摘要:

AbstractIn an attempt to justify the use of cryopreserved versus fresh articular cartilage (AC) allografts, we used transmission electron microscopy (TEM) to study the ultrastructure of fresh versus frozen‐thawed AC with or without a dimethyl sulfoxide (DMSO) treatment. AC explants were cut aseptically from the femoral condyles of healthy, mature rabbits when they were killed. Half of all explants were incubated in Ham's F‐12 medium, supplemented with antibiotics and with or without 7.5% DMSO, frozen to −80°C, stored for 24 h, and thawed rapidly. These, and the control explants, were fixed with glutaraldehyde, paraformaldehyde, and acrolein in cacodylate buffer. Sections were stained for acid phosphatase (APase), postfixed with osmium, embedded, and examined under TEM. The typical organization of the matrix and the cells was noted in control sections. The chondrocytes contained intact nuclei, organelles, and discrete plasma membrane. Although some endoplasmic reticula and nuclear membrane appeared intact, distinct ultrastructural changes were observed in frozen‐thawed samples treated with DMSO. These changes included condensation of chromatin, large lipid droplets, partly disrupted plasma membrane, and pericellular precipitation of APase‐positive crystalites. In sections not treated with DMSO, the cytoplasm was extensively vacuolated and no distinct organelies could be detected in the chondrocytes. Little difference was noted between the matrix organization of fresh or frozen‐thawed samples. Our results suggest that distinct ultrastructural changes occur in the chondrocytes following freeze‐thawing of intact AC and that DMSO pretreatment may contribute to improvement in the cryopres

ISSN:0736-0266    

DOI:10.1002/jor.1100110102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractReconstruction of physeal regions excised from the distal femoral chondroepiphysis was attempted in a murine model. Cultured chondrocytes of varying developmental time from the same inbred strain of mice were used for replacement. Vascularity, matrix formation, and cell division, as well as growth, were assessed. The cultured chondrocytes did not produce growth. Consistent with this, cell division, as assessed with incorporation of tritiated thymidine, was not normal. However, the cultured chondrocytes did receive a nutritional supply from the host and did continue matrix formation after transplantation.

ISSN:0736-0266    

DOI:10.1002/jor.1100110103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe precision of a modified microsphere technique to measure blood flow in the hind limb of the rabbit was determined. Regional (local) injections made via a catheter in the aorta and blood withdrawn through a catheter in the hind limb enabled deposition of a high concentration of microspheres in the tissues while minimizing the number of microspheres needed for accurate measurement.95Niobium and141cerium‐labeled 16 μm diameter microspheres were used. Blood flow was measured in 15 locations of muscle and skin for simultaneous injections into the aorta and left ventricle (group A), simultaneous injections of a mixture into the left ventricle (group B), and ventricular injections given 1 h apart (group C). No significant differences in mean blood flow measurements were found. Correlation coefficients between local and ventricular injections ranged from 0.89–0.99 and between 0.994 and 0.999 for two simultaneous ventricular injections. The variability over time was greater, with correlations between the first and second injections ranging from 0.13–0.939. Precision of the local technique compared with the ventricular technique can be kept within 30% with five or six animals. The advantage of this technique over ventricular injections is in the measurement of blood flow in small tissue samples when the number of microspheres deposited from ventricular injections is insuff

ISSN:0736-0266    

DOI:10.1002/jor.1100110104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSeveral methods have been employed in the study of bone perfusion. We used a method of determining inert gas wash‐out by mass spectrometry in the study of blood flow rates in pigs. The method was validated by comparison of the result obtained with inert gas wash‐out to that with measurement by microspheres. Furthermore, the effect of decreased inlet flow and venous congestion on the bone perfusion data was tested. The undisturbed bone blood flow was not significantly different when measured with wash‐out of inert gas (7 ± 0.7 ml/min/100 g) or with microspheres (9 ± 2.9 ml/min/100 g), and the methods were correlated. Perfusion was reduced significantly, to 20% of the original value, after arterial occlusion. The changes in wash‐out curves and accumulation of radioactive tracer provided substantial evidence for impaired intraosseous circulation following venous obstruction also. In conclusion, the study showed that this method of determining inert gas wash‐out is feasible for studies of local perfusion rates in bone. The flow rates obtained by wash‐out correlated well with the results of microsphere studies. In this animal model, both methods detected a fivefold reduction in flow rate after clamping of the arterial inflow. Obstruction of the venous outflow also impaired blood flow and lowered the ce

ISSN:0736-0266    

DOI:10.1002/jor.1100110105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe influence of external load on the blood flow of the rabbit tibia was assessed by laser Doppler flowmetry (LDF). Blood flow readings were obtained from three adolescent and three adult female New Zealand White rabbits whose tibiae previously had been pinned with modified orthopaedic pins. Readings were obtained from the exposed mid‐shaft of the tibia of each hind leg before, during, and after loading. The loading was either static or sinusoidal intermittent. The LDF resulted in a reading from the tibia which was consistent with the recordings of blood flow; the traces were similar to the pulsatile nature of pulse pressure recordings. After loading of the tibia, in both the adolescent and adult rabbits the effects were an increase in blood flow, as measured with LDF, on the tensile aspect, and a decrease in flow on the compressive side. These changes were statistically significant (p<0.01) as measured by a Studentttest. This change in flow reached a plateau with change in strain. Furthermore, the changes in flow produced by loading continued as long as the load was applied. A response similar to reactive hyperaemia occurred on the compressive aspect of the tibia; there was an increase of blood flow above the resting level after removal of the static load. The effect of a sinusoidal intermittent load was less than that of a static load, and the differences in flow between tensile and compressive aspects was not significant. The changes induced offer further insight into factors controlling bone remodellin

ISSN:0736-0266    

DOI:10.1002/jor.1100110106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractTechniques of tissue exclusion have been used previously in qualitative investigations of the vascularity of long bones, after experimental fracture; we quantified their effects on bone blood flow in rabbits. Thirty‐six adult rabbits were divided into three groups in which flow was measured, with the microsphere technique, 1 and 2 weeks after osteotomy. In Group 1, osteotomy of the tibial shaft only was done; in Group 2, osteotomy was done with exclusion of the periosteum and muscle by a silicone rubber sheath; and in Group 3, osteotomy was done with exclusion of the marrow by reaming and insertion of an intramedullary nail. All involved limbs were immobilized in a cast. In Group 1, cortical flow increased but marrow flow did not change, which suggests that the changes in cortical flow were mediated by a supply paralleling that of the marrow. In Group 2, the changes in cortical flow were abolished, which implies that this parallel supply is from the periosteum and extraosseous tissues. In Group 3, cortical flow was not significantly reduced, which demonstrates reeruitment of this periosteal and extraosseous supply. These results lend support to the hypothesis that the blood supply to the healing diaphysis is principally from the periosteum and extraosseous tissues during the early peak period of blood flo

ISSN:0736-0266    

DOI:10.1002/jor.1100110107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe effect of strain rate on the mechanical properties of the rabbit anterior cruciate ligament (ACL) and patellar tendon (PT) was evaluated. The medial portion of the ACL was loaded to tensile failure at rates of 0.003, 0.3, and 113 mm/s, and the middle third of the PT was loaded at rates of 0.008, 0.8, and 113 mm/s. The load was recorded with a high‐speed measurement plotting system, and each test was videotaped for strain analysis. The nonlinear portion of the stress‐strain curve was curve‐fit to an exponential function having two nonlinear constants, representing the initial modulus, and rate of change of the modulus. The modulus of the rabbit PT was found to be 89% higher than that of the ACL. The initial modulus and rate of change of the modulus also were greater for the PT than for the ACL. The modulus of the PT was shown to be more sensitive to strain rate than that of the ACL; a 94% increase was observed for the PT, and a 31% increase was observed for the ACL; a 94% increase was observed for the PT, and a 31% increase was observed for the ACL. There was no effect of strain rate on the mode of failure of either the ACL or the PT; all but three of the specimens failed at the insertion

ISSN:0736-0266    

DOI:10.1002/jor.1100110108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractProteoglycan content and tissue morphology were examined in tendons and ligaments from 24 cadavers, ranging in age at the time of death from 1.5 months to 83 years. The region of the human tibialis posterior tendon that passes under the medial malleolus was characterized by cells having a rounded shape, positive staining with alcian blue, and higher glycosaminoglycanuronic acid content than in the more proximal region of the same tendon. Analysis of proteoglycans by sodium dodecyl sulfate/polyacrylamide gel electrophoresis indicated that the predominant small proteoglycan of the proximal/tensional region was decorin, whereas two types of small proteoglycans (decorin and biglycan) and large proteoglycans were present in the region passing under the medial malleolus and presumably subjected to compressive and shear forces in addition to tension. The pattern of proteoglycan accumulation in the compressed region of tendon was basically similar for all individuals and showed no distinctive trends related to age after puberty. In terms of type and amount of proteoglycan, the patellar tendon was like the tensional region of the tibialis posterior. Glycosaminoglycan content in the lateral collateral ligament and anterior cruciate ligament, however, was twofold higher than in the tendons. The ligaments contained large as well as small proteoglycans, just as in the compressed region of tendon.

ISSN:0736-0266    

DOI:10.1002/jor.1100110109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractBone loss is known to occur under plates used for internal fixation. Its exact location and extent and its relationship to the plate‐bone contact area was investigated in 36 adult beagles. Plates with two different contact areas were fixed unilaterally to intact femora for periods of 8 and 24 weeks. After removal, the bones were assessed radiographically, histologically, histomorphometrically, and biomechanically. Two processes that affect the bone after plating became apparent. One is a short‐term process, possibly caused by the interference of the plate with the blood supply to the cortex. This is followed by necrosis, which induces porosis. The second independent process is caused by the tendency of the bone to adapt to the new state of mechanical loads that results from the load sharing by the plate. The first stage of this process is expressed through swift changes in the bone cross‐sectional area under the plate by remodeling in all three envelopes: haversian, periosteal, and endosteal. This stage is followed by a gradual remodeling towards a steady state, in which the final cross‐section of the bone is attained. Both processes affected the bone simultaneously during plate fixation. The process caused by the vascular interference ceases after some time, and only the process due to stress‐shielding prevails for a lo

ISSN:0736-0266    

DOI:10.1002/jor.1100110110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractTo examine the presence of substances which inhibit calcification in human ligamentum flavum, the inhibitory effect of an Na2HPO4extract of the flavum was determined in terms of the in vitro calcium uptake of the ligamentum flavum matrix. Additionally, grafts of extracted and non‐extracted dry ligamentum flavum matrices were transplanted into the dorsal muscles of rats, and calcification in the grafts was examined radiologically and histochemically. In order to determine if component cells of human ligamentum flavum produce calcification inhibitors, ligamentum flavum cells were cultured, and the crystal inhibitor activity of the culture medium was measured by a seed test which used hydroxyapatite as the nucleus of precipitation. The calcification reaction system demonstrated that the ligamentum flavum extract contains an inhibitory factor for calcium uptake by the ligamentum flavum matrix. The seed test revealed that human ligamentum flavum cells produce calcification inhibitor activit

ISSN:0736-0266    

DOI:10.1002/jor.1100110111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY