bluuebunny/crossref_metadata_2025 huggingface dataset:
Dupuytren's disease: Comparative growth dynamics and morphology between cultured myofibroblasts (nodule) and fibroblasts (cord)
Authors: Berg Jerry S. Vande , Gelberman Richard H. , Rudolph Ross , Johnson Duane , Sicurello Paula
Published: February 2005

The excised palmar fascia of 11 patients with Dupuytren's disease was separated clinically into nodules and cords. Myofibroblasts were seen by light and electron microscopy in each of the nodules, but the cords generally lacked myofibroblasts. Only one cord specimen had microscopic features that were intermediate between nodule and cord. Electron microscopy demonstrated that in vivo differences between myofibroblasts from nodules and fibroblasts from cords and control skin samples could be preserved in vitro. Growth studies showed slower growth of cultured myofibroblasts (mean ± SD generation time 68.7 ± 15 h) than cord‐derived fibroblasts (mean ± SD generation time 51.5 ± 0.9 h). These data suggest that the life cycle of the myofibroblasts from Dupuytren's disease nodules differs from that of fibroblasts found in cordlike tissues. These myofibroblasts have biological characteristics nearly identical to those of myofibroblasts found in other contracting tissues, such as granulating wounds and breast cancer.
Penetration of Staphylococcus aureus into sutured wounds
Authors: Hirshman H. Paul , Schurman David J. , Kajiyama Glen
Published: February 2005

An animal model was developed to study whether Staphylococcus aureus could penetrate a sutured wound. Six days after bacteria were applied to sutured incisions, viable organisms could be recovered from the depths of the wounds in the majority of cases. Specifically, bacteria could be recovered in 23 of 24 wounds when they were applied 1 day after suturing, in 17 of 24 wounds when they were applied 4 days after suturing, and in 13 of 24 when applied 7 days after suturing. When Steri‐strips® were used to close the wounds, bacteria could not be recovered from any of 24 wounds when bacteria were applied 4 or 7 days after wound closure. When bacteria were applied 5 min after sutures had been placed but without incision, bacteria could be recovered in three of 12 cases and in two of 12 cases when they were applied 7 days after suturing. These results demonstrate that bacteria can penetrate sutured wounds. The sutures themselves probably contributed to this phenomenon.
Kinematic and EMG patterns during slow, free, and fast walking
Authors: Murray M. P. , Mollinger L. A. , Gardner G. M. , Sepic S. B.
Published: February 2005

Kinematics and electromyographic (EMG) activity were recorded in seven normal women during walking at slow, free, and fast speeds. Speed‐related differences were found in the stride dimensions, temporal components, and most of the simultaneous displacement patterns of body segments measured. For most of the muscles tested, the amplitude of normalized EMG activity decreased as walking speed decreased. The findings emphasize the importance of accounting for the effect of speed itself on measurements of gait.
A biomechanical comparison of various methods of stabilization of subtrochanteric fractures of the femur
Authors: Tencer A. F. , Johnson K. D. , Johnston D. W. C. , Gill K.
Published: February 2005

Subtrochanteric femoral fractures with and without bony contact were simulated in cadaver specimens, fixed with one of seven different types of intramedullary or plate implants, and tested biomechanically. The implants used were Enders pins, Zickel nail, compression hip screw, AO angled blade plate, and intramedullary locked nail systems of the Klemm‐Schellman, Brooker‐Wills, and Grosse‐Kempf types. Femur‐implant constructs using intramedullary devices were a maximum of 5% as stiff in torsion as intact cadaveric femora tested in the same manner, while plate‐fixed fractures were nearly 50% as stiff. In bending, all devices except the Enders pins were ∼80% as stiff as intact femora. Loss of bony contact at the fracture site had little effect on stiffness except in the case of the keyless compression hip screw, where the screw rotated freely in the barrel. In combined bending and compression to failure, a test to simulate forces due to body weight, the intramedullary locked rods were found to support between 300 and 400% of body weight while the plate systems failed at loads between 100 and 200% of body weight.
Functional evaluation of total knee replacement
Authors: Laughman R. Keith , Stauffer Richard N. , Ilstrup Duane M. , Chao Edmund Y. S.
Published: February 2005

The assessment of patients following prosthetic knee replacement suffers from a lack of objective criteria. An automated method of laboratory assessment that permits the objective evaluation of knee joint function is described. Nine biomechanical parameters were statistically selected, weighted, and combined to develop a Performance Index (Ip). One hundred ninety‐two patients (274 diseased knees) were studied prior to total knee replacement surgery, with 107 patients (138 knees) returning for a 1‐year postoperative study. Preoperative rheumatoid knees were found to have significantly poorer function than those involved with degenerative disease. Overall, the patients experienced a marked improvement 1 year post‐total knee replacement (TKR), with their functional scores approaching the lower limits of normal. Prostheses were assessed according to generic classes as well as specific design types. The newer generation devices were found to produce better functional results. In the patients receiving Anametric and Total Condylar total knee devices, a patellar resurfacing component was found to produce improved knee function in comparison with patients receiving the same prosthesis but without patellar resurfacing.
Bone density in osteopenic women: A modified distal radius density measurement procedure to develop an “at risk” value for use in screening women
Authors: Grubb S. A. , Jacobson P. C. , Awbrey B. J. , McCartney W. H. , Vincent L. M. , Talmage R. V.
Published: February 2005

This study measured radial and lumbar spine bone density in postmenopausal white female patients with nontraumatic fractures and their agematched controls. Bone density measurements were made with a single‐beam densitometer. Distal radial bone density measurements were made at the site at which the radius and ulna are separated by 5 mm, which is ∼5 mm from the distal radioulnar joint. Lumbar spine density was obtained using a dualbeam densitometer. Density at the commonly used “2/3” site near the midradius was also measured. Forty‐six crush fracture osteoporotic patients, 35 hip fracture patients, and 20 osteopenic patients referred to the clinic for back pain or excessive bone loss but with no history of nontraumatic fracture were studied. Bone density values at all sites in the patient populations were statistically reduced from control values (p < 0.01). At a mean age of 62 years, density of the midradius was 12% below the control value. However, both vertebral and distal radial densities (“5 mm” site) were 25% below control values. The spine/distal radius ratio remained constant. It was demonstrated that bone density at the modified distal radial site could be used to predict vertebral density in osteopenic patients. An “at risk” value useful in screening procedures was determined as that distal radius density value ⩾95% of all values from fracture patients—325 mg/cm2. It is concluded that distal radial density at the new “5 mm” site can be used in conjunction with midradius density as a preliminary test for both generalized and trabecular bone mass loss in women.
Cell culture of rabbit meniscal fibrochondrocytes: Proliferative and synthetic response to growth factors and ascorbate
Authors: Webber Richard J. , Harris Mary G. , Hough Aubrey J.
Published: February 2005

This study was undertaken to determine whether the cells of the fibrocartilaginous meniscal substance are capable of proliferation and matrix synthesis. Cells were isolated from the fibrocartilaginous menisci of young New Zealand white rabbits, and grown in two alternative culture regimens differing only in the basal nutrient medium used to initiate primary monolayer growth. Under each culture regimen, the cells attached and proliferated both initially and after passage into secondary (2°) culture. Differences were noted in cell morphology and time to reach confluence in primary (1°) culture. Upon passage into 2° culture, the fibrochondrocytes assumed two distinct morphological changes were accompanied by differences in the population doubling time and incorporation of 35SO4 into sulfated proteoglycans. The proliferation of both fibrochondrocyte subtypes was stimulated by the addition of either pituitary fibroblast growth factor (FGF) or human platelet lysate in a dosedependent manner. Both FGF (10 ng/ml) and ascorbate (40 μg/ml) decreased 35‐sulfate incorporation, whereas only ascorbate was found to alter the amount of sulfated glycosaminogly can in the pericellular coat. We conclude that the fibrochondrocytes of the meniscal substance are capable of replication and synthesis of matrix macromolecules if given the proper stimuli. Additionally, there may be two subpopulations of fibrochondrocytes that can be distinguished by their in vitro behavior.
Finger joint contact areas and pressures
Authors: Moran James M. , Hemann John H. , Greenwald A. Seth
Published: February 2005

Although the joints of the index finger are similar geometrically and kinematically, the occurrence of degenerative joint disease is more frequent and severe in the distal interphalangeal joint. Much circumstantial evidence exists to suggest a mechanical cause for the observed differences in frequency. This article presents the results of in vitro experiments designed to determine contact areas and average pressures in the joints of the human index finger for positions simulating tip pinch and power grasp. The results show that the highest average contact pressures do, in fact, occur in the distal interphalangeal joint. Average joint contact pressure correlates well with clinically observed patterns of frequency of degeneration and degenerative joint disease score. This correlation between clinical experience and experimental results indicates that mechanical stress is among the factors responsible for the initiation and/or propagation of degenerative joint disease in the joints of the finger.
Kinematic behavior of the human wrist joint: A roentgen‐stereophotogrammetric analysis
Authors: de Lange A. , Kauer J. M. G. , Huiskes R.
Published: February 2005

Using a roentgen‐stereophotogrammetric measurement system, the three‐dimensional kinematic characteristics of each carpal bone in two human wrist joints were obtained as the hands were moved in vitro through dorsopalmar flexion and through radioulnar deviation, both in the supinated and pronated positions of the hand. The results were described in terms of Euler rotation angles and showed that in flexion, the distal carpal bones may be considered as one fixed group while the proximal carpals may not. For the deviation motion, quite different rotational excursions for the carpal bones were observed, therefore, none of the two rows may be assumed acting as rigid groups. In both of the hand motions performed, all carpal bones moved synchronously and uniformly. These results demonstrate that accurate measurements of three‐dimensional carpal‐bone motions are feasible by using an adequately refined roentgen‐stereophotogrammetric system. The detailed and precise kinematic information obtained can serve as a database for future developments of functional wrist‐joint models, and will provide more insight into carpal‐bone behavior, useful in clinical diagnosis and surgical reconstruction procedures.
Antibodies to synovial‐derived cells in patients undergoing artificial prosthesis implants
Authors: Ende Norman , Orsi Ernest V. , Buechel Frederic F. , Baturay Nesrine Z. , Zelikoff Judy T.
Published: February 2005

In this preliminary study, the authors have found cytotoxic complement‐dependent synovial antibodies in the serum of patients undergoing prosthesis implantation; these were particularly evident in those patients undergoing revision surgery. In order to demonstrate the synovial antibodies, it was necessary that the authors modify the method they had previously used in their studies of cytotoxic lung and kidney antibodies. While conventional trypsinization dispersion produced synovial target cells that would not react in the test system, mechanical dispersion successfully produced target cells sensitive to complement‐dependent cytotoxic antibodies. In this study, synovial antibodies reacted similarly to cells derived from the synovium of different individuals, but they did not react to cells derived from tissues other than synovium. This tissue specificity was confirmed by absorption studies that indicated the synovial antibodies to be organ specific. Whether these cytotoxic synovial antibodies can be predictive of the impending loss of an artificial prosthesis, or somehow be directly involved in the failure mechanism of that prosthesis, will require additional studies.
Chemotherapy‐induced alterations in the biomechanics of rat bone
Authors: Pelker Richard R. , Friedlaender Gary E. , Panjabi Manohar M. , Markham Thomas , Hausman Michael , Doganis Andrew C. , McKay Jim
Published: February 2005

The effects of methotrexate and doxorubicin (Adriamycin) on intact and fractured bone were studied in a rat model. Methotrexate, 0.1 mg/kg i.p., was administered five times a week, or doxorubicin, 1 mg/kg i.v., was given once a week. Animals were killed and evaluated at 4, 8, 12, and 16 weeks after surgical production of a unilateral femoral osteotomy and initiation of the chemotherapeuitic program. Both intact and fractured bones were tested to failure in rapid torsion, and the torque, angular deformation, stiffness, and energy were measured. There was a significant alteration in the strength of the healing osteotomies in doxorubicin‐ and methotrexate‐treated animals compared with the control group. The torsional strength of intact bone was not significantly altered by either drug protocol over the period of this observation.
Swing phase control with knee friction in juvenile amputees
Authors: Hicks R. , Tashman S. , Cary J. M. , Altman R. F. , Gage J. R.
Published: February 2005

Above‐knee amputees have a slower than normal walking velocity. In conventional prostheses the solution has been to apply knee friction to attempt to match the cadence of the prosthetic limb. Using kinematic data, we investigated the effect of variable knee friction on the swing phase of gait in juvenile amputees. The subjects were instructed to walk at a comfortable pace and were tested repeatedly with varying amounts of knee friction. We found that the excursion of the prosthetic shank as measured by knee range of motion was altered by changing the amount of knee friction. The period of the prosthetic shank remained constant when measured dynamically during gait. Therefore, knee friction is an effective means of providing the amputee with a more symmetrical appearing gait by matching the heel rise of the prosthetic limb to the sound limb. It is not an effective means, however, of matching the cadence of the prosthetic limb to the sound limb.
Forces in the normal and abnormal hand
Authors: An K. N. , Chao E. Y. , Cooney W. P. , Linscheid R. L.
Published: February 2005

An analytc model for human hand force analysis was developed through anatomical study and measurement of multiple cadaveric specimens. A method of solution was developed to determine muscle and joint force distributions under various isometric hand functions. Applications of this model to abnormal conditions include studying the effects of tendon laceration, neuromuscular weakness, and surgical restoration by tendon transfer. Limitations and further applications of the model are discussed in detail.
Morphological and biochemical effects of sodium morrhuate on tendons
Authors: Maynard J. A. , Pedrini V. A. , Pedrini‐Mille A. , Romanus B. , Ohlerking F.
Published: February 2005

The purpose of this study was to determine some of the morphological and biochemical effects of sodium morrhuate injections into intact rabbit patellar tendons and Achilles tendons. The effects of one, three, and five 100 μ1 injections of sodium morrhuate on tendon circumference, cell content, collagen fibril diameter, collagen‐proteoglycan relationships, water content, amino sugar content, and hydroxyproline content were investigated over periods of 1, 4, and 9 weeks. In general, sodium morrhuate injected tendons were larger in diameter and contained more cells, smaller collagen fibrils, increased water and amino sugar content, and reduced hydroxyproline content compared with their contralateral controls. As a sclerosing agent, sodium morrhuate appears to mimic the early stages of an injury‐repair sequence when injected directly into intact tendons. Whether sodium morrhuate may hasten repair responses or improve joint laxity remains to be determined.
Comparative study of neutral proteoglycanase activity by growth plate zone
Authors: Ehrlich Michael G. , Tebor Gary B. , Armstrong Ann L. , Mankin Henry J.
Published: February 2005

The degradation of proteoglycans has been considered an essential step in the process of endochondral ossification. Neutral proteases, described in the growth plate, have been implicated in this process. If these neutral proteases are important in the endochondral process, their level of activity should be highest at the point where calcification is occurring. This study measures neutral protease activity with a quantitative viscometric assay throughout all zones of the bovine growth plate. The results demonstrate that the enzyme is present throughout all zones of the growth plate. However, enzyme levels in the lower hypertrophic and calcifving zones are significantly higher than anywhere else. The enzymes came from the cartilage cells and not from the invading vasculature. This implied proof of the role of neutral proteases in the endochondral process implies that by inhibiting this class of enzymes, one should be able to block endochondral ossification.
Amelioration of oxygen‐induced osteoporosis in the in vitro fetal rat tibia with a capacitively coupled electrical field
Authors: Brighton Carl T. , Nichols Claude E. , Arangio George A.
Published: February 2005

Near‐term fetal rat tibiae were grown in M.E.M. Eagle/NCTC 135/15% newborn calf serum in 5% carbon dioxide and 5, 10, 21, 35, 60, and 90% oxygen for 3, 7, 10, and 14 days. Linear growth of the explants, as measured from macrophotographs of the explants at day zero and each of the days above, was greastest in the lower oxygen concentrations and least in the days above, was greastest in the lower oxygen concentration and least in the higher oxygen concentrations. Breaking strengths of the tibial diaphyses were signigicantly reduced in those explants grown in 60 and 90% oxygen. When the fetal rat tibiae were grown in 60% oxygen for 7 days and were subjected to a capacitively coupled electrical signal (sine wave, 60 kHz, 10 V peak‐to‐peak output signal; current density and field in the culture dish calculated to be 5.2 μA/ cm2 and 0.32 mV/cm, respectively), the breaking strengths and middiaphyseal widths were statistically significantly greater than control tibiae grown in 60% oxygen alone. It is concluded that an appropriate capacitively coupled elecmalian long bone model.
Monitoring the healing of a tibial osteotomy in the rabbit treated with external fixation
Authors: Kaplan S. J. , Hayes W. C. , Mudan P. , Lelli J. L. , White A. A.
Published: February 2005

Fercture site axial rigidity was monitored nonestructively at weekly intervals during healing of tibial osteotomies in adult rabbits. Two groups of 20 rabbits each were treated with external fixators of two different rigidities. Four animals from each group were killed at 3,5,6,7, and 8 weeks to determine the bending moments at failure of the healing fractures. Normal fracture healing was accompanied by characteristic phases in the development of fracture site axial rigidity. From 0 to 3 weeks there was a period of low and approximately constant rigidity, followed by a linear increase during 3 to 5 weeks to an approximately three to four times greater rigidity. The maximum average normalized axial rigidities were reached at 6 weeks and were 57% (high rigidity group) and 77% (low rigidity group) of the untreated contralatreal controls. The Maximum average normalized failure moments occurred at 8 weeks and were 48% (high rigidity) and 44% (low rigidity) of controls. The differences due to fixator rigidity were not statistically significant except for a large increse in failure moments at 3 weeks for the low rigidity group. Axial rigidities were correlated (r2 = 0.74 and 0.53, respectively) with failure moments, but only during the first 6 weeks. The monitoring technique provides a nondestructive means for following the biomechanical progress of fracture healing in in an animal model. The occurrence of the characteristic increase in fracture site axial rigidity at 3 to 5 weeks can also be used to distinguish between normal and abnormal healing.
Parametric analyses of pin‐bone stresses in external fracture fixation devices
Authors: Huiskes R. , Chao E. Y. S. , Crippen T. E.
Published: February 2005

Problems occuring in the use of external fixators for bone fractures include pin‐bone interface necrosis, infection, and loosening. These may be initiated and enhanced by Pin‐bone interface stress levels. Based on stress data from finite element method (FEM) models, an analytical “closed‐form” model of the local pin‐bone configuration in long‐bone fracture fixation is developed. This model is relatively simple and useful for routine applications in combination with clinical studies and animal experiments. Although approximate well with more sophisticated FEM analysis results.

The analytical model is used for extensive parametric analyses, investigating the effects on the pin‐bone interface stress distribution of frame configuration parameters, pin diameter and modulus, bone dimensions, and elastic characteristics. The results indicate that these stresses may reach very high levels under unfavorable circumstances but can be drastically reduced by increasing the bending rigidity of the pin, reducing the side‐bar separation and applying full‐pin configuration in favor of half‐pins.
Microvascular and histologic effect of circumferential wire on appositional bone growth in immature dogs
Authors: Wilson James W. , Rhinelander Frederic W. , Stewart Charles L.
Published: February 2005

Circumferential wires were placed around both midshaft femora of six immature dogs. On one side the wires were placed under the periosteum and on the other side the wires were placed over the periosteum. All wires were tightened to an equivalent tension. A diffuse growth of periosteal new bone occurred in those femora in which wires were placed under the periosteum but not in those over the periosteum. Corresponding microangiographs at 3 weeks in those femora in which wires were placed under the periosteum revealed dramatically increased medullary and periosteal vascularity coupled with histologic active trabecular bone formation. In those femora in which the wires were placed over the periosteum, even though the placement of the wires should supposedly have been the most detrimental, vascularity was not restricted. There were perfused vessels within the cortex directly under the wires. At 8 weeks the wires in both preparations were becoming encased in the growing cortical bone. Cerclage did not devitalize immature bone nor did it restrict adjacent appositional bone growth.
In vivo bone mineral analysis throughout skeletal growth in rats: Differences due to sex or vitamin D deficiency
Authors: Awbrey Brain J. , Hagaman John R. , Lester Gayle E. , Talmage Roy V.
Published: February 2005

This study reports a new technique for the measurements of bone mineral content (BMC) in live rats. A single photon absorptiometric instrument has been adapted for rapid, reproducible measurement of BMC. Four bone sites were selected for use, based on ease of positioning and reproducibility of measurement; these were as follows: proximal femur, midfemur, proximal seventh caudal vertebra, and midseventh caudal vertebra. Significant increases were detected when BMC was measured at biweekly intervals from weaning to 18 weeks of age in normal male rats. Comparison of body growth and changes in BMC of male and female rats with age showed that body weight gain of female rats slowed earlier than that of male rats whereas BMC increased at similar rates in both sexes. Vitamin D deprivation from day 24 of life resulted in decreased BMC at all four measurement sites compared with such measurements in normal control rats. Differences were detectable after 8 weeks of age and occurred despite the maintenance of serum calcium levels within normal range and only slight reduction in body weights of vitamin D deprived rats. These studies demonstrate that single photon absorptiometry can be used to mointor changes in BMC in live rats on a routine basis without harm to the animals. Changes in BMC such as those due to growth or vitamin D deprivation can easily be quantitated using this technique.
Descriptive anatomy of fibrocartilaginous menisci in the finger joints of the hand
Authors: Fisher D. M. , Elliott S. , Cooke T. D. V. , Forrest W. J.
Published: February 2005

Observations were made from the dissection of 156 digital joints (thumbs excluded). In all joints fibrocollagenous menisci projected into the articular cavity from a ring‐like structure based on the joint capsule. These meniscal structures separated the articulating cartilage surfaces at the margins of the joint. Histological examination confirmed a fibrocartilaginous nature of the tissue which demonstrated positive staining for proteoglycans and collagen fibers. Although generally similar in form, these meniscal structures varied in extent when compared between joint groups. The greatest amount and articular contribution was noted in metacarpophalangeal joints with least being found distally.
Bovine xenograft collateral ligament replacement in the dog
Authors: McMaster William C.
Published: February 2005

A Study of the use of glutaraldehyde‐stabilized bovine xenograft material as a collateral ligament replacement in 16 dogs has been done. Six xenograft implant complexes harvested 4 months postoperatively failed in tension at 772.2 ± 463.5 versus 799.7 ± 162.7 N ( ± 1 SD) for controls (p > 0.05, paired t test). Histologic evaluation in 10 dogs after implants of up to 1 year duration demonstrated a progressive invasion of the xenograft by host tissues. Xenograft remnants were easily identifiable at 1 year. The host tissues invaded in parallel to the passive collagen scaffolding of the xenograft and consisted of vessels and fibroblastic elements that produced collagen of host origin.
Piezoelectric internal fixation devices: A new approach to electrical augmentation of osteogenesis
Authors: Cochran G. V. B. , Johnson M. W. , Kadaba M. P. , Vosburgh F. , Ferguson‐Pell M. W. , Palmeiri V. R.
Published: February 2005

Prototype testing has been accomplished on a piezoelectric, internal fixation plate. This device combines a piezoelectric material with an internal fixation device as an integrated structure that provides mechanical stability, together with self‐generated electrical stimulation, for treating fractures and nonunion. In bench and animal tests we have demonstrated that cyclical loading can cause a device of this type to generate electrical charge while attached to bone. After rectification, direct currents within the range known to stimulate osteogenesis can be produced by weighed‐bearing loads. Furthermore, electrical output of the implants can be increased by externally applied ultrasonic energy. These twin developments and significantly to the potential armamentarium of devices to enhance bone healing.
Experimental temperature rise in human hip joint in vitro in simulated walking
Authors: Tepic S. , Macirowski T. , Mann R. W.
Published: February 2005

Although 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

A 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

Flexor 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

We 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

This 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

Technetium‐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

Using 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

Secreted 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

The 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

The 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

The 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

Stressed 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

The 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.