Intramedullary interlocking nails are used for fracture fixation. During this process, a long metallic implant is integrated through the medullary canal at one end of a long bone. The intramedullary nail may itself traverse a fracture or it may be used as a firm support for other nails, pins and screws that fixate a fracture. Nails are less flexible and thicker as compared to rods that are simple solid cylinders that can’t be fixated with pins or screws.
The nails generally comprise of distal and proximal holes for the insertion of interlocking pins and screws that fixate the implant to the bone. Nails can be both hollow and solid and can have square, circular or more complicated cross-sections.
The large diameter nails require the medullary cavity reaming prior to implantation. Besides, nails can also be located in a retrograde or antegrade manner. This means integration through the distal or proximal end of the medullary canal of a long bone. Usually, retrograde implantation is used for the treatment of the femoral diaphysis fractures.
When nails are implanted without locking pins or screws, then this provides splintage, angulation of a fracture and lateral displacement control. However, this does not offer rotational control. Nails at both distal and proximal ends provide translational and rotational control of a fracture as well as prevent distraction and impaction. This is known as static locking.
When a femur or tibia fracture has healed to a specific degree, then it is possible to remove locking devices at one or the other end so that weight bearing can lead to dynamic compression of the fracture. This is known as the nail dynamization.
There is an extensive range of femoral nails due to the more complicated anatomy of the femur. These nails can be integrated in a retrograde or antegrade fashion.