Behavior of Calculated Nail Head Strength in Soil-Nailed Structures

Nail head strength is one of the parameters used in design of soil-nailed structures. It determines the stability of the nailed structure against failure involving the facing element. The nail head strength is a function of a number of factors, primarily the material strengths, vertical and horizontal nail spacing, and the nail head connection details. The variations in nail head strength as a result of changes in the vertical and horizontal soil-nail spacing and material strength properties are examined in this paper. Both temporary and permanent facing design is considered. For equal vertical to horizontal spacing, the nominal nail head strength for a temporary facing decreases continuously as the spacing is increased. The nominal nail head strength for permanent facing decreases initially and then remains nearly constant. For a fixed vertical spacing (Sv) the nail head strength for temporary facing decreases linearly as the horizontal spacing (Sh) increases. For permanent facing the nail head strength decreases very slowly for vertical to horizontal nail spacing ratio between 0.8 and 1.0 and then declines rapidly. The nail head strength increases most rapidly with increase in facing thickness. Higher strength reinforcement and concrete have a relatively smaller influence in raising the nail head strength. Charts are presented that can help in optimizing the design of soil-nailed structures.     

Pyridostigmine bromide and Gulf War syndrome

A problem arose when the reamed tibia nail was replaced by a massive unreamed tibia nail. Of the nail fractures, it is difficult to remove the distal fragment from the medullary cavity. It may also happen that the connecting screw between the insertion handle and the nail breaks off at the edge of the implant, which complicates removal of the nail. The authors have developed a technique for removing the implant without having to saw a fissure in the marrow. A concave instrument is slid over the part of the nail left behind after which the two are connected by means of a K wire. This method has been successfully applied in two patients.     

Various possibilities for managing subtrochanteric fractures

Subtrochanteric fractures are highly unstable. For treatment, open reduction and internal fixation are the method of choice. The 95 degrees condylar plate is widely used for stabilization of these fractures. Alternative devices are the gamma nail and the recently developed intramedullar nail with a twisted plate which allows immediate postoperative weight bearing. The reported complications of the gamma nail restrict its general application, whereas preliminary reports of the intramedullar nail with the twisted plate are encouraging. Further clinical data are necessary before its general application can be recommended.     

Influence of Overburden Pressure on Soil–Nail Pullout Resistance in a Compacted Fill

Soil nailing has been widely used in many places in the world in the last two decades because of its technical and economical advantages. The nail–soil interface shear strength is an important parameter in soil nail design. This parameter is governed by a number of factors, among which the influence of the overburden pressure (or soil depth) is the most controversial. There are differing views concerning the effect of overburden on the nail–soil interface shear strength. In order to examine the influence of the overburden pressure, a series of laboratory pullout tests on soil nails installed in compacted completely decomposed granite fill have been conducted using two pullout boxes. Numerical simulations have also been carried out and the results are compared with the pullout test data. The procedures of the pullout tests and new features of the pullout boxes used are briefly described. Changes of the vertical stress in soil close to the nail throughout the course of soil nail installation and pullout are presented and discussed in detail. It is observed from the results of this study that the installation process of soil nail induced significant vertical stress changes in soil around the soil nails, and that the soil nail pullout shear resistance is independent of the overburden pressure (or soil depth).     

Nail disorders. Diagnosis and treatment of infectious, inflammatory, and neoplastic nail conditions

Nail disorders are very common, and about 50% of all nail conditions are of fungal etiology. A proper diagnosis is essential because many nail conditions look alike. Diagnosis and treatment of other nail disorders, such as psoriasis, lichen planus, and neoplasms, are discussed.     

Thermal latency in radiofrequency ablation

The relative nail producing capacity of different regions within the nail matrix has not been quantified. In order to do this, the number of nail plate cells in the dorsoventral axis of 12 human great toenails was counted at five sites in the longitudinal axis, and compared with direct measurements of nail plate thickness at the same sites. The mean number of nail cells in the nail plate reached a maximum at the lunula, with no further increase along the length of the nail bed. At the mid-point between the proximal tip of the germinal matrix and lunula, mean cell numbers achieved 81% of the value at the lunula. Mean nail thickness was only 90% of its maximum at the lunula, with a further significant increase (P = 0.02) between the lunula and end of the nail bed. These observations suggest that the proximal nail matrix is the main source of nail within the matrix. This is consistent with clinical experience where distal matrix surgery has a low potential for scarring in comparison with proximal matrix surgery. The additional finding of increased nail thickness, but not cell numbers, along the nail bed make it likely that cells within the nail plate change shape as they move distally.     

Keep the nail plate on with Histoacryl

Sutures are commonly used to secure nail plates after nail-bed repair. Here we describe a technique to secure nail plates using an adhesive--Histoacryl blue (n-butyl-2-cyanoacrylate). We report a series of 16 avulsed nail plates secured with Histoacryl after nail bed repair with a satisfactory end result.     

In-shoe biaxial shear force measurement: the Kent shear system

Involvement of the nail unit in pemphigus vulgaris is thought to be uncommon. However, trachyonychia, nail atrophy, onychomadesis, onycholysis, nail bed erosion, onychoschizia, subungual haemorrhage, nail pitting, nail plate discoloration, cross-ridging of nail plate, Beau's line and paronychia have been reported. These manifestations may be due either to secondary extension of the bulla adjacent to the nail or primary involvement of the nail bed, nail matrix and nail fold. We report four patients with pemphigus vulgaris who developed paronychia with a corresponding exacerbation of their cutaneous lesions. Nail fold biopsy and direct immunofluorescence revealed features of permphigus vulgaris. Treatment with immunosuppressive agents showed simultaneous improvement of both cutaneous and nail lesions.     

Beta 2-adrenergic receptor and angiotensin II receptor modulation of sympathetic neurotransmission in human atria

BACKGROUND: Cultures of epidermal cells are commonly used to study skin biology and differentiation. Recently a method to culture nail matrix cells has been established. OBJECTIVE: We report the biologic characteristics of nail matrix cells in vitro compared with those of epidermal keratinocytes. METHODS: Human nail matrix cells were isolated and cultured in defined medium. Electron-microscopic examination, growth rate, integrin expression and keratin synthesis pattern were evaluated. In addition, the cells were cultured in serum-containing medium. RESULTS: Nail matrix cells appear to be larger than human epidermal keratinocytes and, at the ultrastructural level, they contain a higher euchromatin/heterochromatin ratio and a lower nucleus/cytoplasm ratio and have a higher growth rate. The synthesis of "hard" keratins was detected at all calcium concentrations. Immunofluorescence analyses showed the expression of alpha 2, alpha 3, and alpha 6 integrin subunits. When cultured in serum-containing medium, nail matrix cells produced an outgrowth of epithelium and a spontaneous migration phenomenon associated with a tendency to stratify in a semilunar area that resembles the architecture of the nail matrix. The pluristratified epithelium showed characteristic markers of nail differentiation. CONCLUSION: Culture of nail matrix cells may represent a useful model to study the biologic properties of nail structure, alterations in some nail diseases and the effects of drugs.     

Atopy and reaction to nail dust inhalation

Inhalation of nail dust is a chronic problem facing podiatric physicians. This problem is compounded in physicians who develop allergic reactions to nail dust. This article defines atopy, reviews the characteristics of nail dust, and suggests methods to reduce the potential hazard that nail dust presents to the podiatric physicians and their employees.     

Modified Küntscher's nail for the proximal femur fixation after corrective osteotomies in children (author's transl)

The authors describe the development in the design of the modified Küntscher's nail with two fins on its upper part, assigned for the fixation of proximal femur after corrective osteotomies in children. Detailed explanation about the nails construction and its biomechanical characteristics are presented. The fixation of the nail in the proximal and distal femoral part, as well as on the site of osteotomy is particularly analyzed. On the base 423 operated cases, where the modified Küntscher's nail was applied, the authors conclusion is that the nail is very suitable for the correction of proximal femur deformities in children.     

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A rare case of congenital palmar nail syndrome is described. Nomenclature of this rare form of ectopic nail is discussed and a classification of the palmar nail deformity is offered.     

Field Pullout Testing and Performance Evaluation of GFRP Soil Nails

Glass fiber–reinforced polymer (GFRP) materials provide practical solutions to corrosion and site-maneuvering problems for civil infrastructures using conventional steel bars as reinforcements. In this study, the feasibility of using GFRP soil nails for slope stabilization is evaluated. The GFRP soil nail system consists of a GFRP pipe installed by the double-grouting technique. Two field-scale pullout tests were performed at a slope site. Fiber Bragg grating (FBG) sensors, strain gauges, linear variable displacement transformers (LVDTs), and a load cell were used to measure axial strain distributions and pullout force-displacement relationships during testing. The pullout test results of steel soil nails at another slope site are also presented for comparison. It is proven that the load transfer mechanisms of GFRP and steel soil nails have certain difference. Based on these test results, a simplified model using a hyperbolic shear stress-strain relationship was developed to describe the pullout performance of the GFRP soil nail. A parametric study was conducted using this model to study some factors affecting the pullout behavior of GFRP soil nails, including nail diameter, shear resistance of soil-grout interface, and ratio of interface shear coefficient to the Young’s modulus of the nail. The results indicate that the GFRP soil nail may exhibit excessive pullout displacement and thus a lower allowable pullout resistance than with the steel soil nail.     

Indications for use of the long Gamma nail

A retrospective analysis of 42 patients treated by intramedullary nailing with the Gamma nail with a mean followup of 22.4 months is reported. The indications for the use of this nail were subtrochanteric fractures in 31 cases, diaphyseal femoral fractures in 10 cases, and segmental fracture in one case. Seven cases of the diaphyseal fractures were renailings for a previously placed nail. There was one pathologic fracture in the subtrochanteric group and three in the diaphyseal group. The indications of this new technique and its complications are analyzed.     

The scleroatrophic syndrome of Huriez: a cancer-prone genodermatosis

We report a 24-year-old woman, her 6-year-old son and her 17-month-old daughter, who all suffer from a rare congenital genodermatosis first delineated by Huriez et al. in the 1960s. The clinical features of this autosomal dominant condition include scleroatrophy of the hands and feet, nail hypoplasia, mild palmoplantar keratoderma and hypohidrosis. Histological changes are non-specific, but immunohistological and ultrastructural examination in our index patient revealed an almost complete absence of epidermal Langerhans cells in the affected skin. This new finding may be linked to the cancer proneness of the scleroatrophic skin. In this family, the grandmother had died at the age of 37 years from metastatic squamous cell carcinoma which had arisen on the thenar eminence.     

In-vitro permeability of the human nail and of a keratin membrane from bovine hooves: prediction of the penetration rate of antimycotics through the nail plate and their efficacy

In contrast to the partition coefficient octanol/water the molecular size of penetrating drugs has a noticeable influence on the permeability of the human nail plate and a keratin membrane from bovine hooves. The relationship between permeability and molecular weight is founded on well-established theories. The correlation between the permeability of the nail plate and that of the hoof membrane allows a prediction of the nail permeability after determination of the drug penetration through the hoof membrane. The maximum flux of ten antimycotics (amorolfine, bifonazole, ciclopirox, clotrimazole, econazole, griseofulvin, ketoconazole, naftifine, nystatin and tolnaftate) through the nail plate was predicted on the basis of their penetration rates through the hoof membrane and their water solubilities. An efficacy coefficient against onychomycoses was calculated from the maximum flux and the minimum inhibitory concentration. Accordingly, amorolfine, ciclopirox, econazole and naftifine are expected to be especially effective against dermatophytes, whereas in the case of an infection with yeasts only, amorolfine and ciclopirox are promising.     

Use of the Gamma nail in the treatment of fractures of the proximal femur

Fractures of the proximal femur are, more than ever, an important challenge in the field of traumatology. The Gamma nail, a combination of advantages of the sliding screw with the intramedullary nail, represents an efficient technique in the management of these fractures. A series of 224 fractures of the proximal femur in which this nail was used is reported. The average age of the patients was 79.2 years. The mean healing time was 68.2 days in 99.4% of the cases. The incidence of perioperative complications was 10.3% showing that, in most of the cases, the complications occurred because of poor technique. Postoperative complications occurred with an incidence of 14.1%. Seven cases of migration of a proximal screw, six shaft fractures, and one broken nail were the most important complications. The device allowed for early mobilization and full weightbearing of the affected hip regardless of the type of fracture. With adequate surgical technique and experience, the advantages of the Gamma nail increases as the complication rate diminishes.     

Treatment of nail bed avulsions with split-thickness nail bed grafts

Experimental studies with squirrel monkeys indicated the feasibility of split-thickness grafting of segments of the nail bed. Thin grafts, when taken from the nail bed, achieved excellent take over of the avulsed areas. Thirty-one patients with avulsion of segments of the nail bed were treated with split-thickness nail bed grafts. The injured nail bed had sufficient residual nail bed to serve as a donor site in 24 patients. The remaining seven patients required split-thickness grafts from the lateral one third of the great toe. Of the 31 treated nail beds, there was a total of five deformities in which there was either nonadherence of the nail or irregularity of the nail surface. Twenty-six had nails with no deformity. No deformities occurred in the graft donor area. The split-thickness nail bed graft offers the advantage of frequent availability of tissue on the same injured digit and the absence of donor site deformity, whether on the same injured digit or a donor great toe.     

土钉支护及其应用

土钉支护是一种用于土体开挖和边坡稳定的新型支挡结构，具有良好的延性破坏特征。通过土钉支护在济钢中厚板厂二期工程中的应用实例，介绍了土钉支护的局部和整体稳定性计算及工程设计方法，并指出土钉支护应注意的问题。     

Rapid Pullout Test of Soil Nail

This technical paper describes the rapid pullout response of soil nail embedded in dry clean sand. In the rapid pullout test, soil nail is pullout by a tensile impulse load with loading duration that is long enough to eliminate the influence of the stress wave propagation phenomenon. The results of these experiments showed the influence of loading rate on pullout response is highly dependent on the roughness condition of the nail surface. For rough nail, the prepeak rapid pullout response was significantly stiffer in the load-displacement characteristic and higher in peak pullout strength when compared to the corresponding quasi-static pullout response. While for a smooth nail, a negligible difference between rapid and quasi-static pullout response was noticed. In light of these limited experimental results, the radiation damping effect appears to be the dominant contributor to the enhancements in prepeak rapid pullout response of rough nail. “Actual” damping coefficient that quantifies the damping resistance mobilized in a rapid pullout test was found not to be constant but to decrease with the increase in pullout displacement.