bluuebunny/crossref_metadata_2025_split huggingface dataset:
A technique for the evaluation of the contributions of knee structures to knee mechanics in the knee that has a reconstructed anterior cruciate ligament
Authors: Feder Seth M. , Butler David L. , Holden John P. 
Published: February 2005

AbstractA technique to quantify the restraining action of specific knee structures during anterior/posterior (A/P) tibial displacement tests in the goat knee that has a reconstructed anterior cruciate ligament (ACL) is described. Joint specimens were mounted in an instrumented test stand to measure both the forces on, and resulting translations of, the tibia in the A/P direction. The intact grafted knee was tested first, after which structures were sequentially cut or removed, or both, and the test was repeated. The ACL graft remained intact in the joint during this process; therefore, subsequent axial failure testing was possible. Analysis of the resulting force‐displacement curves allowed the percentage contribution and anterior joint stiffness to be determined for each structure at a fixed anterior displacement in 12 goat knees 6 months after ACL allografting. The allografts were found to provide about 56% of the total restraining force, more than any other structure examined. Studies of this kind will be important in the documentation of the changing role of an autograft or allograft in a reconstructed knee over time.
Evaluation of bone‐grafting materials in a new canine segmental spinal fusion model
Authors: Muschler George F. , Huber Bryan , Ullman Thomas , Barth Richard , Easley Kirk , Otis James O. , Lane Joseph M. 
Published: February 2005

AbstractThis paper describes a new canine segmental spinal fusion model for the comparison of bone‐grafting materials. The test sites in the model are three separate posterior interfacet‐interlaminar fusion sites in the lumbar spine (L1‐2, L3‐4, and L5‐6). The outcome was assessed by scoring of the fusion sites for union and by mechanical testing of fused segments. The results from two experiments are presented. Autogenous cancellous bone was the most effective material tested and had a statistically superior score for union compared with all other materials (p = 0.01). The results with an osteoconductive matrix of collagen and ceramic alone were no better than those with the controls (no graft). However, addition of an extract of matrix‐derived proteins (15–30 kDa) to the collagen‐ceramic carrier appeared to improve the score for union. The inclusion of nonresorbed ceramic granules had no evident effect on the mechanical properties of fusions, with a comparable score for union. This model appears to be a sensitive and efficient method for the comparison of graft materials. Advantages over previously described models are discussed.
Posture affects motion coupling patterns of the upper cervical spine
Authors: Panjabi Manohar M. , Oda Takeori , Crisco Joseph J. , Dvorak Jiri , Grob Dieter 
Published: February 2005

AbstractMeasurements of motions of the cervical spine are used to help diagnose the problems of clinical instability due to degenerative changes and trauma. For a better interpretation of the three‐dimensional motions of the upper cervical spine, knowledge of the effects of posture on these motions is necessary. Seven fresh human cadaveric C0–C3 spinal specimens were utilized. Each specimen was put in three distinct sagital plane postures: full flexion, neutral, and full extension. At each posture, two load types were applied: left and right axial torques, and left and right lateral bending moments up to 1.5 Nm. The resulting three‐dimensional relative motions of C0–C1 and C1–C2 were measured, with use of nonconstraining stereophotogrammetry, in the form of load‐displacement curves. We found that the curves were nonlinear. The most dramatic change due to modification in posture was found in coupled sagittal plane rotation, which changed from extension at extended posture to flexion at flexed posture at both levels and in response to both load types. For the axial torque, the main axial rotation and coupled lateral bending changed little with posture. For the lateral bending moment, the main lateral bending rotation and coupled axial rotation decreased; the latter changed direction at C1–C2 as the spine was put into flexed posture. The motions for the right and left load applications generally were mirror images, except for the coupled sagittal plane rotations, which did not change with the direction of the load.
Laser doppler flowmetry for estimation of bone blood flow: Studies of reproducibility and correlation with microsphere technique
Authors: Lausten Gunnar Schwarz , Kiær Thomas , Dahl Benny 
Published: February 2005

AbstractThe blood flow in the femoral condyles of six pigs was measured by the microsphere technique and by laser Doppler flowmetry (LDF) before and after clamping of the external iliac artery. A significant decrease in the bone blood flow was found with both microsphere and LDF measurements, and a high correlation was found between the two methods. After release of the arterial clamp, the LDF values rapidly returned to approximately the same values as before clamping. In a second part of the study, the LDF output signal was studied in the intertrochanteric area of eight patients. The reproducibility of two LDF measurements at the same location was within 15%. The temporal variability of the LDF signal during 10 min of recording showed only slight variations. It is concluded that LDF is relative in nature and that the mean LDF output signal is suitable for monitoring dynamic responses of the bone blood flow to various stimuli. Several consecutive measurements have to be performed if the blood flow at different locations of a specific bone are to be compared with each other.
Effects of complete stress‐shielding on the mechanical properties and histology of in situ frozen patellar tendon
Authors: Ohno Kazunori , Yasuda Kazunori , Yamamoto Noritaka , Kaneda Kiyoshi , Hayashi Kozaburo 
Published: February 2005

AbstractThe effects of freezing and stress‐shielding on the mechanical properties and histology of the patellar tendon (PT) were studied with the use of 28 mature Japanese white rabbits. The PT was frozen in situ by liquid nitrogen to kill the fibroblasts and then, for stress‐shielding, a stainless‐steel wire, installed between the patella and the tibial tubercle, was stretched to release all tension in the PT. After being allowed unrestricted activity in their cages for 1, 2, 3, or 6 weeks, the animals were killed, and the PTs were excised for mechanical and histological study. The cross‐sectional area of the frozen and stress‐shielded PT started to increase significantly 1 week after the treatment and leveled off at 3 weeks. In contrast, the tensile strength and elastic modulus begar to decrease significantly at 1 week, falling to 15% of the control values at 6 weeks. Histologically, cells were absent until 2 weeks after freezing and stress‐shielding, although new cells appeared by 3 weeks. Splitting and fragmentation of collagen bundles were observed beginning at 2 weeks. These results indicate that complete stress‐shielding led to substantial changes in the mechanical properties of the once‐frozen PT, even in the absence of the tissue remodeling process by fibroblasts.
In vitro photodynamic therapy of musculoskeletal neoplasms
Authors: Hourigan A. J. , Kells A. F. , Schwartz H. S. 
Published: February 2005

AbstractPhotodynamic therapy is a tumoricidal modality that utilizes an inactive pharmacologic agent that becomes activated on exposure to visible light. Neoplasms selectively retain and accumulate photosensitizers at levels generally higher than surrounding non‐neoplastic tissues. The purpose of this study was to establish a testing method for in vitro investigation of the effects of photodynamic therapy on human musculoskeletal neoplasms by examination of the sensitivity of these tumors to photoactivation. Three human musculoskeletal neoplasms were cultured, exposed to the photosensitizer Photofrin, and then studied for their response to photodynamic therapy after laser activation. Giant‐cell tumor, dedifferentiated chondrosarcoma, and osteosarcoma were examined with use of strict experimental controls. The photoradiation conditions during photodynamic therapy were kept constant. Cell viability was determined as a function of energy dose. We concluded that the three musculoskeletal tumors were susceptible to in vitro photodynamic therapy and the test system was reproducible. The optimal in vitro nontoxic incubation concentration of Photofrin was 3 μg/ml. A differential cytotoxic response to photodynamic therapy was exhibited by the musculoskeletal neoplasms as a function of increased dosages of energy.
Effect of ischemic storage on endothelium in canine bone
Authors: Roorda Jan , Wood Michael B. 
Published: February 2005

AbstractThe limits of room temperature (24°C) and hypothermic (4°C) storage for preservation of endothelial eccrine function were investigated with use of an ex vivo perfusion apparatus model of the cannulated canine tibia. Norepinephrine‐induced contraction of smooth muscles in both the presence and absence of acetylcholine was compared, with and without selective blockade of endothelial‐derived relaxing factor (EDRF). At room temperature, release of EDRF deteriorated after 24 h and was absent after 48 h of storage. At 4°C, endothelial eccrine activity appeared unimpaired for as long as 72 h of storage. From 96–192 h of storage at 4°C, release of EDRF was suggested, but with an attenuation of its effect on smooth muscle. At 216 and 504 h of storage at 4°C, no endothelial eccrine activity was demonstrated.
Stem curvature and load angle influence the initial relative bone‐implant motion of cementless femoral stems
Authors: Berzins Aivars , Sumner Dale R. , Andriacchi Thomas P. , Galante Jorge O. 
Published: February 2005

AbstractA 6 df measurement system was used to investigate the initial relative bone‐implant motion of two types of cementless total hip replacement femoral components—a straight stem and a curved stem. Five pairs of fresh frozen femurs from human cadavers were tested with loads applied to the femoral head at angles characteristic of level walking, stair‐climbing, and rising from a chair. The most important findings were that (a) the resultant proximal translations were twice as high with the straight stem as with the curved stem at load angles encountered in stair‐climbing and rising from a chair, (b) both stem types had more motion at load angles encountered in stair‐climbing and rising from a chair than in level walking, with the increases ranging from 3 to 14‐fold, (c) there was as much as 66‐fold more motion distally than proximally, and (d) the amount of interface motion varied by 5‐fold between the medial and lateral surfaces of the distal part of the implant because of the combined effects of translation and rotation. The amount of initial bone‐implant motion of the femoral component was found to be particularly sensitive to off‐axis loading; this suggests that stair‐climbing and rising from a chair should be avoided in the early postoperative period when a cementless porous‐coated femoral stem has been used.
Effects of local compression on peroneal nerve function in humans
Authors: Hargens Alan R. , Botte Michael J. , Swenson Michael R. , Gelberman Richard H. , Rhoades Charles E. , Akeson Wayne H. 
Published: February 2005

AbstractA new apparatus was developed to compress the anterior compartment selectively and reproducibly in humans. Thirty‐five normal volunteers were studied to determine short‐term thresholds of local tissue pressure that produce significant neuromuscular dysfunction. Local tissue fluid pressure adjacent to the deep peroneal nerve was elevated by the compression apparatus and continuously monitored for 2–3 h by the slit catheter technique. Elevation of tissue fluid pressure to within 35–40 mm Hg of diastolic blood pressure (∼40 mm Hg of in situ pressure in our subjects) elicited a consistent progression of neuromuscular deterioration including, in order, (a) gradual loss of sensation, as assessed by Semmes‐Weinstein monofilaments, (b) subjective complaints, (c) reduced nerve conduction velocity, (d) decreased action potential amplitude of the extensor digitorum brevis muscle, and (e) motor weakness of muscles within the anterior compartment. Generally, higher intracompartmental pressures caused more rapid deterioration of neuromuscular function. In two subjects, when in situ compression levels were 0 and 30 mm Hg, normal neuromuscular function was maintained for 3 h. Threshold pressures for significant dysfunction were not always the same for each functional parameter studied, and the magnitudes of each functional deficit did not always correlate with compression level. This variable tolerance to elevated pressure emphasizes the need to monitor clinical signs and symptoms carefully in the diagnosis of compartment syndromes. The nature of the present studies was short term; longer term compression of myoneural tissues may result in dysfunction at lower pressure thresholds.
Temporal patterns of stromelysin‐1, tissue inhibitor, and proteoglycan fragments in human knee joint fluid after injury to the cruciate ligament or meniscus
Authors: Stefan Lohmander L. , Roos Harald , Dahlberg Leif , Hoerrner Lori A. , Lark Michael W. 
Published: February 2005

AbstractStromelysin‐1, tissue inhibitor of metalloproteinases‐1 (TIMP‐1), and proteoglycan fragments were quantified in knee synovial fluid samples in a cross‐sectional study of patients who had injury to the anterior cruciate ligament or the meniscus. The average concentrations of stromelysin‐1 and TIMP‐1 increased 25‐fold and 10‐fold within the first day after the trauma, respectively, and the concentration of proteoglycan fragments increased 4‐fold. From approximately 1‐6 months after injury, the levels of these markers were higher after injury to the cruciate ligament than after injury to the meniscus. From 6 months to 18 years after trauma, however, the levels of stromelysin‐1 and TIMP‐1 in patients who had an injury to the ligament were the same as the levels in patients who had a meniscal lesion. but the levels were increased compared with those for a reference group of healthy volunteers. The molar balance of stromelysin‐1 to TIMP‐1 in synovial fluid in both groups of injured joints changed from a balance representing an excess of free inhibitor in the normal joint to one representing an excess of free enzyme in the injured joint. The increased release of these markers to joint fluid both early and late after trauma may be caused by a change in the loading patterns in the knee with an injured ligament or meniscus or by synovitis induced by bleeding. The increased release may be associated with the frequent development of posttraumatic osteoarthritis in patients with these injuries.
In vivo inflammatory response to polymethylmethacrylate particulate debris: Effect of size, morphology, and surface area
Authors: Gelb Howard , Ralph Schumacher H. , Cuckler John , Baker Daniel G. 
Published: February 2005

AbstractParticulate debris, including that from polymethylmethacrylate (PMMA) cement, is observed commonly in the membrane surrounding loose joint prostheses. Such debris is assumed to cause an inflammatory response and contributes to osteolysis and failure of the implant. A subcutaneous rat air‐pouch model was used to assess quantitatively the in vivo effects of the size, morphology, and surface area of PMMA particles on the acute inflammatory response. PMMA particles were divided into three groups. In Group A, mechanical grinding of cured bone cement produced irregularly shaped particles; Group B included spherical particles of PMMA powder (Simplex P); and Group C consisted of commercially prepared spherical latex particles. All three groups had two size distributions: < 20 μm and 50–350 μm. For a given mass or dose, the small, irregularly shaped mechanically produced particles in Group A elicited a significantly greater inflammatory reaction than the large particles in Group A, as expressed by the release of tumor necrosis factor (TNF), neutral metalloprotease (NMP), and prostaglandin E2 (PGE2) and the white blood cell (WBC) count within a 24‐hour period. Similar findings were seen in Group B. Particles in Group C were used to compare the effect of absolute numbers of large and small particles and surface area. Large (10–126 μm) spherical PMMA particles at a dose of 1.7 × 106 particles/ml caused a significantly higher inflammatory response, as measured by WBC count and production of NMP and PGE2, than small (1–10 μm) spheres at a dose of 4 × 106 particles/ml. However, the production of TNF in the rats was significantly increased with small particles (p < 0.05) at a concentration 4‐fold less than that with the large particles (4 × 105 compared with 1.7 × 106 particles/ml). This finding may reflect a different cellular mechanism for the TNF component of the inflammatory response than is measured by WBC counts or by levels of PGE2 and NMP. As the calculated surface area of the PMMA particles increased, a threshold level was reached, at which point the inflammatory response increased dramatically. The size of particles has a role in the prolongation and intensity of the release of specific cytokines. The total surface area of the particles appeared to be an important factor in determining the inflammatory response, as measured by WBC count, PGE2, TNF, and NMP.
Sagittal configuration of the spine and growth of the posterior elements in early scoliosis
Authors: Xiong Bo , Sevastik John , Hedlund Rune , Sevastik Bo 
Published: February 2005

AbstractThe early changes of the sagittal alignment of the spine and the asymmetry between the posterior and anterior elements were determined on the basis of 134 lateral and 167 anteroposterior radiographs obtained from a control group and from patients with early scoliosis. The radiographs were allocated into four groups according to the degree of the Cobb angle. In thoracic curves with a Cobb angle of more than 8°, the kyphosis and the vertebral sagittal wedge angle decreased in comparison with the control group. The sagittal‐wedge angle of the disc did not change significantly with increasing Cobb angle. The pedicle height in relation to the vertebral height, considered to represent the growth of the posterior element in relation to the growth of the anterior element, was not significantly different in the scoliotic groups as compared with the control group. The results indicate that changes of the sagittal configuration of the spine occur early in idiopathic scoliosis and that they are associated with disturbed growth of the vertebral body but not of the posterior elements. These findings seem to reflect a simulataneous deformation in the coronal and sagittal planes rather than a single growth disturbance in any specific plane.
Load affects remodeling of transplanted, autogenous bone‐patellar tendon‐bone segments in a rabbit model
Authors: Muneta Takeshi , Lewis Jack L. , Stewart Nathaniel J. 
Published: February 2005

AbstractThe question of whether or not load affects the remodeling of a transplanted autogenous free graft was addressed by removal of the patella‐patellar tendon‐tibial tubercle complex from the right knees of 15 New Zealand White rabbits. The tubercle was split, and the tendon was divided with each half trimmed to an equal width. The autograft complex was transplanted into a subcutaneous tunnel on the back of the rabbit. Controlled cyclic loads were applied via transcutaneous sutures to half of the graft, while the other half remained unloaded. The mechanical stiffness and strength and the cell density of loaded and unloaded halves of the autograft were measured in nine animals at 3 weeks and in six animals at 6 weeks. Five autografts from four additional rabbits served as unimplanted controls. An analysis of variance showed that the loaded portions of the autografts had a significantly higher failure strength (mean of 90%) and were significantly stiffer (mean of 62%) than the unloaded halves at 3 and 6 weeks. Failure strength was significantly greater (mean of 90%) at 3 weeks than at 6 weeks. The autografts were less stiff and had a lower failure strength than the unimplanted controls, with the greatest difference occurring in the unloaded segments at 6 weeks. Histology revealed that both loaded and unloaded segments demonstrated an increase in cellularity at 6 weeks compared with 3 weeks. This report introduces a model for the study of the effect of load on soft‐tissue grafts and demonstrates that loading affects the remodeling process of a transferred autograft.
Effect of animal age and chronicity of interleukin‐1 exposure on cartilage proteoglycan depletion in vivo
Authors: Arner Elizabeth C. 
Published: February 2005

AbstractRheumatoid arthritis and osteoarthritis are characterized by an early depletion of cartilage proteoglycans, which leads to a decrease in cartilage compressibility and, eventually, to a loss of joint function. Interleukin‐1, which is thought to have a role in mediating this loss of proteoglycans in arthritis, induces an acute depletion of proteoglycans from articular cartilage following intra‐articular injection in rabbits. As the structure and metabolism of proteoglycans are known to change with age, my laboratory investigated the effect of age on depletion and recovery of proteoglycans in response to interleukin‐1 in the rabbit. Loss of cartilage proteoglycans induced by interleukin‐1 was less servere in immature animals, increased until the age of sexual maturity, and then remained constant. The rate of recovery and compensatory overshoot in the rate of proteoglycan synthesis following challenge with interleukin‐1 was more rapid in immature animals and may have been responsible for the quicker return of the cartilage proteoglycan content to control levels in younger animals. With multiple exposures to interleukin‐1 at time intervals too short for recovery to occur, smaller amounts of interleukin‐1 induced loss of proteoglycans, and the proteoglycan content and the rate of synthesis remained depressed longer after treatment had stopped. The decreased ability of mature cartilage to replace proteoglycans rapidly after exposure to cytokines would increase the probability of subsequent inflammatory episodes before recovery is complete; this may result in increased susceptibility of adult cartilage to proteoglycan depletion.
Comparative study of the intrinsic mechanical properties of the human acetabular and femoral head cartilage
Authors: Athanasiou K. A. , Agarwal A. , Dzida F. J. 
Published: February 2005

AbstractBiphasic creep indentation methodology and an automated indentation apparatus were used to measure the aggregate modulus, Poisson's ratio, permeability, thickness, creep and recovery equilibrium times, and percentage of recovery of normal articular cartilage in 10 human hip joints. These properties were mapped regionally to examine the mechanical factors involved in the development of site‐specific degenerative lesions in the acetabulum and femoral head. The results indicate that there are significant differences between these properties regionally in the acetabulum and femoral head and between the two anatomical structures. Specifically, it was found that cartilage in the superomedial aspect of the femoral head has a 41% larger aggregate modulus than its anatomically corresponding articulating surface in the acetabulum. In addition, the supermedial aspect of the femoral head has the greates aggregate modulus (1.816 MPa) within the hip joint. During sitting, the inferior portion of the femoral head is in contact with the anterior acetabulum, and the anterior acetabulum has a 53% greater aggregate modulus than the inferior femoral head. This area below the fovea on the femoral head has the least aggregate modulus (0.814 MPa) within the hip joint. These mismatches in the compressive modulus of opposing articulating surfaces may contribute to degeneration of cartilage in the superomedial acetabulum and the inferior femoral head. Our findings support the clinical observation that these areas are frequent sites of early degeneration.