摘要:

AbstractThe relative values of dynamic and static bone imaging with hydroxymethylenediphosphonate technetium 99m (99mTc HDP) as an indicator of bone blood flow was investigated in the tibia of mature dogs. The dynamic bone scan consisted of 60 1‐s images formed after the intravenous injection of99mTc HDP, and the static bone scan was a 45‐min uptake image. Blood flow to the tibia was determined by using radioactively labeled microspheres. Studies were carried out in control dogs, in dogs in which blood flow was increased in one leg with ATP, and in dogs in which blood flow was decreased in one leg with norepinephrine. A significant (p<0.001) linear relationship between the dynamic scan values and bone blood flow was found at a wide range of blood flow rates. When blood flow increased by more than 50%, the effects of “diffusion limitation” were seen in the static scans: increase in tracer uptake was disproportionately small for a significant increase in blood flow. There is no method currently available for estimating bone blood flow by a noninvasive technique. The method described here may be useful for providing a semiquantitative measure of bone blood flow. This improved versatility of bone imaging may have a role in the management of osteomyelitis or complicated fractures, or in assessing the viability of vascularized bone

ISSN:0736-0266    

DOI:10.1002/jor.1100020111

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

年代:1984

数据来源: WILEY

摘要:

AbstractSingle‐passage experiments in which bone‐seeking tracers are injected arterially at the same time as microspheres to determine an extraction ratio are only valid if the maximum transit time through bone is less than the minimum recirculation time. This validity was investigated by injecting various intravascular and more diffusible tracers into the hearts or aortas of rats and rabbits at different times before the rapid cessation of circulation. At no time between 4 and 60 s after injection did the bone concentration of any of the tracers fall to negligible values. Removal of unbound tracer is therefore not complete before recirculation starts, and the single‐passage technique is invalid. Measurements of bone blood flow based on the clearance of18F cannot be substantiated, as its extraction is flow depe

ISSN:0736-0266    

DOI:10.1002/jor.1100020112

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe midplate structural rigidities of metal‐ and plastic‐plated intact canine femora were experimentally determined after initial plate application and 8 weeks afterin vivoimplantation. Composite beam theory significantly overestimated the bending rigidities of the metal‐plated bones. The rigidities of the plastic‐plated bones were nearly identical to that of the isolated bone, as composite beam theory predicted. Plating with either plate increased the intracortical porosity and caused the deposition of periosteal new bone, which was greater with plastic than with metal plates. The increased rigidities provided by the attachment of the metal plates and, hence, the degree of bone strain shielding were variable. Platings for 8 weeks which provided little strain shielding with either metal or plastic plates caused an increase in bone flexural rigidity (measured after plate removal) with respect to the contralateral control. Platings that provided increasing amounts of strain shielding caused a decreasing midplate bone rigidity (measured after plate removal) and increasing bone deposition at the outer screws. These findings suggest that the surgical implantation of any plate (metal or plastic) will provide a net stimulus to bone formation and consequently increased bone structural rigidity, even though intracortical porosity is increased. If the plate significantly reduces the normal loads borne by the bone, however, there is a net stimulus to remove bone, resulting in a loss of midplate structural rigidity within 8 weeks of impla

ISSN:0736-0266    

DOI:10.1002/jor.1100020113

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe effects of irradiation on the normal temporal progression of the physical properties of healing fractures were studied in a rat model. Fractures were surgically produced in the femur, stabilized with an intramedullary pin, and irradiated. One group of rats was exposed to 2,500 rads in divided doses over 2 weeks, beginning 3 days after fracture, and compared to a control group with fractures which were not irradiated. Animals were sacrificed at periodic intervals and the bones were tested to failure in torsion. The torque, stiffness, and energy increased and the angle decreased for the nonirradiated specimens in the expected fashion. This progression was deleteriously altered in the irradiated femurs.

ISSN:0736-0266    

DOI:10.1002/jor.1100020114

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

年代:1984

数据来源: WILEY

摘要:

AbstractTo develop a technique for the production of a standard closed experimental fracture, a new apparatus was designed and tested on 40 male Sprague‐Dawley rats. First, the femur was treated with an intramedullary Steinmann pin. The femoral diaphysis was then fractured by means of a blunt guillotine driven by a dropped weight. Radiographically, this technique resulted in a highly reproducible transverse fracture. There was minimal comminution and minimal angulation of the intramedullary pin. Histologically, there was minimal soft tissue damage. Mechanical testing showed that all fractures healed. Pin removal was accomplished with ease and without disturbance of the healed fracture site. The apparatus is simple to use and inexpensive to build. Through its use, a highly reproducible closed fracture model is establishe

ISSN:0736-0266    

DOI:10.1002/jor.1100020115

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

年代:1984

数据来源: WILEY

ISSN:0736-0266    

DOI:10.1002/jor.1100020116

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

年代:1984

数据来源: WILEY