Search

Fracture-dislocations of the elbow remain among the most difficult injuries to manage. Historically, the combination of an elbow dislocation, a radial head fracture, and a coronoid process fracture has had a consistently poor outcome; for this reason, it is called the terrible triad. An elbow dislocation associated with a displaced fracture of the radial head and coronoid process almost always renders the elbow unstable, making surgical fixation necessary. The primary goal of surgical fixation is to stabilize the elbow to permit early motion. Recent literature has improved our understanding of elbow anatomy and biomechanics along with the pathoanatomy of this injury, thereby allowing the development of a systematic approach for treatment and rehabilitation. Advances in knowledge combined with improved implants and surgical techniques have contributed to better outcomes.

A laboratory investigation of the geotechnical properties of a marine clay saturated with a series of monovalent, divalent, and trivalent cations revealed large differences in behavior which depend on the exchangeable cations. The exchangeable cations employed in this study are sodium (Na), potassium (K), ammonium (NH4), magnesium (Mg), calcium (Ca), and aluminum (Al) in order of increasing valency. An increase in the valency of the adsorbed cations leads to an improvement in the geotechnical properties of the marine clay, while for a constant valency an increase in the hydrated radius of the adsorbed cations results in a lower rate of consolidation. Analysis of the results show that geotechnical properties are improved for the marine clay with cations having higher valency and smaller hydrated ionic radius in the adsorbed complex. The beneficial changes in properties can be attributed to the improvement in the efficiency of flocculation as the valency of the adsorbed cations increases and the hydrated io...

The type of cations present in the adsorbed double layer of any clayey soil can significantly control the soil's compressibility. This technical note examines the influence of exchangeable cations on the compressibility of a marine clay. An experimental investigation of the compressibility properties of marine clays with a series of monovalent, divalent, and trivalent cations revealed large differences in behavior. The exchangeable cations employed in this study were sodium (Na+), potassium (K+), ammonium (NH4+), magnesium (Mg2+), calcium (Ca2+), and aluminum (Al3+) in order of increasing valency. The results indicate that the compressibility properties are significantly affected by the valence and size of the adsorbed cations. An increase in valency leads to a reduction in compression index, and at a constant valency an increase in the hydrated radii of the adsorbed cations resulted in an increase in compressibility. Further, it has been found that preconsolidation pressure increases with valency of the ...

Lime has been successfully used as an additive to the soil to improve soil behavior. Cation exchange is considered to be one of the important reactions responsible for the improvement in the soil characteristics. This technical note presents the results obtained from model lime columns installed in a marine clay bed formed in the laboratory test tank. The diffusion of lime into the surrounding soil from the columns was confirmed through the increase in the values of pH and lime content (CaO) measured from a number of samples taken in between the columns. Further, there is an increase in the cation exchange capacity.

A laboratory study of the hydraulic conductivity (HC) of a marine clay with monovalent, divalent and trivalent cations revealed large differences in HC. The exchangeable cations employed in this study are Na, K, NH4, Mg, Ca and Al in order of increasing valency. An interpretation of the results derived from consolidation tests suggests that HC is significantly affected by the valency and size of the adsorbed cations. An increase in the valency of the adsorbed cations leads to quicker rates of consolidation and higher HC, while, for a constant valency an increase in the hydrated radius of the adsorbed cations results in a lower rate of consolidation and HC. The reduction in HC was related to the dispersion and deflocculation of clay. Lower valency and higher hydrated radii of the exchangeable cations enable the double layer repulsive forces to predominate, thereby increase dispersion and defloccalation. ? 1995, The Clay Minerals Society.