medicine encyclopedia----Implant-medicine

medical encyclopedia

Implant (medicine)

An implant is a medical device made to replace and act as a missing biological structure (as compared with a transplant, which indicates transplanted biomedical tissue). The surface of implants that contact the body might be made of a biomedical material such as titanium, silicone or apatite depending on what is the most functional. In some cases implants contain electronics e.g. artificial pacemaker and cochlear implants. Some implants are bioactive, such as subcutaneous drug delivery devices in the form of implantable pills or drug-eluting stents.

Orthopedic implants to repair fractures to the radius and ulna. Note the visible break in the ulna. (right forearm)

In orthopedic surgery, implants may refer to devices that are placed over or within bones to hold a fracture reduction while prosthesis would be the more appropriate term for devices that replace a part or whole of a defunct joint. In this context implants may be placed within or outside the body. Dental implants are one of the few medical devices which permanently cross the boundary between the inside and the outside of the body, since the base of the implant is osseointegrated in the bone of the mandible or maxilla and the top of the implant is in the mouth, where it can be crowned with an artificial tooth.

A bio-implant may be defined as a biomaterial surgically implanted in a person's body to replace damaged tissue. Common areas of application include orthopedic (especially maxillofacial) re-constructive prosthesis, cardiac prostheses (artificial heart valves like the Chitra heart valve), skin and cornea.

Implant-medicine : Complications

• Implant fails to osseointegrate
• Failure of components to fit properly
• Implant or its components fracture
• Peri-implantitis (inflammatory reaction around the implant) and bone loss
• Prosthetic failure
• Aesthetics
• (late deep) Infection

Implant-medicine : Failures

There have been many examples of implant failures, including rupture of silicone breast implants, hip joints and heart valves, all of which have caused FDA intervention. The consequences of implant failure depend on the critical nature of the implant, and its position in the body. Thus heart valve failure is likely to threaten the life of the individual, while breast implant of hip joint failure is less likely to be life-threatening.