While the human body is a wonder, sometimes medical science can help improve it. Injuries, birth defects, arthritis and wear and tear are all reasons that the body sometimes needs the help of medical science. Artificial joints can be the answer to all of these problems.

Joints are parts of our skeletal structure that help us to move and function. They allow our limbs to bend and are designed to hold the weight our body naturally carries. As they wear out, the body becomes less mobile and often experiences pain. A joint replacement procedure can often combat both problems. Some of the more commonly replaced joints include:

• Hip
• Knee
• Wrist
• Ankle
• Finger
• Elbow

But what exactly are these artificial joints made of? Many patients are concerned with the new “body parts” that they are about to receive and want to know more about the artificial joints. The truth is, every artificial joint is a little different. It depends upon which joint is being replaced and the needs of that particular joint. An artificial knee has to be sturdy because it supports body weight, while fingers and elbows need to be capable of bending regularly. If an artificial joint is not designed for function, then there is no point in incorporating it into medical care. The materials used to make the prosthetic joints are key to both durability and function.

Metal- Metal is one of the most commonly used materials. It is strong, durable and can be shaped to match the human form. Metal portions of the artificial joint are generally the part of the joint that provides stability or helps the body carry weight. Some common types of metal used are:

• stainless steel
• titanium
• chrome
• cobalt alloys.

Plastic- Plastic is another common material. Plastic can also be formed into any shape. In addition to that, many types of plastic are strong yet less dense than metal, providing the artificial joint with flexibility. Plastic parts allow artificial joints to restore mobility because they are more giving than metal. Joints that require lots of movement (fingers, knees and elbows) generally have plastic parts. Another benefit of plastic is that it can be used in combination with metal in a manner that restores mobility but does not create the grinding that two metal parts working together would create.

Ceramic- Ceramics are becoming more popular in some joint replacement procedures, especially hip replacements. Ceramic is strong yet has a smooth finish. This provides durability and reduces the friction caused by different pieces of the joint rubbing together as the body uses the joint for daily activities. Excessive friction can cause complications with artificial joints and sometimes another surgical procedure must be done down the road to fix these problems.

Bone Cement- Some artificial joints are built so that the organic body parts they come into contact with–most often bone– grow into and around them. This holds the artificial joint in place. In other cases artificial joints can be attached to bones with screws or metal pins. When these two options are not employed, a product called bone cement is. Bone cement is a synthetic product made mostly of a chemical called polymethylmetacrylate. It is used to help attach the artificial joint to the surrounding bone. It works more like grout than glue. Bone cement fills in gaps in between the artificial joint and bone and helps to connect the two.

Artificial joints can be a great treatment option for the right patients. They allow problems to be addressed with the body that likely affect the patients’ lives on a daily basis. The technology is still evolving but do not worry, it is established. Artificial joints have been in use for over fifty years and have changed the lives of thousands of patients.

If you would like more information on joint care, visit the University Hospital and Medical Center’s Orthopedic Department online. If you have other medical questions, we encourage you to call our Consult-A-Nurse® hotline at 1-866-442-2362.