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Total Hip Arthroplasty

This is a modern hip replacement stem. The outer surface is "porous coated". The metal is sprayed onto the stem such that the metal has spaces which are similar to the natural spaces of bone. This allows the bone to grow directly into the metal.

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Total hips have been done now for over 60 years. Due to improved technology, the success and life expectancy of total hips have improved dramatically. There are well over 300,000 total hips performed in this country alone every year. Much marketing is done by the manufacturers, some of which may be confusing or even misleading.

Since Sir John Charnley of England, who is considered the father of total hip arthroplasty, introduced the technique in the United States in the early 1960s, bone cement has been used to secure the implants to bone. In the United States today, however, most implants are placed into the bone without cement.There are several different types of coating which can be applied to the implant allowing bone to grow directly to the implant.

The results of these implants are excellent, with no significant differences in the outcomes. Again, Dr. Clyburn's advice is to choose your surgeon and allow your surgeon to choose your implant. Cement is still used in special cases such as older patients with severe osteoporosis (soft bone).

The first picture shows the cup of the total hip implanted in the bone. Even in this picture it can be seen that the bone is grown to the cup.	In the second picture, it is seen microscopically, that the bone is growing directly into the spaces between the metal "beads".

Cemented vs. Uncemented Implants
Bone cement which is Poly-methylmethacrylate (PMMA) has been used in total hips since the early 1960's. It is still used widely about the world, but its use in total hips in the U.S. is declining. Bone cement provides an excellent initial fixation, but with time, may crack and loosen. Most implants in this country are placed without cement using porous coated technology. Cement is still commonly used in older, osteoporotic patients. Dr. Clyburn developed and patented an improved device for injection of cement.

Bone cement is used in total knee replacement routinely as it has been found that cemented total knees have improved results over uncemented knees.