摘要:

AbstractThe compressive, tensile, and swelling properties of articular cartilage were studied at two time periods following transection of the anterior cruciate ligament in the knee of greyhound dogs. An experimental protocol was designed to quantify the essential equilibrium and biphasic material properties of cartilage in tension, compression, and shear, as well as the parameters of isometric swelling behavior. All properties were measured at several sites to elicit differences between sites of frequent and less frequent contact. Hydration was determined at each site and was compared with the material properties of cartilage from corresponding sites. There were extensive changes in all compressive, tensile, and swelling properties of cartilage after transection of the anterior cruciate ligament. Twelve weeks after surgery, the intrinsic moduli were reduced significantly in compression (approximately 24% of control values), tension (approximately 64%), and shear (approximately 24%), and the hydraulic permeability was elevated significantly (approximately 48%). Significant increases in hydration (approximately 9%) also were observed, as well as a strong correlation of hydration with hydraulic permeability. The pattern of these changes was not found to differ with site in the joint, but significant differences were observed in the magnitude of change for cartilage from the femoral groove and the femoral condyle. The pattern and extent of changes in the material properties following transection of the anterior cruciate ligament indicate that altered loading of the joint severely compromises the overall mechanical behavior of articular cartilage. The observed loss of matrix stiffness in compression, tension, and shear is associated with increases in the deformation of the solid matrix, a diminished ability to resist swelling, and the increase in hydration observed in this study. The increased swelling and elevated water content were related directly to the increase inhydraulic permeability; this suggests an associated loss of fluid pressurization as the load support mechanism in the degenerated cartilage. Without a successful mechanism for repair, damage to the solid matrix may progress and lead to further degenerative changes in the biochemistry, morphology, and mechanical behavior of articular cartilage.

ISSN:0736-0266    

DOI:10.1002/jor.1100120402

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe levels of proteoglycan aggregate components (link protein, keratan sulfate epitope, and total sulfated glycosaminoglycan) were determined in the synovial fluid lavages of dogs with experimental osteoarthritis or disuse atrophy. A model of experimental osteoarthritis was created by transection of the anterior cruciate ligament of the right knee; studies were carried out 6 and 12 weeks after surgery. Joint disuse was studied at 4 and 8 weeks after initiation of the disuse. Recovery after disuse also was studied in joints that had 3 weeks of remobilization after 4 or 8 weeks of disuse. Synovial fluid lavages from the right knee joints of untreated animals were used as controls. The concentrations of keratan sulfate epitope, sulfated glycosaminoglycan, and link protein in the synovial fluid lavages at 6 and 12 weeks after transection of the anterior cruciate were elevated compared with the control values. Similar analysis of the fluid after disuse showed that the levels of keratan sulfate epitope and sulfated glycosaminoglycan were increased compared with the control levels and the levels after transection. However, the concentration of link protein in the fluid after disuse was not significantly different from the control level. The levels of keratan sulfate epitope and sulfated glycosaminoglycan in the synovial fluid lavages after disuse with recovery were high, but the levels of link protein remained low. The results indicate that the catabolism of proteoglycan aggregates in articular cartilage during early osteoarthritis and disuse is different. The determination of keratan sulfate epitope in synovial fluid lavages appears to provide a relatively general indication of proteoglycan catabolism, whereas increased levels of link protein may be more indicative of cartilage degeneration.

ISSN:0736-0266    

DOI:10.1002/jor.1100120403

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe changes in the tensile mechanical properties and biochemical composition of the superficial zone of articular cartilage were examined in a canine model of early osteoarthritis generated by transection of the anterior cruciate ligament. Sixteen weeks following ligament transection, the tensile stiffness of the articular cartilage was decreased by 44% and the ion‐induced stress relaxation of the tissue was increased by 57% compared with the contralateral control. Biochemical analyses indicated that the water content of the experimental tissue was increased by 13%, which was reflected as an apparent 37% decrease in the proteoglycan content and a 36% decrease in the collagen content (expressed per wet weight). The hydroxypyridinium crosslink density was decreased in the experimental tissue by 11%. A significant negative correlation was found between the ion‐induced stress relaxation and the hydroxypyridinium crosslink density in both control tissue (R = −0.56) and experimental tissue (R = −0.70). No correlation was noted between the tensile stiffness and the biochemical composition of the tissue. These results suggest that, in the superficial zone of articular cartilage, the structure of the tissue may play a more important role than the composition in the determination of its mechanical properties. A major event observed in the model of early osteoarthritis appears to be the disruption and remodeling of the collagen network in the superficial zone of the articular ca

ISSN:0736-0266    

DOI:10.1002/jor.1100120404

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

年代:1994

数据来源: WILEY

摘要:

AbstractCartilage resurfacing by chondrocyte implantation, with fibrin used as a vehicle, was examined in large (12 mm) full‐thickness articular cartilage defects in horses. Articular chondrocytes, isolated from a 9‐day‐old foal, were mixed with fibrinogen and injected with thrombin, in a 1:1 mixture, into 12 mm circular defects on the lateral trochlea of the distal femur of eight normal horses. The contralateral femoropatellar (knee) joint served as a control in which the defect was left empty. Synovial fluid from the femoropatellar joints was sampled on days 0, 4, 7, 30, 120, and 240 postoperatively. Groups of four horses were killed at 4 or 8 months postoperatively, and the repair tissue was evaluated by gross and histologic examination with use of hematoxylin and eosin and safranin O staining and by autoradiography. Biochemical analyses included quantitation of proteoglycan, total collagen, and type‐II collagen in the repair tissue. Grossly, grafted defects had improved filling of the cartilage lesions: histologically, these areas consisted of differentiated chondrocytes in the deep and middle zones. The cellular arrangement in these zones resembled that of hyaline cartilage. The control defects contained poorly attached fibrous tissue throughout. Grafted tissue at 8 months had increased proteoglycan synthesis evident by both safranin O staining and autoradiography. Glycosaminoglycan quantitation by dye‐binding assay confirmed a significantly elevated glycosaminoglycan content in grafted defects (58.8 μg/mg of dry weight) compared with control defects (27.4 μg/mg; p<0.05). Similarly, the levels of chondroitin sulfate/dermatan sulfate was significantly elevated in the grafted defects, and this was the predominant glycosaminoglycan epitope present. There was a statistically significant (p<0.05) increase in type‐II collagen in the grafted tissue at 8 months (61.2% grafted; 25.1% control). This resurfacing attempt with use of allograft chondrocytes, secured in large full‐thickness articular defects with polymerized fibrin, resulted in an improved cartilage surface in comparison with the control defects, a significantly greater aggrecan level, and a significantly higher proportion of t

ISSN:0736-0266    

DOI:10.1002/jor.1100120405

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

年代:1994

数据来源: WILEY

摘要:

AbstractTwo models involving altered joint loading were compared with regard to their effects on the biochemical composition and proteoglycan aggregate structure of articular cartilage. Disuse atrophy was created in greyhound dogs by nonrigid immobilization of the right knee in 90° of flexion, and joint instability was created by transection of the anterior cruciate ligament. Similarities and differences between the two experimental groups at two different time periods were examined to investigate why joint instability induces progressive and irreversible changes to the articular cartilage, whereas joint disuse induces changes that may be reversible when the joint is remobilized. The following studies were performed on the cartilage from all experimental and control groups: (a) compositional analyses to determine water, uronate, and hydroxyproline contents; (b) high performance liquid chromatography for detection of hyaluronan and chondroitin sulfates; and (c) centrifugation analyses of nondissociatively extracted and purified proteoglycans to isolate and quantify the populations of monomers and slow and fast‐sedimenting families of aggregates. In general, all cartilage was found to have a decreased ratio of proteoglycan to collagen after 4 weeks of disuse, and this ratio returned to control values at 8 weeks. In contrast, cartilage had an elevated ratio of proteoglycan to collagen as well as increased hydration at 12 weeks after transection of the anterior cruciate ligament. The most striking contrast between the two models was the finding of an approximately 80% decrease in the content of hyaluronan at both time periods after transection of the anterior cruciate ligament, with no evidence of a change after disuse. The results of centrifugation analyses indicated a significant decrease in the quantity of proteoglycan aggregates in both models. However, this decrease was associated primarily with a loss of slow‐sedimenting aggregates after disuse and a loss of both slow and fast‐sedimenting aggregates after transection of the anterior cruciate ligament. Furthermore, the population of fast‐sedimenting aggregates. The preservation of fast‐sedimenting aggregates as well as hyaluronan after periods of joint disuse but not joint instability suggests a possible mechanism for the reversibility of cartilage changes. Although the proteoglycan aggregates were depleted after disuse atrophy, it is possible that an aggregate‐depleted matrix could recover when normal proteoglycan synthesis is resumed. In contrast, although synthesis may be maintained or elevated after transection of the anterior cruciate ligament, the matrix may not be repopulated with aggregates because there is an insufficient amount o

ISSN:0736-0266    

DOI:10.1002/jor.1100120406

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe feasibility of magnetic resonance imaging and the magnetization transfer technique for measurement of diurnal fluid changes in lumbar discs was studied with the use of 13 healthy subjects. The diurnal height loss of the subjects ranged from 13 to 21 mm. The disc signal in T2‐weighted magnetic resonance imaging increased as much as 25% after overnight bed rest, presumably due to the enhanced influx of water. The change in magnetization transfer parameters also suggested increased hydration of the disc after bed rest. Magnetic resonance imaging techniques can be used for indirect measurement of the changes in fluid content and the interaction of water with macromolecules in the dis

ISSN:0736-0266    

DOI:10.1002/jor.1100120407

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

年代:1994

数据来源: WILEY

摘要:

AbstractPeriosteum has been shownin vitroandin vivoto have a chondrogenic potential that permits it to be used for cartilage regeneration. A useful donor site should have good chondrogenic potential, availability of a large quantity of periosteum, and relative ease of access, and it should be associated with a low rate of morbidity. We hypothesized that the chondrogenic potential of periosteum varies from one bone to another and among different regions of the periosteum from a single bone. A total of 370 periosteal and 37 fascia lata (control) explants were taken from the skull, the ilium, the scapula, the upper, middle, and lower medial proximal tibia, the posterior proximal tibia, and the distal tibia of 2‐month‐old New Zealand rabbits. The explants were cultured for 6 weeks in agarose/Dulbecco's modified Eagle medium to which 10 ng/ml of transforming growth factor‐β1 was added during the first 2 weeks. Skeletal muscle and fascia lata were used as controls. In addition, the thickness, cell density, and total cell count of the cambium layer were measured in 24 explants from the donor sites on the ilium and the upper, middle, and lower proximal tibia. At 6 weeks, histomorphometry and quantitative collagen typing were performed. The periosteal donor sites could be grouped into three categories according to chondrogenic potential: ilium (best), scapula and tibia, and skull (no chondrogenesis). The scapular periosteum was slightly better than that from the tibia. Within the tibia, the upper and middle zones of the proximal region were similar and were slightly better than the lower proximal tibia or the distal tibia. The cellularity of the cambium layer correlated positively with the amount of cartilage as a percentage of the total area. The results of this study indicate that iliac periosteum exhibited the best overall chondrogenic potentialin vitrobut that periosteum from the traditionally used medial proximal tibia also was excellent. Periosteum from the skull was not chondrogenic. The chondrogenic potential of periosteum varies from bone to bone and within the periosteum from one bone. This variation in chondrogenic potential among donor sites may be due to a difference in the total cell count of the cambium

ISSN:0736-0266    

DOI:10.1002/jor.1100120408

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

年代:1994

数据来源: WILEY

摘要:

AbstractA study was undertaken to examine the role of bacterial adherence in the development of infection at the site of an implant. The amount ofin vitroadherence ofStaphylococcus epidermidiswas greatest for stainless steel, followed by polymethylmethacrylate and commercially pure titanium, and was least for polymethylmethacrylate with gentamicin. These materials then were preincubated withS. epidermidisand implanted. The number of organisms that were isolated and the rate of infection followed the same pattern as that in thein vitrostudies. Materials that were not preincubated with bacteria also were implanted and bacteria were injected into the site. The number of organisms isolated from the site and the rate of infection were lower than those for the preincubated materials, but the trend was the same as in both thein vitroand thein vivostudies. The rates of infection and colonization correlated with the propensity for the organisms to adhere to a given material. Materials colonized withS. epidermidisat the time of implantation caused a high rate of infection. The ability of organisms to adhere to a materialin vitrois correlated with their propensity to cause biomaterial‐based infectio

ISSN:0736-0266    

DOI:10.1002/jor.1100120409

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

年代:1994

数据来源: WILEY

摘要:

AbstractParticulate polymethylmethacrylate debris has been implicated in the inflammatory response observed surrounding loosened cemented implants. The rat subcutaneous pouch model and the Howie implant model (used to study bone resorption) were used to quantify the response to mechanically produced endotoxin‐free polymethylmethacrylate debris with and without 10% (wt/vol) BaSO4. In the rat subcutaneous pouch model, the inflammatory response to polymethylmethacrylate particles containing BaSO4was greater than the response to plain polymethylmethacrylate particles of similar size. Increased inflammation was measured by leukocyte counts and levels of prostaglandin E2, tumor necrosis factor, and neutral metalloprotease. In addition, particulate polymethylmethacrylate with BaSO4caused significantly greater bone resorption in the Howie model than did particulate plain polymethylmethacrylate. Inin vitrostudies, particulate polymethylmethacrylate with BaSO4stimulated more prostaglandin E2, neutral metalloprotease, and tumor necrosis factor from human monocytes in culture and stimulated greater proliferation of synovial cells than did particulate plain polymethylmethacrylate. The presence of BaSO4appears to significantly intensify the inflammatory response to polymethylmethacrylate debri

ISSN:0736-0266    

DOI:10.1002/jor.1100120410

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe effect on chondrocyte metabolism of culture surfaces sputter‐coated with various materials used for orthopaedic implants was studied and correlated with the stage of cartilage cell maturation. Confluent, fourth‐passage chondrocyts from the costochondral resting zone and growth zone of rats were cultured for 6 or 9 days on 24‐well plates sputter‐coated with ultrathin films of titanium, titanium dioxide, aluminum oxide, zirconium oxide, and calcium phosphate (1.67:1). Corona‐discharged tissue culture plastic served as the control. The effect of surface material was examined with regard to cell morphology; cell proliferation (cell number) and DNA synthesis ([3H]thymidine incorporation); RNA synthesis ([3H]uridine incorporation); collagenase‐digestible protein, noncollagenase‐digestible protein, and percentage of collagen production; and alkaline phosphatase‐specific activity, both in the cell layer and in trypsinized chondrocytes. Cell morphology was dependent on surface material; only cells cultured on titanium had an appearance similar to that of cells cultured on plastic. While titanium or titanium dioxide surfaces had no effect on cell number or [3H]thymidine incorporation, aluminum oxide, calcium phosphate, and zirconium oxide surfaces inhibited both parameters. Cells cultured on aluminum oxide, calcium phosphate, zirconium oxide, and titanium dioxide exhibited decreased collagenase‐digestible protein, noncollagenase‐digestible protein, and percentage of collagen production, but [3H]uridine incorporation was decreased only in those chondrocytes cultured on aluminum oxide, calcium phosphate, or zirconium oxide. Chondrocytes cultured on titanium had greater alkaline phosphatase‐specific activity than did cells cultured on plastic, but the incorporation of [3H]uridine and production of collagenase‐digestible protein, noncollagenase‐digestible protein, and percentage of collagen was comparable. The response of chrondrocytes from the growth zone and resting zone to culture surface was comparable, differing primarily in magnitude. Cell maturation‐dependent effects were evident when enzyme activity in trypsinized and scraped cells was compared. These results indicate that different surface materials affect chondrocyte metabolism and phenotypic expressionin vitroand suggest that implant materials may modulate the phenotypic

ISSN:0736-0266    

DOI:10.1002/jor.1100120411

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

年代:1994

数据来源: WILEY