Mission Magazine - The "hip" way to replace joints

The "hip" way to replace joints

August 2002

by Will Sansom

When the other 7-year-olds were running and jumping, Evangeline Harper was feeling pain in her joints. Though she wanted to keep up with her classmates on the playground, she couldn’t. She always hurt, and no one knew why. "I had good friends growing up, but people did not understand a child with arthritis," she said. "They thought it was something only older people should have."

Arthritis destroys cartilage, the sponge like cushioning normally found in joints. In the absence of healthy cartilage, bone rubs on bone, causing friction and extreme pain.

But the days of suffering are over for Harper.

A year after bearing her son, Daniel, she underwent a hip replacement performed by Jay D. Mabrey, M.D., associate professor of orthopaedics at the Health Science Center. The surgery freed Harper of her pain and corrected a
2-inch discrepancy in the length of her legs.

In 2001, she began to have severe knee pain. Again, she called Dr. Mabrey. "I remember thinking, "Why go through this pain when Dr. Mabrey has the skill and the technology to fix it?"

In patients such as Harper, surgeons implant metal shafts into hollowed-out bone. The bone re-grows around the shaft, which has a ball at the end. The ball fits inside a socket made of plastic, implanted where the old joint and cartilage used to be.

More than half a million patients need joint replacements each year. While the procedure brings a tremendous amount of relief, it’s not permanent and it’s not perfect. But it can be. In part three of The Mission’s special series on biomedical engineering, doctors fight to extend the life of joints, while scientists discover ways to create new cartilage.