Screw preload is the clamping or stretching force that occurs across the interface of the implant components that are being attached via screw tightening. Screw preloading has been shown to increase the screw’s fatigue strength as well as improve the locking effect. To set the screw preload within its optimal range, the correct amount of torque must be applied. However, this can be a complicated process as the torque applied in preloading a screw can be affected by a variety of factors. These factors include the material which the screw is made of, the screw’s stiffness, construction, and shape, the integrity of the screw and joint, and the condition of the surrounding surfaces. A screw’s level of preloading should be more than the biting force but less than the elastic limit and may fall within a 75-90 percent range of the material’s elastic limit to prevent the screw from loosening under moderate loads.