Bone Implants
The Amazing World Of Bone Implants
Although bone implants are nothing new, tremendous strides have been made over the past few years and continue to be made to this very day. Bone implants are often the best solution when a bone is damaged beyond its ability to repair itself, or a bone or part of a bone is missing.
One of the problems those specializing in bone implants have always faced is finding a substitute material that is as strong as bone and at the same time is compatible with bone and other body tissues. Bone of course can be grafted, and quite often a piece of bone is taken from somewhere else in the body and grafted onto a damaged bone or is used to joint two pieces of bone that have become separated and in effect have a piece missing. The femur is the usually candidate as a source of spare bone material, primarily because of its size, and the fact small pieces of bone can be safely removed without compromising the strength of the femur itself.
The Weak Link - The main problem encountered in using something other than bone itself in bone implants lies in the method of attaching the implant to existing bone. While the implant material can be as light as bone and just as strong, it can be difficult to attach the implant to the bone in a manner which will not eventually weaken the bone itself. Hip replacement surgery has been done quite successfully for many years, and the material used in place of the ball joint and surrounding bone is for all practical purposes indestructible. Somewhere along the line however the implant material has to be connected to bone, and this is the weak link in the chain, preventing a hip replacement or similar types of procedures from lasting forever. Materials such as titanium, used in the screws to attach artificial implant material to bone will, as it is denser ands stronger than bone, eventually weaken the surrounding bone causing the bond between the bone and the implant to eventually fail.
When a piece of bone is taken from another part of the patient's body, say the femur, the implant is called an autologous implant. If the bone is given by another donor, it is called an allopathic implant. Autologous bone implants are generally preferred, as the risk of rejection of the implant is quite low. At times a mesh-like structure used as an implant with the hope that the existing bone will use the mesh to grow new bone.
LENS Technology - Recently. a great deal of research has been directed towards developing metal-ceramic, porous metals, and other bio materials for use in bone implants. One of the guiding technologies behind this is LENS technology, where the LENS is a Laser Engineered New Shaping machine. One of the major challenges in this area is that of finding bio materials, especially ceramic materials, that are compatible with the body and won't be rejected. Calcium phosphate is one of the compounds under serious consideration, as it leads to the development of bio materials that closely mimic actual bone. Mimicking bone isn't always all that easy. Bone is strong enough to carry heavy loads, yet internally bone is quite porous, and even sponge-like. To complicate matters further, the porous structure of internal bone isn't uniform throughout the bone, but tends to vary in accordance with the loads the bone is generally required to support.
The ability to undergo bone implants without widespread cases of rejection has made life much better for countless individuals. This is an area where although much is possible, there are still new horizons under study, and new and exciting bone implant techniques and products can be expected in the very near future.