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Plantar pressure analysis of diabetic rockerbottom deformity in total contact casts.

In a previous study, we examined plantar pressures under normally arched individuals in casts. The investigation described in this article was designed to assess plantar pressure distribution in subjects with Charcot midfoot collapse and rockerbottom deformity in standard short leg casts and total contact casts. Our results show that both types of casts significantly reduced midfoot pressures. No significant differences were noted between the two casting groups.

Aged↗

The mechanism of plantar unloading in total contact casts: implications for design and clinical use.

Although the total contact cast (TCC) has been shown to be an extremely effective treatment for the healing of plantar ulcers in diabetic patients, little is known about the biomechanics of its action. In this study, plantar pressure and ground reaction force measurements were obtained from over 750 foot contacts as five subjects with known elevated plantar forefoot pressures walked barefoot, in a padded cast shoe, and a TCC. Peak plantar pressures in the forefoot were markedly reduced in the cast compared with both barefoot and shoe walking (reductions of 75% and 86% respectively, P < 0.05). Peak plantar pressures in the heel were not, however, significantly different between the shoe and the TCC, and the longer duration of heel loading resulted in an impulse that was more than twice as great in the cast compared with the shoe (P < 0.05). An analysis of load distribution indicated that the mechanisms by which the TCC achieves forefoot unloading are (1) transfer of approximately 30% of the load from the leg directly to the cast wall, (2) greater proportionate load sharing by the heel, and (3) removal of a load-bearing surface from the metatarsal heads because of the "cavity" created by the soft foam covering the forefoot. These results point out some of the "essential design features" of the TCC (which are different from what had been previously supposed), support the use of the TCC for healing plantar ulcers in the forefoot, but raise questions about its utility in the healing of plantar ulcers on the heel.

Adult↗

Reductions in basal limb blood flow and lumen diameter after short-term leg casting.

PURPOSE: We tested the hypotheses that short-term casting immobilization of a leg would reduce basal blood flow and vascular conductance and induces structural alterations in femoral artery. METHODS: Right knee and ankle joints of eight healthy young men were immobilized with casting for 7 d. Before and immediately after casting, and 14 d after the cast was removed, femoral artery hemodynamics and structure were measured using a high-resolution ultrasound. RESULTS: Femoral artery lumen diameter in the immobilized leg decreased after the immobilization (P < 0.05) and returned to baseline during the recovery period, in which the subjects did not receive any special rehabilitation treatment. Femoral artery intima-media thickness (IMT) and IMT/lumen ratio in both legs did not show significant changes throughout the interventions. In the immobilized leg, femoral artery blood flow and vascular conductance decreased (-23 to 24%) after the immobilization (all P < 0.05). These parameters returned to the baseline during the recovery period, and there were no significant differences between the baseline and recovery values. In the control leg, femoral blood flow and vascular conductance did not change throughout the investigation. After 7 d of casting, femoral arterial distension, an index of arterial distensibility, tended to decrease in the immobilized leg but not in the control leg. CONCLUSION: We concluded that a short-term immobilization of lower limb decreases basal limb blood flow and arterial lumen diameter. These results suggest that basal limb blood flow and lumen diameter decrease rapidly upon the cessation of muscular weight bearing and locomotor activity, and may be modulated by an ordinary level of physical activity.

Adult↗

Displaced fractures of the hip in children. Management by early operation and immobilisation in a hip spica cast.

Fractures of the hip in children have been associated with a very high rate of serious complications including avascular necrosis (up to 47%) and coxa vara (up to 32%). Over a period of 20 years, we have treated displaced fractures by early anatomical reduction, internal fixation and immobilisation in a spica cast to try to reduce these complications. We have reviewed 18 patients who had a displaced non-pathological fracture of the hip when under 16 years of age. Their mean age at the time of the injury was eight years (2 to 13). They returned for examination and radiography at a mean follow-up of eight years (2 to 17). Each patient had been treated by early (" 24 hours) closed or open reduction with internal fixation and 16 had immobilisation in a spica cast. By Delbet's classification, there was one type-I, eight type-II, eight type-III, and one type-IV fractures. There were no complications in 15 patients. Avascular necrosis occurred in one patient (type-III), nonunion in one (type-II, one of the two patients who did not have a cast) and premature physeal closure in one (type-I). There were no cases of infection or complications as a result of the cast. Our treatment of displaced hip fractures in children by early reduction, internal fixation, and immobilisation in a spica cast gave reduced rates of complications compared with that of large published series in the literature.

Adolescent↗

Analysis of fetal and maternal microvasculature in ruminant placentomes by corrosion casting.

Vascular corrosion casting is a useful tool for studying the vascular architecture of complex organs. The synepitheliochorial placenta of ruminants is composed of two closed blood circuits, a fetal and a maternal one. The microvasculature of each circuit has the shape of the corresponding cotyledon (villous trees) and caruncle (crypts). These two compartments interdigitate with each other in a complementary fashion. Understanding three-dimensional vascular arrangements is facilitated by scanning electron microscopy of vascular corrosion casts. Methods to be used in the generation of vascular casts from fetal and maternal placentomal blood vessels are described, with special emphasis on casting resins and corrosion using potassium hydroxide. The procedure of splitting larger casts following gelatin embedding and freezing is also presented.

Animals↗

Techniques to improve the seating of castings.

A convergence of 20 degrees for full crowns is the most likely to be seen clinically, as determined by random measurements taken at a dental laboratory. Castings did not seat without cement, by an average of 215 micron at 10 degrees of convergence, or by 99 micron at 20 degrees of convergence. Biting forces will seat a casting approximately 150 micron, but will cause random concentrations of force against tooth structure, thus compressing it. All castings tend to rebound from this position. Zinc phosphate and polycarboxylate cemented crowns seated to 33 micron and 20 micron respectively when relieved, but each were elevated to 112 micron when not relieved. A silicophosphate cement displaced crowns with 20 degrees of convergence 122 micron under "ideal" clinical conditions, even when relieved; and with CBA 9080 cement, more than 500 micron. A die relief method was found to be the most suitable of the three casting compensation techniques. Casting retention, after cementation, was increased by 25%.

Cementation↗

Dispersion of aerosol particles in an airway cast of a dog.

Aerosol bolus dispersion was measured in the first branching generations of a replicate hollow cast. The cast was made from a solid cast of a beagle-dog tracheobronchial tree. The dispersion was measured after penetration of boluses into different volumetric depths, with different particle sizes and flow rates into the cast. An enhanced flow rate led to a decreasing dispersion in the cast. Particle size up to about 4 microns has no significant effect on dispersion.

Aerosols↗

Functional splinting versus plaster cast for ruptures of the ulnar collateral ligament of the thumb. A prospective randomized study of 63 cases.

In a prospective randomized study that included 63 consecutive thumbs with injuries of the ulnar collateral ligament of the metacarpophalangeal (MCP) joint of the thumb, plaster cast immobilization was compared with functional treatment with a splint. The splint allowed flexion and extension of the MCP joint, but prevented ulnar and radial deviation of the thumb. The study included both operated on and nonoperated on cases where surgery was performed only when the torn ligament was regarded as displaced. Of 40 thumbs treated nonsurgically, 21 were treated with a cast and 19 with a splint. Of 23 thumbs treated surgically, 10 were immobilized postoperatively in a plaster cast and 13 were treated with the splint. At the follow-up examination after 15 (11-41) months, there was no difference between the treatment groups as regards stability, range of motion, strength of the injured thumb, and length of sick leave. However, the patients considered the splint more comfortable than plaster cast immobilization. We conclude that immobilization of the thumb after a ligamentous injury with a movable splint is strongly preferred by the patients and that the functional results of this technique are equal to plaster cast immobilization after both surgical and nonsurgical treatment.

Adolescent↗

Morphological evidence of pulmonary vascular leakage through gaps observed with casting methods and S.E.M.

We have used selective casting methods to separate pulmonary elastin from vascular elastin in the lungs of rabbits, dogs and pigs. The lungs are digested with 0.1 N NaOH at 75 degrees C for 24 approximately 48 hours with frequent turning as the lungs are filled with air to about 80% of the vital capacity prior to the casting which is done at pressure of 20 approximately 50 mmHg. After vascular injections, we saw many small globular bits of casting material well separated from cast vessels and lying in the pulmonary elastin. Surface forces should make the casting material creep along the vessels even if they are not completely filled, so that the spherical shape is the one expected if the case is extruded into the parenchymal space and the air space. We conclude that this suggests that the pulmonary circulation is partially and temporarily 'open' as seen in the spleen and some other organs, rather than a completely 'closed' one as is generally accepted. At least some of these extravasations may be associated with lymphatics, although we have not proved this.

Animals↗

Three experimental designs testing orthopedic casting material strength.

Three methods for testing the comparative strength of orthopedic casts have been considered. Two of the tests, three-point-beam-bending and diametral compression, were expected to yield information about "material" strength, and a third simulated an actual cast yielding information about "structural" strength. In one study using these three methods, differences in strength were detected in the material tests, but not in the structural test. Thus, the authors believe that tests of material strength alone are insufficient to establish clinically relevant differences between the strength of orthopedic casts. Adequate testing must include structural tests like the cast-cylinder test described in this article if meaningful and clinically relevant conclusions are to be drawn regarding the comparative strength of the actual cast. Since both the three-point-beam-bending and diametral compression tests produced essentially the same results, both tests are probably not necessary. However, each of these two tests does serve to substantiate the results of the other.

Casts, Surgical↗

The Ponseti method of treatment for congenital clubfoot: importance of maximal forefoot supination in initial casting.

The correction of cavus deformity requires further supination of the forefoot. In the Ponseti method, the initial cast is applied with the forefoot supinated such that the plane of the metatarsal heads is parallel to the long axis of the tibia. This study reviewed Pirani scores of 27 patients with 38 clubfeet treated over an 18-month period by the Ponseti method to evaluate changes in midfoot deformity after the initial cast. Initial average scores for severity of the lateral border deformity, medial crease, and talonavicular joint reducibility decreased from 0.92, 0.75, and 0.75, respectively, to 0.73, 0.25, and 0.5, respectively, after the first cast. The improvement in Pirani scores provides support for the efficacy of the initial cast to reduce the cavus and also increase the reducibility of the midfoot. Failure to address the cavus deformity with the initial cast as described by Ponseti may lead to persistent rigidity and incomplete correction.

Casts, Surgical↗

Possible segregation caused by centrifugal titanium casting.

The possibility of the segregation under solidification process using a centrifugal casting machine was investigated using an electron probe microanalyzer with elemental distribution map, line analysis and quantitative analysis. When a very small quantity of platinum was added to local molten titanium during the casting process, macroscopic segregation was observed under conditions of density difference of 0.1 g/cm3 at the most, confirming that the centrifugal force of the casting machine is extremely strong. When a Ti-6Al-4V alloy was cast, however, no macroscopic segregation was observed. The centrifugal force of the casting machine examined in the present study hardly results in the body-force segregation in this titanium alloy.

Alloys↗

Development of casting investment preventing blackening of noble metal alloys Part 2. Application of developed investment for type 4 gold alloy.

The objective of this study was to evaluate the efficacy of the developed investment for the prevention of blackening of a cast Type 4 gold and to analyze the oxides on its surface in relation to the blackening of the alloy. The experimental investments were prepared using a gypsum-bonded investment in which boron (B) or aluminum (Al) was added as a reducing agent. A Type 4 gold alloy was cast into the mold made of the prepared investment. The effect of the additives was evaluated from the color difference (deltaE*) between the as-cast surface and the polished surface of the cast specimen. B and Al were effective to prevent the blackening of a Type 4 gold alloy and the color of the as-cast surface approached that of the polished surface with increasing B and Al content. The prevention of the blackening of the gold alloy can be achieved by restraining the formation of CuO.

Aluminum↗

[Reproduction of interocclusal relationship on stone casts].

We fabricate a prosthesis by the indirect method. To fabricate a prosthesis functionally harmonized with the stomatognathic system, the interocclusal relationship must be reproduced on stone casts as accurately as possible. In this study, two subjects (one male, age 28; one female, age 31) were selected, and the occlusal contacts of complete arch stone casts made by three different impression methods were observed and compared with the true occlusal contacts in the intercuspal position in the mouth. To take the interocclusal records, we used a silicone bite checker. The following results were obtained. The occlusal contact points reproduced on the stone casts made by a conventional custom tray and a stock tray were rather low; that is, the number of occlusal contact points was less, and the size of the occlusal contact area was smaller, than in vivo. The states of the occlusal contact on the casts made by the same method differed from each other. On the bite-impression technique, the reproduction of occlusal contact was superior to that of the others. The shape, area, and number of contact regions under 60 micrometers were similar to contact regions under 30 micrometers in the mouth. There was no significant difference in reproduction between the custom tray and the stock tray. It is likely that the results were due to the distortion of the jaws and periodontal tissue during clenching at the intercuspal position, which could not be reproduced on the stone casts made by both the conventional custom and stock trays.

Adult↗

Casting methods and plantar pressure: effects of custom-made foot orthoses on dynamic plantar pressure distribution.

Foot orthoses are widely used to treat various foot problems. A literature search revealed no publications on differences in plantar pressure distribution resulting from casting methods for foot orthoses. Four casting methods were used for construction of orthoses. Two foam box techniques were used: accommodative full weightbearing method (A) and functional semiweightbearing method (B). Also, two suspension plaster casting techniques were used: accommodative casting (C) and functional subtalar joint neutral position (Root) method (D). Their effects on contact area, plantar pressure, and walking convenience were evaluated. All orthoses increased the total contact area (mean, 17.4%) compared with shoes without orthoses. Differences in contact areas between orthoses for total plantar surface were statistically significant. Peak pressures for the total plantar surface were lower with orthoses than without orthoses (mean, 22.8%). Among orthoses, only the difference between orthoses A and B was statistically significant. Differences between orthoses for the forefoot were small and not statistically significant. The gait lines of the shoe without an insole and of the accommodative orthoses are more medially located than those of functional orthoses. Walking convenience in the shoe was better rated than that with orthoses. There were no differences in perception of walking convenience between orthoses A, B, and C. Orthosis D had the lowest convenience rating. The four casting methods resulted in differences between orthoses with respect to contact areas and walking convenience but only slight differences in peak pressures.

Adult↗

A simplified method of total contact casting for diabetic foot ulcers.

A simplified method of total contact casting for diabetic plantar ulcerations is described in which a standard, well-molded short-leg walking cast is applied. Weekly cast changes are performed initially, followed by longer cast change intervals. Either fiberglass or plaster casting tape appears equally efficacious. Healing of all ulcers was demonstrated in 12 patients treated with this technique.

Aged↗

Quantitative microvascular corrosion casting by 2D- and 3D-morphometry.

As a system of tubes (blood vessels) the cardiovascular system changes actively and passively diameters to adapt its transport capacities for respiratory gases, nutrients, heat, metabolites and waste products to and off the body's organs, tissues and cells. In most healthy organs blood vessels form a hierarchically arranged three-dimensional network with the geometry defined by vessel diameters, interbranching distances (defining branching frequencies and number of branching sites, i.e. nodes), intervascular distances, and branching angles. In the present study 2D- and 3D-morphometry is applied to quantify these parameters and their changes as they occur in resin casts during metamorphosis of the tadpole lung (2D-morphometry) and filter apparatus vasculature (3D-morphometry). It is shown that 2D-morphometry should be limited to the analysis of high powered images of flat two-dimensional vascular networks (example: tadpole lung alveolar vascular bed) to prevent underestimation of parameters. In contrast, 3D-morphometry can be applied over a wide range of magnifications whereby accuracy of measurements increases with the portion the structure to be measured occupies within the field of view. Together with a careful control of precasting conditions (application of vasoactive drugs, anaesthetics), casting conditions (pressure during rinsing and casting, amount of final shrinkage of casting media), and postcasting conditions (thermal burdening during maceration, sputtering, evaporation, and SEM inspection; thickness of conductive metal layers) 3D-morphometry enables to gain reliable data from resin casts of highly complex real vascular networks in healthy and diseased organs in the developing, juvenile, adult and aged state, as well as in different physiological states.

Aging↗

[A study of dental cast by using 3D laser non-contact measurement and analysis].

OBJECTIVE: To research and develop a new scanning 3-D digitization system for noncontact measuring of dental cast. METHODS: By using two pulsate motor to make the synthetic movement of the dental cast, a special semiconductor laser and two special line-array CCD, the 3D coordinate could be gotten from the surface of the dental cast in any where. The program which is developed by Visual C++ language and run under the Windows surroundings can control the scanner, rebuild the 3D graphics and measure the coordinate of the dental cast. RESULTS: The system offers 70 mm x 70 mm x 70 mm measurement scope, 0.01 mm resoling power < 0.1 mm mean deviation, 25 mins for single cast scanning. CONCLUSION: This system provides many advantages such as in precision, simplicity, high efficiency, and wide range of measurement contents with complete direct view. It also supplied us some new functions which can not be done with traditional way of measurement.

Dental Casting Technique↗