摘要:

AbstractA lipid material extracted from the omentum has previously been shown to contain a potent angiogenetic activator (20), capable of creating intense vasoproliferation in traumatized tissues (19). This study was undertaken to analyze the efficacy of local administration of this omental lipid fraction on osseous vascularization and bone repair. An osteoperiosteal segmental femoral defect in the rat was replaced by a demineralized allogenic bone graft exposed to continuous local delivery of omental lipid via an implanted miniosmotic pump. Saline solution delivered in the same way served as a control. Neovascularization and bone formation in the transplant were quantitatively evaluated by means of dynamic radioisotopic bone imaging, radiographic photodensitometry, microangiography, and biomechanical testing. Compared with the control group, the omental lipid angiogenic fraction–treated specimens showed an 80% overall increase (p<0.001) in bone density as well as a twofold increase (p<0.001) in regional blood perfusion, maximal at 2 weeks following surgery. At 12 weeks, biomechanical testing demonstrated significantly higher union rate (p<0.05) and strength (p<0.01) in the treated specimens as compared with the controls. These data demonstrate that the omental lipid fraction factor has potent angiogenic properties that enhance bone blood perfusion and bone regeneratio

ISSN:0736-0266    

DOI:10.1002/jor.1100070202

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe internal fixation of diaphyseal fractures by bone plates is a well recognized treatment. The normal physiological stress of bone is reduced by plates that cause a negative balance of bone‐remodeling processes. Many investigators have shown that the degree of stress protection is dependent on the rigidity of the plates. It was the aim of this study to quantify mechanical and morphological changes at different locations in a plated diaphyseal bone as a function of differing plate rigidity. Two types of plates with the same size but different materials were used. The stainless steel plates had a modulus of elasticity and bending stiffness 3.2 times higher than the carbon fiber reinforced carbon plates. Both types of plates were applied to the intact right and left femora of six foxhounds for 6 months. The stiffer stainless steel plates led to a significantly higher bone loss and correspondingly greater loss of mechanical properties. These effects were greatest directly beneath the plate and less with increasing distance from the plat

ISSN:0736-0266    

DOI:10.1002/jor.1100070203

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of a single dose of irradiation on the biomechanical parameters of the fracture healing process were studied in a rat model. Intramedullary pinning was performed before production of a closed femoral midshaft fracture. The experimental group was exposed to 900 rad 3 days after fracture and was compared with a control group with a similar fracture that received no irradiation. Animals were killed at intervals ranging from 2–16 weeks after surgery and the bones were tested until failure in torsion. In the irradiated groups, a delay of 4 weeks was noted in the biomechanical parameters associated with fracture healing (torque to failure, torsional stiffness, angle to failure, and biomechanical stage). Despite this delay in the normal temporal progression, the staging and stiffness approached normal controls within an 8‐week period. However, the torque to failure remained below normal levels at the conclusion of this study. These results differ from a previous study using an open fracture mo

ISSN:0736-0266    

DOI:10.1002/jor.1100070204

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

年代:1989

数据来源: WILEY

摘要:

AbstractEpiphyseal distraction of the left distal femur was accomplished in 18 chondrodystrophic dogs (age 19–22 weeks). A distraction rate of 0.5 mm/day was applied by means of a unilateral device. Epiphysiolysis occurred after 4 to 9 days. Lengthening was continued for 3 weeks. The animals were killed at 3 (Group 1; n = 5), 19 (Group 2; n = 10), and 71 (Group 3; n = 3) weeks after the end of distraction to verify the magnitude of elongation at removal of the device (Group 1) and at the time of growth cessation (Groups 2 and 3), and to register possible permanent secondary joint changes (Group 3). The average lengthening of 1.2 cm (12.3%) at removal of the device was reduced to 0.7 cm (6.4%) at cessation of growth. The middiaphyseal diameter of the elongated femur was enlarged after the lengthening procedure in all animals. The average torsional strength of the elongated femur compared with the contralateral control was 83% in Group 1, 98% in Group 2, and 107% in Group 3. Degenerative changes were observed in the knee joints of three animals in each group. A two‐way analysis of variance was applied for all data sets to test differences between control and elongated bones and between time periods. The reduction in gained length by retardation of residual growth in the distal femur was significant (p<0.05). The difference in external diameter between lengthened and control bones was significant in Groups 1 and 3 (p<0.05). We conclude that early onset of bilateral lengthening by epiphyseal distraction in chondrodystrophic bone required in successive treatment of bone segments may result in significant loss of gained length due to reduction of residual growth. The observed degenerative changes in the knee joint are a sequela that calls into question the use of the method in the fe

ISSN:0736-0266    

DOI:10.1002/jor.1100070205

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

年代:1989

数据来源: WILEY

摘要:

AbstractA lower incidence of hip fracture in black women has been reported by several studies. The most frequently proposed explanations for this phenomenon have included a genetically greater bone mass, better preservation of bone due to the fact that certain populations of black women perform more physical labor, and the impact of other unidentified environmental and/or life‐style factors. This retrospective study demonstrates that low body weight is as significant a risk factor for hip fracture in black women as it is in white women. Coupled with the known higher prevalence of obesity in the older black female population, the findings of this study suggest that differences in body weight may be a significant and possibly sufficient explanation for the lower incidence of hip fracture in black wome

ISSN:0736-0266    

DOI:10.1002/jor.1100070206

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe report effects of adding insulin‐like growth factor I (IGF‐I) and methionyl human growth hormone (GH), alone or in combination, to adult bovine articular chondrocytes plated at high density. Purified human and synthetic IGF‐I stimulated chondrocyte DNA and proteoglycan synthesis. GH had no effect on either process. However, GH added in combination with IGF‐I increased proteoglycan, cell‐associated proteoglycan, and keratan sulfate synthesis over levels observed with IGF‐I alone. IGF‐I and GH did not alter the hydrodynamic size of proteoglycans or synthesis of collagen. Our results show that GH and IGF‐I act together to stimulate adult chondrocyte extracellular m

ISSN:0736-0266    

DOI:10.1002/jor.1100070207

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

年代:1989

数据来源: WILEY

摘要:

AbstractUsing the knee joints of New Zealand White rabbits, a baseline study was made to determine the intrinsic capability of cartilage for healing defects that do not fracture the subchondral plate. A second experiment examined the effect of autologous chondrocytes grown in vitro on the healing rate of these defects. To determine whether any of the reconstituted cartilage resulted from the chondrocyte graft, a third experiment was conducted involving grafts with chondrocytes that had been labeled prior to grafting with a nuclear tracer. Results were evaluated using both qualitative and quantitative light microscopy. Macroscopic results from grafted specimens displayed a marked decrease in synovitis and other degenerative changes. In defects that had received transplants, a significant amount of cartilage was reconstituted (82%) compared to ungrafted controls (18%). Autoradiography on reconstituted cartilage showed that there were labeled cells incorporated into the repair matrix.

ISSN:0736-0266    

DOI:10.1002/jor.1100070208

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

年代:1989

数据来源: WILEY

摘要:

AbstractFibrocartilaginous regions of bovine deep flexor tendon were treated with chondroitinase‐ABC and trypsin in order to extract proteoglycans from the extracellular matrix and thereby investigate the contribution of proteoglycan and collagen organization to tissue material properties. Chondroitinase‐ABC digestion of tendon specimens for 24 h resulted in extraction of 60% of tissue glycosaminoglycan and leaching of the degraded large proteoglycan from the tissue residue. The totally degraded core protein of the small dermatan sulfate proteoglycan remained with the tissue residue, indicating that it is specifically associated with the tissue residue and that this association is not dependent on the glycosaminoglycan chains. Treatment of residues with trypsin after chondroitinase‐ABC digestion depleted the specimens of proteoglycan. Bulk swelling tests on enzyme‐extracted specimens showed that the distinct swelling properties of the fibrocartilaginous regions of the distal flexor tendon could be partially accounted for by elevated levels of proteoglycan. Swelling tests also showed that the distinct collagen organization of this region contributes significantly to the tissue's material properties. These results suggest that the fibrocartilaginous organization and composition of the articulating layer of distal tendon are adapted for mechanical requirements unique to this site, which receives compressive and frictional loads in addition to tensil

ISSN:0736-0266    

DOI:10.1002/jor.1100070209

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

年代:1989

数据来源: WILEY

摘要:

AbstractTendon repair following trauma, rupture, or surgery involves both synthesis and degradation of collagen in order to reweave new collagen bundles in with the old. Using an in situ assay on polyacrylamide gels containing gelatin, we have identified protease activity from tendon tissue and from tendon cells in culture. A population of synovial cells from the epitenon surrounding the tendon as well as the tendon fibroblasts themselves were examined. The cells and the conditioned medium from both cell populations exhibited a major band of gelatin‐degrading activity at 70 kdaltons and a minor band of activity at 60 kdaltons. When preparations were reacted withp‐aminophenylmercuric acetate (APMA) before electrophoresis, a third band appeared at 63 kdaltons. The main band at 70 kdaltons comigrated with a [35S]methionine‐radiolabeled protein band. Inhibitor and pH studies identified the enzymes as neutral metalloproteases requiring disulfide bonds for activity. No proteolytic activity was detected on casein‐containing gels, ruling out the presence of stromelysin. Since electrophoresis in the presence of SDS would separate the metalloprotease from the smaller molecular weight inhibitor (TIMP), these in situ assays provide a sensitive screening system for gelatindegrading enzymes present in tendon without prior removal

ISSN:0736-0266    

DOI:10.1002/jor.1100070210

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

年代:1989

数据来源: WILEY

摘要:

AbstractA rabbit model for anterior cruciate ligament (ACL) reconstruction using autogenous patellar tendon was utilized to study the early events of autograft cellular dynamics. Biochemical, autoradiographic, histological, and vascular injection techniques demostrated that the native autograft cell population rapidly necroses. This repopulation occurs without a vascular contribution; cells entering the autograft are reliant upon synovial fluid nutrition.

ISSN:0736-0266    

DOI:10.1002/jor.1100070211

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

年代:1989

数据来源: WILEY