There are plenty of recordings where foreign materials have been embedded in the tissue of living human beings. What makes an implant integrate successfully? And how come some materials integrate while other materials can smoothly be removed from the body even after a longer period of contact or insertion?
The list of materials used throughout history is long
One of the earlier records of a successful implant is that of spear point, which was embedded in the hip of a man who lived several thousand years ago. According to archeologists, the spear point did not seem to impede the man's daily life. He was described as a healthy and active person. Even though the spear point had healed in nicely, the implant probably was not planned. There are however several records of, what can be assumed to be intentional use, of foreign material to mend or replace broken body parts. One early example is from the Mayan era, where nacre from seashells was used as dental implants .
Throughout history, the materials used to mend, support or replace tissue are many. Ranging from naturally occurring ones such as ant jaws, sheep intestine, plant fibers, hair and wool threads in the early days, to man-made and engineered materials such as metals, ceramics, polymers, etc in modern times [1, 2].
Not all materials work
Today, foreign materials are routinely used in contact with our bodies, and there are few body parts where a supporting, mending or replacing structure could not be used. But even though the list of materials used throughout history is very long, there is no guarantee that a foreign material will be tolerated by the body. In the early days, when there was no understanding of concepts such as sterilization and biocompatibility, attempts to use foreign materials to mend and replace tissue would most surely often have failed.
Surface interaction processes are key
So what makes a material tolerable by the body? And what makes a material integrate into the surrounding tissue? The answer to these questions lies at the surface interaction processes, and what happens there – short term and long term. The outcome is determined by how small molecules, such as water, start to interact with the surface of the material, followed by protein and other biomolecules, and then finally cells. Many factors play a role in how the chain of events will play out, for example, the chemistry of the material, leachables, shape, and mechanics .
Science on surfaces – a bigger perspective on the small
Learn more about what happens at the interface between a biomaterial and a physical when they meet in this epsiode of Science on surfaces - a bigger perspective on the small. We talk about the concept of biocompatibility, what complications that can arise if the intended surface interactions do not take place and how an understanding of the interfacial processes can be used to design implants and other products with certain functionality.
 Biomaterials Science, An introduction to materials in medicine, 3rd ed. Edited by Buddy D. Ratner, Allan. S Hoffman, Frederick J. Shoen, Jack E. Lemons
 The history and evolution of sutures in pelvic surgery, J R Soc Med. 2011 Mar 1; 104(3): 107–112.