ISSN:0736-0266    

DOI:10.1002/jor.1100140302

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

年代:1996

数据来源: WILEY

摘要:

AbstractGrowth of bone into cementless prosthetic components is compromised after revision of failed joint prostheses and by osteoporosis, gaps, and micromotion. We studied the effects of recombinant human transforming growth factor‐β1 adsorbed on ceramic coated implants on the improvement of mechanical fixation and bone growth on the implant. Unloaded cylindrical grit‐blasted titanium alloy implants were inserted bilaterally into both the medial and lateral femoral condyles of 10 skeletally mature mongrel dogs. The implants measured 10 mm in length and 6 mm in diameter and were initially surrounded by a 2 mm gap. One implant had an uncoated titanium surface and three implants were coated with tricalcium phosphate and 0, 0.3, or 3.0 μg of recombinant human transforming growth factor‐β1. The dogs were killed at 6 weeks. Mechanical testing showed a 3‐fold increase in fixation for the 0.3 μg dose of recombinant human transforming growth factor‐β1 and a 2‐fold increase for the 3.0 μg dose. Histological analysis of bone growth on the implant demonstrated that maximal stimulation occurred with the 0.3 μg dose, but bone volume in the gap was maximally stimulated by the 3.0 μg dose and increased 2‐fold over control values. The majority of tricalcium phosphate was resorbed after the 6‐week observation period. This study suggests that recombinant human transforming growth factor‐β1 adsorbed onto implants coated with tricalcium phosphate ceramic can enhance mechanical fixation and bone growth on the implant. The use of transforming growth factor‐β1 on ceramic coated prosthetic components may help to improve the functional outcome of cement

ISSN:0736-0266    

DOI:10.1002/jor.1100140303

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

年代:1996

数据来源: WILEY

摘要:

AbstractThree porous ceramic bone graft materials were compared with regard to their ability to heal a 2.5 cm defect created surgically in a bilateral canine radius model. The ceramic materials were analyzed at 12 and 24 weeks after surgery and included tricalcium phosphate, hydroxyapatite, and collagen hydroxyapatite, which contained a mixture of 35% tricalcium phosphate and 65% hydroxyapatite with added collagen. Each material was evaluated alone and with added bone marrow aspirate. All the implants were compared with a graft of autogenous cancellous bone in the contralateral radius. Biomechanical testing and radiographic evauation revealed that the addition of bone marrow aspirate was essential for tricalcium phosphate and hydroxyapatite to achieve results comparable with those of cancellous bone. Collagen hydroxyapatite performed well without the addition of bone marrow, although the addition of marrow did have a positive effect. Further qualitative radiographic and histological analysis demonstrated that tricalcium phosphate was the only ceramic that showed any sign of degradation at 24 weeks. This observed degradation proved to be an important factor in evaluating radiographs because the radiodensity of collagen hydroxyapatite and hydroxyapatite interfered with the determination of radiographic union. At 24 weeks, tricalcium phosphate with bone marrow was the material that performed most like cancellous bone. In this study, the biomechanical and radiographic parameters of tricalcium phosphate with bone marrow were roughly comparable with those of cancellous bone at 12 and 24 weeks. Tricalcium phosphate was the only implant that showed significant evidence of degradation at 24 weeks by both histological and radiographic evaluations, and this degradation took place only after a degree of mechanical competence necessary for weight‐bearing was achieve

ISSN:0736-0266    

DOI:10.1002/jor.1100140304

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

年代:1996

数据来源: WILEY

摘要:

AbstractTendon healing and integration of tendon grafts may be site or donor specific. To determine if differences exist in sensitivity to growth factors that have the potential to influence tendon repair, we compared the effects of recombinant human insulin‐like growth factor‐I on various types of tendon segments. The dose response effects on proteoglycan, collagen, noncollagen protein, and DNA synthesis were investigated in short‐term explant cultures of intrasynovial intermediate and proximal segments of deep flexor tendons, extrasynovial segments of deep flexor tendons, and Achilles tendons of rabbits. The four different types of tendon segments cultured in media without recombinant human insulin‐like growth factor‐I synthesized similar amounts of each of the matrix components. Intrasynovial proximal segments synthesized 15 times less DNA than other tendon segments. Recombinant human insulin‐like growth factor‐I stimulated matrix and DNA synthesis of all tendon segments in a dose‐dependent manner in intervals from 10 to 1,000 ng/ml. The potency (LogED50) of the stimulation did not differ between the segments. The estimated maximal stimulation (Emax) of proteoglycan synthesis by recombinant human insulin‐like growth factor‐I was higher, and of collagen and noncollagen protein synthesis was lower, in intrasynovial proximal segments as compared with that of the other types of segments. In contrast, the estimated maximal stimulation of DNA synthesis by recombinant human insulin‐like growth factor‐I was 6‐fold higher than controls in all types of tendons. These findings demonstrate differences in mitotic capacity between anatomical regions of tendons during culture without recombinant human insulin‐like growth factor‐I and in matrix synthe

ISSN:0736-0266    

DOI:10.1002/jor.1100140305

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

年代:1996

数据来源: WILEY

摘要:

AbstractA rabbit model was used to discover whether the effects of stress shielding on the mechanical properties of the patellar tendon depend on the degree of stress reduction. Ninety mature female Japanese White rabbits were divided into three groups: completely stress‐shielded, partially stress‐shielded, and shamoperation and contralateral controls. In the experimental groups, tension applied to the patellar tendon was 0%, approximately 30%, and 100%, of the normal tension, respectively, with a polyester artificial ligament. Tensile tests were carried out on patella‐patellar tendon‐tibia complexes harvested 1, 2, 3, 6, or 12 weeks after surgery. The tensile strength decreased in comparison with the sham‐operation group to 50.2, 13.5, 9.7, and 20.7% in the completely stress‐shielded group and to 75.2, 57.6, 59.6, 57.3, and 72.9% in the partially stress‐shielded group. The tensile strength in the completely stress‐shielded group was significantly less than that in the partially stress‐shielded group at 1, 2, 3, and 6 weeks. The cross‐sectional area of the patellar tendon significantly increased to 132, 206, 237, and 136% in the completely stress‐shielded group and to 136, 170, 175, 155, and 127% in the partially stress‐shielded group, compared with the sham‐operation group. The cross‐sectional area of the completely stress‐shielded tendon was significantly larger than that of the partially stress‐shielded tendon at 1, 2, and 3 weeks. This study demonstrated that effects of stress shielding on the mechanical properties of the patellar tendon were dependent on

ISSN:0736-0266    

DOI:10.1002/jor.1100140306

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

年代:1996

数据来源: WILEY

摘要:

AbstractWhether the central core of an anterior cruciate ligament autograft reconstruction is nutritionally compromised at a time when revascularization is known to be complete has not been determined by methods that detect matrix synthesis. In a canine model of anterior cruciate ligament reconstruction with patellar tendon autograft, the adequacy of the supply of metabolites for cellular matrix synthesis was determined by autoradiographic analysis. Total collagen synthesis and cellularity were also quantified. Total collagen synthesis was found to be significantly elevated (p = 0.014 by analysis of variance) in the ligament reconstructions as compared with normal anterior cruciate ligaments or patellar tendons, but cellularity was not (p = 0.13 by analysis of variance). Autoradiography demonstrated even distribution of [3H]proline incorporation throughout the graft and normal tissue. When revascularization was complete, there was an adequate supply of metabolites for cellular synthesis of protein macromolecules within all regions of the ligament reconstruction. At 3 months after reconstruction, the grafts were found to be actively remodeling their collagen matrix. Since the long‐term function of an anterior cruciate ligament autograft is dependent on viable fibroblasts to maintain the collagen matrix, the canine anterior cruciate ligament reconstruction contains living cells that are able to remodel the matrix under appropriate condition

ISSN:0736-0266    

DOI:10.1002/jor.1100140307

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe clinical success of limb replantation and tissue transfer is partly dependent on the duration of ischemia experienced by the amputated part. This study focused primarily on the damage that occurs during this ischemic period. An experimental system was implemented that allowed the observation of contractile function in totally isolated skeletal muscle after ischemia. Contractile function was selected as an indicator of ischemic damage because normal function is the ultimate goal of replantation. All experiments were performed on the rat extensor digitorum longus. The muscles were subjected to ischemic periods of 1.5, 3.0, and 5.0 hours and were stored in either a hypothermic (4°C) or a room‐temperature (23°C) environment during the ischemic interval. After the ischemic period, all muscles were transferred to a tissue bath and were subjected to contractility testing, followed by fatigue testing. In both groups, muscle function decreased as the ischemic interval was increased. A significant difference in function between the normal control and the muscles of both ischemic group implied that ischemic injury had occurred in the hypothermic and room‐temperature muscles, even with the relatively short 1.5‐hour ischemic interval. After each ischemic interval, however, the hypothermic muscles produced significantly greater contractile force than the room‐temperature muscles in both the contractility and the fatigue tests. After 1.5 hours of ischemia, the contractile force in the hypothenic group was about three times as great as that observed in the room‐temperature group. These results indicated that muscle function after a period of totally isolated ischemia is protected by hypothermic preservation. They also support the advisability of storage of amputated parts and free muscle flaps in hypothermic environments before replantation, even after relatively brief intervals

ISSN:0736-0266    

DOI:10.1002/jor.1100140308

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe cellular mechanism through which osseous breast cancer metastases induce the focal destruction of bone (tumor osteolysis) is unknown. An athymic mouse model designed for the study of tumor osteolysis was developed and the influence of two human breast cancer tumors on bone was studied. Tumor‐induced osteolysis occurred between 7 and 10 weeks after inoculation of mouse femora with MDA‐MB‐231 or MDA‐MB‐435s breast cancer cells. An increase in osteoclast number and an increase in osteoclast size (area) were detected when tumor‐bearing and sham‐injected limbs were compared.In vitroanalysis of the influence of the tumor‐conditioned medium on osteoclast‐mediated bone resorption revealed that this conditioned medium stimulated the resorption by increasing both the number of osteoclasts bound to bone and the number of bone resorption pits formed per osteoclast. In addition,in vitroanalysis of the influence of breast cancer tumor cells on osteoclast formation or survival, or both, demonstrated that breast cancer cells induced a dramatic increase in the number of osteoclasts detected in culture. Taken in total, these findings suggest that human breast cancer tumors induce osteolysis by enhancing osteoclast adherence to bone, stimulating osteoclast‐mediated bone resorption, and either prolonging the survival of osteoclasts or increasing o

ISSN:0736-0266    

DOI:10.1002/jor.1100140309

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe development of cartilaginous elements of long bone during embryogenesis and postnatal bone repair processes is a complex process that involves skeletal cells and surrounding mesenchymal periosteal cells. Relatively little is known of the mechanisms underlying these processes. Previous studies from this and other laboratories have suggested that the extracellular matrix protein tenascin‐C is involved in skeletogenesis. Usingin situhybridization and immunofluorescence, we extended those studies by comparing the expression of tenascin‐C with that of syndecan‐3, which belongs to a family of cell surface receptors with which tenascins are known to interact. We found that syndecan‐3 transcripts at first were very abundant in the presumptive periosteum surrounding the diaphysis of early chondrocytic skeletal elements in chick limb. As the elements developed further syndecan‐3 gene expression decreased in the diaphyseal periosteum, whereas it became stronger around the early epiphysis and within the forming articular cells. However, as the diaphyseal periosteum initiated osteogenesis and gave rise to the intramembranous bone collar, syndecan‐3 gene expression increased again. At early stages of skeletogenesis, the tenascin‐C gene exhibited patterns of expression that were similar to, and temporally followed, those of the syndecan‐3 gene. At later stages, however, tenascin‐C gene expression was markedly reduced during intramembranous osteogenesis around the diaphysis. In addition, although syndecan‐3 gene expression was low in osteoblasts and osteocytes located deep into trabecular bone, tenascin‐C gene expression remained strong. Thus, tenascin‐C and syndecan‐3 display distinct temporal and spatial patterns of expression in periosteum and during the development of long bone. Given their multidomain structure and specific patterns of expression, these macromolecules may regulate site‐specific skeletal processes, including interactions between developing periosteum and chondrocytes and delineation of the early cart

ISSN:0736-0266    

DOI:10.1002/jor.1100140310

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

年代:1996

数据来源: WILEY

摘要:

AbstractFluorescent staining techniques were used in combination with confocal and conventional fluorescent microscopy to determine the location of viable chondrocytes in frozen and thawed osteochondral articular cartilage. The results showed that cell survival was confined to the superficial layer of the cartilage matrix. The addition of a cryopreservative agent (dimethyl sulfoxide) increased chondrocyte survival but only in the same layer. There was no evidence of cell survival in the middle or deep layers of the cartilage with or without the use of dimethyl sulfoxide. Under the conditions employed in this study, chondrocyte survival in a cryopreserved osteochondral allograft appears to be limited to the superficial layer of the articula cartilage.

ISSN:0736-0266    

DOI:10.1002/jor.1100140311

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

年代:1996

数据来源: WILEY