Over his eight-year career as a rodeo clown, Robert Dutruch took a lot of hard hits.

After retiring, Dutruch’s left hip constantly reminded him of the regular contact he made with bulls in the arena.

“I was literally dragging my left leg almost behind me,” says Dutruch, now a 59-year-old medical salesman and photographer in Covington.

A degenerative hip condition had caused so much damage doctors told him his only option was a hip replacement. But Dutruch put off the surgery until the pain was unbearable.

“You get tired of getting up in the morning and hurting so bad,” he says.

The number of Americans requiring joint replacement surgery grows every year.

Between 1993 and 2009, the number of total knee replacements more than tripled, while total hip replacements doubled, according to a study published last month in the Journal of Bone and Joint Surgery.

Joint replacement surgeries are expected to continue increasing steadily over the next two decades, the American Academy of Orthopaedic Surgeons predicts. One study links the rise in artificial joints to obesity, while some doctors point to the active lifestyles of the Baby Boom generation.

“The general population is more active — not just our youth — in general more active,” says Dr. Kevin Darr, a Covington orthopedic surgeon. “Living with joint pain — the population does not want to live with pain. They want to pursue their activities.”

As the number of joint replacements have gone up, the technology behind them has also vastly improved.

For Dutruch, a degenerative hip issue had malformed the ball-shaped head of the femur to an oblong knob. An active scuba diver and artistic photographer, the pain in his hip caused him to curtail his activity for two years.

Physical therapy had not worked.

Dr. Darr, who says he prefers non-surgical solutions, told him joint replacement was his only option.

“I had bone rubbing on bone,” Dutruch says. “There’s not much you can do with it.”

Replacing a joint removes the arthritis that has developed from overuse or injuries.

“You basically cut out arthritis and replace it with metal and plastic materials of good quality,” Darr says.

Artificial joints today last longer than previous generations, Darr says.

They are made of longer-lasting metal and plastic and mimic the natural motions of hips, knees and shoulders.

Thirty-eight years ago, Ted Ellerbee, of Central, hyperextended both knees when an ash tree he was cutting struck him, popping both legs back. At 32, he was too young for a knee replacement, so he kept working.

As a cabinet maker, truck driver and a hunter and fisherman, he led an active life. But after 17 years, his joints wore out, and Ellerbee depended on a cane.

About a decade ago, Ellerbee heard that artificial joints were lasting much longer. Having both knees replaced changed his life, he says.

“I threw that cane away, and I never looked back,” says Ellerbee, now 70.

Ellerbee’s knees healed better than he expected. He took on new projects afterward, like building his own boat, a river cruiser the size of a tug boat.

“I never would have been able to do something like that,” he says. “I never would have attempted it.”

In addition to the better, longer-lasting joints, technology has helped improve the surgical process, Darr says. Computers assist surgeons in placing the implant in the ideal location.

“We are limited by our eyesight, what we can perceive,” he says. “With computer-assisted techniques, the accuracy can increase.”

After Dutruch’s hip replacement four years ago, he was able to stand and walk the day of the surgery and felt “100 percent” in two months. As a former respiratory therapist, he knew how advanced joint replacement surgery was, but the speed with which he recovered stunned him.

“I had become so used to the pain that the first time I stood up, the fact it didn’t hurt was amazing,” Dutruch says. “It was absolutely phenomenal.”

Hip- and knee-replacement patients regularly leave the hospital and start moving around the day of the surgery, Darr says.

A few new surgical techniques have made it possible for many patients to resume normal activities within a few weeks or months of operating and stay healthy for a longer time.

Today, Dutruch rarely thinks of his new left hip.

“The one regret I had is that I waited as long as I did,” he says. “Had I known what it would be like to not have the pain and how I could get back to my normal activities of daily living, I would have done it two years before.”