Fractures can heal by either direct or primary fracture healing or secondary fracture healing. Direct or primary fracture healing occurs with absolute stability, such as with open reduction and interfragmentary compression achieved through a lag screw or plate placed in compression mode. Secondary fracture healing, on the other hand, occurs with relative stability and movement at the fracture site, such as with cast or brace, intramedullary nail, or plate placed in a bridging mode. The type of fracture healing that occurs depends on the mechanical stability present at the fracture site.

Perren's strain theory is the concept that tissue growth cannot occur when strain conditions exceed the tissue strain tolerance. Fracture gap strain is defined as the relative change in the fracture gap divided by the original fracture gap. Rigid internal compression fixation minimizes strain and leads to direct or primary fracture healing. On the other hand, indirect or secondary fracture healing occurs with relative stability and callus formation.

A stress riser, also known as a concentrator, is a localized area of an object where stresses are higher than in the surrounding material. Stress risers can increase the likelihood of crack growth and implant failure, especially when combined with cyclic loading or corrosion.

Tapping is necessary to convert the torque applied by the surgeon into compression instead of cutting threads and overcoming the friction between the screw thread and the bone. Without tapping, less of the torque is used to produce compression, which can reduce the strength and stability of the resulting fixation.