Why are the TriGen implants available in such an odd variety of diameters?
The TriGen nail is selected in “odd sizes” for the following reasons. First, in the past, nail sizes increasing in 1 mm increments were available from 8 mm to 21 mm. This created an inventory of 14 different diameters. These sizes were based on the original concepts of Kuntcher, who used an interference fit to fill the canal to prevent collapse in comminuted fractures. With the advent of interlocking, the implant no longer functions biomechanically as a nail (interference fit), but rather as an intermedullary splint. Therefore large diameter implants are not needed to fill the canal. Secondly, when strength is considered, many surgeons believe that larger diameter nails result in a stronger implant. Again, when Kuntcher developed his implants, they were made from a stamped piece of stainless steel, that was then rolled and pressed. The only way the nail could be strengthened was to increase its diameter. For the largest diameters, he even advocated “stacking”, i.e., placing two nails d
