Present and future capabilities of MCNP

Several new capabilities have been added to MCNP4C including: (1) macrobody surfaces; (2) the superimposed mesh importance functions, so that it is no longer necessary to subdivide geometries for variance reduction; and (3) Xlib graphics and DVF Fortran 90 for PCs. There are also improvements in neutron physics, electron physics, perturbations, and parallelization. In the more distant future we are working on adaptive Monte Carlo code modernization, more parallelization, visualization, and charged particles.

Alternatives to Autogenous Bone Graft: Efficacy and Indications.

Bone grafting is frequently used to augment bone healing with the numerous approaches to reconstructing or replacing skeletal defects. Autologous cancellous bone graft remains the most effective grafting material because it provides the three elements required for bone regeneration: osteoconduction, osteoinduction, and osteogenic cells. Autologous cortical bone graft provides these three components to a limited extent as well and also provides the structural integrity important in reconstruction of larger defects. However, because autogenous grafting is associated with several shortcomings and complications, including limited quantities of bone for harvest and donor-site morbidity, alternatives have been used in a wide range of orthopaedic pathologic conditions. Grafting substitutes currently available include cancellous and cortical allograft bone, ceramics, demineralized bone matrix, bone marrow, and composite grafts. No single alternative graft material provides all three components for bone regeneration. The clinical applications for each type of material are dictated by its particular structural and biochemical properties. Composite grafts consisting of several materials are often used to maximize bone healing, especially where the grafting site is compromised.