Implants are widely used to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. Medical implants are man-made devices, in contrast to a transplant, which is a transplanted biomedical tissue. The surface of implants that contact the body might be made of a biocompatible material such as titanium or silicone depending on what is the most functional. In the case of orthopedic implants, like spinal implants, the manner in which the implant is attached to the patient is an important consideration.
In many situations, screws are used to secure the implant to hard tissue (e.g. bone) of the patient. One consideration in using screws during orthopedic implantation procedures is ensuring proper screw orientation with respect to the implant when the screw is advanced into the bone. Another consideration is easing the implantation process for an attending medical professional, for example a surgeon installing the implant.