Generally, it is a foreign body temporarily or permanently implanted in the human body to restore natural or aesthetic function of injured organ. The most common material used in orthopedics is metal (titanium alloy or surgical steel) or combination of metal and ceramics, polymers or composites. Each material is tested for biocompatibility.
The obligatory certification procedures for medical devices guarantee the patient safety.
However, it does not eliminate very rare cases of an implant rejection or allergic reaction.