This is a clinical picture showing an intramedullary nail. It looks as though this is a femoral antegrade nail as it has an anterior bow, it has multiple locking options proximally and it is cannulated distally. They are usually made of titanium.

IM nails stabilize a fracture by acting as internal splints with load-sharing characteristics.

Splintage is defined as a construct in which micromovement can occur between bone and implant, providing only relative stability without interfragmentary compression. Callus forms at the fracture site.

It depends on how it is used.

In more comminuted fracture patterns, nail is used as a load-bearing device on which all the forces applied to the limb, so-called load-bearing. Ideally, a nail should be used as a load-sharing device, but in certain situations, it will be used as a load-bearing device.

The bending stiffness of a cylindrical cross-section is proportional to the fourth power of its radius as described by the second moment of area. In the case of a hollow cylinder, the bending stiffness is proportional to the fourth power of the outer radius minus the fourth power of the inner radius. As such, for any given material, a hollow cylinder is less stiff than a solid cylinder of the same outer diameter. If, however, a constant volume of material is used for construction of an IM nail of fixed length, then the use of a hollow nail would allow a greater outer radius to be used, resulting in a stiffer nail.

I would need to decide if I want to achieve primary or secondary bone healing. If the fracture was significantly comminuted, I would ideally choose to plate in bridging mode with fracture healing by indirect or secondary fracture healing with callus formation. Simple fractures could be treated with interfragmentary compression. Ideally, plate position should be on the tension side of the fracture. I would need to decide the length of the plate itself, the number and relative position of screws needing to be inserted and the type of screws to be used (standard cortical screws, cancellous screws, locking screws, etc.). The plate length should be 2–3 times higher than the overall fracture length in comminuted fractures and 8–10 times higher in simple fractures. The plate screw density should be kept below a value of 0.5, indicating that less than half of the plate holes are occupied by screws. Two screws (monocortical or bicortical) on each main fragment is the minimum number of screws needed to keep the plate bone construction stable. Such a construct will fail if one screw breaks due to overload or if the screw loosens, so it is generally advised to add another screw to each side of the fracture construct. Plating offers two different fixation concepts – splinting and interfragmentary compression. Comminuted fractures are best treated using a splinting technique because local bone and soft tissue devascularization can be minimized, while in simple fractures interfragmentary compression is preferred as a stabilization tool. When nailing the position, the length and diameter of the nail as well as the position of the locking bolts are more or less given and standardized by the local anatomy of the broken bone segment as well as the implant design.

The working length of a plate is defined as the distance across a fracture site between the two nearest points where the bone is fixed to the plate, e.g., the distance between the two screws closest to the fracture.

The working length of a plate can be altered by changing screw position. Screws placed close to a fracture create a short working length, which increases a plate’s construct stiffness. Screws placed further from the fracture site increase the working length and produce a less-stiff construct that permits more motion at the fracture gap.

There is the potential to create stress concentration with the risk of plate fracture. Placing screws further from the fracture site can decrease the risk for plate fatigue failure.