Bones need replacing for numerous reasons. Disease, infection and trauma are the main reasons.
Degenerative disease such as arthritis often cause pain and loss of mobility for the sufferers, and replacement of joints can provide the return of mobility and end to the related pain.
Bones crushed by trauma can often be repaired or replaced with currently available prostheses, which restore use of limbs.
Synthetic bone is very useful in the alteration of bone deformities.
The most often used form of bone replacement is stainless steel or titanium. Both are highly reliable and strong, but for some patients they can still present problems such as:
- imbalanced limbs
- minute release of metallic particles from tear
- need for revision of the surgery due to loosening and wear (1-3% of patients)
- pain and disability
Providing a building block from which real bone can grow is more desirable for bone replacement. The replacement of bone often requires non-standard shapes and the need for bone replacement that is malleable and more customized still remains. Science continues to search for bone replacements that behave more like real bone. There are currently several studies underway that show promise in fulfilling this goal.
Researchers in Korea have been investigating a method referred to as electrospinning. This technique spins a polymer-biomaterial of zirconia and biphasic calcium phosphate around a bundle of steel wires that are 0.3 mm in diameter. The wire is removed, leaving a sponge-like structure that is strong and porous and contains canal-like structures for the passage of natural bone-building fluids. Several columns are then combined around a central structure. The constructions mimics that of real bone by providing a softer, more porous inner layer and a stronger, channel filled outer layer.
In Germany, engineers have discovered a valuable use for Styrofoam. Using a polyurethane foam matrix, engineers formed a structure around it with standard titanium implants. When the matrix is heated, what is left is a porous, lace-like, titanium web. The result is a flexible, more realistic bone-like structure. The manufacture of this product is expected to begin soon.
One method currently under testing and awaiting approval by the U.S. Food and Drug Administration is a process that uses sea ice. Scientists found that a frozen calcium sludge creates a lightweight, strong calcium scaffold when the water is extracted. The structure is like that of abalone shells.
In Italy, another technique showing promise is the use of wood. After the wood is heated, oxygen and calcium are added, the wood is heated once more with a solution of phosphate. The process offers a structure strong enough to replace bone, and is being investigated in sheep.