bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of medial meniscectomy and coronal plane angulation on in vitro load transmission in the canine stifle joint
Authors: Newman Alan P. , Anderson D. Ron , Daniels A. U. , Jee Ken W. 
Published: February 2005

AbstractThe purpose of this study was to determine the in vitro load transmission characteristics of the canine stifle joint, paying particular attention to the positioning effect of the meniscus in the coronal plane. The intact joint was first loaded, and then tested under two different loading conditions after a complete medial meniscectomy. The first set of test conditions attempted to simulate those used by previous investigators, by ignoring the spacer effect of the meniscus and not repositioning the joint after its removal. The second set of tests was carried out after the joint was repositioned in the coronal plane to allow initial contact to occur in both tibiofemoral compartments. It is presumed that this occurs subsequent to a meniscectomy in vivo, following the application of any weight‐bearing load. As with previous investigators, it was found that after meniscectomy the joints produced slightly larger displacements and lower stiffnesses than when intact (no significant differences from intact). However, repositioning the meniscectomized joint produced markedly smaller displacements (35–49%, p < 0.01) and greater stiffnesses (47–123%, p < 0.05) over the range of forces analyzed, compared with the intact joint. The ratio of dissipated to input energy was 42% for the intact joint, and rose following meniscectomy to 54% (p < 0.05) with repositioning and 55% (p < 0.05) without repositioning. Measured contact area decreased by 17% (p < 0.05) following meniscectomy alone, and by 12% (p < 0.05) following meniscectomy with repositioning. Since repositioning of the joint subsequent to meniscectomy (accounting for the loss of the meniscal spacer) resulted in an increse in structural stiffness, it was concluded that the medial meniscus decreases the structural stiffness of the intact stifle joint. In addition, the meniscus has a role in elastic energy storage and increasing contact area. This study is intended to serve as a baseline comparison for future in vivo studies on meniscetomy, meniscal repair, and meniscal replacement, in addition to more fully elucidating the mechanism of load transmission. A model is presented to explain both the decrease in stiffness after meniscectomy without repositioning and the increase in stiffness after meniscectomy with repositioning, employing linear springs of unequal length and different stiffnesses. After removal of the softer meniscal element and allowing joint approximation to occur, loading of the stiffer articular element results in an initially stiffer preparation.
Centrifugal characterization of proteoglycans from various depth layers and weight‐bearing areas of normal and abnormal human articular cartilage
Authors: Müller Francisco J. , Pita Julio C. , Manicourt Daniel H. , Malinin Theodore I. , Schoonbeck John M. , Mow Van C. 
Published: February 2005

AbstractUltracentrifugal polydispersity differential [g(S)] distributions were determined for the proteoglycans of various postmortem human articular cartilage samples extracted from six lateral patellar grooves in nondissociative conditions after mild collagenase digestion of the tissue. The samples consisted of 53 slices (250 μm thick), from normal, mildly fibrillated, and extensively ulcerated knee joints. When statistically analyzed in various subgroupings, the obtained average sedimentation coefficients and polydispersity profiles supported the following conclusions: (a) loss of proteoglycan aggregation and sedimentability is confirmed to be a primary sign of cartilage matrix degradation; (b) higher S values for proteoglycans of the high weight (HW)‐bearing areas and lower values for those of the low weight (LW)‐bearing areas were a typical finding in normal cartilage samples; (c) inversion of this pattern was indicative of matrix degradation, suggesting that the HW regions are more affected than the LW‐bearing areas; (d) the average S value distribution across cartilage thickness tended to resemble the corresponding proteoglycan content versus distance from articular surface; and (e) the deepest cartilage layer had, in most cases, the smallest amount of aggregates while the highest average sedimentability was observed at the middle zone of the normal samples. In the discussion, a role of proteoglycan aggregation for providing a means to “pack” more proteoglycans within the collagen meshwork and to control the generation of osmotic pressure gradients is suggested.
Circulatory and mechanical response of skin to loading
Authors: Sangeorzan Bruce J. , Harrington Richard M. , Wyss Craig R. , Czerniecki Joseph M. , Matsen Frederick A. 
Published: February 2005

AbstractWe investigated the tolerance of skin to mechanical loading over the tibia and over the tibialis anterior muscle in 12 normal volunteers. Surface load, subcutaneous tissue pressure, skin deformation under load, and transcutaneous partial pressure of oxygen (TcPo2) were simultaneously monitored. The skin over bone showed a significantly stiffer load deformation relationship than the skin over muscle (p < 0.001). The displacement required to reduce TcPo2 to 0 over bone, 1.1 ± 0.3 mm (mean ± standard deviation), was significantly less than that required over tibialis anterior muscle, 5.4 ± 1.1 mm (p < 0.001). The applied pressure required to reduce TcPo2 to 0 was significantly greater for skin over muscle (71 ± 16 mm Hg) than for skin over bone (42 ± 8 mm Hg) (p < 0.001). However, the subcutaneous pressure required to reduce TcPo2 to 0 was not significantly different for skin over muscle (36 ± 11 mm Hg) than for skin over bone (28 ± 10 mm Hg) (p > 0.05). Our results indicate that skin over muscle tolerates greater locally applied loads and deformations because the pressure is lower within the tissue than when similar loads and deformation are applied to skin over bone. Cutaneous perfusion, as indicated by TcPo2, seems to be linked more closely to the subcutaneous tissue pressure than to the surface load or deformations. These results provide some data for predicting mechanical and physiologic response to locally applied loads such as those that may be encountered in prosthetic wear.
New technique for producing uniform partial lacerations of tendons
Authors: Hitchcock Thomas F. , Candel Antimo G. , Light Terry R. , Blevens Alexander D. 
Published: February 2005

AbstractPrevious experimental studies of partial flexor tendon lacerations have used tendons cut by hand with magnification and a scalpel. When we biomechanically tested chicken flexor tendons lacerated by hand through 75% of their cross‐sectional area, the tensile strength of the residual tendons varied substantially among specimens from different chickens as well as between digit matched pairs of tendons from the same animal. A device was designed that uses standard scalpel blades to create a uniform tendon laceration by leaving a constant area of tendon intact regardless of original tendon size or shape. With the instrument we have called the “tenotome,” a second group of chicken flexor tendons were lacerated through 75% of their cross‐sectional area. Biomechanical testing of the tendons cut with the tenotome showed significantly less variation when compared with the tendons cut by hand. Use of the tenotome permits the establishment of a more uniform model for partial flexor tendon injuries, and potentially decreases the number of specimens needed to demonstrate statistical significance.
Cytosolic ionized calcium concentration in isolated chondrocytes from each zone of the growth plate
Authors: Iannotti J. P. , Brighton C. T. 
Published: February 2005

AbstractIn isolated chondrocytes from the growth plate, there is an increase in both the cytosolic ionized calcium concentration and in total cell calcium content as the cells approach the mineralization front. The reserve zone chondrocytes have a cytosolic ionized calcium concentration, [Ca2+]i, of 124 ± 23 nM and a total cell calcium content, CaT, of 12.8 ± 6.8 nmol/mg cell protein. Proliferative zone chondrocytes have a [Ca2+]i of 172 ± 29 nM and a CaT of 16.1 ± 11.8 nmol/mg cell protein. Hypertrophic zone chondrocytes have a [Ca2+]i of 273 ± 49 nM and a CaT of 35.8 ± 16 nmol/mg protein. Chondrocytes isolated from the entire growth plate have a [Ca2+]i of 132 ± 29 nM and a CaT of 13.2 ± 2.5 nmol/mg cell protein. Chondrocytes isolated from noncalcifying hyaline cartilage have a [Ca2+]i of 85 ± 10 nM and a CaT of 11.5 ± 1.4 nmol/mg cell protein. There appears to be a correlation between intracellular calcium accumulation, an increase in the intracellular ionized calcium concentration, and the process of cartilage matrix mineralization.
Production of catabolin by synovium from an experimental model of osteoarthritis
Authors: Sabiston C. Paul , Adams Mark E. 
Published: February 2005

AbstractCatabolic factors from synovium, or catabolins, may be important in the pathogenesis of osteoarthritis. The synovial production of catabolin in osteoarthritis was studied using the experimental model of osteoarthritis induced by section of the anterior cruciate ligament. At 1, 4, and 32 weeks after operation, the synovium was harvested, cultured, and the synovial conditioned medium assayed for catabolic activity. The synovial conditioned medium from the operated joints was significantly more capable of inducing cartilage destruction (p < 0.05) than was the synovial conditioned medium from the unoperated knees. However, when the results were expressed relative to the weight of synovium, the differences were not significant. These results suggest that the increased production of catabolic synovial factors in early experimental osteoarthritis is probably a result of the synovial hypertrophy.
Histological and biomechanical assessment of articular cartilage from stored osteochondral shell allografts
Authors: Kwan M. K. , Wayne J. S. , Woo S. L.‐Y. , Field F. P. , Hoover J. , Meyers M. 
Published: February 2005

AbstractNormal and stored articular cartilage from the medial tibial plateaus of mature canine knee joints were evaluated histologically and biomechanically. The medial plateaus from the right knee (control) were assessed fresh, while the left (stored) were preserved in culture media at 4°C for 3, 7, 14, or 28 days and then evaluated. Biomechanically, confined compression tests were performed on all specimens to determine the aggregate modulus and apparent permeability of the articular cartilage. Histologically, Safranin O– and hematoxylin and eosin (H&E)–stained sections were evaluated. All stored cartilage specimens had an aggregate modulus on average lower than normal, but the differences were not significant (p > 0.10). The apparent permeability was on average higher than but also not significantly different from normal (p > 0.10). Time in storage (up to 28 days) did not have a significant effect on the biomechanical properties of stored cartilage normalized by control values (p > 0.50). Safranin O and H&E histological evaluation also showed no overall changes in cell appearance or staining of the stored cartilage when compared with control for the time periods studied.
Effect of aging on tensile mechanical properties of the rabbit distal femoral growth plate
Authors: Guse Roy J. , Connolly John F. , Alberts Russ , Lippiello Louis 
Published: February 2005

AbstractTensile tests to failure were performed on the distal femoral growth plate of rabbits. The measured tensile forces, together with animal weight and dimensional measurements of the femur, were used to develop a noninvasive method of predicting growth failure loads and to examine the effects of age on the tensile strength of the growth plate. Growth plate failure load correlated with rabbit weight, (r = 0.93), femoral length, (r = 0.91), and contoured growth plate surface area, (r = 0.74). Regression analysis for these relationships allowed for failure load prediction if animal weight, femoral length, or growth plate surface area was known. Nominal stress (failure load/surface area) was calculated and correlated with animal weight (age) for each distal femoral growth plate utilizing two surface area estimating techniques; growth plate surface contour and growth plate cross‐sectional enlargement. A strong association was found with either technique. The growth and maturation of growth plate cartilage is of major importance in pediatric orthopaedics. This study demonstrated that the age‐dependent increases in tensile mechanical properties of the growth plate do not result merely from growth plate enlargement or conformational changes. The changing tensile mechanical properties of the growth plate may explain why transphyseal distraction used clinically has produced varied and somewhat unpredictable results. Our study suggests that dose‐response investigations are needed to define safe and optimal transphyseal distraction tensions before further clinical application is pursued.
Axial rotation component of thoracic scoliosis
Authors: Stokes Ian A. F. 
Published: February 2005

AbstractThe axial rotation (rotation about a vertical axis) of the vertebrae, of the ribs, and of the back surface are components of the deformity recognized clinically as the “rib hump” in thoracic scoliosis. Relationships of these rotations to the lateral deviation and lateral curvature of the spine were studied in 40 patients with idiopathic scoliosis. Stereoradiographs of the spine and rib cage were used to measure three components of axial rotation: rotation of the vertebrae, of the rib cage, and of the plane of maximum curvature of the spine. Stereotopographs of the back surface were digitized to measure the axial rotation of the back surface.In individual patients, there were high correlations of all components of axial rotation at each spinal level with the corresponding vertebral lateral deviation from the spinal axis. By regression analyses of the maximum values of each rotation in each curve, the rotation of the apex vertebra was found to be generally of lesser magnitude than the rotation of the plane of maximum curvature of the spine and in an opposite sense in kyphotic curves. The rib cage rotation was generally of lesser magnitude than the vertebra rotation, and the back surface rotation was less than both of these skeletal rotations.Vertebra rotation correlated most closely with lateral deviation of the spine. Simple segmental coupling of axial rotation and lateral bending could not be responsible for this axial rotation.
Transverse stability of the carpus. An analytical study
Authors: Garcia‐Elias Marc , An Kai‐Nan , Cooney William P. , Linscheid Ronald L. , Chao Edmund Y. S. 
Published: February 2005

AbstractThe stabilizing structures of the transverse carpal arch were studied utilizing an analytical model based on a rigid body spring model theory. This method was used to calculate the relative motion between carpal bones, the distribution of compressive forces in the intercarpal joints, and the tensions in the ligaments under simulated dorsopalmar compression. The contribution of each ligament against the effect of compression was determined by removing ligaments from the model. A multivariate analysis of variance disclosed that sectioning the flexor retinaculum alone does not significantly modify the distribution of forces in ligaments and joints (p = 0.33), and decreases dorsopalmar carpal stiffness by only 7.8%. In contrast, isolated removal of the palmar hamate–capitate ligament causes a pronounced weakening of the carpal structure, from an average fo 232 to 131 N/mm (p < 0.01). If the flexor retinaculum is removed in addition to releasing one palmar intercarpal ligament, a gross instability of the carpal arch is created.
Evaluation of injection techniques in recording of intramuscular pressure
Authors: Styf Jorma 
Published: February 2005

AbstractRecording of intramuscular pressure by using the injection technique in different ways has been evaluated in 12 healthy subjects and 12 patients with medial tibial syndrome. Pressure recording with an injection needle was compared to the recerding by a Teflon catheter with multiple side holes at its tip. Following an injection of 0.07 ml, the intramuscular pressure was significantly higher when it was recorded with the injection needle. Pressure recorded with an injection needle by the “meniscus method” was found to be significantly closer to the preinjection pressure compared to the injection technique described by Whitesides et al. (13). Pressure readings by the “meniscus method” after injection, and by a catheter or needle with multiple side holes, decrease the drawbacks of the injection technique.
Effects of experimental graded compression on blood flow in spinal nerve roots. A vital microscopic study on the porcine cauda equina
Authors: Olmarker Kjell , Rydevik Björn , Holm Sten , Bagge Ulf 
Published: February 2005

AbstractCompression injuries of spinal nerve roots are very common. However the basic pathophysiology of these conditions is not fully understood. In this study a model is presented for experimental graded compression of the nerve roots of the pig cauda equina, including a technique for vital microscopic studies on the microcirculation flow of the intrinsic vessels of the nerve roots during compression. With this model critical pressure levels for compressioninduced occlusion of the arterioles. capillaries, and venules of the intrinsic vasculature of the nerve roots were determined. The study showed that the average minimum pressure in the inflated balloon required to stop the flow in the arterioles was 127 mm Hg (SD = 18, n = 11), in the capillaries 40 mm Hg (SD = 6, n = 12), and in the venules 30 mm Hg (SD = 10, n = 12). The average mean arterial pressure (MAP) was 150 mm Hg (SD = 14, n = 12). There was a statistically significant correlation (p > 0.001) between the MAP and the pressure required to stop the flow in the arterioles (r = 0.83, n = 14), but no correlation between MAP and capillary (r = 0.09 NS, n = 20) or venular (r = −0.28 NS, n = 34) occlusion pressure. After the nerve roots had been compressed at 50 or 200 mm Hg for 10 min or 2 h, the recirculation started immediately. There was a hyperemia during the first 10 min, with a dilatation of the vessels, particularly the venules. In nerve roots exposed to compression for 2 h at either 50 or 200 mm Hg, an intraneural edema developed. Compression can thus induce changes in the blood flow of spinal nerve roots and may, even at low pressures where only venular congestion occurs, lead to alteration in function.
“Interventional angiography.” A possible role in intraoperative balloon occlusion catheterization of lacerated pelvic arteries
Authors: Morrison Kenneth M. , Ebraheim Nabil A. , Savolaine Edward R. , Jackson W. Thomas 
Published: February 2005

AbstractThe use of interventional angiography has been limited in the past to the angiography suite. Significant technical difficulties have been associated with transfer of the unstable patient from the operating room for this procedure. However, current radiographic sophistication now exists to allow rapid intraoperative digital subtraction angiography of uncompromised quality to be performed. An animal model using these techniques is presented.
Roentgenographic and biomechanical analysis of lumbar fusions: A canine model
Authors: Gurr Kevin R. , McAfee Paul C. , Warden Karen E. , Shih Chi‐Ming 
Published: February 2005

AbstractAn animal model of anterior and posterior column instability was developed to allow in vivo observation of bone remodeling and arthrodesis after spinal instrumentation. Various combinations of spinal fusions and instrumentation procedures were performed after an initial anterior and posterior destabilizing lesion was created at the L5–L6 vertebral levels in 35 adult beagles. After 6 months of postoperative observation, there was improved probability of achieving a spinal fusion if spinal instrumentation had been used. All biomechanical testing was performed after removal of instrumentation to test the inherent stiffnesses and quality of the spinal fusions. The fusions performed in conjunction with instrumentation (group V = Harrington instrumentation and posterolateral fusion; group VI = Luque instrumentation and posterolateral fusion) demonstrated the greatest axial rotation stiffnesses (group V, p < .05); axial compressive stiffness (group V, p < .05); and flexural stiffness (group VI, p < .05). The results show that a spinal fusion can be more reliably achieved and will be more rigid if it is accompanied by spinal instrumentation.
Stereological study of the developing distal femoral growth plate
Authors: Lippiello Louis , Bass Randall , Connolly John F. 
Published: February 2005

AbstractThe distal femoral growth plate has a uniquely convoluted structure comprised of four mammillate processes. Factors contributing to the development of these processes and overall plate geometry were explored using three‐dimensional image analysis of the canine distal femoral epiphysis. The growth plate at birth remains relatively flat until ossification of the epiphysis begins at 1 week of age. Epiphyseal ossification proceeds eccentrically, projecting in the medial‐lateral and anterior‐posterior directions. Growth plate activity indexed by [3H]thymidine labeling and plate thickness revealed regional differences in cell proliferation. This was measured as a decreased labeling index and thinning of the growth plate in areas capped by the ossifying epiphysis. The eccentric ossification pattern and associated variations in growth plate activity result in definition of an “intraphyseal” groove and medial‐lateral oriented sulcus. The groove and sulcus bisect the plate into four quadrants, giving rise to a convoluted structure composed of four areas of plate elevations termed mammillary processes (MP). By 5 weeks, the pattern of ossification results in greater development of the MP in the anterior‐medial quadrant and in decreasing order, in the posterior‐medial, anterior, and posterior‐lateral quadrants. By 10 weeks, a uniform rate of cell proliferation was observed coincident with completion of ossification of the epiphysis. The data suggest that localized variations in growth plate proliferation are associated with ossification of the epiphysis. The eccentric pattern of this ossification may give rise to MP and a highly convoluted structure.
Comparison of the trabecular and cortical tissue moduli from human iliac crests
Authors: Kuhn J. L. , Goldstein S. A. , Choi R. , London M. , Feldkamp L. A. , Matthews L. S. 
Published: February 2005

AbstractThe purpose of this study was to design a method to produce and test mechanically microspecimens of trabecular and cortical tissue from human iliac crests, and compare their measured moduli. Rectangular beam specimens were prepared on a low‐speed diamond blade saw and a miniature milling machine. The final specimen dimensions ranged from ∼50–200 μm for base and height. The modulus of each specimen was measured using three‐point bending tests across a span length of 1.04 mm and performed at a constant rate of displacement. A subset of specimens was recovered for a radiographic estimation of degree of mineralization. The results showed the mean trabecular tissue modulus of all iliac crest specimens to be 3.81 GPa, whereas cortical tissue specimens averaged 4.89 GPa. This was a significant difference according to a two‐way analysis of variance that controlled for differences between donors. No strong correlations were found between modulus and mineral density. Future investigations that consider other microstructural characteristics and their contributions to modulus, and specimen size effects, are indicated.