bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental temperature rise in human hip joint in vitro in simulated walking
Authors: Tepic S. , Macirowski T. , Mann R. W. 
Published: February 2005

AbstractAlthough reported frictional coefficients in synovial joints are very low, a computer model of the human hip joint in simulated walking predicted a temperature rise of several degrees Celsius. To confirm this prediction, physical experiments were conducted in vitro on intact human hip joints dynamically loaded and articulated as in walking. Thermisters were placed in subchondral bone in both the acetabulum and femoral head, just below the cartilage layers. The surrounding saline bath was maintained at 37°C. Measured temperatures as high as 2.5°C above the 37°C were recorded in the subchondral bone. Loading that simulated the stance/swing phases of gait but without articulation produced no significant increase in temperature; thus fluid flow perse is not significantly energy dissipative; the prime source is friction at the articulating surfaces.
In vitro method for measuring synthesis rates in the intervertebral disc
Authors: Bayliss M. T. , Urban J. P. G. , Johnstone B. , Holm S. 
Published: February 2005

AbstractA method for culturing intervertebral disc tissue in vitro under conditions that control changes in hydration and minimize loss of proteoglycans has been developed. Disc slices were enclosed in small‐pore dialysis tubing and incubated in medium containing polyethylene glycol (PEG). By varying the PEG concentration, different external swelling pressures could be applied to the tissue. The rate of glycosaminoglycan synthesis in rabbit and dog disc was then measured using [35S]sulphate as a precursor. Synthesis rates varied with final hydration of the tissue, and the highest rates were found at hydrations close to those found in vivo. Under conditions of controlled hydration, rabbit nucleus has a higher rate of glycosaminoglycan synthesis than annulus. However, the rates measured in sagittal slices of dog disc decreased from the outer to the inner regions of the anterior annulus, reaching a minimum value in the nucleus and then increasing again in the posterior part of the annulus. The results show that in the intervertebral disc, measured rates depend on culture conditions.
Effect of pulley excision on flexor tendon biomechanics
Authors: Peterson William W. , Manske Paul R. , Bollinger Bruce A. , Lesker Peggy A. , McCarthy John A. 
Published: February 2005

AbstractFlexor tendon function following excision of various portions of the fibro‐osseous pulley system was measured biomechanically using a tensile testing machine. The biomechanical parameters measured were tendon excursion (the excursion of the tendon required to fully flex the digit) and work of flexion (the area under the force‐excursion curve, representing all the forces that resist tendon flexion). In this experiment, work of flexion included the forces necessary to accomplish full digital flexion against a 15‐g counterweight, as well as the frictional forces that resist tendon gliding. The results indicate that the work of flexion was affected to a greater degree by pulley loss than was tendon excursion, suggesting that it is a more sensitive measurement of tendon function. A2 was found to be the single most important pulley for flexor tendon function, followed by A4. However, both A2 and A4 had to be present if near‐normal hand function was to be achieved; sacrificing the A1 pulley was not associated with a significant loss of flexion. The “pulley effect” of the skin and soft tissue as a supplement to the fibro‐osseous pulleys in reducing tendon bow‐stringing was also noted. Although the parameters of tendon excursion and work of flexion were used in this study to determine the effect of pulley loss on tendon function, they can also be used to evaluate other flexor tendon studies, such as pulley reconstruction.
Balance reactions and eye–hand coordination in idiopathic scoliosis
Authors: Adler Neil , Bleck E. E. , Rinsky L. A. , Young Wise 
Published: February 2005

AbstractWe undertook this study to determine if subclinical postural control mechanisms were abnormal in idiopathic scoliosis. Ninety‐one female patients and fifty‐seven age‐matched female controls were examined. We used a force plate ataxiometer to quantitate postural sway in the standing position and recorded the displacement and acceleration of the center of pressure during static stance and under perturbation with eyes opened and closed. A joystick‐controlled video system was used to measure reaction time and eye–hand motor coordination. The scoliosis group demonstrated significantly less sway during two of the eight standing balance conditions and on the remaining balance tests there was a similar trend, albeit nonsignificant. The reaction time for the scoliosis group was also significantly slower, but the accuracy was not significantly worse. We noted no statistical differences between progressive and nonprogressive or between braced and unbraced patients. The subgroup of patients whose curves progressed despite bracing had a tendency to demonstrate greater stability on all standing tests. They also exhibited faster reaction times and less error in eye–hand coorindation than other patient groups. No correlation existed between severity of curve and test performance. We found no indication of deficient balance in idiopathic scoliosis, and the tests could not predict curve progression.
Delayed use of hyperbaric oxygen for treatment of a model anterior compartment syndrome
Authors: Strauss Michael B. , Hargens Alan R. , Gershuni David H. , Hart George B. , Akeson Wayne H. 
Published: February 2005

AbstractThis study examines the effect of delayed exposure to hyperbaric oxygen on muscle necrosis and edema development following compartment syndromes in the canine hindlimb. Compartment syndromes (100 mm Hg for 8 h) were generated in one anterolateral compartment of six anesthetized dogs. After a 2‐h delay, three 1‐h hyperbaric oxygen treatments (2 atm absolute pure oxygen) were given during the next 12 h. Two days later, technetium‐99m stannous pyrophosphate (99mTc Sn‐PYP) was injected intravenously; 3 h later, samples were obtained from the pressurized and contralateral control muscles, weighed for edema development, counted for 99mTC Sn‐PYP uptake, and evaluated histologically. Hyperbaric oxygen treatments, even when delayed 2 h, reduced muscle necrosis and intramuscular edema to negligible levels (p < 0.05) compared with untreated animals. In addition, muscle morphology remained essentially normal in all hyperbaric oxygen‐treated animals. We conclude that even if hyperbaric oxygen treatments are delayed 2 h, edema and muscle necrosis are reduced significantly in a model compartment syndrome.
Localization of technetium‐99m methylene diphosphonate in bone using microautoradiography
Authors: Einhorn Thomas A. , Vigorita Vincent J. , Aaron Alan 
Published: February 2005

AbstractTechnetium‐99m methylene diphosphonate ([99mTc]MDP) is the most widely used bone‐scanning agent today. In order to determine the precise bone locus of 99mTc corresponding to the delayed bone scan image, and to test the potential clinical use of this agent in enhancing the information obtained by bone scan, we employed [99mTc]MDP in this microautoradiographic study of normal bone and bone repairative tissue. Four white rabbits underwent operations in which two 1.5‐mm drill holes were created in the subtrochanteric regions of both of their femora. An additional four white rabbits underwent sham operations of their femora, in which neither drilling nor periosteal injury occurred. Two rabbits were controls and did not undergo operation. After 7 days, the first two groups of rabbits were injected with [99mTc]MDP and bone scanned 2 h later. After the scans were completed, all three groups of animals were killed and their femora histologically processed for microautoradiography and routine histopathology. In the two groups that were injected with [99mTc]MDP, all bones showed the isotope to be clearly localized along mineralization fronts. The isotope was occasionally found in the substance of the osteoid, but was absent from the cytoplasm and nuclei of osteoblasts and osteocytes. Osteocytic lacunae showed the presence of isotope at their borders, but no identifiable pattern of isotope uptake was noted. Neither osteoclasts nor Howships lacunae showed isotope uptake. The animals that received drill holes showed corresponding areas of uptake by bone scan, whereas those that did not receive drill holes showed no bone scan activity at these sites. The histological findings were qualitatively similar in the bones from both groups of animals, but were quantitatively greater in the bones undergoing repair. The uninjected animals showed no positive chemography on their slides, indicating that the histological fixing and embedding solutions did not introduce artifacts into the technique. Skeletal scintigraphy has been shown to be a valuable clinical tool in the assessment of pathological conditions of bone. Through the use of microautoradiography, a correlation between the information gained by a bone scan and that of a bone biopsy or excised bony lesion can be made. This may aid in the assessment of the biological behavior of tumors or other pathological conditions of bone, as well as the precision of the bone scan in defining or localizing an osseous lesion.
Auditory biofeedback in spastic diplegia
Authors: Kassover Mindy , Tauber Carolyn , Au Jan , Pugh James 
Published: February 2005

AbstractUsing a simple auditory feedback device that produces a continuous buzzing signal on heel contact, we studied the effects of augmented auditory biofeedback on the gait of four spastic diplegic children. The purpose of the biofeedback was to attempt to increase dorsiflexion at heel strike without causing other compensatory changes at the knee and hip, which might lead to crouch gait. We measured velocity, stride length, and thigh, knee, and ankle angles at the heel strike, midswing, and toe‐off phases of gait. Four subjects, aged 5–8 years, were given a standard gait training program, supplemented with biofeedback two times per week in a clinical setting and 1 h daily in a home program over an 8‐week period. Three computer video gait analyses of the sagittal plane were conducted without biofeedback in the pre‐ and post‐training conditions and twice with biofeedback over the course of treatment. We performed linear regression analysis of joint angles at heel strike, midswing, and toe‐off as a function of days into the study for each patient. Angle–angle diagrams for a test subject before, during, and after treatment indicate changes toward a normal gait pattern with biofeedback. The linear regression analysis showed a statistically significant (p < 0.01) shift toward dorsiflexion at heel strike with repeated exposure to biofeedback. A compensatory crouch gait was not induced. The linear regression analyses for hip and knee angles were not statistically significant (p > 0.25), indicating a disassociation of movement among hip, knee, and ankle.
Monensin stimulation of arylsulfatase B activity in human chondrocytes
Authors: Colofiore J. R. , Schwartz E. R. 
Published: February 2005

AbstractSecreted and intracellular arylsulfatase B (ASB) activities were measured in normal and osteoarthritic (OA) human chondrocyte cultures in the absence and presence of monensin, ammonium chloride, and chloroquine. Of the three agents added, only monensin produced a significant stimulation of secreted enzyme activity. Osteoarthritic cells consistently exhibited a threefold higher level of secreted specific ASB activity than did normal cells, with or without monensin. When compared with normal cells, OA cells also consistently exhibited a twofold heightened intracellular specific enzyme activity both in the absence or presence of monensin. With increasing dosage of monensin, secreted and intracellular ASB activity increased for both OA and normal cells. Total enzyme activity of secreted and intracellular ASB was found to be cell density dependent. No inhibition of secreted or intracellular ASB activity was observed for sparsely plated cultures. In contrast to sparse cultures, an inhibition of secreted ASB, with or without monensin, was observed in densely plated cultures. Intracellular total activity was not inhibited by high‐density cultures. Secreted ASB activity was found to be time‐dependent after passage. Enzyme activity was maximal at 6 h in both OA and normal cells and decreased by the end of 24 h both in serum‐free medium and in serum‐free medium with monensin. When compared with normal cells, OA cells expressed higher levels of ASB activity under all test conditions. This heightened activity therefore appears to be a property inherent in the OA chondrocyte.
Ultrastructural study of the short‐term effects of chymopapain on the intervertebral disc
Authors: Suguro Toru , Oegema Theodore R. , Bradford David S. 
Published: February 2005

AbstractThe initial effects of chymopapain, a chemonucleolytic agent, on the intervertebral disc of dogs were studied by light and electron microscopic techniques. Fragments of nucleus pulposus and annulus fibrosis were incubated with chymopapain up to 24 h in vitro. Proteoglycans and matrix proteins were rapidly removed, while collagen fibers remained intact up to 24 h. For several hours, most cells remained normal in appearance with only slight swelling and an increased number of vacuoles. After exposure to the protease for 24 h cells in both the annulus and nucleus showed extensive membrane damage and some were necrotic, but many survived relatively intact. These results suggest that, similar to the results of the digestion of cartilage with other proteases, the cells of the disc can survive brief chymopapain exposure during chemonucleolysis procedures and could serve as a source for regenerating tissue. The nature of the regeneration may depend on the extracellular scaffold that remains and the nutrition available to tissue as well as the age and biomechanical state of the disc. As for clinical significance, chemonucleolysis is an important nonsurgical alternative for treating prolapsed disc. The cells of nucleus and annulus can survive short‐term exposure to treatment, and thus be responsible for partial regeneration of the tissue. This regeneration may be important in preventing long‐term degenerative disease in the facet joints caused by increased pressure due to decreased disc height.
An anatomical comparison of the human and bovine thoracolumbar spine
Authors: Cotterill Paul C. , Kostuik J. P. , D'Angelo G. , Fernie G. R. , Maki B. E. 
Published: February 2005

AbstractThe bovine spine has been frequently selected as the model for in vitro mechanical studies. A comparative anatomical study has been presented describing important differences and similarities between selected areas in the adult human and calf thoracolumbar spinal segment. Differences in column length and curvature were observed. The total length of the adult bovine vertebral column was found to be on average 209 cm longer than the adult human spine. Equivalent throacolumbar lengths were obtained by selecting 6–8 week‐old dairy calves, which because of their young age had the benefit of consistent bone density. The bovine spine was found to have only a single cervical lordotic curve and a single thoracolumbar kyphotic curve (2). A quantitative comparison of selected dimensions of vertebrae T6, T12, and L3 was performed, and significant findings are discussed. The bovine spinous processes were found to be on average 111% greater in length at level T6, which contributed to a 56% greater total anterior/posterior length at this level in comparison to the vertebrae of an adult male. A 23% greater bovine intertransverse length at level L3 was also shown. The orientation of the human and bovine superior facets, while being in the same general plane and direction, varied as much as 10.5 and 107% at vertebral level L3 on the two axes measured. These significantly different measurements were considered important factors that can influence experimental results when using the bovine spine as a model.
A unifying principle relating stress to trabecular bone morphology
Authors: Fyhrie D. P. , Carter D. R. 
Published: February 2005

AbstractThe relationships between cancellous bone apparent density, trabecular orientation, and stress are developed and a mathematical theory describing these relationships is proposed. The bone is assumed to be a self‐optimizing material. Using a continuum model, sufficient conditions are developed which ensure that, for a given stress encountered during normal activity, the theory will predict both trabecular orientation and apparent density. Using two special approaches, one based on optimizing strain energy density (stiffness) and the other on optimizing strength, the relationship between apparent density and stress is derived. This is the first time that a single theory has been advanced to predict both the orientation and apparent density of cancellous bone.
Ion concentration effects on the zeta potential of bone
Authors: Berretta Deborah A. , Pollack Solomon R. 
Published: February 2005

AbstractStressed bone generates an electrical potential, the sign of which reverses in the presence of specific concentrations of sodium, potassium, or calcium ions. A study was designed to test the hypotheses, drawn from stress‐generated potential (SGP) studies, that the reversal in polarity of the zeta potential of bone is the cause of this SGP polarity reversal. The zeta potential of bone particles, prepared from fresh bovine metatarsals as homogeneous 5 μm dispersions, was measured by free‐fluid electrophoresis in different concentrations of sodium chloride. The zeta potential of bone particles reversed sign at a sodium ion concentration that was the same as that found to reverse measured SGPs, namely 0.74 molar. This finding is consistent with the hypothesis that streaming potentials are the cause of SGPs in fluid‐saturated bone. It was possible to obtain electrophoretic mobility histograms, and hence zeta‐potential histograms, of bone particles by using a Pen Kem, Inc. (Bedford Hills, NY, U.S.A.) “3000” Automated Electrokinetic Analyzer. At sodium ion concentrations at which bone particles were nearly neutral, the zeta‐potential histograms indicated a broad distribution of particle charge, with some particles being negative, some positive, and some neutral. In addition, it was found that particles prepared from Formalin‐fixed bone produced the same electrokinetic results as those prepared from fresh bone, and that the addition of MOPS buffer caused the zeta potential to invert sign from negative to positive values at ion concentrations exceeding 3.0 molar.
Malignant neoplasms associated with orthopedic implant materials in rats
Authors: Memoli Vincent A. , Urban Robert M. , Alroy Joseph , Galante Jorge O. 
Published: February 2005

AbstractThe carcinogenic potential of 22 orthopedic prosthetic materials was studied by implantation in bone in Sprague‐Dawley rats and evaluated by complete autopsy examination performed at the time of death or at the end of the 30 month experimental period. When the number of malignancies in these rats was compared with control and sham‐operated animals, a small increase in sarcomata was observed in animals bearing metal alloy implants containing high contents of cobalt, chromium, or nickel. An increased incidence of lymphomata with bone involvement was also observed in rats bearing metal implants when compared with control and sham‐operated animals.
Laser doppler flowmetry for bone blood flow measurement: Correlation with microsphere estimates and evaluation of the effect of intracapsular pressure on femoral head blood flow
Authors: Swiontkowski Marc F. , Tepic S. , Perren S. M. , Moor R. , Ganz R. , Rahn B. A. 
Published: February 2005

AbstractLaser Doppler flowmetry (LDF) was used to measure bone blood flow in the rabbit femoral head and femoral condyles. To correlate the LDF output signal blood cell flux to in vivo blood flow, simultaneous measurements using LDF and 85Sr‐labeled microspheres were made in an adult rabbit model. There was no correlation between the two methods for blood flow in the femoral condyles and the correlation between the two methods for blood flow in the femoral head does not achieve statistical significance. An LDF signal of 0.4 V was approximately equal to a microsphere measured flow rate of 0.4 ml blood/g bone/min. The strength of the correlation in the latter case may have been affected by (a) large arteriovenous shunts, (b) inadequate mixing of the microspheres with a left ventricular injection, and (c) insufficient numbers of microspheres present in the bone samples with which to satisfy the mathematical requirements of the microsphere method. When LDF was used to evaluate the effect of elevated intracapsular pressure on femoral head blood flow in skeletally mature rabbits, femoral head subchondral bone blood flow declined with increasing intracapsular pressure from a baseline value of 0.343 ± 0.036 to a value of 0.127 ± 0.27 at 120 cm of water pressure. The decline in femoral head blood flow was statistically significant at pressures of 40 cm of water or higher (p < 0.001), and evaluation of sections of the proximal femora made from preterminal disulphine blue injections confirmed these findings. Intracapsular tamponade has an adverse effect on femoral head blood flow beginning well below central venous pressure and should be considered in the pathophysiology of posttraumatic and nontraumatic necrosis of the femoral head. Laser Doppler flowmetry was easy to use and appears to be a reproducible technique for evaluating femoral head blood flow, offering distinct advantages over the microsphere technique for measuring bone blood flow. Further studies of the in vivo calibration of the LDF method for bone blood flow are necessary for the method to have potential for clinical application.
Joint reaction to polyethylene implantation: A method for inducing osteoarthritic change and osteophyte formation in the rabbit knee joint
Authors: Garcia Fernando , Mitrovic Dragoslav R. 
Published: February 2005

AbstractJoint lesions were induced by implantation of a rigid piece of polyethylene sutured under the patella and quadriceps tendon of the rabbit's right knee. Compared to the left sham‐operated knee, follow‐up studies revealed progressive changes that consisted of early and transient synovial hyperemia and proliferation and late osteoarthritis. By day 7 after surgery, soft synovial‐like tissue proliferated around the implant and the articular margins of the femoral trochlea indicating primitive “osteophytic” protuberances (synovio‐phytes). By day 15 after surgery, the synoviophytes had acquired a more solid consistency and were composed mostly of fibrocartilage covered by a fibro‐cellular synovial lining (chondrophytes). By that time, this tissue was invaded with vascular channels; signs of ossification were already present in the deepest layer adjacent to bone. Between the 2nd and 12th weeks, this fibro‐cartilaginous tissue, except for the surface fibrous or fibrocartilaginous layer, was progressively replaced by immature bone (osteophyte). Secondary bone remodeling started soon after the first lamellae of immature bone were deposited. Complete integration of the osteophyte into the distal femur occurred during the 2nd and 3rd month.