摘要:

AbstractA positive bone scan in an experimental model of bilateral ulna diaphyseal bone grafts demonstrated early bone repair in both vascularized and nonvascularized orthotopic ulna autografts. A positive bone scan did not correlate with the perfusion of the vascularized and nonvascularized grafts as measured by microangiograms done 1 week postoperatively. In this model, if the bone scan is intended to monitor the circulatory status and viability of the bone graft, it must be done earlier than 1 week postoperative prior to the onset of creeping repair in both vascularized and nonvascular ulna autografts.

ISSN:0736-0266    

DOI:10.1002/jor.1100050302

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

年代:1987

数据来源: WILEY

摘要:

AbstractA study was conducted to see whether a biomechanical model previously validated for predicting the lumbar spine internal loads imposed by the performance of easy and moderately strenuous physical tasks was also adequate for predicting loads imposed by heavy exertions. Lumbar trunk muscle myoelectric activities were measured in 10 healthy young adult men performing a variety of less strenuous and more strenuous tasks while standing upright, and these were compared to the lumbar muscle contraction magnitudes predicted by the model. For the less strenuous tasks, measured activities and predicted forces showed strong linear correlations, confirming the validity of the model at those load levels. Model predictions for the more strenuous tasks were often found to be inadequate. Contrary to model‐incorporated assumptions, substantial antagonistic muscle contractions sometimes occurred, intraabdominal pressurization may sometimes have contributed substantially to the maintenance of structural equilibrium, and the ligamentous tissues of the trunk seemed sometimes to develop substantial passive resistances to bending and twisting moment

ISSN:0736-0266    

DOI:10.1002/jor.1100050303

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

年代:1987

数据来源: WILEY

摘要:

AbstractPlatelets from adolescents with minimal curve scoliosis (mcs) (7–18?) and healthy control subjects were examined for morphometry under the electron microscope and tested for calcium content and surface negative charge. These parameters have previously been found to be abnormal in severe idiopathic scoliosis (is) patients. Significantly more patients than control subjects showed deviations from normal in all tests. Two tests in particular, the average number of dense bodies per cell and an increased surface negative charge, were the most frequent abnormalities. In an attempt to assess the possibility of using platelet tests for prediction of curve progression, statistical comparisons were made and discriminant scores were generated for each patient. The results were compared with the clinical findings after a 2‐to 3.5‐year follow‐up. The predictions proved to be incorrect although each of the five patients who had curve progression had some platelet abnormality. It is concluded that although platelet pathology does occur in early idiopathic scoliosis, it cannot be used as a prognostic indicator of curve prog

ISSN:0736-0266    

DOI:10.1002/jor.1100050304

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

年代:1987

数据来源: WILEY

摘要:

AbstractPosterior lumbar spinal fusion was performed on five mature greyhounds. Two months prior to death, all of the surgical and five age‐matched control greyhounds were given Na235SO4(1.0mCi/kg) intravenously. All fusion animals were killed 6 months postoperation, and discs beneath the fusion mass as well as those adjacent to it (parafusion discs) were sampled separately and dissected into the nuclei pulposi and annuli fibrosi (AF). Proteoglycans (PGs) were extracted with 4.0MGuHCI and then purified by CsCI density gradient ultracentrifugation. These PG monomers were subjected to Sepharose CL‐2B chromatography, and their hydrodynamic size and ability to aggregate were determined. The level, extractability, and hydrodynamic size of PGs in the AF of fusion discs were found to be greater than those in control discs, as were the keratan sulfate core protein complexes prepared by chondroitin ABC lyase digestion. The ability of the 60‐day‐old PG subunit populations, isolated from fusion discs, to aggregate was also higher than controls. There was, however, no difference between the galactosamine/glucosamine, galactosamine/protein, glucosamine/protein, or hexuronate/protein ratios of PGs in fusion and contro

ISSN:0736-0266    

DOI:10.1002/jor.1100050305

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe biomechanical functions of the internal components of the intervertebral disc are not well understood. The surface deformation of 17 human cadaveric lumbar intervertebral discs was studied by photogrammetry by adhering small optical targets to the disc surface and thereby recording the length, bulge, and vertical height of lines on the disc surface representing annular fibers. Discs were studied in pure compression, flexion and extension, axial rotation, and shear. Two definitions of a fiber were investigated: first with the end‐points of the fiber on the vertebra (“bone‐to‐bone” definition), second, where the end points of the fiber were just before the disc vertebra junction (the “disc‐only” definition). Measurements were compared with a “constant‐volume” physical model and with a mathematical model of the intervertebral disc. Fiber strains were 6% or less under physiological conditions. Comparison of results from the two definitions of fiber length showed greater strains for the disc‐only definition in compressive loading. Fiber strains were less than in the constant‐volume model of comparable dimensions in compressive loading by a factor of about two, thus suggesting fluid loss or end‐plate deformations in the physiologic conditions. The mathematical model indicated that the surface strain for intervertebral discs is very sensitive to the disc‐height: diameter ratio and to fluid loss from the disc but is less sensitive to

ISSN:0736-0266    

DOI:10.1002/jor.1100050306

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe effectiveness of a sintered hydroxyapatite‐tricalcium phosphate (HA‐TCP) ceramic in bridging large diaphyseal defects in the canine ulna was studied. One‐hundred percent morselized HA‐TCP, a 50:50 mixture of morselized HA‐TCP, and autogenous cancellous bone, and 100% autogenous cancellous bone were used to bridge 2.5‐cm defects in the left ulnae of three groups of six dogs each. At 24 weeks the ulnae were explanted and studied by radiography, microradiography, mechanical testing, and histology. Pure HA/TCP was not osteoinductive, and four of six ulnae in this group progressed to a fibrous nonunion. The HA/TCP‐cancellous bone mixture and pure cancellous bone were approximately equal in effect, leading to good callus formation at 4 weeks and strong bony union by 24 weeks, with no evidence of bioincompatibility. Morselized HA/TCP promises to be useful as a graft extender when mixed with autogenous ca

ISSN:0736-0266    

DOI:10.1002/jor.1100050307

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

年代:1987

数据来源: WILEY

摘要:

AbstractFatigue test specimens of Simplex P bone cement (Howmedica Inc., Rutherford, NJ) prepared according to the manufacturer's instructions and specimens of Simplex P prepared by centrifuging the cement immediately after mixing were subjected to fully reversed tension‐compression fatigue tests at initial strain levels ranging from 0.01 to 0.001. S:N curves for both cement preparations were generated and compared on the basis of regression analysis, Weibull analysis, and Student'sttests. Centrifuged Simplex P was able to withstand significantly more fatigue cycles than uncentrifuged Simplex P at all strain levels tested. Importantly, at the more physiologic strain levels of 2,000 and 1,000 microstrain, the centrifuged cement demonstrated superior fatigue life. Specifically, at the 1,000‐microstrain level eight of the 11 uncentrifuged specimens fractured before undergoing 10 million cycles. Of those that failed, the average number of cycles to failure was 1.8 million with a range of 560,000 to 4 million cycles. In contrast, all 11 centrifuged specimens tested at 1,000 microstrain remained intact at 10 million cyc

ISSN:0736-0266    

DOI:10.1002/jor.1100050308

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe valgus stabilizers of the elbow have been identified anatomically, but their relative importance has not been quantified. The purpose of this study was to analyze the acute changes of the torque‐displacement curve to valgus stress following (a) section of the posterior portion of the medial collateral ligament; (b) excision of the radial head; (c) prosthetic replacement of the radial head; and (d) excision of the anterior portion of the medical collateral ligament. Thirty cadaver specimens underwent load‐displacement testing in three positions: 0°, 45°, and 90° of flexion. The anterior portion of the medial collateral ligament was the primary stabilizer of the elbow to valgus stress. The relative contribution of the posterior ligament was minimal. After excision of the radial head alone, the slope of the load‐displacement curve decreased an average of 30%. Silicone rubber radial head replacement did not significantly improve the stability to valgus stress after radial head

ISSN:0736-0266    

DOI:10.1002/jor.1100050309

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

年代:1987

数据来源: WILEY

摘要:

AbstractInstrumented devices for knee‐drawer tests have become popular in orthopaedics relatively recently. The objective of the present study was to document the effects of several parameters on the accuracy and reproducibility of anterior‐posterior (AP) drawer measurements. An instrumented knee‐drawer tester for AP laxity evaluations was constructed, based on the differential displacement method, measuring shifts of the tuberosity relative to the patella. The accuracy of the AP‐shift was determined with the parallel use of a highly accurate roentgen stereo photogrammetric (RSP) measurement system on two postmortem leg specimens. The effects of relative motion between patella and femur were negligible. In addition to AP shifts, significant knee flexion and tibial rotations occurred, although the foot and the thigh were fixed as well as possible. The differential displacement method was effective in circumventing this problem. The accuracy of the AP shift was>10%. The reproducibility of the AP drawer parameters (shifts and compliances) was determined in normal subjects and patients. Tests were made to evaluate the effects of different observers, time sequences, and different days. In addition, effects of muscle relaxation were studied. Overall, the shift parameters at different forces were found to be reproducible to between 5 and 15%. The slopes (compliances) of the laxity curves, at different forces, were found to be reproducible to between 20 and 40%. The reproducibility was principally affected by deviations in the subject positioning pr

ISSN:0736-0266    

DOI:10.1002/jor.1100050310

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

年代:1987

数据来源: WILEY

摘要:

AbstractShaving of the articular cartilage on the undersurface of the patella was carried out in mature white New Zealand rabbits to determine whether the removed cartilage reformed or the shaving led to later evidence of degenerative arthritis. The animals were followed for as long as 15 months after surgery, at which time patellae were removed and examined by light and electron microscopy. The depth of shaving varied considerably; however, no evidence of repair and no evidence of degenerative arthritis was noted in either the superficial or deeply shaved patellae. It is concluded that such superficial cartilage defects neither repair or produce subsequent degenerative arthritis.

ISSN:0736-0266    

DOI:10.1002/jor.1100050311

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

年代:1987

数据来源: WILEY