bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Normal 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

Tensile 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

The 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

The 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

Recording 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

Compression 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

The 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

An 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

The 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

The 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.
An in vitro study of anterior cruciate ligament strain induced by quadriceps and hamstrings forces
Authors: Draganich L. F. , Vahey J. W.
Published: February 2005

Strain in the anteromedial fibers of the anterior cruciate ligament [ACL(am)] was studied in six cadaver knees. ACL(am) strain was measured in five knees during the application of isometric quadriceps forces alone and simultaneously applied isometric quadriceps and hamstrings forces at 10° increments from 0° to 90° of knee flexion. ACL(am) strain during muscle loading was measured with respect to the ACL(am) strain measured with the knee in its resting position (neutral or near neutral position). A sixth knee was used to investigate the reproducibility of the resting position and quadriceps‐induced ACL(am) strains. The strains induced in the ACL(am) by the quadriceps were significantly greater than 0 at knee flexion angles from 0 to 40° and not significantly different from 0 for 50 to 90° The ACL(am) strains induced by simultaneously applied hamstrings and quadriceps forces were not significantly different from 0 at any of the knee flexion angles tested. Simultaneously applied hamstrings and quadriceps forces significantly reduced ACL(am) strain at 10, 20, and 90° of knee flexion compared to the ACL(am) strain induced by quadriceps forces alone. The hamstrings are potentially capable of both significantly reducing and negating quadriceps‐induced ACL(am) strain at 10 and 20° of knee flexion.
The effect of maturation and aging on the structure and content of link proteins in rabbit articular cartilage
Authors: Flannery Carl R. , Urbanek Paul J. , Sandy John D.
Published: February 2005

We have examined extracts of articular cartilage from rabbits aged 3–100 weeks for evidence of age‐related changes in the structure and content of link protein (LP) in this tissue, with the following findings: (a) Two major molecular weight forms of LP were seen on SDS–PAGE (41 and 48 kDa) and the proportion of these changed markedly with age. The 48 kDa species was predominant in young animals (representing about 78% of the total LP at 5 weeks) whereas the 41 kDa species increased in amount with age (representing 35% of the total LP at 100 weeks). A minor form of about 43 kDa, representing less than 20% of the total, was present only during the growth phase. A small amount of fragmented link protein (less than 5% of the total) of about 25–30 kDa was present in samples from mature and aged rabbits only. (b) The quantitation of LP in guanidinium: HCl extracts of cartilage, by radioimmunoassay with monoclonal antibody 8‐A‐4, was markedly influenced by the conditions of preparation and pretreatment of samples. Assays of dialyzed guanidine extracts following treatment at 80°C for 15 min in 0.025% (w/v) SDS indicated that immature and mature cartilage contains about 50 and 180 μg of LP/g of tissue, respectively. On the other hand, assays following treatment at 100°C for 20 min in 0.1% (w/v) SDS suggested that rabbit cartilage contains about 300 μg of LP/g of tissue at all ages; finally, assay of CsCl purified proteoglycan samples under these conditions indicated a content of about 500 μg of LP/g at all ages. (c) Calculations based on the analysis of proteoglycan preparations for aggregating monomer and link protein suggest that a LP:aggregating monomer molar ratio of about 0.9 is maintained in the articular cartilage throughout maturation and aging in the rabbit.
Is longitudinal bone growth influenced by diurnal variation in the mitotic activity of chondrocytes of the growth plate?
Authors: Stevenson Sharon , Hunziker Ernst B. , Herrmann Wolfgang , Schenk Robert K.
Published: February 2005

The diurnal variations in the mitotic index, height, and rate of linear bone growth were determined and correlations between these parameters examined. Young, unweaned, female Wistar rats were housed under standardized conditions, labeled with a fluorochrome 60 h before sacrifice, and killed at intervals throughout a 24‐h period, specifically 0600, 1200, 1800, and 2400. The proximal tibial epiphyseal growth plates were collected and processed, and the mitotic index, growth plate height, and the rate of linear bone growth were measured. The mitotic index measured at 0600 was significantly higher than that measured at 1800 and 2400. Growth plates of rats sacrificed at 1200 were taller than those of rats sacrificed at 1800, but there was no difference between heights of growth plates from rats sacrificed at other times. Daily growth rate for all rats averaged 283.9 μm/day and there were no statistically significant differences between daily growth rates measured at any time period. Our findings imply that in comparative, quantitative structual studies of animal groups, sacrifice should be carried out at identical times of the day, since, given a constant speed of vascular ingrowth and diurnal variation in width, relative diurnal accumulation and depletions of cells may take place. We also suggest that the daily growth rate and mitotic index be measured directly and not be considered a function of the height of the growth plate.
Nonhuman primate bites
Authors: Janda David H. , Ringler Daniel H. , Hilliard Julia K. , Hankin Rebecca C. , Hankin Fred M.
Published: February 2005

Nonhuman primate (monkey) bites to researchers and attending animal care staff may present problems in patient management. Such inoculations can transmit serious bacterial and viral infections to the human handlers. Significant local and systemic manifestations can subsequently develop following such an injury. Since Herpesvirus simiae (B virus) is enzootic in Asiatic monkeys of the genus Macaca, and since B virus infection in humans is usually fatal, additional prophylactic and therapeutic measures must be taken when persons are bitten by macaque monkeys. Primate bites require early aggressive intervention.
Electromyogram (EMG) recordings from the subscapularis muscle: Description of a technique
Authors: Németh Gunnar , Kronberg Margareta , Broström Lars‐ÅKe
Published: February 2005

Operative treatments for recurrent dislocation of the shoulder usually focus on the subscapularis muscle because it is supposed to contribute to the joint stability. It is of clinical interest to record the EMG from the subscapularis muscle in order to interpret its function. The purpose of the present study was to describe a safe and reliable route to reach the muscle, deeply located between the scapula and the thoracic cage, with fine‐wire EMG electrodes. Twenty‐four shoulders were investigated in 12 volunteers. A hypodermic needle containing bipolar fine‐wire electrodes was inserted in the posterior axillary line with the subjects in the supine position, and the arm held in an abducted and externally rotated position. Three criteria confirmed the location of the electrodes: experience of periosteal pain when the needle reached the costal surface of the scapula, drawing‐in of the wires 3–4 cm when the subject adducted his arm, thereby rotating his scapula downward, and raw EMG recorded during typical movements. Additionally, in four shoulders, the electrode location was checked with computed tomography. There were no complications from this technique, and the subjects felt no pain from the fine‐wire electrodes during arm movements. We conclude that the described technique is a safe and reliable method of reaching the subscapularis muscle with EMG electrodes.
Bone resorption in orthotopic and heterotopic bone of dichloromethylene bisphosphonate‐treated rats
Authors: Nilsson Olle S. , Bauer Henrik C. F. , Brosjö Otte , Törnkvist Hans
Published: February 2005

The effect of the bisphosphonate dichloromethylene biphosphonate (Cl2MBP) on orthotopic and heterotopic bone, induced by implants of demineralized bone matrix (DBM) in rats was analyzed, with special reference to bone resorption. The heterotopic bone was formed by induction for 3 weeks; at this time, the rats were given daily subcutaneous injections of 3 mg/kg of body weight of Cl2MBP or saline, until sacrifice. Prior to the start of treatment, the animals were given 45Ca and [3H]proline to label the inorganic and organic components of bone, respectively. Groups of rats were sacrificed at intervals from 1 to 31 days after isotope injection, and the net formation of bone and the elimination rates of the two isotopes were studied in the heterotopic bone, in diaphyseal and metaphyseal bone, and in teeth. The treatment with Cl2MBP caused a doubling of the daily net increase in mineral of the induced heterotopic bone, and a less pronounced increase in the ash content of tibiae. The treatment decreased the elimination rates of both isotopes in the orthotopic and heterotopic bone, showing that decreased bone resorption is the cause of the increased net bone formation.
Update on the use of distal radial bone density measurements in prediction of hip and Colles' fracture risk
Authors: Lester Gayle E. , Anderson John J. B. , Tylavsky Frances A. , Sutton William R. , Stinnett Sandra S. , DeMasi Ralph A. , Talmage Roy V.
Published: February 2005

A controversy has developed around the question as to whether bone density values from the distal radius can be used to accurately predict risk of future fractures. To address this question, two separate studies were undertaken: (a) Bone density was measured in 460 healthy ambulatory women living in retirement centers in the state of North Carolina; 83% of these women were followed for up to 60 months for occurrence of minimal trauma hip and wrist fractures. Thirty‐one minimal trauma fractures were reported in our study population, representing 8% of those followed. The fracture incidence density rate‐showed a close inverse relationship with incremental changes in bone density at the distal site. Twenty‐eight of the 31 fractures were reported in women with bone density values below the 325‐mg/cm2 “at risk” value. (b) Bone density values of the distal radius and the lumbar spine from 360 women (aged 18–85 years) from the Chapel Hill area were used to analyze the error in predicting individual spinal density from the distal radial density. Although the overall correlation was high (r = 0.67) and the confidence intervals were narrow, the prediction intervals were quite wide. Thus, prediction of an individual value of spine density from the distal radius density would result in a value with a range too wide to be clinically useful. We conclude that singlephoton absorptiometry appears to be a useful tool for screening normal populations of asymptomatic women for prediction of hip or Colles' fracture risk or individual values for spinal density.
Stimulation of adult chondrocyte metabolism by a thyroid‐derived factor
Authors: Jones Deryk G. , Smith R. Lane
Published: February 2005

This paper reports the effects of adding partially purified bovine thyroid calcitonin, thyrocalcitonin, to adult bovine articular cartilage cells. Thyrocalcitonin stimulated chondrocyte proliferation fourfold under low serum (0.5%) culture conditions. In serum‐free medium, thyrocalcitonin stimulated cell proliferation more than twofold. With high‐density cultures in serum‐free medium, chondrocyte glycosaminoglycan (GAG) synthesis was stimulated 60% by thyrocalcitonin. Cell‐associated radioactivity was increased twofold. In contrast to thyrocalcitonin, addition of human and salmon calcitonin peptides as well as the thyroid hormones T3 and T4 had no effect on adult cartilage cell proliferation or GAG synthesis. The data reported here suggest the existence of a thyroid‐derived factor, independent of calcitonin peptides or thyroid hormones, which stimulates adult articular chondrocyte metabolism.
Dynamic electromyography. I. Numerical representation using principal component analysis
Authors: Wootten M. E. , Kadaba M. P. , Cochran G. V. B.
Published: February 2005

A complete description of human gait requires consideration of linear and temporal gait parameters such as velocity, cadence, and stride length, as well as graphic waveforms such as limb rotations, forces, and moments at the joints and phasic activity of muscles. This results in a large number of interactive parameters, making interpretation of gait data extremely difficult. Statistical pattern recognition techniques can simplify this problem. For this approach to be successful, first it is necessary to reduce the number of interactive parameters to a manageable set. In this study, we present an application of principal component analysis as a means for representing graphic waveforms in a parsimonious manner. In particular, we concentrate on representing the phasic muscle activity recorded using surface electrodes from ten major muscles of the lower extremity of 35 normal subjects during level walking. A 32 point vector is created in which each point of the vector represents the normalized area under the curve of a portion of rectified and smoothed electromyographic signal, expressed as a function of gait cycle. Principal components are computed and the first few weighting coefficients are retained as features to represent the original EMG data. We show that the corresponding basis vectors span parts of the gait cycle where the most variability between individual subjects exists. We also show that the basis vectors can be used to represent the EMG data of subjects not originally used to generate the basis vectors.
Blood flow evaluation of vascularized bone transfers in a canine model
Authors: Siegert John J. , Wood Michael B.
Published: February 2005

Blood flow in vascularized bone transfers was evaluated in a canine model. Cortical bone blood flow was determined in undisturbed control bone, vascularized heterotopic bone transfers, and nonvascularized cortical bone grafts by means of the radionuclide‐labeled microsphere technique. Four animals were studied at 2 days, three at 1 week, eight at 2 weeks, four at 4 weeks, and three at 6 weeks postoperatively. In the 2‐day animals, the vascularized bone transfers exhibited intermediate levels of blood flow (1.4 ± 0.4 ml/100 g of bone/min) compared with undisturbed control bone (2.7 ± 0.5 ml/100 g of bone/min) and conventional cortical bone grafts (0.0 ± 0.0 ml/100 g of bone/min). At 1 week postoperatively, the differences in blood flow values of the vascularized transfers (1.7 ± 0.7 ml/100 g of bone/min) and control bone (1.4 ± 1.0 ml/100 g of bone/min) and of the nonvascularized grafts (0.2 ± 0.1 ml/100 g of bone/min) and control bone (1.6 ± 1.1 ml/100 g of bone/min) were no longer significant. At 2 weeks postoperatively, blood flow had increased in both graft groups. At 4 weeks postoperatively, the bone blood flow values in the vascularized transfers (4.8 ± 1.4 ml/100 g of bone/min) were significantly greater than the bone blood flow in control specimens (1.6 ± 0.5 ml/100 g of bone/min) and conventional cortical bone grafts (2.5 ± 2.0 ml/100 g of bone/min). At 6 weeks postoperatively, the bone blood flow values in the vascularized transfers (4.0 ± 2.1 ml/100 g of bone/min) remained greater than the bone blood flow in control specimens (1.7 ± 0.5 ml/100 g of bone/min) and conventional cortical bone grafts (2.5 ± 2.7 ml/100 g of bone/min), but the differences were no longer significant.
Bone blood flow after spinal paralysis in the rat
Authors: Takahashi Hiroshi , Yamamuro Takao , Okumura Hideo , Kasai Ryuichi , Tada Kenji
Published: February 2005

The goal of this study was to investigate the acute and chronic effects of paralysis induced by spinal cord section or sciatic neurotomy on bone blood flow in the rat. Regional bone blood flow was measured in the early stage with the hydrogen washout technique and the change of whole bone blood flow was measured in the early and the late stages with the radioactive microsphere technique. Four to 6 h after cordotomy at the level of the 13th thoracic vertebra, the regional bone blood flow in the denervated tibia increased significantly (p < 0.01). After hemicordotomy with rhizotomy at the same level, the regional bone blood flow in the denervated tibia increased significantly (p < 0.05) 6 h postoperatively. The whole bone blood flow in the denervated tibia had also increased significantly (p < 0.05) at 6 h and at 4 and 12 weeks postoperatively. After sciatic neurotomy, the regional and the whole bone blood flow in the paralytic tibia did not change significantly. The present study demonstrated that monoplegic paralysis caused an increase in bone blood flow in the denervated hind limb from a very early stage. It was suggested that the spinal nervous system contributed to the control of bone blood flow.
Spondylosis in sand rats: A model of intervertebral disc degeneration and hyperostosis
Authors: Moskowitz Roland W. , Ziv Israel , Denko Charles W. , Boja Betty , Jones Paul K. , Adler Jonathan H.
Published: February 2005

This study defines gross, histopathologic, and radiologic changes associated with intervertebral disc degeneration in a spontaneously occurring form of the disease in aging sand rats (Psammomys obesus). Sand rats (male/female) fed lab chow supplemented with desert salt bush were sacrificed at periods of 3‐30 months. Lateral thoracolumbar spine films were obtained. At sacrifice, spines were surgically exposed and gross findings were recorded; after fixation/decalcification, histopathologic studies were carried out using hematoxylin and eosin, and Safranin‐O with fast green counterstain. Metabolic studies included correlations of pathologic and radiologic findings with blood glucose and insulin levels. Disc‐space narrowing and subchondral endplate sclerosis increased radiologically with age, with more severe lower lumbar disc lesions. Ligamentous calcifications ventral to involved discs and caudal vertebrae were common. Disc thinning and anterior vertebral bony/cartilaginous spurs were more marked with age. Microscopy revealed loss of nucleus pulposus physaliform cells, chondrocyte replication, disc necrosis, and ossification. Hyperglycemia with and without hyperinsulinemia was common. No statistically significant differences in pathologic findings were noted, neither in diabetic versus nondiabetic nor in hyperinsulinemic animals. The sand rat is a model of disc degeneration; similarities with possible overlap with diffuse idiopathic skeletal hyperostosis syndrome were noted.
A histological study of local anesthetic‐induced muscle degeneration and regeneration in the monkey
Authors: Carlson Bruce M. , Shepard Beverly , Komorowski Thomas E.
Published: February 2005

Small amounts (1–2 ml) of local anesthetics (bupivacaine, lidocaine, and mepivacaine) were injected into the abductor pollicis brevis muscles of 35 monkeys. Control muscles were injected with saline. The muscles were preserved for histology from 4.5 h to 48 days after the injection. Histological damage to muscle fibers was evident from the time of the first sampling. Invasion of damaged muscle fibers by phagocytic cells was prominent by 2–3 days postinjection. At 4 to 5 days, areas of muscle fiber damage were characterized by dense concentrations of phagocytes and mononuclear myoblastic cells. At 6 days, fields of early myotubes were evident. Maturation of myotubes into immature cross‐striated muscle fibers occurred over the next week. Occasional myotubes or immature regenerating muscle fibers were seen as late as 28 days. The topographical pattern of muscle fiber degeneration and regeneration showed a concentration along the surfaces of muscle fascicles or, if intrafascicular, around the presumed site of injection.
The effects of test environment and cyclic stretching on the failure properties of human patellar tendons
Authors: Haut Roger C. , Powlison Amy C.
Published: February 2005

There is a need to document the mechanical properties of patellar tendon allografts used for reconstructive surgery of the damaged anterior cruciate ligament, especially the effects of irraidiation sterilization. The purpose of this study was to investigate the influences of in vitro test environment and low‐level cyclic stretching prior to failure tests on nonirradiated and irradiated human graft tissues. Bilateral patellar tendons were split and each half processed accordingly. Some graft tissues were stretched cyclically at 2.5 mm deformation before failure. Experiments were performed in a 37°C saline bath or with tissues moistened with a drip of the same. The irradiated grafts relaxed less and generated less slack length in the drip environment than the nonirradiated controls. Cyclic stretching did not alter failure characteristics of either graft tissue. While no significant differences in the tensile responses or failure characteristics were noted for irradiated and nonirradiated grafts in the drip, in the bath environment the nonirradiated tissues had greater strength and modulus. This resulted in there being a significant difference between irradiated and nonirradiated tissue responses in a heated saline bath environment. These experimental results exemplify the need to control in vitro test environments in the evaluation of various sterilization and preservation protocols for soft tissue allografts.
High susceptibility of human articular cartilage glycosaminoglycan synthesis to changes in inorganic sulfate availability
Authors: van der Kraan Peter M. , Vitters Elly L. , de Vries Bernard J. , van den Berg Wim B.
Published: February 2005

The effect of sulfate concentration in the medium on glycosaminoglycan synthesis in articular cartilage of five different species was examined in relation to the physiological serum sulfate concentration in these species. Only the rate of sulfated glycosaminoglycan synthesis in human articular cartilage was sensitive to small deviation from the physiological sulfate concentration. A reduction in the sulfate concentration from 0.3 mM (physiological) to 0.2 mM resulted in a 33% reduction in glycosaminoglycan synthesis. In addition, we studied the effect of arthritic and “osteoarthritic” alterations in murine cartilage on the dependence of glycosaminoglycan synthesis on low sulfate concentrations. Arthritic and “osteoarthritic” cartilage had a similar dependence on the sulfate concentration in the medium as normal cartilage. Glycosaminoglycan synthesis in human articular cartilage appears to be very sensitive to the potential sulfate‐depleting effects of drugs used in the treatment of rheumatoid arthritis and osteoarthritis.
Bone and cartilage changes following experimental varus or valgus tibial angulation
Authors: Wu D. D. , Burr D. B. , Boyd R. D. , Radin E. L.
Published: February 2005

The purpose of this work was to determine whether subchondral bone changes are an integral part of the development of osteoarthrosis of the knee following experimentally created tibial angulation. Thirty degree varus or valgus proximal tibial osteotomies were created in female New Zealand white rabbits. Bone and cartilage changes were assessed grossly, radiologically, and histologically. Thirty‐four weeks following osteotomy, severe cartilage changes, including osteophytes, fibrillation, derangement of cell columns, and cloning, were evident on the overloaded condyle, accompanied by increased subchondral bone density. The pattern of cartilage deterioration was different from that found in other experimental, mechanically induced arthroses. We conclude that osteoarthrosis is a final common pathway for mechanically induced joint failure, and that progressive cartilage change is associated with increased subchondral bone density.
Mechanism of failure of the ligamentum flavum of the spine during in vitro tensile tests
Authors: Sikoryn T. A. , Hukins D. W. L.
Published: February 2005

Thirty ligamenta flava were dissected from pig lumbar spines with their attachments to the bone of the laminae still intact. These specimens were tested to failure, in tension, at strain rates of 0.03 and 0.2s‐1. Video recordings ligaments became detached from the bone. The maximum stress that the ligaments were able to transmit was approxmately 3 MPa. However, the corresponding strain was higher when testing at the slower strain rate than at the faster rate; these strains were 1.6 ± 0.5 and 1.0 ± 0.3, respectively. All specimens were able to transmit stress after the maximum value had been attained because threads of ligament continued to remain attached to bone. Complete failure did not occur until the last of these threads had pulled away. Scanning electron micrographs showed no ligament, other than a few isolated pieces of fibre, adhering to bone after failure had occurred.
Effects of variation in systemic blood pressure on intraosseous pressure, PO2, and PCO2
Authors: Kiær Thomas , Grønlund Jørgen , Jensen Birgit , Svalastoga Eiliv
Published: February 2005

Several regulatory mechanisms have been shown to influence the intraosseous circulation. The influence of general hypovolemia on bone circulation and possible regulatory effects were investigated by recording the intraosseous pressure and PO2 and PCO2 continuously by mass spectrometry in rabbits. Hypovolemia was induced by repeated bleedings. The intraosseous and arterial pressures were found to be linearly related. The intraosseous PO2 already decreased after the first step of bleeding and decreased more than 50% of the initial value after an average blood loss of 40 ml. The intraosseous PCO2 showed an opposite pattern. The experimental PO2 vs. arterial pressure curves were similar to curves obtained by a computer simulation that assumes the blood flow to be proportional to the intraosseous pressure.
A reduced‐modulus acrylic bone cement: Preliminary results
Authors: Litsky Alan S. , Rose Robert M. , Rubin Clinton T. , Thrasher Elliott L.
Published: February 2005

Excessive local contact stress is implicated as an important factor in the initiation of the loosening process after total joint arthroplasties. A reduced‐modulus acrylic bone cement, which decreases the bone‐cement interface stresses, was developed to test this hypothesis. The formulation consists of butylmethacrylate beads, having a glass transition temperature of 27°C in a methylmethacrylate matrix. This cement, polybutylmethylmethacrylate (PBMMA), has an elastic modulus one‐eighth that of standard PMMA bone cement, 0.27 vs. 2.1 GPa, at body temperature. In vivo use in a pilot study using the sheep total hip arthroplasty model shows a reduction in the rate of loosening of femoral components when compared both radiographically and mechanically with PMMA controls.
The geometry of the adult canine proximal femur
Authors: Sumner Dale R. , Devlin Terrance C. , Winkelman D. , Turner Thomas M.
Published: February 2005

The canine is often used as a model to study functional bone adaptation after total hip replacement. To improve our understanding of the model, we defined the central tendencies and statistical variations in the crosssectional geometry, angle of anteversion, and cervicodiaphyseal angle of the proximal femur in 15 adult male mongrel dogs and compared the results with published reports of the human femur. Numerous similarities in the crosssectional geometry of the canine and the human femur were noted, supporting the use of the canine as a model. The two species differed in that the orientation of the principal axes in the proximal cross sections was not related to the angle of anteversion in the canine femur, whereas these angles are related in humans. In addition, the canine medullary canal is larger than the human medullary canal relative to the external dimensions of the femur, and hence the canine has relatively thinner cortical bone. This difference in femoral crosssectional geometry may explain, in part, why the canine provides an accentuated model of bone loss in hip arthroplasty experiments.
Wrist‐joint ligament length changes in flexion and deviation of the hand: An experimental study
Authors: de Lange A. , Huiskes R. , Kauer J. M. G.
Published: February 2005

A method to study ligament‐length patterns in situ with roentgenstereophotogrammetry, using strings of glued tantalum markers, was developed. The method was tested against a bone‐to‐bone marking method in five carpal ligaments in three specimens, whereby the hand was moved through dorsopalmar flexion and radioulnar deviation. The “glued‐string” marking method was found to be superior to the bone‐to‐bone marking method. The length patterns obtained were found to be reproducible in the specimens and different from earlier expectations presented in the literature. The radiocapitate ligament seems to limit the displacements of the capitate in both radial and ulnar deviation, and dorsal flexion. The radiolunate ligament has the same effect for the lunate. Both the dorsal radiotriquetrum and the palmar triquetrocapitate ligaments seem to play a stabilizing role in the neutral position of the hand, whereas the radiotriquetrum ligament also has a function in palmar flexion and the triquetrocapitate ligament functions in dorsal flexion, ultimately resisting these excursions. These findings require confirmation in more extensive experiments, whereby the relationship between ligament length patterns and carpal motion axes is investigated.
Effect of direct current stimulation on bone growth after distraction epiphysiolysis of the rabbit tibia
Authors: van Roermund Peter M. , Hoekstra Anne , Visser Walter J. , Renooij Willem
Published: February 2005

The effect of direct current stimulation on bone formation during limb lengthening was tested in a lower leg lengthening model in the rabbit. Limb lengthening was performed by distraction epiphysiolysis. A specially designed external distraction device was placed at the tibia. The distractor allowed 10 mm of lengthening in 4 weeks. Two weeks after starting the distraction, a platinum electrode was passed through the anterior cortex below the tibial tuberosity and advanced via the medullary cavity so that the tip rested in the elongated zone. Stimulation started at the time of placement of the electrodes and was continued for 3 weeks. The electrode in the elongated zone served as the cathode; the anode was placed subcutaneously. A 20 μA stimulus was selected. A control group received the same treatment without stimulation. Bone formation in the elongated zone was evaluated by histology and scintigraphy. The data from this experiment show that direct current stimulation in the early phase of a limb lengthening procedure had no effect on the extent of bone formation in the elongated zone.
Biochemical characterization of long‐term culture of the swarm rat chondrosarcoma chondrocytes in agarose
Authors: Kucharska Anna M. , Kuettner Klaus E. , Kimura James H.
Published: February 2005

Difficulty in maintaining phenotypic stability of the Swarm rat chondrosarcoma in long‐term monolayer cultures has prompted investigation of alternative conditions that would enable extended maintenance of these cells, permitting use of the tumor as a model system for the long‐term study of proteoglycan metabolism. Morphological analysis of the growth of the chondrosarcoma chondrocytes in agarose has shown stability of the culture over a 20 day period with respect to the ability of the cells to proliferate and synthesize an Alcian blue‐positive extracellular matrix. The present study confirms these findings through analysis of the growth characteristics of the culture and the pattern of proteoglycan‐rich matrix at a rate dependent on the initial plating density and concentration of serum in the culture medium. These factors similarly affect the proliferative capabilities of the culture as demonstrated by the growth curves obtained at different culture conditions. During 20 days in culture, the cells synthesize an aggregating chondroitin sulfate proteoglycan and collagen type II, typical of cartilage and this chondrosarcoma. In addition, small molecular weight proteoglycans were found to be present at concentrations of up to 10% of the total proteoglycan population. Degradative rates are slow, the proteoglycan half‐life is about 30 days, but can be enhanced with retinol, reducing the half‐life to 2 days.
Attachment of epiphyseal cartilage cells and 17/28 rat osteosarcoma osteoblasts using mussel adhesive protein
Authors: Fulkerson John P. , Norton Louis A. , Gronowicz Gloria , Picciano Paul , Massicotte J. Mathieu , Nissen Carl W.
Published: February 2005

These experiments show that mussel adhesive protein (MAP) enhances the attachment of osteoblasts and epiphyseal cartilage cells to plastic culture dishes and Vitallium. When MAP was applied to culture plate surfaces, there were two‐ to fivefold increases in the numbers of cells attaching compared to control surfaces (no MAP). Results were confirmed using two different cell attachment assay techniques. Osteoblast replication and culture on MAP is possible, suggesting that MAP is not toxic to cells. MAP also holds applied cells to surfaces as initially attached.
The use of two nutritional indicators in identifying long bone fracture patients who do and do not develop infections
Authors: Puskarich Cheryl L. , Nelson Carl L. , Nusbickel Fred R. , Stroope Henry F.
Published: February 2005

One hundred consecutive orthopedic long bone fracture patients requiring surgical fixation were nutritionally assessed using both the nutritional index of Rainey‐MacDonald et al. and total lymphocyte count. The ability of these two parameters to identify correctly those patients who do and do not develop postoperative complications was assessed using several error rate measures, which included sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. Fourteen of our patients developed postoperative complications. All complications observed were infections. The accuracy of the nutritional index and total lymphocyte count in predicting patient outcome was 78 and 51%, respectively. The positive and negative predictive values calculated for the nutritional index were 36 and 94%, respectively. Total lymphocyte count analysis resulted in positive and negative predictive values of 15 and 87%, respectively. In our sample of patients, the nutritional index was a better predictor of patient outcome than total lymphocyte count, as indicated by the higher accuracy rate calculated for the nutritional index. Based upon positive predictive value results, neither of these indicators was most accurate in identifying patients who did develop infections. Not unexpectedly, both indicators were best in identifying those patients who did not develop postopertive infections.