摘要:

AbstractThe flow‐independent (intrinsic) tensile modulus of the extracellular matrix of human knee joint cartilage has been measured for normal, fibrillated, and osteoarthritic (removed from total knee joint replacements) cartilage. The modulus was determined in our isometric tensile apparatus and measured at equilibrium. We found a linear equilibrium stress‐strain behavior up to ∼15% strain. The modulus was measured for tissues from the high and low weight‐bearing areas of the joint surfaces, the medial femoral condyle and lateral patello femoral groove, and from different zones (surface, subsurface, middle, and middle‐deep) within the tissue. For all specimens, the intrinsic tensile modulus was always less than 30 MPa. Tissues from low weight‐bearing areas (LWA) are stiffer than those from high weight‐bearing areas (HWA). The tensile modulus of the ECM correlates strongly with the collagen/proteoglycan ratio; it is higher for LWA than for HWA. Osteoarthritic cartilage from total knee replacement procedures has a tensile stiffness le

ISSN:0736-0266    

DOI:10.1002/jor.1100040401

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe studied the effects of mechanical and osmotic compression on sulphate incorporation into glycosaminoglycans of human femoral head cartilage. We found that both mechanical and osmotic compression produce the same lowering of sulphate uptake relative to uncompressed controls. It appears that this effect is not associated with changes in solute transport or changes in solute concentration in the matrix, but is due, in part at least, to an increased osmotic pressure acting on the chondrocytes. A second mechanism of action might be involved directly through the increased proteoglycan concentration in the pericellular environment, resulting from a reduction in the water content. We also found that glycosaminoglycan synthesis returned to its control level when the conditions prevailing in the matrix, in the absence of pressure or added solute, were restored.

ISSN:0736-0266    

DOI:10.1002/jor.1100040402

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to determine if articular cartilage was able to accumulate fibronectin, a large molecule of 440,000 daltons, from the external medium, and if so, to compare the extent of accumulation by normal and osteoarthritic cartilage and to localize the sites of fibronectin accumulation within the articular cartilage. The uptake of canine serum albumin, another protein present in plasma and synovial fluid with a lower molecular weight (67,000 daltons) and a lower pI, was compared. Purified plasma fibronectin and canine albumin were labelled with125I orN‐hydroxysuccinimidobiotin by standard procedures and incubated with articular cartilage explants. The125I‐fibronectin that had bound to cartilage components was extracted with 4Murea, and both extract and cartilage residues were counted. Cartilage accumulated fibronectin to a greater extent than albumin. For normal cartilage, a level of saturation appeared to be reached at an external concentration for fibronectin of about 150 μg/ml. Degenerated cartilage accumulated about 10‐fold more fibronectin than normal cartilage. Biotinylated fibronectin was localized within frozen sections of articular cartilage by probing with peroxidase‐linked avidin. Fibronectin accumulation in normal cartilage was restricted to the articular surface and the cut edge. In degenerated cartilage, penetration of fibronectin was more extensive but proceeded only from the articular surface. Staining of adjacent sections with peroxidase‐linked antifibronectin antibody confirmed previous observations that endogenous fibronectin is present throughout the cartilage matrix. The possibility that synovial fluid fibronectin could be a source of cartilage fibronectin, especially in degenerated cartilage, was

ISSN:0736-0266    

DOI:10.1002/jor.1100040403

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

年代:1986

数据来源: WILEY

摘要:

AbstractJoint lesions were induced by implantation of a rigid piece of polyethylene sutured under the patella and quadriceps tendon of the rabbit's right knee. Compared to the left sham‐operated knee, follow‐up studies revealed progressive changes that consisted of early and transient synovial hyperemia and proliferation and late osteoarthritis. By day 7 after surgery, soft synovial‐like tissue proliferated around the implant and the articular margins of the femoral trochlea indicating primitive “osteophytic” protuberances (synovio‐phytes). By day 15 after surgery, the synoviophytes had acquired a more solid consistency and were composed mostly of fibrocartilage covered by a fibro‐cellular synovial lining (chondrophytes). By that time, this tissue was invaded with vascular channels; signs of ossification were already present in the deepest layer adjacent to bone. Between the 2nd and 12th weeks, this fibro‐cartilaginous tissue, except for the surface fibrous or fibrocartilaginous layer, was progressively replaced by immature bone (osteophyte). Secondary bone remodeling started soon after the first lamellae of immature bone were deposited. Complete integration of the osteophyte into the distal femur occurred during the 2n

ISSN:0736-0266    

DOI:10.1002/jor.1100040404

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

年代:1986

数据来源: WILEY

摘要:

AbstractChondrocytes from the Swarm chondrosarcoma, a transplantable rat tumor, have been difficult to maintain in tissue culture for extended periods due to a time‐dependent alteration of the culture to a more fibroblastic pheno‐type. This feature precluded the use of these cultures to examine chronic conditions that may affect cell metabolism, and the homogeneity or heterogeneity of the tumor cells within the culture population could not be examined. Use of suspension culture in agarose stabilized the chondrocyte phenotype, permitting long‐term culture. Clones of tumor chondrocytes were established in agarose and were examined over 2–3 weeks for evidence that the cells were accumulating a proteoglycan‐rich extracellular matrix, as determined by positive staining by Alcian blue, and were undergoing cell division. Nearly 90% of the cloned cells exhibited a prominent extracellular matrix by day 7 of culture and greater than 99% did so by day 14. Cell division did not occur to any great extent until days 6–7 of culture. After this lag, the cells appeared to undergo logarithmic growth, with a cell generation time of about 12 days. By 20 days of culture, between 80 and 90% of the initial clones contained multiple cells, indicating that nearly all the cells were in, or had entered, the cell cycle. These results suggest that the chondrocytes from the rat chondrosarcoma form a homogeneous cell population with respect to their ability to synthesize an extracellular matrix

ISSN:0736-0266    

DOI:10.1002/jor.1100040405

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe aim of this study was to test the hypothesis that fibronectin in cartilage of osteoarthritic joints accumulates in increased quantities in response to a reduction in proteoglycan content in the matrix. We determined fibronectin content in an ELISA system, uptake of plasma125I‐fibronectin from the medium, and glycosaminoglycan content by a dye method. The proteoglycan content of canine articular cartilage was reduced by co‐incubation of the cartilage with canine synovium, partially purified catabolin, or retinoic acid. Data suggested that proteoglycan loss alone was not sufficient to result in the increased fibronectin accumulation that has been reported in the deteriorating articular cartilage of osteoarthritic joints. Cartilage that lost as much as 75% of its proteoglycan content did not have increased fibronectin content and did not take up more fibronectin from the external medium. A related goal of this study was to evaluate the percentage of water in proteoglycan‐depleted but disease‐free cartilage, as the percentage of water is known to be elevated in osteoarthritic cartilage. Data indicated that the percentage of water in the depleted cartilage increased in proportion to the decrease in proteoglycan content, but the total amount of water in the cartilage did not increase; water content appeared to be unchanged. Under the conditions used, the proteoglycan content was reduced and the percentage of water was elevated, but fibronectin content was not increased. Thus, the cartilage incubated in vitro did not mimic osteoarthritic ca

ISSN:0736-0266    

DOI:10.1002/jor.1100040406

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

年代:1986

数据来源: WILEY

摘要:

AbstractA continuous 5‐V peak‐to‐peak, 60 kHz capacitively‐coupled sine wave signal was applied to the proximal tibial growth plate in fifteen 9‐week‐old male New Zealand white rabbits for 6 weeks. A pair of flexible stainless steel “injectrodes” was held in place medially and laterally on the surface of the proximal hindlimb in each rabbit by means of tape wrappings. The electrodes were connected to a 9‐V battery‐operated power unit carried in a dorsal pouch in a body vest worn by each rabbit. Control animals wore the identical apparatus, only the power unit was inactive. Small Tantalum markers were inserted into the anteromedial aspect of the proximal tibial metaphysis 1 cm distal to the proximal tibial growth plate in all of the animals, control and experimental, 2 weeks prior to the onset of electrical stimulation. The distance between the proximal lateral tibial spine and the Tantalum marker, between the Tantalum marker and the apex of the distal tibial intercondylar notch, and between the proximal tibial spine and the distal notch was measured from roentgenograms made at the time of bone marker insertion, at the time of electrode application to the limb, and at the end of the stimulation period. Results indicate that there was no significant difference in tibial lengths between the stimulated and control groups. There was significantly less total body weight gain in both the experimental and control animals than that which occurred in paired normal animals during the same period of time. This failure to thrive may be responsible for the resultant lack of longitudinal growth stimulation of the capacitive coupling. The observed failure to thrive was thought to be due to encumbrance imposed on the rabbits by the legwrap

ISSN:0736-0266    

DOI:10.1002/jor.1100040407

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

年代:1986

数据来源: WILEY

摘要:

AbstractIn osteochondrosis juvenilis Scheuermann, foci of various sizes in the cartilaginous end plates of the vertebral bodies display a loosening or complete interruption of the collagen fibers. These findings, together with an alteration and occasional absence of the growth zone, may result in the typical deformation of the vertebral bodies. Electron micrographs of the areas with optically absent collagen fibers reveal collagen fibrils. They are arranged in an irregular pattern. We conclude that a disturbance of collagen or ground substance biosynthesis is of importance in the pathogenesis of juvenile osteochondrosis.

ISSN:0736-0266    

DOI:10.1002/jor.1100040408

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect on tendon gliding of flexor sheath excision versus incision/closure following primary flexor tendon repair was examined biomechanically and histologically in forty‐one chickens. There was no significant difference in either the tendon excursion required to fully flex the digit or in the work of flexion (the integration of the forces that resist tendon gliding during excursion) between the sheath excised and sheath closed groups. The results were unaffected by postoperative immobilization or intermittent passive motion. Histologically, it was noted that at 3 weeks the healing tendon was surrounded by a layer of granulation tissue that was nearly indentical in both the sheath excised and the sheath closed digits. Of note was the finding that a synovial lining could not be identified in those digits that had previously undergone sheath closure. However, at 6 weeks postoperatively, a new gliding surface could be identified surrounding the tendon in both the sheath excised and the sheath closed digits. This study indicates that closure of the flexor sheath after primary tendon repair does not improve tendon gliding as measured biomechanically. Despite its repair, the flexor sheath does not maintain its synovial characteristics as demonstrated histologically, and a new sheath must subsequently be forme

ISSN:0736-0266    

DOI:10.1002/jor.1100040409

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

年代:1986

数据来源: WILEY

摘要:

AbstractA rabbit model for anterior cruciate ligament (ACL) reconstruction using autogenous avascular patellar tendon (PT) was utilized to study the early events of graft incorporation. Histological observations demonstrated that autografts were centrally acellular with a peripheral rim of cells at 2 weeks, a central focal proliferation of cells at 3 weeks, and a cellular homogeneous distribution by 4‐weeks postoperation. Graft necrosis followed by cellular proliferation suggested that a different population of cells other than the native PT fibroblasts may be inhabiting the graft. The extrinsic contribution of cells was studied by selective destruction of native PT cells with liquid nitrogen immersion prior to reconstruction of the ACL. The intrinsic contribution of cells was evaluated by sequestration of the PT graft in a semipermeable membrane before it was used to reconstruct the ACL. Histological analysis of tissue that was liquid N2treated, used as an autograft, and then harvested 3‐weeks post‐operation revealed fibroblastic incorporation of the graft. In contrast, no cells were observed in semipermeable membrane sequestered autografts. These data suggest that autogenous ACL autografts of PT origin are repopulated by cells of external origin. In vitro control studies that were carried out in parallel demonstrated that PT fibroblasts could survive in tissue culture, but not in the synovial environment of the ACL. This suggests that fibroblasts from different sources have different, tissue‐specific nutritional requi

ISSN:0736-0266    

DOI:10.1002/jor.1100040410

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

年代:1986

数据来源: WILEY