L‐Y. , MacKenna Deidre A. , Akeson Wayne H. 
Published: February 2005

AbstractThe effects of immobilization of the knee joint on the mechanical and ultrastructural properties of the anterior cruciate ligament have not been well documented. Our goal was to determine these effects in a rabbit model and to assess the effect of knee flexion angle during immobilization. The knee joint was immobilized in either 170° or 105° of flexion, and new methodologies were utilized to determine the mechanical properties of the anterior cruciate ligament. In specimens from knees that had been immobilized, the cross‐sectional area of the ligament was 74% of the control value. The stress‐strain curve was altered slightly, and the strain at failure increased 32–40%. The modulus and stress at failure did not decrease significantly. There was no significant difference between the mechanical properties of the knees immobilized at 170° and 105° of flexion. Histological and ultrastructural evaluation demonstrated changes in the shape and intracellular makeup of the fibroblasts from the ligament after immobilization. This cellular response may account for the alterations in the mechanical properties of the anterior cruciate ligament.
Reduction of patellofemoral contact forces following anterior displacement of the tibial tubercle
Authors: Singerman Robert , White Craig , Davy Dwight T. 
Published: February 2005

AbstractRetropatellar pain often accompanies malalignment syndromes and frequently is attributed to excessive patellofemoral contact stresses. Elevation (anterior displacement) of the tibial tubercle has been recommended to relieve these conditions. The degree to which patellar contact forces are decreased and the extent to which elevation alters medial‐lateral forces have not been studied directly. We performed anterior translation of the tibial tubercle in knees from cadavers and measured the effect on the magnitude of the three‐dimensional patellofemoral contact force with use of a specially designed 6‐degrees‐of‐freedom force transducer, with the natural patellar articular surface in place. Measurements were made in nine knees (average age 67 years, range 46–92 years). The resultant contact force decreased linearly with increasing tubercle elevations of as much as 2.5 cm. The average reduction per centimeter of elevation was 17% of the force measured with no elevation. Elevation of the tubercle had an inconsistent effect on the medial‐lateral component of the contact force. As the elevation was increased, six knees exhibited an increase in the medial‐lateral component of the contact force acting medially on the knee and three knees exhibited a decrease in this force component. The results of this study show that, while elevation of the tubercle without medialization reduced the total contact force on the patella, the medial‐lateral component of this force was altered it an unpredictable way.