bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reliability after repeated use of a torque screwdriver employed for halo pin fixation
Authors: Garfin Steven R. , Botte Michael J. , Woo Savio L.‐Y. , Nickel Vernon L. 
Published: February 2005

AbstractIt has been recommended that halo torque screwdrivers be used only once. To determine if this advice is justified on biomechanical grounds, five commercially available torque screwdrivers were cycled 1,600 times each in an Instron testing machine over a 7‐day period. The screwdrivers displayed an initial error from the dial reading at both 6 and 10 in‐lb of only ± 0.3 in‐lb. After cyclic loading and retesting, the percent deviation from original calibration was 8% at both 6 and 10 in‐lb. These data demonstrate the accuracy and dependability of the torque screwdrivers and imply that repeated use of these devices should be safe.
Structure of newly synthesised (35S)‐proteoglycans and (35s)‐proteoglycan turnover products of cartilage explant cultures from dogs with experimental osteoarthritis
Authors: Carney Stephen L. , Billingham Michael E. J. , Muir Helen , Sandy John D. 
Published: February 2005

AbstractThe structure of newly synthesised proteoglycans from explant cultures of cartilage from joints subjected to transection of the anterior cruciate ligament (osteoarthritic) and from normal (non‐ or sham‐operated) joints was examined. The structure of the products of proteoglycan turnover was also examined using explants of normal and osteoarthritic cartilage maintained in culture for a 48 h chase period. The findings were as follows: (a) Newly synthesised (35S)‐proteoglycans extracted from cartilage explants from osteoarthitic joints whether examined 3 weeks, 3 months, or 6 months after surgery were larger than those from corresponding normal cartilage. This can be explained by the synthesis in osteoarthritic cartilage of abnormally long chondroitin sulphate chains on newly synthesised proteoglycans. (b) The extracts also contained a newly formed small proteoglycan species that was unable to interact with hyaluronic acid. The porportion of thei species was higher in osteoarthritic cartilage compared with normal, examined 3 weeks after surgery, but was generally absent from cartilage obtained 3 and 6 months after surgery. (c) Compared with controls, a smaller proportion of the (35S)‐ proteoglycans released into the maintenance medium of explant cultures of osteoarthritic cartilage during a 48 h chase period was able to interact with hyaluronic acid. However, although furnished with longer (35S)‐glycosaminoglycan chains, these proteoglycans were smaller than those from control explants.
Evidence for different sources of stress‐generated potentials in wet and dry bone
Authors: Otter M. , Shoenung J. , Williams W. S. 
Published: February 2005

AbstractPhysiologically moist bone and dry bone behave differently when tested for electrical response to cantilever bending. To characterize this difference more precisely, voltages were generated in the same specimen in each of the two states via the same testing procedure—changing the electrode‐to‐force distance by moving the electrodes and holding the force position constant. In the dry state, a nonsystematic pattern of voltages versus electrode position was generated. In the wet state, a linear relationship was found. Furtive on wetting the specimen. The implication is that different electromechanical transduction mechanisms are involved in the wet dry cases. The dominant mechanism in the wet case is taken to be the streaming potential rather than piezoelectricity.
Stress analyses of joint arthroplasty in the proximal humerus
Authors: Orr T. E. , Carter D. R. 
Published: February 2005

AbstractFinite element stress analyses were performed on the proximal humerus before and after the simulated implantation of stemmed, metallic prosthetic components with porous sintered surfaces for direct bony attachment. Design geometries with surfaces at the prosthetic head/bone interface that were (a) convex, (b) flat, and (c) concave were studies. Analyses for each of the three geometries were conducted to reflect (a) bone ingrowth on all the prosthesis/bone surfaces and (b) bone ingrowth only along the underside of the prosthetic humeral head (assuming the stem was not coated with a porous material). Three loading conditions were used to model various degrees of abduction of the arm. Results indicated that in the normal humerus the compressive joint forces are transmitted from the articular surface through cancellous bone to the inferior cortical shell. Concentration of the rotator cuff muscles created tensile stresses in the superolateral cancellous bone and the superior cortical shell of the humerus. Results of the implanted numeral component models indicated that the use of a prosthesis with bone ingrowth along the stem would cause marked stress shielding proximally whereas the use of implants with porous ingrowth only on the underside of the humeral head replacement produced stress fields more similar to the normal humerus. The convex, flat, and concave surfaces provided similar load transfer from the component to the underlying bone in all loading cases. Other prosthetic head designs that may offer better initial stability produced stress fields similar to those of existing prostheses.
Contact finite element stress analysis of the hip joint
Authors: Rapperport D. J. , Carter D. R. , Schurman D. J. 
Published: February 2005

AbstractTwo‐dimensional finite element analyses were conducted of the normal hip using contact elements at the joint surface. The models studied were constructed for a slice through the pubis, acetabulum, and ilium. In the analyses the proximal femur was pressed into the acetabulum and intraarticular pressures and principal stresses in the joint region were determined for different load magnitudes and directions and various boundary conditions. Three sets of boundary conditions were examined: (a) deformable pubic symphysis, (b) rigid pubic symphysis, and (c) simulations of experimental studies. In the deformable model the pubic symphysis was free to displace in the sagittal plane and rotate. In the rigid model the pubic symphysis was rigidly fixed. Superoposterior loading resulted in high‐contact pressures at the acetabular dome for all sets of boundary conditions. For the deformable model subject to a more medially directed load the acetabulum closed in such a manner as to squeeze the head of the femur creating high‐contact pressures superiorly and inferiorly. This resulted in significant compressive stresses in the superior dome cancellous bone and inferior cancellous bone. The cumulative effect of this squeezing action with normal biological remodeling may cause elongation of the femoral head resulting in asphericity and incongruity of the unloaded hip joint articular surfaces. Rigidly fixing the pubic symphysis stiffened the model and resulted in principal stress patterns that did not reflect trabecular density or orientations as well as those of the deformable pubic symphysis model. Finite element simulations of previous experimental studies modeled the close proximity of the fixation to the fixation to the excised acetablulum. These boundary conditions prevented the squeezing caused by pelvis deformations. The resulting contact areas, pressure distributions, and bone stresses were very different from those of more anatomic, deformable pubic symphysis model. These findings demonstrate the sensitivity of hip contact pressures and stresses to imposed boundary conditions and indicate that care should be taken to simulate anatomic conditions in experimental and theoretical studies.
Trabecular bone strength patterns at the proximal tibial epiphysis
Authors: Hvid Ivan , Hansen Stig Lau 
Published: February 2005

AbstractThe longitudinal compressive strength of trabecular bone from the human proximal tibial epiphysis was investigated in 12 autopsy specimens using multiple penetration tests with a small diameter indentor. Strength profiles were visualized by three‐dimensional computerized reconstruction as a function of location on the resection surfaces. There were large variations of the maximal values between individuals, but the patterns obtained were remarkably uniform. The medial condyle showed the highest peak value in all but one knee with a mean medial‐to‐lateral peak value‐ratio of 1.7. At the medial condyle the high strength area was relatively large with peak values being obtained centrally and anteriorly; the lateral condyle showed a more restricted, posteriorly localized area a high strength. Beneath the menisci, bone strength gradually decreased toward the margins of the condyles; likewise, bone strength decreased to reach very low values at the intercondylar region. There was a significant reduction of bone strength with the distance from the subchondral resection surface. This reduction was most pronounced at the high strength areas.
Geometric, elastic, and structural properties of maturing rat femora
Authors: Keller T. S. , Spengler D. M. , Carter D. R. 
Published: February 2005

AbstractGeometric, elastic, and structural properties of growing rat femora were determined from bending and torsion tests followed by bone sectioning and measurement of areal properties. Rosette strain gages bonded to the bone surface measured the strain during testing. A computer generated elliptical cross‐sectional representation of the cross section geometry was used for calculation of material and structural properties. All structural and material properties increased with increasing age, exhibiting age‐related changes that were best represented by an allometric or “heterauxic” growth pattern (y = axb) up to maturity. The femoral axial, flexural, and torsional rigidity increased 5.7, 10.1, and 14.8 fold, respectively, during maturation from 21 to 119 days of age. The increase in whole bone rigidity during maturation was caused primarily by changes in geometry. The bone tissue tensile longitudinal elastic modulus and shear modulus approximately doubled, and the shear strength increased approximately fourfold over this same period. Following maturity, a much slower increase in bending and torsional properties was noted. The results suggest that bone structural properties are regulated by changes in both geometric and material properties.
Synovial fluid nutrient delivery in the diathrial joint: An analysis of rabbit knee ligaments
Authors: Amiel David , Abel Mark F. , Kleiner Jeffrey B. , Lieber Richard L. , Akeson Wayne H. 
Published: February 2005

AbstractThe role of synovial fluid in providing nutrition to rabbit knee ligaments and menisci was evaluated by intraarticular injection of a labeled collagen precursor, tritiated proline. Incorporation of this substrate as tritiated hydroxyproline was measured in collateral and cruciate ligaments and menisci. The injectate volume (0.35 ml) did not appreciably change the overall joint pressure as measured by a wick catheter; therefore, no alteration of synovial membrane diffusion characteristics resulted. The concentration of the injected proline (0.52 mg%) was well below that normally present in serum (2.65 mg%). Therefore, incorporation of this substrate was not driven by a concentration gradient and represented normal uptake of synovial fluid and physiological incorporation of label as measured by the presence of tritiated hydroxyproline. Autoradiography was performed on all ligaments and menisci, and demonstrated concentration of the isotope and its metabolite (tritiated proline and tritiated hydroxyproline, respectively) in and around fibroblasts. This study indicates that rabbit knee ligaments and menisci can derive nutrition from a synovial fluid source.
The in vivo kinematics of the rheumatoid wrist
Authors: Evans James S. , Blair William F. , Andrews James G. , Crowninshield Roy D. 
Published: February 2005

AbstractThe objectives of this study were (a) to describe the three‐dimensional in vivo kinematic behavior of wrists affected by rheumatoid arthritis, (b) to correlate kinematic parameters and two radiographic indices of carpal disease, and (c) to describe the in vivo kinematic behavior of the Swanson Silastic wrist implant. Fifteen normal wrists, 17 rheumatoid wrists, and 7 wrists with Silastic wrist implants were tested using a three‐dimensional sonic digitizing system. The motion of the hand segment relative to the forearm segment, corresponding to the positions exhibited during flexion‐extension motion (FEM) and radial‐ulnar deviation (RUD), was described using the equivalent screw displacement (ESD) concept. The mean magnitudes of ESD rotation for both FEM and RUD were statistically different (p < 0.05) among the normal, rheumatoid, and implant groups. The remaining ESD parameters (i.e., mean values for the translation, the direction angles of the ESD axis, and the intercepts of this axis with the planes of motion), the minimum separation between the FEM and RUD axes, and the coordinates of the midpoint of this separation were not statistically different (p > 0.05) among the normal, rheumatoid, and implant groups. The two radiographic indices (carpal collapse and carpal translation) did not correlate with the magnitude of rotation or with any other ESD parameter.
Vascular reorganization and return of rigidity in fracture healing
Authors: Chidgey L. , Chakkalakal D. , Blotcky A. , Connolly J. F. 
Published: February 2005

AbstractThe present study addresses the relationship between vascular reorganization and the biomechanical changes occurring during canine long bone fracture healing. A middiaphyseal osteotomy of the radius was performed, and angiographic studies were carried out using India ink injections from 2 to 12 weeks postosteotomy. The radii were harvested, subjected to nondestructive four‐point bend testing on an Instron, and then sectioned and cleared according to the Spaltholtz technique. The observed microangiographic patterns were correlated with the calculated rigidity values. Quantitative bone blood flow measurements around the osteotomy were performed on a different group of animals, using the radiotracer microsphere technique, at 3, 6, and 9 weeks postosteotomy to correlate with our qualitative microangiographic results. We demonstrated a direct and predictable relationship between the phase of vascular reorganization and the rigidity. This correlation was present even in our delayed union specimens.
The in vitro effect of gold complexes on bone resorption
Authors: Katz J. M. , Gray D. H. 
Published: February 2005

AbstractMouse calvaria were maintained in organ culture without serum additives. The effects of three gold complexes—aurothioglucose, aurothiomalate, and auranofin—on active bone resorption (45Ca release) and hydroxyproline synthesis were determined. The influence of these compounds on DNA and protein synthesis and lysosomal enzyme release from calvaria was also assessed. All gold complexes reduced bone resorption to some extent, with auranofin being the most potent within a narrow concentration range (10−6 M). This concentration of auranofin also significantly inhibited collagen synthesis, although DNA and protein synthesis were unaffected. None of the compounds tested appeared to mediate their action via significant inhibition of lysosmal enzyme release.
The bone growth chamber for quantification of electrically induces osteogenesis
Authors: Buch F. , Albrektsson T. , Herbst E. 
Published: February 2005

AbstractA dividable titanium implant was inserted in the tibial metaphysis of rabbits, which permitted a numerical evaluation of ingrowing bone. The implant on the test side was used as cathode and was connected to a subcutaneously located stimulator delivering constant current of either 5 μA, 20 μA, or 50 μA. A corresponding control implant was inserted in the other tibia of the same animal and treated likewise, but was not connected to the stimulator. Distally to each implant, a platinum‐iridium screw was inserted into the cortex and connected on the test side to the stimulator to serve as the anode. The results showed a 2.4‐fold increase in bone formation with 5 μA. In the 20‐μA group, there was 2.6‐fold more bone in the test chambers. Direct current (DC) stimulation with 50 μA caused a clear decrease of bone volume, with an average of 48% less bone in the test implants. The results indicate that 5 and 20 μA direct current enhance bone ingrowth into a titanium implant that is used as a cathode. The osteogenesis seemed to be more pronounced in the case where the chamber was used as a cathode compared to earlier experiments in which the cathode was placed at a distance of 5 mm from the implant.
Cervical spine biomechanics: A review of the literature
Authors: Huelke Donald F. , Nusholtz Guy S. 
Published: February 2005

AbstractThis article reviews the many clinical and laboratory investigative research reports on the frequency, causes, and biomechanics of human cervical spine impact injuries and tolerances. Neck injury mechanisms have been hypothesized from clinically observed cervical spine injuries without laboratory verification. However, many of the laboratory experiments used static loading techniques of cervical spine segments. Only recently have dynamic impact studies been conducted. Results indicate that crown‐of‐head impacts can routinely produce compression of the neck with extension or flexion motion. However, the two‐dimensional (midsagittal) movement of the head bowing into the chest does not routinely produce flexion/compression type damage to the cervical spine. Flexion/compression damage to the cervical spine can be produced by prepositioning the subject so that upon impact, a three‐dimensional motion of the head and neck occurs. Future laboratory research is needed to determine the forces and impact directions required to produce the various known fracture types and dislocations for a clear, accurate description of the cervical spine impact dynamics.
Bone ingrowth into weight‐bearing porous fiber titanium implants. Mechanical and biochemical correlations
Authors: Barth Elin , Ronningen Helge , Solheim Ludvig Fjeld , Saethren Birgitte 
Published: February 2005

AbstractBone ingrowth into weight‐bearing porous fiber Ti‐6AI‐4V implants in rat tibias was assessed for the amount, composition, and mineralization rate 3, 12, and 26 weeks after implantation. The data were compared with the ipsiand contralateral metaphyseal controls and related to the ultimate bending stresses of the distal bone/implant interfaces. From the 3rd to the 12th week there was rapid bone ingrowth and also marked decline in mineralization rate of the ingrowing bone. After 12 weeks the implants were macroscopically pervaded by bone. The ultimate bending stresses increased from the 3rd to the 12th week and reached 45% of that of controls after 26 weeks. There was a linear proportionality between the amount of bone ingrowth and interfacial strength but a curvilinear relationship between bone maturity in terms of calcium/hydroxyproline and calcium/phosphorous ratios and interfacial strength. Stepwise multiple regression analysis showed that the interfacial strength depends on the amount and the maturity of the ingrown bone. Compared with the calcium/hydroxyproline ratio, the calcium/phosphorous ratio was an unreliable predictor of interfacial strength.
Incorporation of purified plasma fibronectin into explants of articular cartilage from disease‐free and osteoarthritic canine joints
Authors: Burton‐Wurster Nancy , Lust George 
Published: February 2005

AbstractThe purpose of this study was to determine if articular cartilage was able to accumulate fibronectin, a large molecule of 440,000 daltons, from the external medium, and if so, to compare the extent of accumulation by normal and osteoarthritic cartilage and to localize the sites of fibronectin accumulation within the articular cartilage. The uptake of canine serum albumin, another protein present in plasma and synovial fluid with a lower molecular weight (67,000 daltons) and a lower pI, was compared. Purified plasma fibronectin and canine albumin were labelled with 125I or N‐hydroxysuccinimidobiotin by standard procedures and incubated with articular cartilage explants. The 125I‐fibronectin that had bound to cartilage components was extracted with 4 M urea, and both extract and cartilage residues were counted. Cartilage accumulated fibronectin to a greater extent than albumin. For normal cartilage, a level of saturation appeared to be reached at an external concentration for fibronectin of about 150 μg/ml. Degenerated cartilage accumulated about 10‐fold more fibronectin than normal cartilage. Biotinylated fibronectin was localized within frozen sections of articular cartilage by probing with peroxidase‐linked avidin. Fibronectin accumulation in normal cartilage was restricted to the articular surface and the cut edge. In degenerated cartilage, penetration of fibronectin was more extensive but proceeded only from the articular surface. Staining of adjacent sections with peroxidase‐linked antifibronectin antibody confirmed previous observations that endogenous fibronectin is present throughout the cartilage matrix. The possibility that synovial fluid fibronectin could be a source of cartilage fibronectin, especially in degenerated cartilage, was discussed.
Effect of flexor sheath integrity on tendon gliding: A biomechanical and histologic study
Authors: Peterson William W. , Manske Paul R. , Kain Christopher C. , Lesker Peggy A. 
Published: February 2005

AbstractThe effect on tendon gliding of flexor sheath excision versus incision/closure following primary flexor tendon repair was examined biomechanically and histologically in forty‐one chickens. There was no significant difference in either the tendon excursion required to fully flex the digit or in the work of flexion (the integration of the forces that resist tendon gliding during excursion) between the sheath excised and sheath closed groups. The results were unaffected by postoperative immobilization or intermittent passive motion. Histologically, it was noted that at 3 weeks the healing tendon was surrounded by a layer of granulation tissue that was nearly indentical in both the sheath excised and the sheath closed digits. Of note was the finding that a synovial lining could not be identified in those digits that had previously undergone sheath closure. However, at 6 weeks postoperatively, a new gliding surface could be identified surrounding the tendon in both the sheath excised and the sheath closed digits. This study indicates that closure of the flexor sheath after primary tendon repair does not improve tendon gliding as measured biomechanically. Despite its repair, the flexor sheath does not maintain its synovial characteristics as demonstrated histologically, and a new sheath must subsequently be formed.