摘要:

AbstractThis study tested the effect of fluid‐induced shear on interleukin‐6 expression in normal human articular chondrocytesin vitro. As determined by Northern blot analysis, interleukin‐6 mRNA expression occurs in chondrocytes from osteoarthritic cartilage but not in normal chondrocytes. Applying fluid‐induced shear stress to primary high density cultures of chondrocytes increased interleukin‐6 mRNA signal 4‐fold at 1 hour and 10 to 15‐fold at 48 hours compared with unsheared control cultures. At 48 hours, fluid‐induced shear stress increased interleukin‐6 protein levels in the culture medium 9 to 10‐fold compared with unsheared controls, mRNA signals for interleukin‐1α, interleukin‐1β, and tumor necrosis factor‐α in RNA from sheared or control chondrocytes were not detected by Northern blotting. Transforming growth factor‐β mRNA signal was detectable but was not affected by shear. In contrast, human lung fibroblasts (WI‐38) responded to fluid‐induced shear with increased signal for transforming growth factor‐β but not interleukin‐6, mRNA. Both cell types did respond to interleukin‐1α with increased interleukin‐6 mRNA signal. These data demonstrate that distortional forces, such as fluid‐induced shear stress, alter interleukin‐6 levels in normal chondrocytesin vitroand suggest that increased interleukin‐6 expression in osteoarthritic cartilage may result, in part, from

ISSN:0736-0266    

DOI:10.1002/jor.1100140112

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

年代:1996

数据来源: WILEY

摘要:

AbstractTo examine the effect of alendronate (4‐amino‐1‐hydroxybutylidene bisphosphonate) on fracture repair, the drug was given to mature beagle dogs orogastrically at 2 mg/kg/day for 9 weeks preceding fracture, 16 weeks after fracture, or both before and after fracture (25 weeks). A transverse mid‐diaphyseal fracture of the right radius was surgically induced and was stabilized by external coaptation splinting. Fracture healing and bone remodeling were evaluated by radiography, gross and histological examination, and bone histomorphometry. The mechanical properties of the fracture callus were determined by a four‐point bending test. Radiographs and gross and microscopic examination demonstrated normal bone healing at the fracture site in all dogs. In dogs that received alendronate during the fracture healing period, at 16 weeks the calluses were approximately 2–3 times larger than those in dogs that received a placebo during the healing period. This is consistent with slower callus bone remodeling, an expected pharmacological effect of the compound. Bone histomorphometry demonstrated that treatment with alendronate did not inhibit bone formation or mineralization. Mechanical testing showed that the ultimate load at failure and the flexural rigidity of both the fractured and contralateral intact bone were unaffected by treatment with alendronate. Therefore, in this study, treatment with alendronate before or during fracture healing, or both, resulted in no adverse effects on the union, strength, or mineralization of bone in mature

ISSN:0736-0266    

DOI:10.1002/jor.1100140113

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

年代:1996

数据来源: WILEY

摘要:

AbstractA computerized motion sensor was used to record the three‐dimensional components of interfragmentary motion during healing in three patients with closed, low‐energy fractures of the tibial diaphysis treated with functional braces. At the first measurement session, 2 weeks after fracture, the patients applied approximately 15 kg to the injured limb. Although this produced 1–4 mm of translation of the fragments, this was recovered when the load was removed. The maximum rotational and angulatory displacements often occurred as the patients rose from the chair with no weight applied to the limb and frequently were reduced as the 15 kg of load was applied. Under load, the maximum axial rotation was 3° and the maximum angular displacement was 1°. As with the translations, the initial rotational and angulatory positions of the fragments were recovered when the load was removed and the patient returned to the seated position. At 8 weeks, the patient applied full body weight, producing a maximum interfragmentary translation of 0.5 mm and maximum axial rotation or angulation of 0.5°. Abundant peripheral callus formed in all three fractures, and they healed by 15 weeks through typical gradual consolidation and mineralization of the callus, accompanied by a corresponding reduction in interfragmentary

ISSN:0736-0266    

DOI:10.1002/jor.1100140114

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

年代:1996

数据来源: WILEY

摘要:

AbstractA rat model of a femoral segmental defect was used to specifically test the hypothesis that autogenous marrow has the osteogenic capability to heal a bone defect. The variables analyzed included the ratio of the marrow volume to the defect, implantation of live or dead marrow, and remodeling of established nonunions by implantation of live marrow. The uniqueness of this model allows biomechanical evaluation of the new bone formed by the implant. When live marrow was implanted, woven bone formed at 3 weeks, progressing to early lamellar bone at 6 weeks, with subsequent remodeling for as long as 12 weeks in a volumetric fashion (p<0.05). Bone marrow, when placed in a fresh femoral defect and given in sufficient amounts, produced a rate of union comparable with that of autologous bone grafts. Mature lamellar bone formed by marrow was evaluated biomechanically: the results were statistically comparable with those of cancellous bone grafts at 12 weeks. Significant bone formation occurred when marrow was percutaneously injected in femoral nonunions, although union and remodeling did not take place in this rat model. Implantation of dead marrow resulted in rare cellular infiltration and minimal bone formation in a manner comparable with that of autogenous cancellous bone grafts. These results indicate that bone marrow can lead to structurally functional bone regeneration in an orthotopic location.

ISSN:0736-0266    

DOI:10.1002/jor.1100140115

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

年代:1996

数据来源: WILEY

摘要:

AbstractDistraction osteogenesis and bone remodelling after the end of bone transport were investigated in one femur each of six adult male sheep. A newly designed internal distraction device was used. A custommade osteosynthesis plate was fixed on the lateral side of the femur, and two transporting plates driven by a transcutaneously inserted screwdriver moved two bone cylinders simultaneously over a 40 mm defect. An additional plate was applied ventrally to stabilize the device. Bone transport was begun 2 weeks postoperatively at 1 mm/day at each transporting plate until they came into contact. New bone formation within the distraction gaps was evaluated by computed tomography scans and was quantified at 4 and 6 months by dual energy x‐ray absorptiometry as well as histomorphometry on polyfluorochrome‐labelled undecalcified ground sections and microradiographs. At 4 months, all distraction gaps were bridged by abundant newly formed bone trabeculae, which were reduced and condensed to cortex‐like layers of new bone at 6 months. Less new bone was always found under the lateral device than in the unplated medial and dorsal segments, but the amount of new bone under the ventral plate was comparable with that in the unplated regions. The results of this pilot study show that distraction osteogenesis can be achieved with an internal device such as this one and that recorticalization and restoration of a medullary canal occur despite the relatively rigid internal stabilization by the p

ISSN:0736-0266    

DOI:10.1002/jor.1100140116

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

年代:1996

数据来源: WILEY

摘要:

AbstractGrowth of chondrocytes into a xenogeneic chondroepiphyseal matrix was investigated in anin vitroexperimental model by combining viable calf chondrocytes with chick epiphyseal matrix devoid of viable chondrocytes. The chondrocytes were harvested from the wrist joints of newborn calves and cultured for 2 days. The epiphyses were harvested from the distal femurs and the proximal tibias of fetal chicks after development was arrested at 17 days by freezing. The epiphyseal specimens were prepared in four ways. These included femoral and tibial epiphyses without holes and femoral and tibial epiphyses with holes made by a laser. These epiphyseal specimens were co‐cultured with calf chondrocytes for various periods. After digestion of the epiphyseal matrix, viable chondrocytes were counted in suspension. Chondrocyte division in the matrix was assessed by [3H]thymidine incorporation. The growth of calf chondrocytes into the xenogeneic chick matrix was evaluated by fluorescence microscopy on fresh thick epiphyseal sections. The percentage of viable chondrocytes in the xenogeneic epiphyseal matrix increased with culture time to a maximum at day 21. The addition of laser‐drilled holes was found to extend a plateau of chondrocyte viability until day 29. A decrease in cell viability was detected at later observation points. This study demonstrates that xenogeneic matrix may serve as a morphogenetic scaffold for chondrocytic gro

ISSN:0736-0266    

DOI:10.1002/jor.1100140117

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

年代:1996

数据来源: WILEY

摘要:

AbstractMassive cortical autografts and allografts have been found to incorporate into host bone very slowly and thus are subject to complications such as fatigue fracture and infection. In order to understand and improve the process of osteogenesis in these types of bone grafts, a new experimental model was developed using bone discs from rat calvaria prepared by demineralization and drilling of 0.5 mm diameter holes with a pulsed, 2.94 μm wavelength Erbium: Yttrium‐Aluminum‐Garnet laser. Four types of bone discs were analyzed: untreated (Type I), demineralized (Type II), laser‐ablated (Type III), and laser‐ablated then demineralized (Type IV). The discs were transplanted into a subcutaneous site in adult Sprague‐Dawley rats and followed for as long as 6 weeks. Histologic analysis of the discs at weekly intervals with use of hematoxylin and eosin staining confirmed the presence of new bone growth in Type‐II and Type‐IV discs. The amount of new bone growth in each disc was estimated by determining the mineral x‐ray attenuation coefficient, which is proportional to mineral density, from digitized radiographs of the discs. The results showed that the processes of demineralization (p<0.001) and laser ablation with demineralization (p<0.05) were both significant in enhancing new bone growth in this model. This study demonstrated that osteoinduction can be fostered in cortical bone through the processes of demineralization and laser ablation. To the extent that laser ablation may allow maintenance of structural integrity while altering the surface geometry in such a way as to promote ingrowth of new bone, this experimental model represents an advance in understanding how osteogenesis in cortical bone grafts m

ISSN:0736-0266    

DOI:10.1002/jor.1100140118

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

年代:1996

数据来源: WILEY

摘要:

AbstractIt is known that afferent neurons play a protective role in knees made unstable by transection of the anterior cruciate ligament. However, it is not known whether cutting the anterior cruciate ligament has an effect on the response of the sensory neurons that innervate the joint. In this study, the responsiveness (activation threshold and position sensitivity) of single, mechanically sensitive afferent neurons from the cat knee was evaluated by a series of extension, internal, and external rotations. The anterior cruciate ligament then was cut and the same procedure was repeated. Transection of the ligament increased joint laxity for all types of rotations. The responsiveness of the neurons was not changed significantly by cutting the ligament (p>0.05). Therefore, capsule afferents continue to behave normally in joints in which the anterior cruciate ligament has been transected.

ISSN:0736-0266    

DOI:10.1002/jor.1100140119

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

年代:1996

数据来源: WILEY

摘要:

AbstractTendon structure is governed largely by factors regulating the anabolic and catabolic phases of tenocyte metabolism. Little is known about the mechanisms that regulate the synthesis, activation, and action of metalloproteinases, which are key enzymes in a multifactorial cascade controlling homeostasis of the extracellular matrix. In the present study, we investigated the effect of tension on collagenase‐induced degradation of the tendonin vitroby assessing changes in structural and material properties measured during tensile failure tests. Devitalized right‐left pairs of rabbit patella‐patellar tendon‐tibia units were maintained under culture conditions in the presence of 60 U/ml highly purified collagenase for 20 hours. One randomly selected unit from each animal was subjected to a tension that produced a constant 4% elongation or strain (n = 10); the contralateral unit served as a slack comparison (n = 10). In one series of experiments (immediate, n = 5), the tension was applied immediately prior to collagenase exposure. In a second series (delayed, n = 5), it was delayed for 4 hours to allow time for the collagenase to diffuse into the tendon. Additional devitalized and nonincubated units (n = 6) were used as normal controls. Collagenase exposure caused large decreases in stiffness and elongation to failure in slack units. This resulted in greater than 80% reductions in both maximum failure force and energy to failure. In contrast, the loaded unit in both experimental protocols had significantly greater stiffness than control units. In both the immediate and the delayed protocols, the loaded tendons had significantly higher stiffness and failed at significantly higher elongations and maximum forces than the slack tendons. Diffusion studies with and without tension showed the tension did not inhibit diffusion of collagenase into the tendon but did significantly decrease the water content from 64.6 to 57.8%. The data suggest that stresses and strains of the extracellular matrix may modify the kinetics of the bacterial collagenase‐collagen interaction. Matrix stress and strain may be an important and overlooked factor that modulates the susceptibility of collagen to proteolytic de

ISSN:0736-0266    

DOI:10.1002/jor.1100140120

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

年代:1996

数据来源: WILEY

摘要:

AbstractNeuromuscular electrical stimulation and voluntary muscle contraction are two exercise modes widely used in rehabilitation to strengthen skeletal muscle. Since there is debate as to which mode is most effective, we compared electrical stimulation with voluntary contraction performed at matched intensities following reconstructive surgery of the anterior cruciate ligament. Forty men and women, aged 15–44, were randomly assigned to either an electrical stimulation or a voluntary contraction group. None of the subjects had a previous history of neuromuscular injury. The subjects received treatment for 30 minutes a day, 5 days a week, for 4 weeks. Knee extension torque was monitored during treatment to try to match the absolute muscular tensions (quantified as “activity”) achieved during therapy. To match the activity of the subjects in the electrical stimulation group, who were treated at the highest stimulation intensity they could tolerate, the subjects in the voluntary contraction group were paced at progressively increasing intensities corresponding to 15, 25, 35, and 45% of the injured limb's maximum voluntary torque during weeks 1, 2, 3, and 4, respectively. We found no significant difference between the groups in terms of maximum voluntary knee extension torque throughout the study period. In addition, 1 year after surgery, there was still no significant difference between groups with regard to knee extension torque (p>0.4). These data suggest that neuromuscular electrical stimulation and voluntary muscle contraction treatments, when performed at the same intensity, are equally effective in strengthening skeletal muscle that has been weakened by surgical repair of the anterior cruciate lig

ISSN:0736-0266    

DOI:10.1002/jor.1100140121

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

年代:1996

数据来源: WILEY