bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of replacement cells for the anterior cruciate ligament autograft
Authors: Kleiner Jeffrey B. , Amiel David , Roux Richard D. , Akeson Wayne H. 
Published: February 2005

AbstractA rabbit model for anterior cruciate ligament (ACL) reconstruction using autogenous avascular patellar tendon (PT) was utilized to study the early events of graft incorporation. Histological observations demonstrated that autografts were centrally acellular with a peripheral rim of cells at 2 weeks, a central focal proliferation of cells at 3 weeks, and a cellular homogeneous distribution by 4‐weeks postoperation. Graft necrosis followed by cellular proliferation suggested that a different population of cells other than the native PT fibroblasts may be inhabiting the graft. The extrinsic contribution of cells was studied by selective destruction of native PT cells with liquid nitrogen immersion prior to reconstruction of the ACL. The intrinsic contribution of cells was evaluated by sequestration of the PT graft in a semipermeable membrane before it was used to reconstruct the ACL. Histological analysis of tissue that was liquid N2 treated, used as an autograft, and then harvested 3‐weeks post‐operation revealed fibroblastic incorporation of the graft. In contrast, no cells were observed in semipermeable membrane sequestered autografts. These data suggest that autogenous ACL autografts of PT origin are repopulated by cells of external origin. In vitro control studies that were carried out in parallel demonstrated that PT fibroblasts could survive in tissue culture, but not in the synovial environment of the ACL. This suggests that fibroblasts from different sources have different, tissue‐specific nutritional requirements.
Biochemical, histological, and biomechanical analyses of canine tendon
Authors: Okuda Y. , Gorski J. P. , An K.‐N. , Amadio P. C. 
Published: February 2005

AbstractTo define the matrix composition and architecture of canine flexor tendon, and to correlate tissue structure with applied mechanical loading, five anatomical regions of flexor tendon were studied. Histologically, two prominent fibrocartilaginous areas were observed on concave aspects of the tendon. The location of the major fibrocartilaginous area at the metacarpophalangeal joint correlated well with the region predicted by biomechanical modeling to be under greatest compressive loads during standing and claw movement. Comparative biochemical analysis showed an elevated water content, a fivefold higher hexuronic acid content, and a larger hydroxylysine/hydroxyproline ratio in this region relative to that for more tendinous areas. The major glycosaminoglycan component of fibrocartilaginous areas was chondroitin sulfate, whereas in other areas dermatan sulfate and hyaluronic acid dominated. Cell density and DNA analyses indicated a slightly higher cellularity for fibrocartilaginous areas and the region of vinculum insertion. These data document the existence of discrete areas of specialization within the flexor tendon that appear to be an adaptation to nutritional and mechanical factors.
Fracture failure mechanisms in patients with osteogenesis imperfecta
Authors: Alman Benjamin , Frasca Peter 
Published: February 2005

AbstractThis investigation examines the failure mechanism of bone from patients with osteogenesis imperfecta (OI). Mechanical testing and ultrastructural analysis of surgically obtained bone specimens, from patients with OI and from approximately age matched normal controls, were performed. Small rectangular bone samples (1.0 mm × 1.2 mm × 15mm) with a prismatic cross section were put under three‐point bending to determine the work to fracture. Furthermore, the fracture surface was observed with scanning electron microscopy (SEM). The SEM observation of partially dissected lamellae was also performed to determine the collagen organization of the bone. The OI bone has a consistently lower work to fracture and reduced collagen organization than the normal controls. The fracture surface of the OI bone is rough and exhibits a “pull‐out” type of morpholgy, as opposed to the smoother fracture surface of the controls. This study shows that a relatively simple mechanical test utilizing a small amount of bone can differentiate between a diseased state (OI) and a normal state of bone.
Evaluation of double‐exposure holographic interferometry for biomechanical measurements in vitro
Authors: Manley M. T. , Ovryn B. , Stern L. S. 
Published: February 2005

AbstractDouble‐exposure holographic interferometry is a nondestructive testing technique for measuring displacement and strain in a test object. A standard hologram contains three‐dimensional information about an object. However, the holographic interferogram has additional information, as a series of interferece bands overlaid on the three‐dimensional image of the object contains information about object deformation. Interferograms were produced for intact cadaveric femora and cadaveric femora with implanted titanium alloy and cobalt‐chromium alloy femoral components. A force was applied to the femoral head to simulate single leg stance, and changes in specimen deformation were observed as additional incremental loads were applied. We have observed that the femur behaves as a bending beam and that the holographic technique allows the position of maximal deflection to be identified and the magnitude of femoral displacement from the load axis to be determined at any point within the field of view. The effects of the modulus of the implanted stem on the bending characteristics of the composite structure were clearly seen in the interferograms. This communication presents a photographic analysis of the double exposure interferograms recorded, as well as a critique of the technique for biomechanical measurements in vitro.
Differences in matrix vesicle concentration among growth plate zones
Authors: Buckwalter Joseph A. , Mower Donald , Schaeffer Janice 
Published: February 2005

AbstractWe studied the proximal tibial growth plates of 15‐day‐old mice to determine if matrix vesicle concentration varies among growth plate zones or between the pericellular and territorial matrix compartment and the interterritorial matrix compartment. Growth plates were examined by electron microscopy and divided into five zones: reserve zone (RZ), upper proliferative zone (UPZ), lower proliferative zone (LPZ), upper hypertrophic zone (UHZ), and lower hypertrophic zone (LHZ) which included the calcifying zone. We measured the diameter and volume fraction of matrix vesicles and calculated their numerical density and volume per cell and number per cell in the pericellular and territorial matrix and in the interterritorial matrix of each zone. In the pericellular and territorial matrix compartment, the matrix vesicle concentration progressively decreased from the RZ to the LHZ. Changes in matrix vesicle concentration in the interterritorial matrix followed a different pattern. Between the RZ and the UPZ, matrix vesicle numerical density declined slightly and then increased to peak values in the LPZ and UHZ, followed by a decline between the UHZ and the LHZ. These changes in matrix vesicle concentration paralleled previously reported changes in intramitochondrial calcium content (8), suggesting that matrix vesicle production in growth plate may be related to intracellular calcium concentration. The existence of the maximum concentration of matrix vesicles in the LPZ and UHZ longitudinal septa which do not mineralize followed by a decline in matrix vesicle concentration in the LHZ longitudinal septa which mineralize suggests that a high concentration of matrix vesicles may be needed to prepare the matrix for mineralization or to initiate mineralization and that matrix vesicles are depleted during mineralization.
In‐vitro ligament tension pattern in the flexed knee in passive loading
Authors: Ahmed A. M. , Hyder A. , Burke D. L. , Chan K. H. 
Published: February 2005

AbstractTensions generated in selected bands of the four major ligaments of the flexed knee (40–90°) have been measured in vitro when the tibia is subjected to passive anterior translation and axial rotation with and without a compressive preload. The measurements were made in 30 fresh‐frozen specimens using the buckle transducer attached to the anteromedial band of the anterior cruciate ligament [ACL (am)], the posterior fibers of the posterior cruciate ligament [PCL (pf)], the superficia fibres of the medial collateral ligament [MCL (sf)], and in the total lateral collateral ligament (LCL). Particular attention was placed on the evaluation of the performance of the transducer specific to such measurements in order to minimize the errors associated with the use of this transducer. The results indicate that, among the measured ligaments, substantial tension (>20 N) is generated only in the ACL (am) in tibial anterior translation up to 5 mm. The tension pattern generated in response to tibial axial rotation, however, is complex and exhibits considerable variation between specimens. In general, both the MCL (sf) and LCL are tensed at all tested flexion angles, with the tension in external rotation being significantly greater than in internal rotation. At 40° of flexion, the ACL (am) bears tension mainly in internal rotation, while at 90° of flexion the PCL (pf) is tensed in both senses of rotation. The response of the LCL shows marked variation among specimens; very small tension (15 N) is generated in internal rotation in 48% of the specimens, and in either sense of rotation in 20% of the specimens. The tension in the ACL (am) in internal rotation is invariably greater in those specimens in which LCL tension is negligible. This correlation between increased ACL (am) function and inadequate LCL restraint appears significant in terms of ACL injury and repair.
Effect of postnatal age on the ultrastructure of six anatomical areas of canine flexor digitorum profundus tendon
Authors: Okuda Y. , Gorski J. P. , Amadio P. C. 
Published: February 2005

AbstractWe report findings of a transmission electron microscopic study comparing the morphological appearance of cells and extracellular matrix of two fibrocartilaginous regions of canine flexor digitorum profoundus (FDP) tendon with that for typical tendinous regions. In addition, we determined the size distribution of collagen fibrils in six anatomical areas of the tendon from animals of three different ages. Average collagen fibril diameters for each of the six anatomical sites of 11‐week‐old FDP tendon were consistently different from that for older tissue. As growth proceeds, fibrils in tendinous regions almost double in size and take on a broad bimodal distribution. Collagen diameters in fibrocartilaginous areas do not increase, but rather decrease in size with age. Finally, the cells and associated pericellular matrix of fibrocartilaginous areas of adolescent and mature FDP tendon are ultrastructurally distinct from those of typical tendinous regions. On the contrary, the cellular morphology of 11‐week‐old tendon was invariant regardless of the anatomical region examined. In summary, fibrocartilage of canine FDP tendon, although not evident at 11 weeks of age, is well established by 6–12 months after birth and is the result of cellular and extracellular matrix specialization.
Local compression patterns beneath pneumatic tourniquets applied to arms and thighs of human cadavera
Authors: Hargens Alan R. , McClure A. Gavin , Skyhar Michael J. , Lieber Richard L. , Gershuni David H. , Akeson Wayne H. 
Published: February 2005

AbstractDistributions of tissue fluid pressure were examined beneath a standard pneumatic tourniquet in six upper extremities and six lower extremities of fresh human cadavera, disarticulated at the shoulder and hip, respectively. A standard 8‐cm‐wide tourniquet cuff was applied at mid‐humerus or mid‐femur position. Tissue fluid pressures were measured by 100‐cm‐long slit catheters inserted parallel to the bone at four tissue depths: (a) subcutaneous, (b) subfascial, (c) mid‐muscle, and (d) adjacent to bone. All arms and thighs were studied at the following cuff pressures: 100, 150, 200, 250, 300, 400, and 500 mm Hg. Tissue fluid pressure was always maximal in subcutaneous tissue at mid‐cuff. Transmission of cuff pressures to deeper tissues was significantly less (p < 0.01) in the thighs with a girth of 40–52 cm than in the arms with a girth of 22–23 cm. At the four tissue depths studied, tissue fluid pressures fell steeply in a longitudinal direction near the cuff edge to levels near zero at points 1–2 cm outside each cuff edge. Our results suggest that wider cuffs are required on thighs than on arms to provide a bloodless field during limb surgery and to minimize underlying tissue injury associated with high cuff pressures. Our recommendation for wider tourniquet cuffs than those presently used during orthopaedic surgery is contrary to recent prevailing knowledge.
Natural history of acute septic arthritis in an avian model
Authors: Alderson Mark , Nade Sydney 
Published: February 2005

AbstractAn experimental model of acute septic arthritis is described, utilizing the injection of S. Aureus into chicken hock joints. The course of the infection was monitored over a 14‐day period by measurement of chicken growth rate, histopathology of the joint, number of bacteria, and number and type of leukocytes in the synovial fluid. Bacterial numbers decreased initially then increased rapidly over the first 24 h. Leukocyte counts rose sharply, starting between 60 and 90 min after injection. Gross destruction of articular cartilage was observed at 4 days, and appeared to be initiated by the adherence of the staphylococci to the cartilage surface followed by their penetration and invasion of vascular tunnels in the epiphyseal cartilage. Extensive (but focal) erosion of the articular surface was evident by 14 days.
Normative childhood EMG gait patterns
Authors: Shiavi Richard G. , Green Neil , McFadyen Brad , Frazer Mardon , Chen Jason 
Published: February 2005

AbstractThe population characteristics of the linear envelopes of the electromyograms measured from seven lower extremity muscles in children were studied during locomotion. The variability and changes in pattern with respect to walking speed and age were investigated using statistical properties and analysis of variance of the envelopes. All muscles studied showed changes in their patterns that were associated with different walking speeds. Some changes concerned the relative intensity of existing phases of activity. The most remarkable trend was that all envelopes tended to have more consistent patterns as speed increased. With regard to age, within the span of 4–11 years, only the two high muscles studied demonstrated appreciable differences.
Warping of cross sections in the torsion of long bones with internal fracture fixation plates
Authors: Beaupré G. S. , Carter D. R. 
Published: February 2005

AbstractTorsion of noncircular beams results in warping of each cross section. When noncircular cross sections are constrained to remain plane, the resulting shear stress distribution is different from what Saint Venant torsion (with warping) would predict. This has practical implications to the stress analysis of plated long bones subjected to torsional loadings. Analyses in which warping is not allowed predict incorrect stress fields in the plate and bone and overpredict the amount of stress shielding associated with fracture plate fixation.
Surface strain on human intervertebral discs
Authors: Stokes Ian A. F. 
Published: February 2005

AbstractThe biomechanical functions of the internal components of the intervertebral disc are not well understood. The surface deformation of 17 human cadaveric lumbar intervertebral discs was studied by photogrammetry by adhering small optical targets to the disc surface and thereby recording the length, bulge, and vertical height of lines on the disc surface representing annular fibers. Discs were studied in pure compression, flexion and extension, axial rotation, and shear. Two definitions of a fiber were investigated: first with the end‐points of the fiber on the vertebra (“bone‐to‐bone” definition), second, where the end points of the fiber were just before the disc vertebra junction (the “disc‐only” definition). Measurements were compared with a “constant‐volume” physical model and with a mathematical model of the intervertebral disc. Fiber strains were 6% or less under physiological conditions. Comparison of results from the two definitions of fiber length showed greater strains for the disc‐only definition in compressive loading. Fiber strains were less than in the constant‐volume model of comparable dimensions in compressive loading by a factor of about two, thus suggesting fluid loss or end‐plate deformations in the physiologic conditions. The mathematical model indicated that the surface strain for intervertebral discs is very sensitive to the disc‐height: diameter ratio and to fluid loss from the disc but is less sensitive to the helix angle of the fibers.
The evaluation of a biphasic calcium phosphate ceramic for use in grafting long‐bone diaphyseal defects
Authors: Moore D. C. , Chapman M. W. , Manske D. 
Published: February 2005

AbstractThe effectiveness of a sintered hydroxyapatite‐tricalcium phosphate (HA‐TCP) ceramic in bridging large diaphyseal defects in the canine ulna was studied. One‐hundred percent morselized HA‐TCP, a 50:50 mixture of morselized HA‐TCP, and autogenous cancellous bone, and 100% autogenous cancellous bone were used to bridge 2.5‐cm defects in the left ulnae of three groups of six dogs each. At 24 weeks the ulnae were explanted and studied by radiography, microradiography, mechanical testing, and histology. Pure HA/TCP was not osteoinductive, and four of six ulnae in this group progressed to a fibrous nonunion. The HA/TCP‐cancellous bone mixture and pure cancellous bone were approximately equal in effect, leading to good callus formation at 4 weeks and strong bony union by 24 weeks, with no evidence of bioincompatibility. Morselized HA/TCP promises to be useful as a graft extender when mixed with autogenous cancellous bone.
Comparison of the fatigue characteristics of centrifuged and uncentrifuged simplex P bone cement
Authors: Davies Jeff P. , Burke Dennis W. , O'Connor Daniel O. , Harris William H. 
Published: February 2005

AbstractFatigue test specimens of Simplex P bone cement (Howmedica Inc., Rutherford, NJ) prepared according to the manufacturer's instructions and specimens of Simplex P prepared by centrifuging the cement immediately after mixing were subjected to fully reversed tension‐compression fatigue tests at initial strain levels ranging from 0.01 to 0.001. S:N curves for both cement preparations were generated and compared on the basis of regression analysis, Weibull analysis, and Student's t tests. Centrifuged Simplex P was able to withstand significantly more fatigue cycles than uncentrifuged Simplex P at all strain levels tested. Importantly, at the more physiologic strain levels of 2,000 and 1,000 microstrain, the centrifuged cement demonstrated superior fatigue life. Specifically, at the 1,000‐microstrain level eight of the 11 uncentrifuged specimens fractured before undergoing 10 million cycles. Of those that failed, the average number of cycles to failure was 1.8 million with a range of 560,000 to 4 million cycles. In contrast, all 11 centrifuged specimens tested at 1,000 microstrain remained intact at 10 million cycles.
Effect of patellar shaving in the rabbit
Authors: Mitchell Nelson , Shepard Nora 
Published: February 2005

AbstractShaving of the articular cartilage on the undersurface of the patella was carried out in mature white New Zealand rabbits to determine whether the removed cartilage reformed or the shaving led to later evidence of degenerative arthritis. The animals were followed for as long as 15 months after surgery, at which time patellae were removed and examined by light and electron microscopy. The depth of shaving varied considerably; however, no evidence of repair and no evidence of degenerative arthritis was noted in either the superficial or deeply shaved patellae. It is concluded that such superficial cartilage defects neither repair or produce subsequent degenerative arthritis.
New experimental procedures to evaluate the biomechanical properties of healing canine medial collateral ligaments
Authors: Woo Savio L.‐Y. , Gomez Mark A. , Inoue Masahiro , Akeson Wayne H. 
Published: February 2005

AbstractBoth clinical and animal studies have indicated that early mobilization and exercise may improve the healing of injured medical collateral ligaments (MCLs). To investigate these effects, transected canine MCLs were subjected to three different treatment regimens: (a) no surgical repair with 6 weeks mobilization; (b) surgical repair with 3 weeks immobilization followed by 3 weeks remobilization; and (c) surgical repair with 6 weeks immobilization. After sacrifice, knee laxity was measured in a newly designed varusvalgus (V‐V) laxity device. Each knee was tested subsequently in tension to determine the structual properties of the femur‐MCL‐tibia complex (FMTC) and the mechanical properties of the healing MCL substance. It was found that the V‐V laxity increased for all experimental knees, but that early mobilization enhanced joint stability. The structural properties of the FMTC and the mechanical properties of the MCL substance were also lower than the contralateral controls. Again, the early mobilization groups had better results.
Production of a reproducible spinal burst fracture for use in biomechanical testing
Authors: Cotterill Paul C. , Kostuik J. P. , Wilson J. A. , Fernie G. R. , Maki B. E. 
Published: February 2005

AbstractWe have developed a technique to create a reproducible spinal burst fracture of the 12th vertebral body using 6–8‐week‐old calf spines with ribs, muscles, and vessels resected. We used the entire thoracolumbar segment of 20 calf spines with a standardized 5‐mm‐deep slice placed onto the body of T12 and the T11–12 disc. We then delivered a proximal‐axial impact to the vertically mounted spine, preflexed to 15° of forward flexion, by dropping a 32‐kg weight, guided by a 1.55‐m steel rod (potential energy = 487 J). Motion was limited to anterior flexion only, at the T12–13 disc, by splinting the rest of the spinal segments. Fractures were documented with the use of radiographs and computed tomography (CT) scans. We noted disruption of the vertebral column and end plates, fracture of the posterior body wall, fracture of the pedicles, and retropulsion of bony fragments into the neural canal. With the production of a reproducible spinal burst fracture model, various spinal fixation devices can be applied and tested.
Streaming potentials: A sensitive index of enzymatic degradation in articular cartilage
Authors: Frank Eliot H. , Grodzinsky Alan J. , Koob Thomas J. , Eyre David R. 
Published: February 2005

AbstractUnder physiological conditions, the extracellular matrix of articular cartilage contains a high fixed‐charge density, associated with its ionized proteoglycan (PG) molecules. Compression of the highly charged cartilage matrix within the physologic range leads to the production of electrical streaming potentials. We observed significant changes in the potential response due to chemical modifications of the matrix, such as extraction of PG and glycosaminoglycan (GAG) moieties using chondroitinase‐ABC and trypsin. The streaming potential was a sensitive index of the degradative loss of these matrix constituents and of the kinetics of the enzymatic degradative process.