istraction osteogenesis (callotasis) has been widely used in patients with limb-length inequality or massive bone defects. This procedure, however, may be associated with a high incidence of physical and psychosocial complications. Callotasis telescoping on a locked intramedullary nail has been used to shorten the period of external fixation. Little attention has been given to the use of locked intramedullary nails in the treatment of complications after callotasis.Between 1990 and 1999, we used locked intramedullary nailing in 27 patients for the treatment of complications after distraction osteogenesis. There were 17 men and ten women with a mean age of 33.2 years (16 to 66). The nail was inserted at a mean of 3.4 weeks (0 to 15) after removal of the external fixator. Simultaneous autogenous bone grafting and soft-tissue reconstruction were also undertaken in seven and two patients, respectively.There was consolidation of the callus or docking site in all patients at a mean of 6.4 months (2 to 14) after surgery. The mean shortening of the callus was 0.7 cm (0 to 2.5). Two patients had infection at the site of a distal screw which resolved after removal of the nail. In 17 patients the nail was removed at a mean of 26 months after its insertion.Locked intramedullary nails are useful in treating complications after distraction osteogenesis in skeletally mature patients. The risk of infection should be borne in mind. Distraction osteogenesis (callotasis) has been widely used in the treatment of patients with leg-length discrepancy or a D massive bone defect.1 There is, however, a high incidence of complications including pin-track infection, fracture of the callus, nonunion of the docking site and delayed formation of callus. There may also be psychosocial complications and poor tolerance by the patient may result in failure or early termination of the procedure.2 Plaster casts or further periods of external fixation and plating have been used in the treatment of fracture or bowing of the callus and premature removal of the external fixator.2,3 Locked intramedullary nails, which have rotatory stability and maintain the length of long bones, have been widely used in the treatment of comminuted fractures. The technique of distraction osteogenesis over an intramedullary nail has also been described. [4][5][6][7] This procedure shortens the period of external fixation and allows an improved range of movement of the adjacent joints. Interlocking nailing after external fixation has also been described for the treatment of compound fractures of long bones. [8][9][10][11][12][13][14] Its use in the treatment of complications after distraction osteogenesis has, however, received little attention. Our aim was to evaluate the results of using locked intramedullary nailing in the treatment of complications after this procedure. Patients and MethodsBetween 1990 and 1999 we undertook 256 procedures for distraction osteogenesis in 223 skeletally mature patients. A total of 26 (10.2%) required internal fixation for complications ...
The properties of turbulence generated by uniform fluxes of polydisperse spherical particles moving through a uniform flowing gas were studied experimentally, emphasizing the properties of the turbulent interwake region surrounding the individual particle wake disturbances. Mean and fluctuating velocities, as well as probability density functions, energy spectra and integral and Taylor length scales of velocity fluctuations, were measured within a counterflow particle/air wind tunnel using particle wake discriminating laser velocimetry. Test conditions involved various binary mixtures of spherical gas particles having nominal diameters of 0.55, 1.1 and 2.2 mm and particle Reynolds numbers of 106, 373 and 990. When combined with earlier measurements limited to monodisperse spherical particles, the test conditions included mean particle spacings of 10-210 mm, particle volume fractions less than 0.003%, direct rates of dissipation of turbulence kinetic energy by particles less than 4%, and turbulence generation rates sufficient to yield streamwise and cross-stream relative turbulence intensities in the range 0.2-1.5%. The turbulent interwake region for these conditions has properties that correspond to the finaldecay period of grid-generated turbulence, involving homogeneous and nearly isotropic turbulence having probability density functions that were well approximated by Gaussian functions with turbulence Reynolds numbers of 0.4-3.5. Mixing rules were developed that successfully extended earlier results for the interwake turbulence properties of monodisperse particle phases to polydisperse particle phases, based on dissipation weighting of the properties of each particle size group. The flow in the final-decay period consisted of vortical regions that filled the turbulent interwake region but were sparse which resulted in several unusual features compared to conventional isotropic turbulence, as follows: enhanced rates of dissipation of turbulence kinetic energy, unusually large ratios of integral/Taylor length scales for small turbulence Reynolds numbers, and decreasing ratios of integral/Taylor length scales with increasing turbulence Reynolds numbers which is opposite to the behavior of conventional gridgenerated turbulence at large turbulence Reynolds numbers. The large range of scales where effects of viscosity were small in the final-decay region also yielded a Kolmogorov-like-5/3 power inertial decay region on dimensional grounds, very similar to the inertial decay region of conventional turbulence at large turbulence Reynolds numbers.
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