摘要:

AbstractImplantation of demineralized bone (DB) in the form of powder or intact segments in extra skeletal sites stimulates new bone formation. Urist and co‐workers presented substantial evidence that there is a noncollagenous protein that has the ability to induce bone formation. One aim of this study was to trace the process of bone formation when DB, in the form of perforated rectangular plates, is implanted subcutaneously in 2‐month‐old rats. A second objective was to determine whether cartilage cells play a role in the formation of bone in this model. Various DB plates with 0.25 mm diameter holes were implanted subcutaneously for 1–4 weeks in rats. One week after implantation, DB plates were covered by vascularized connective tissue that invaded the perforations. Aggregates of chondrocytes were observed within the holes and on periosteal surfaces in only a few specimens. Further cartilage proliferation was not observed, and by the 2nd week there was no evidence of endochondral bone formation. Where these cartilage‐like cells were present, a thin layer of mineral was deposited around them; resorption and fibrous tissue infiltration followed. This aborted form of endochondral calcification was not followed spatially by bone formation. Patent vascularized channels were invaded by alkaline phosphatase‐positive mononuclear cells and fibroblasts, and became enlarged by the enzymatic action of macrophages. The next step involved the calcification of DB plates adjacent to the wide spaces. Osteoclasts now appeared leading to the resorption of this recalcified matrix. The eroded and now enlarged lacunar surfaces were lined by newly formed bone and osteoblasts. This process continued so that, at the end of 4 weeks following implantation, the original DB plates were replaced by trabecular bone. Biochemical data on calcium and alkaline phosphatase levels in the implants paralleled the morphological o

ISSN:0736-0266    

DOI:10.1002/jor.1100070102

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to observe the process of ischemia in osteocytes using light and electron microscopy and to compare the changes in these ischemic osteocytes with those in other types of osteocytes (i.e., degenerative osteocytes in physiological states, steroid‐induced lipid‐accumulating osteocytes) that have been previously reported. Five female Japanese white rabbits were used in this study. Osteochondral chips were taken from one side of the femoral condyle, covered with Millipore filters, and then inserted into the other side of the knee joint. These tissues were examined after 12 h and after 2, 5, 8, and 14 days of ischemia under both light and electron microscopy. Under light microscopy, osteocytes and lacunae were classified into four types: normal osteocyte, pyknotic osteocyte, pale osteocyte, and empty osteocyte lacuna. The number of each type of osteocyte (or lacuna) in a settled area was counted. The ratio of normal osteocytes decreased significantly (p<0.001) after the second day of ischemia. Pyknotic osteocytes increased at 12 h (p<0.01) and 2 days (p40% of the cell types. When viewed by electron microscopy, these necrotic osteocytes were similar to the degenerative osteocytes that have been observed in physiological states and apparently different from lipid‐accumulating osteocytes. The results suggested that there could be at least two types of necrotic processes in osteocytes that eventually lead to cell

ISSN:0736-0266    

DOI:10.1002/jor.1100070103

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

年代:1989

数据来源: WILEY

摘要:

AbstractBone marrow cells (BMCs) from rabbit femora and tibiae were grown in diffusion chambers implanted in rabbit muscle. At 42 days 80% of the BMC chambers exhibited cartilage formation within them. Demineralized bone matrix added to the marrow cell suspension in the chamber accelerated the appearance and increased the number of chambers with cartilage. Mineralization of the cartilage also occurred earlier in the chambers with bone matrix. In a second experiment, a 5‐μA direct current cathode in the bone marrow chamber increased the number of chambers containing cartilage from 50 to 80% at day 25. Mineralization also occurred earlier in the chambers with direct curre

ISSN:0736-0266    

DOI:10.1002/jor.1100070104

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of indomethacin, a nonsteriodal antiinflammatory agent, on bone ingrowth were studied using a rabbit animal model and a porous cylindrical implant system. Bone ingrowth was found to be independent of pore size in the range tested (0.6–1.0 mm). In the control (placebo‐treated) group, there was a significant increase in bone ingrowth between the 2‐ and 8‐week groups of animals. However, in the indomethacin‐treated group, there was no increase in bone ingrowth

ISSN:0736-0266    

DOI:10.1002/jor.1100070105

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe have examined the effect of peptide growth factors on DNA and proteoglycan synthesis by adult bovine articular cartilage in organ culture. The actions of somatomedin‐C/insulin‐like growth factor I (Sm‐C/IGF‐I), insulin, epidermal growth factor (EGF), and fibroblast growth factor (FGF) from bovine pituitary were investigated individually and in combination. FGF stimulated a 10‐fold increase in tritiated thymidine incorporation while other factors used individually did not influence mitotic activity. Used in concert, insulin with EGF and insulin with FGF acted synergistically in stimulating DNA synthesis 20‐fold and 40‐fold, respectively. All of these growth factors, acting individually, significantly enhanced radiosulfate incorporation. This stimulation was additive for Sm‐C/IGF‐I in combination with EGF or FGF, but not with insulin. These data indicate that adult bovine articular chondrocytes possess the capacity to augment both mitotic and differentiated cell functions in response to growth factors. The data further suggest that, with the exception of insulin and Sm‐C/IGF‐I, which appear to share a common mechanism of action, these factors produce their cellular effects via different receptor or

ISSN:0736-0266    

DOI:10.1002/jor.1100070106

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe strain dependence of the intrinsic viscoelastic properties of the cartilage matrix in shear was investigated. Stress relaxation experiments were performed on bovine articular cartilage at shear strains ranging from approximately 3% to 16%. The tissue was found to exhibit nonlinear strain‐dependent viscoelastic behavior, with the nonlinearity occurring primarily in the short‐time transient during stress relaxation. In addition, the equilibrium stress was found to fit a quadratic relation with strain. This relationship was noted to be nearly linear with strain from 3% to 16%. The instantaneous stress was seen to be highly nonlinear, and followed a cubic relationship with applied shear strain. Fung's quasilinear theory can be used to describe the stress relaxation response over the range of strains examined when a nonlinear regression is performed to determine an “average” normalized relaxation function. Alternately, strain dependence can be incorporated into the model to describe and predict more accurately the strain‐dependent stress relaxation

ISSN:0736-0266    

DOI:10.1002/jor.1100070107

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

年代:1989

数据来源: WILEY

摘要:

AbstractDysprosium‐165–ferric hydroxide macroaggregates (165Dy‐FHMA) was used as an agent of radiation synovectomy in an antigen‐induced arthritis model in New Zealand white rabbits. Animals were killed up to 6 months after treatment.165Dy‐FHMA was found to have a potent but temporary antiinflammatory effect on synovium for up to 3 months after treatment. Treated knees also showed significant preservation of articular cartilage architecture and proteoglycan content compared with untreated controls, but only during the first 3 months after treatment. In animals killed 3 and 6 months after treatment there were only minimal differences between the treated and untreated knees, indicating that the antiinflammatory effects on synovial tissue and articular cartilage preservation were not

ISSN:0736-0266    

DOI:10.1002/jor.1100070108

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

年代:1989

数据来源: WILEY

摘要:

AbstractBlood flow rate in the periosteal and endosteal cortices of the diaphysis of long bones was determined in eight anesthetized adult dogs using the radioactively labeled microsphere method. The flow rate in endosteal and periosteal cortices is not significantly different unless the endosteal cortex contains cancellous bone from the medullary cavity. The highest flow rate is in the ulna, with 6.50 ml/min/100 g for the endosteal cortex and 5.15 ml/min/100 g for the periosteal cortex. The lowest flow rate is in the femur, with 2.89 ml/min/100 g for the endosteal cortex and 2.29 ml/min/100 g for the periosteal cortex. The results of this study indicate that variation of blood flow does exist between bones of dogs. However, the flow rates of individual bone on the left and right sides in the same dog are not significantly different. This indicates that the data are reproducible and reliable, and differences are not an inaccuracy of the radioactively labeled microsphere method. The results also demonstrate that there are no significant differences in bone blood flow as measured with small numbers (fewer than 400 microspheres per sample) and large numbers (more than 400 microspheres per sample) of microspheres. The adequate number of microspheres in each bone sample is 150–250. Therefore, a dose of 0.5 × 106spheres/kg body weight can be sufficie

ISSN:0736-0266    

DOI:10.1002/jor.1100070109

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

年代:1989

数据来源: WILEY

摘要:

AbstractMechanical properties of patellar tendon autografts used to replace the anterior cruciate ligament (ACL) in the cynomolgus monkey were measured at four time periods up to 1 year. The ACL was replaced in each knee with the medial half of the patellar tendon: as a vascularized graft (VG) on one side and as a nonvascularized or free graft (FG) on the other. Postoperative care consisted of 4 weeks of cast immobilization at 30° flexion followed by unrestricted activity in a large cage. Both grafts showed low stiffness and maximum force at 7 weeks (24% and 16% of ACL control values, respectively), increasing to 57% of control ACL stiffness and 39% of control maximum force by 1 year. Corresponding material properties, modulus and maximum stress, also increased over time, but at 1 year were only 34% and 26% of ACL values, respectively. The results indicate that retaining vascularity does not prevent significant reduction in graft properties that occur postoperatively, nor does it accelerate the return in strength and stiffness. Tissue stiffness, which returns earlier than maximum force and joint anteroposterior (AP) force displacement data, should be routinely reported in any healing study. Finally, in studies of this kind, the large variation in the results makes sampling only one or two animals from each time period unreliable

ISSN:0736-0266    

DOI:10.1002/jor.1100070110

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

年代:1989

数据来源: WILEY

摘要:

AbstractThis study describes the effect of active joint motion on the maintenance of ligament and meniscus mass in a non–weight‐bearing model of disuse. Denervation and fixation models of immobilization have shown that resorption of isotope and atrophy of mass occured for hard tissue (bone) and soft tissues (ligament, tendon, or meniscus). A unilateral ankle disarticulation model of disuse that maintains active knee motion without weight bearing was studied for 8 weeks in dogs that were chronically prelabeled with three different isotopes. The effects of non–weight‐bearing without denervation or fixation were analyzed for the resorption of isotopes, and net atrophy of bone mass (femur or tibia) and soft‐tissue mass (collateral or cruciate ligaments, menisci). A large and similar loss of all three isotopes, as well as collagen and calcium mass occurred for whole femur and tibia; this indicated that mass loss was equivalent to bone resorption and suggests little replacement with new bone. No loss of isotope or mass per whole tissue occurred for the collateral and cruciate ligaments or menisci. The strength of the femur–anterior cruciate ligament–tibia complex was analyzed by a tensile failure test when a fast rate of deformation was applied; the results did not differ qualitatively or quantitatively between control and experimental limbs. The absence of weight bearing for 8 weeks resulted in marked bone atrophy without resorption or atrophy of soft tissues, or decrease of the mechanical strength for the femurligament–tibia complex. With this model the amount of active joint motion remaining appears able to prevent ligament and meniscus atrophy even though marked bone atrophy occurred dur

ISSN:0736-0266    

DOI:10.1002/jor.1100070111

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

年代:1989

数据来源: WILEY