摘要:

AbstractPreoperative antibiotics are an important measure taken to prevent infection in joint replacement surgery. The local availability of these antibiotics in the operative site is absolutely necessary to ensure adequate prophylaxis against contaminant bacteria. Because pulsatile‐lavage rapid‐recovery systems have become a routine technique of bone preparation in joint reconstruction, we chose to study the effect of these systems on local antibiotic concentrations. We further investigated the effect of irrigation with and without use of a limb tourniquet. For our study, we obtained 23 bone specimens in 16 patients undergoing joint reconstruction (14) or amputation (2). The patients were classified into one of four groups based on whether a tourniquet was applied during the procedure and whether the bone specimens were irrigated. In addition, matched blood samples were obtained to establish that therapeutic serum levels were achieved. Nine patients contributed 13 bone specimens, which underwent vigorous irrigation in vitro. None of these specimens had detectable levels of antibiotics, regardless of whether a tourniquet was used. Seven patients yielded 10 bone specimens, which were not irrigated. Five of these seven patients had detectable levels of antibiotics. In addition, the specimens from limbs without tourniquets had levels that averaged 0.51 μg/ml while those with tourniquets averaged below 0.2 μg/ml. Therefore, the use of vigorous irrigation in bone preparation has a significant deleterious effect on the local presence of previously administered systemic antibiotics. This effect is compounded if the operative site is isolated from continuous blood flow by use of a tourniquet. We therefore recommend that additional measures be taken to ensure that adequate antibiotic levels are present. Two methods that may have efficacy are application of antibiotic‐containing irrigants or antibiotic‐impregnated polymethylmet

ISSN:0736-0266    

DOI:10.1002/jor.1100060302

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe long‐term effects of experimentally induced diabetes on bone were studied in eight male Lewis rats, intravenously (i.v.) injected with 65 mg/kg of streptozocin (STZ) and maintained for 12 months. Eight untreated age‐matched rats served as controls. In the STZ‐treated rats, experimentally induced diabetes was documented by the presence of hyperglycemia at 24 h and at 3 and 12 months. Significantly less weight was gained and less growth occurred in the STZ‐treated rats despite careful attention to feeding and hydration. Mineral alterations were detected in the bones of the animals with experimental diabetes. Decreased hydroxyapatite crystal perfection, decreased Ca/P of the ash, and decreased ash content in the tibial metaphyses with increased ash content in the tibial diaphyses, was noted relative to controls. Bone osteocalcin content was increased in the metaphyses of the STZ‐treated rats. While absolute measures of stiffness, torsional strength and energy absorption were decreased in the bones of the STZ‐treated animals, when torsional strength and stiffness were normalized for differences in both growth and geometry, the normalized stiffness values for the diabetic bones were increased. The results suggest that in experimental diabetes certain aspects of bone mineralization are adversely affected and lead to reduced strength‐related properties. However, a compensatory increase in stiffness occurs. The reason for this increase, although not known, may be related to changes in bone crys

ISSN:0736-0266    

DOI:10.1002/jor.1100060303

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

年代:1988

数据来源: WILEY

摘要:

AbstractSubcutaneous (S.C.) implantation of allogeneic demineralized bone matrix in rats results in endochondral bone formation. In contrast, implants of bovine demineralized bone matrix in rat S.C. tissue show inconsistent cartilage and bone formation, presumably due to an intense inflammatory reaction at the implant site. To overcome this response, a partially purified bone inducing extract was prepared from bovine bone by a series of steps that included demineralization, guanidine/HCI extraction, gel filtration, and cation exchange chromatography. To develop a carrier, the inactive guanidine/HCI‐extracted matrix was then trypsinized to remove the inflammatory and immunogenic components, thus yielding a predominantly collagenous matrix. Bovine composites were prepared by combining different amounts of the bone inducing extract with a carrier that consisted of the trypsinized bone matrix and purified soluble bovine dermal collagen. Subcutaneous implantation of the composite preparation resulted in dose‐dependent endochondral bone formation in rats. The inductive activity and the low‐level inflammatory response were comparable to allogeneic imp

ISSN:0736-0266    

DOI:10.1002/jor.1100060304

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis study was designed to determine whether changes occur in the bioelectric potentials on bone during and after bone stimulation with a 20‐μA direct current (DC) and whether the variations in bioelectric potentials are related to the variations in bone formation. The bioelectric potentials were recorded at different times on the rabbit distal tibial surface, during (current‐on state) and after (current‐off state) DC stimulation with a cathode implanted within the medullary canal. The new bone formed at the end of the experiment was quantitated and related to the bioelectric potentials recorded at current‐on and current‐off states, respectively. Direct current stimulation resulted in electronegative potential spike centered on the cathode tip while current was applied. After electrical stimulation was turned off, the residual potentials at the end of the experiment did not significantly differ from the initial values. Conversely, the time sequence of the changes was significantly different from the control to the experimental group. The variations in the induced potentials at current‐on state were significantly related to the variations in bone formation. This study suggests the existence of a relationship among bioelectric potentials, DC stimulation, and

ISSN:0736-0266    

DOI:10.1002/jor.1100060305

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

年代:1988

数据来源: WILEY

摘要:

AbstractDirect streaming experiments with no significant mechanical deformation have been performed to determine the constituent or constituents of bovine tibia mainly responsible for the production of streaming potentials. Following the approach of Frank and Grodzinsky (5), selective removal of either main constituent—collagen or hydroxyapatite—of the tissue was performed by chemical means, and the streaming potential was remeasured. Demineralized samples were prepared by soaking in formic acid/sodium citrate, and anorganic samples were prepared by boiling and also by sodium hypochlorite treatment. Demineralized samples demonstrated ζ potentials close to those of whole bone samples, whereas anorganic samples had much smaller ζ potentials. Collagen rather than hydroxyapatite mineral is therefore implicated as the constituent of whole bone dominating the streaming potential, in agreement with the observation that collagenous tissues containing no mineral phase, i.e., tendon and cartilage, also exhibit streaming potentials. No sign change was observed in whole bone at high NaCI concentration in solutions containing calcium or at low pH. Although the sign of the signal for anorganic bone could be reversed by the addition of Ca2+or PO43+to the test solutions, the sign of the signal in neither whole bone nor demineralized bone could be so affected. Sign changes in whole bone were observed only with solutions containing basic organic molecules, e.g., protamine sulp

ISSN:0736-0266    

DOI:10.1002/jor.1100060306

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

年代:1988

数据来源: WILEY

摘要:

AbstractLow‐rate epiphyseal distraction of the left proximal tibia using a modified bilateral Hoffmann external fixation device, was accomplished in 14 goats (age 6–7 months). Daily distraction at a rate of 0.5 mm was continued for 5.5 weeks. Epiphysiolysis occurred after 5–9 days. After distraction had been discontinued, the external device was left in situ for fixation for 4 weeks. The animals in group 1 (n = 5), group 2 (n = 3), and group 3 (n = 5) were killed at 4, 16, and 32 weeks, respectively, from the end of the distraction period. The proximal growth plate of the elongated tibia appeared radiolucent at the conclusion of the study but was less distinct and reduced in height as compared with the control leg. The gained length at the end of the distraction period was on the average 2.2 cm (11.9%). This gain in length was reduced with further growth. In group 3, the final gain in length was reduced to half. A reduced cortical thickness of the bone within the area subjected to distractional force was observed. This finding is attributable to stress protection. An interesting observation comparing control and operated tibia was an increase of the cross‐sectional diameter of the elongated bone. Both tibiae of all animals were tested mechanically. The torsional strength of the elongated tibiae as compared with controls was on the average 29% in group 1, 79% in group 2, and 95% in group 3. We conclude that leg lengthening by low‐rate epiphyseal distraction in the proximal tibia is a justifiable alternative to other lengthening procedures in individuals approaching adolescence. In juveniles, lengthening by epiphyseal distraction may result in reduction in the longitudin

ISSN:0736-0266    

DOI:10.1002/jor.1100060307

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe purpose of this investigation was to measure the reduction in bone strength resulting from drill holes in diaphyseal bone and to compare this with finite element and theoretical predictions for stresses in a tubular structure. Fifty‐two pairs of canine femora were tested to failure in four‐point bending. One bone of each pair was used as the control; the other femora had holes of variable size drilled in the lateral cortex. At a ratio of drill hole diameter to bone diameter of 0.2, the bone retained only 62% of its expected strength. A linear regression between the area fraction (the ratio of the cross‐sectional area of the drilled specimen to the control specimen) and the percentage of expected strength yielded a strong positive correlation (R2= 0.79). The average cross sectional properties were used as the basis for linear orthotropic and nonlinear elastic‐plastic finite element models of idealized geometry. The linear models proved insuifficient for prediction of failure loads. The nonlinear models, which accounted for both material plasticity and the stress concentration effects of the defect, yielded good correspondence with the experimental data. While the influence of irregular borders and adaptive remodeling of the bone adjacent to the defect requires further investigation, our results suggest the possibility of prediction of fracture risk based on geometric properties of metastatic lesions. Prophylactic fixation remains a matter of clinical judgement based on the functional demands and expected strength of the affecte

ISSN:0736-0266    

DOI:10.1002/jor.1100060308

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe aim of this study was to analyze the mechanisms by which neutral metalloproteoglycanases (NMPE) degrade proteoglycans (PGs) in the cartilage of an experimental model of osteoarthritis (OA). We demonstrated that chondrocytes in osteoarthritic cartilage synthesize PGs with the same functional characteristics as those found in normal cartilage. Osteoarthritic cartilage contains NMPE in both active and latent forms. Both forms can degrade newly synthesized and endogenous PG macromolecules, as indicated by the reduced hydrodynamic size found in the two PG populations of osteoarthritic cartilage. PG monomers, derived from the included fraction of Sepharose CL2B chromatography, were unable to form aggregates with hyaluronic acid. Reduction and alkylation showed that PG monomers from osteoarthritic cartilage had a small hydrodynamic size, especially after activation with aminophenylmercuric acetate. No significant differences were observed in the size of the chondroitin sulfate chain when normal cartilage was compared with its osteoarthritic equivalent. These results suggest that the proteolytic degradation of cartilage matrix PGs by NMPE occurs at both the hyaluronate‐binding region and at the chondroitin sulfate‐rich region of the core prot

ISSN:0736-0266    

DOI:10.1002/jor.1100060309

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis study details the macromolecular changes in cartilage involving proteoglycan molecules in an animal model of rheumatoid arthritis. In experimental chronic immune synovitis, fluorescein‐conjugated mouse IgG and three monoclonal antibodies (MAbs 2G2, 2E9, and 6C9) portraying differing fine antigenic specificity for rabbit cartilage proteoglycan monomer were utilized to detail alterations in cartilage proteoglycan. In normal and IgG immune animals, fluorescein isothiocynate (FITC)‐conjugated MAbs 2G2 and 2E9 stained cellular/pericellular (C/PC) region intensely. FITC‐MAb 2G2 stained cartilage interterritorial matrix as well. FITC‐MAb 6C9 stained only C/PC area lightly but did not stain matrix. A marked decrease in staining intensity with FITC‐MAb 2G2 was noted in cartilage sections derived from animals with immune synovitis. A corresponding increase in staining of cartilage was noted with FITC‐MAb 6C9. The augmented staining of articular cartilage with FITC‐MAb 6C9 was most prominent in femoral condyle tissue sections, which corresponded to the cartilaginous area, with the greatest severity in gross pathology. There was a slight augmentation of staining with FITC‐MAb 2E9, especially in the C/PC area of medial/femoral cartilage. In addition, the animals with immune synovitis showed abortive cartilage repair exemplified by the presence of chondrocyte cloning (up to 20 cells) which correlated with increased FITC‐MAb 2G2 staining. The differential MAb staining patterns of cartilaginous tissues obtained utilizing FITC‐conjugated monoclonal antibodies with known fine antigenic specificity indicates a modulation of proteoglycans involving predominantly core protein epitopes in the articular cartilage of animals with chron

ISSN:0736-0266    

DOI:10.1002/jor.1100060310

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe most consistent effects of 0.2 mML‐ascorbate on monolayer cultures of rabbit articular chondrocytes were a diversion of incorporated radiosulfate into a pericellular matrix and enhancement of cell proliferation. Only with certain batches of fetal bovine serum (FBS) was there a cell‐for‐cell increase of proteoglycan synthesis. These actions increased as the cell inoculum rose from 0.5 to 2 × 105cells/T25 flask. Maximal effects of ascorbate and D‐isoascorbate were found over a range of 0.05–0.02 mM.L‐Dehydroascorbic acid was less effective than either, and no stimulatory action was exerted byL‐cysteine, glutathione, dithiothreitol, methylene blue, or phenazine methosulfate. Ascorbate increased the hypro:pro ratio of newly synthesized proteins. β‐Aminopropionitrile (1 mM) reduced the proportion of [3H]hydroxyproline and [35S]O4‐proteoglycans in the ascorbate‐supplemented matrix 31 and 7%, respectively. In corresponding electronmicrographs, the number of pericellular filaments was reduced. We conclude: (a) Ascorbate has a general anabolic effect on chondrocytes in culture and enhances matrix assembly through mechanisms other than its redox function; (b) deposition of proteoglycans in the matrix is not simply the result of mechanical entrapment by allysine‐ or hydroxyallysine‐derived cross‐linking of collagen; and (c) contradictory reports on the subject result from variations in the serum employed, inoculum density, and

ISSN:0736-0266    

DOI:10.1002/jor.1100060311

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

年代:1988

数据来源: WILEY